CHALMERS UNIVERSITY OF TECHNOLOGY AND UNIVERSITY OF GÖTEBORG

THE CENTRE FOR MATERIALS SCIENCE

Catalogue of Research Projects

Publication No 1:1993 MC-

The Centre for Materials Science Catalogue of Research Projects Publication No 1:1993

Göteborg, Sweden 1993 Catalogue of Research Projects Publication No 1:1993 ISSN 1104-3539 ISRN CTH-MC-PBS -1 -SE Editor: Associate professor Kent Skarp Published by The Centre for Materials Science Chalmers University of Technology and University of Göteborg

Address: The Centre for Materials Science Chalmers University of Technology S-412 96 Göteborg Sweden Phone:+ 46 31 772 3384 Fax:+ 46 31 77? 3584

Cover illustration: Eric Werner Graphic design: Information Office, Chalmers University of Technology

Printed by Svenskt Tryck Suite 1993 Preface

Materials technology isof vital importance in every area of modern life. Basic scientific research and technological applications go hand in hand and provide mutual stimulation. Economical manufacturing technology, superior device performance, minimized use of raw materials and energy, and diminished environmental impact are key factors constantly providing new challenges for materials research and development. The materials arena is of highly inter- disciplinary character, and many of the most exciting developments lie at the boundaries between traditional disciplines. This was realized at Chalmers University of Technology and University of Gothenburg more than two decades ago and led to the founding of a Centre for Materials Science. The Centre serves as an umbrella for organizations involved in materials research at the two Universities and at certain branch institutes in the Gothenburg region. The general goal of the Centre is to promote materials research among the member organizations as well as to provide a link to industry and to the society at large. Members of the Centre for Materials Science work on most aspects of modern materials research, ranging from single-atom manipulation and theoretical simulations to biomaterials and production engineering. In order to give a presentation of the members and their research, the Centre produces an inventory of materials research projects approximately every four years. The 1993 issue is somewhat more extensive than previous editions, detailing e.g. also scientific equipment and listing work published during the past four years. The aim has been to keep a constant format for the 30 contributions. However, since the Centre has among its members both academic groups and external research institutes, with a different structure and scope than academic groups, there are in some cases slight variations in the organization of the material. As is evident from the list of contents, several members are active in studies of many different classes of materials. The classification of members presented thus gives only an indication of where their major involvement within materials research is found. This booklet, which has a wide distribution among industry, university departments, and local research and governmental organizations, constitutes the first issue of The Centre for Materials Science Publication Se. :es. It is hoped that it will provide ample information on materials research in and around Gothenburg. For more specific information on areas of particular interest to you, please contact the coordinator or the individual researchers named in the text.

Claes-Göran Granqvist Thomas Hjertberg Kent Skarp Chairman (-1993) Chairman (1993-) Coordinator The Centre for Materials Science Organization and Members

Chairman Coordinator Secretary

Chalmers University of Technology and University of Göteborg

School of Physics School of Mechanical and Engineering Physics and Vehicular Engineering Applied State Physics Engineering Metals Condensed Theory Polymeric Materials Electronic Structure of Condensed Matter Production Engineering Experimental Physics Interdisciplinary Materials School of Chemical Engineering Engineering Chemistry Ion and Semiconductor Physics Inorganic Chemistry Materials and Surface Physics Polymer Technology Materials Physics Physical Chemistry Microscopy and Microanalysis Molecular Physics School of Electrical Semiconductor Physics and Heterostructures and Computer Engineering Surface Physics Solid State Electronics

School of Civil Engineering Building materials

The Swedish Institute of Fibre Swedish Ceramic Institute, SCI and Polymer Technology - IFP-PGI - IFP-TEFO Swedish National Testing and Research Institute, SP - Building technology IVF, The Swedish Institute - Chemical Analysis of Production Engineering F isearch - Mechanics - Polymer Technology and Surface Protection/Corrosion

IV Contents Departments and members sorted according to main subject

General materials and surface science Superconductors and nanometer Materials and Surface Physics 2 structures Electronic Structure of Condensed Matter 13 Applied Solid State Physics 174 Thermal Transport Properties of Materials 22 Condensed Matter Theory 196 Interdisciplinary Materials 26 See also Materials Physics Experimental Physics 32 See also Inorganic Chemistry See also Surface Physics Ceramics Materials chemistry Swedish Ceramic Institute, SCI 202 Inorganic Chemistry 46 See also Microscopy and Microanalysis Reaction Dynamics 58 Chemical Analysis - Swedish National Testing and Research Institute, SP 63 Metals Engineering Metals 216 Microscopy and Microanalysis 228 Polymers and fibres Mechanics - Swedish National Testing Materials Physics 70 and Research Institute, SP 240 Polymer Technology 78 Polymeric Materials 87 Polymer Technology and Surface Building materials Protection/Corrosion - Swedish National Building materials 246 Testing and Research Institute, SP 95 Building technology - Swedish National The Swedish Institute of Fibre Testing and Research Institute, SP 257 and Polymer Technology, IFP-TEFO 102 The Swedish Institute of Fibre and Polymer Technology, IFP-PGI 106 Production and materials processing Production Engineering 262 IVF, The Swedish Institute Biomaterials of Production Engineering Research 264 Surface Physics 114

Keywords 268 Clusters and fine particles Molecular Physics 126 Engineering Chemistry 139

Electronic and optoelectronic materials Solid State Electronics 148 Semiconductor Physics and Heterostructures. 157 Liquid Crystals 164 Alphabetical order, see next page. Contents In alphabetical order

Applied Solid State Physics 174

Building materials 246 Building technology - Swedish National Testing and Research Institute, SP 257

Chemical Analysis - Swedish National Testing and Research Institute, SP 63 Condensed Matter Theory 196 Electronic Structure of Condensed Matter 13 Engineering Chemistry 139 Engineering Metals 216 Experimental Physics 32

Inorganic Chemistry 46 Interdisciplinary Materials 26 IVF, The Swedish Institute of Production Engineering Research 264

Keywords 268 Liquid Crystals 164 Materials and Surface Physics 2 Materials Physics 70 Mechanics - Swedish National Testing and Research Institute, SP 240 Microscopy and Microanalysis 228 Molecular Physics 126 Polymer Technology 78 Polymer Technology and Surface Protection/Corrosion - Swedish National Testing and Research Institute, SP 95 Polymeric Materials 87 Production Engineering 262

Reaction Dynamics 58

Semiconductor Physics and Heterostructures. 157 Solid State Electronics 148 Surface Physics 114 Swedish Ceramic Institute, SCI 202 The Swedish Institute of Fibre and Polymer Technology, 1FP-PGI 106 The Swedish Institute of Fibre and Polymer Technology, IFP-TEFO 102 Thermal Transport Properties of Materials 22

VI General materials and surface science

Materials and Surface Physics 2 Electronic Structure of Condensed Matter 13 Thermal Transport Properties of Materials 22 Interdisciplinary Materials 26 Experimental Physics 32

MATERIALS SCIENCE, 199.1 Materials and Surface Physics

Research Summary Address - Theory of Department of Applied Physics - Processes and phenomena at surfaces Chalmers University of Technology - Theory of materials S-412 96 Göteborg, Sweden Phone+46 31 772 3199 The materials- and surface-physics group around Fax+4631 77231 341 Mats Jonson, Bengt Lundqvist, Mats Persson, Robert Shekhter, and Göran Wahnström emphasizes work Staff on fundamental surface physics, with an eye open to Senior Membeis: for applications, theoretical and computational ma- Bengt Lundqvist professor, tekn. dr. terials physics, and mesoscopic physics. Mats Jonson professor, tekn..dr. The surface work is, in particular, focussed on the Mats Persson assoc. prof., docent, tekn.dr. theoretical description of the molecule-surface inter- Robert Shekhter assoc. prof., PhD action, encompassing all aspects on this interaction. Göran Wahnström assoc. prof., docent, tekn.dr. As a prerequisite is a careful characterization of the David Langreth guest professor surface under study, and the interests also include analysis of experimental probes and spectra, and Research associates:» other surface phenomena. Complete descriptions of Shiwu Gao research associate, PhD adsorption, desorption, diffusion, and thin- Bo Hellsing research associate, film growth, and surface reactions are aimed at. The docent,tekn.dr. results may find applications in heterogeneous ca- Li Zhongwen post doc., PhD talysis, energy conversion, and intentionally struc- Davorin Lovric post doc., PhD turing of materials. Alexander Zagoskin post doc., PhD The surface and materials studies share an inter- André Zwartkruis post doc.,PhD est in various potential-energy surfaces and the Graduate Students corresponding electron structures, as well as in Ylva Andersson civ.ing dissipative processes for atomic and molecular mo- Jan-Olof Brånander fil.kand. tion in extended media. Urban Engberg civ.ing. The computational physics uses Monte-Carlo, Christer Engdahl tekn. lie. molecular-dynamics and electron-structure meth- Tony Fonden tekn. lie. ods. Magnus Gisselfält civ.ing. Jonsons, Shekhter's and their collaborator's cur- Anna Grincwajg civ.ing rent interests are in the areas of nanometer structures Peter Hessling civ.ing and mesoscopic systems. The novel nano-technique Tomas Holmquist civ.ing has created a new research field including a strong Thomas Mattson tekn. lie. effort at the submicron laboratory at CTH, and there Stella Papadia tekn. lie. is a close experimental-theoretical collaboration, Johan Strömqvist civ.ing including joint seminars and projects. The activity Thomas Swahn civ.ing on mesoscopic systems covers nanostructures, ultra- Björn von Sydow civ.ing small tunnel junctions, and Coulomb blockade in Uno Yxklinten tekn. lie. one-electron tunneling. Secretary: Erica Värna

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Major Instrumentation electronic spectra of adsorbates. The model has been • Computer facilities: More than twenty modem applied to CO weakly chemisorbed on Cu, where a workstations. good agreement with the experimental XPS spectra has been found. The aim is to calculate the tempera- ture dependence of the XPS spectra of CO on Cu. Lovric and Lundqvist have started a study of Major Fields off Research nanometer-size metal clusters. Recent experiments A: Theoretical Surface and have revealed that the quantum electronic energy Computational Materials Physics states of the nanometer-size metal (gold) clusters participants: Bengt Ltindqvist, Mats Persson, Göran persist upon the deposition of these clusters onto a Wahnström, David Langreth, Shiwu Gao, Bo metallic substrate (tungsten) and that tungsten sin- Hellsing, Li Zhongwen, Davorin Lovric, André gle-atom tips exhibit a localized band structure of the Zwartkruis, Jan-Olof Brånander, Urban Engberg, topmost tip atom. Work in progress deals with Christer Engdahl, Tony Fondén.Thomas Mansson, understanding of these features in the light of the Stella Papadia, Johan Strömqvist, Björn von Sydow, models developed for weakly bound adsorbates. and Uno Yxklinten. References: publications 17,29,55-56,67.

B: Mesoscopic Physics A2: Vlxations at surfaces participants: Mats Jonson, Robert Shekhter, Alexan- K. Burke, David Langreth, Persson and Z. Y. Zhang der Zagoskin, Magnus Gisselfält, Anna Grincwajg, have made a theoretical study of the vibrational Peter Hessling, and Thomas Swahn. contributions to the lineshape of a top bonded ad- sorbate. Dephasingof the adsorbate-substrate stretch modes occurs via anharmonic coupling to lower Research Projects frequency modes. Surprisingly, central forces, which A: Theoretical Surface and are often much larger than bond-bending forces, are Computational Materials Physics found not to contribute to the linewidth. This is due to a cancellation between cubic and quartic terms in Al: Electrons at surfaces the effective coupling to the dephasing modes. This S. Yang, R.A. Bartynski, G. P. Kochanski, Stella cancellation is complete, whenever the probed mode Papadia, Tony Ponden and Mats Persson have dem- has a frequency far above all others in the system, as onstrated the existence of a surface resonance on a for, e.g., H/Si(lll) or the CO stretch in CO on simple metal surface like Al(lll) in an energy metals. For the C-metal stretch in CO on metals the region far from any bulk band gap. In measured cubic term introduces Fermi -resonance effects which scanning-tunneling spectra (STS) a peak is identi- greatly broaden the linewidth and also give rise to fied. Theoretical modelling shows that it derives extra peaks in the absorption spectrum. However, from an electron resonance at the Al surface caused the internal motion of the molecule causes a dramatic by scattering from the bulk lattice. The observed reduction in the magnitude of these effects. One correlation between this peak in the STS and a must look to anharmonic terms in the non-central similarfeature in inelastic photoemission (IPE) spec- (bending) interatomic forces to explain the magni- tra shows that the latter feature is also attributed to tude of the experimental dephasing linewidth. this resonance, rather than a matrix element effect. Using molecular dynamics with embedded-atom Shiwu Gao and Bengt Lundqvist have studied the potentials, Y. Beaudet, L. Lewis and Persson have conditions for having a sustained two-dimensional investigated the role of anharmonicities at the (100) electron in surface Rydberg states. The surface surface of Ni. In accord with recent LEED measure- density and lifetime limited by the intra-band Auger ments, an anomalously large thermal expansion of transition are evaluated in a surface band model the surface is observed, with a concomitant rapid calculation. increase of the mean-square amplitudes of vibration, For temperature effects in the electronic spectra and an extraordinary attenuation of the LEED of adsorbates Davorin Lovric has developed a model intensities. These anomalies appear at a temperature for calculating the substrate screening effects in the of about 900 K, well below the onset of disordering.

MATERIALS SCIENCE, 1993 MATERIALS AND SURFACE PHYSICS

There is no evidence of anomalous softening of the A puzzling observation by S. Andersson is the surface phonons. The results suggest that the ob- anomalous isotope dependence for sticking of H2 served anharmonic behaviour results solely from and D2 molecules on Cu surfaces. In a multi-phonon enhanced vibrational motion. theory for sticking Persson and Lovric arc piesently References: publications 25-27. invesrJgajng if this anomalous isotope effect is present already for the energy transfer to a single A3: Primary surface processes oscillator. André Zwartkruis and Fonden study Auger electron ByD2 nozzle beamexperimentson coldCu(l 11), transfer at simple metal surfaces by means of two Cu(100) and Cu(110) surfaces S. Andersson and different models. In one model Auger rates and Persson have demonstrated that the substrate surface spectra are calculated using metal orbitals from a structure profoundly influences the sticking and planar ieilium surface, and in the other one metal trapping of particles in the physisorption well. crbiials are calculated in a self-consistent potential Comparision between theoretical calculations and for a simplified geometry. In the first-mentioned measured data reveal that this is caused by structure model results for the total neutralization rate for a specific differences in the particle phonon coupling helium ion outside a surface have been calculated to and the collision processes that control the lateral large distances outside the surface. Energy spectra progagation of particles trapped in quasibound states. for the resulting Auger electrons as well as for the Persson and S. Andersson are presently investigat- created holes in the metal conduction band have been ing the crystal face anisotropy of the physisorption computed. The results show that the neutralization welldepthsforH2 and D2 interacting withthe(l 11), process occurs qualitatively differently in two dis- (100) and (110) surfaces of Cu. The effect seems tance regimes outside the surface. At a distance close related to the differences. to the surface (up to about 10 bohr) electron-electron Gao, Lundqvist and Persson have investigated interactions over long distances seem to be unimpor- the importance of electron-hole pairs in processes on tant. For larger ion-surface separations, long range metal surfaces and proposed a mechanism for the interactions become gradually more important. Ex- recently developed atomic switch. This is an atomic- tensions of the model to other types of atomic scale electronic device, whose operation is control- orbitals including dynamical surface screening are led by the displacement of an Xe atom between a in progress. Ni( 110) surface and a W tip of a scanning-tunneling Gao has also studied hot electron scattering at a microscope. The key ingredient is that the electrons GaAs(l 10) surface, using a model calculation. He participating in the current through the switch excite finds that the bulk-surface scattering is mediated by the Xe atom vibrationaily in a double well, sustained the LO phonon emission in the hot electron gas. by the attraction to both surface and tip, and transfer References: publications 50-52,75. it to the other well. This theory accounts for the observed facts and provides additional, easily test- A4: Dynamics of molecule-surface interactions able, predictions. For instance, Gao , Persson and For atom-surface scattering on a rare-gas overlayer Lundqvist explain the power-law dependence of the on a metal surface multi-phonon effects are particu- Xe transfer rate. The atomic switch thus gives an larly evident, due to the presence of low-energy experimental proof of the electron-hole pair mecha- Einstein modes. Charlotta Hedenäs and Persson nism for the energy transfer in dynamical processes have analyzed the sticking coefficient observed by at metal surfaces. Stig Andersson, using both a simple forced-oscilla- Carl Johan Setterlind has made a quantum-me- tor model and a more elaborate single site multi- chanical calculation of electron-stimulated desorption phonon approximation that is able to handle both the (DIET) of positive ions. He finds that DIET de- strong corrugation and phonon inelasticity of these scribed by the Menzel-Gomer-Redhead process is overlayers. The calculation suggests that the effects influenced by the attractive part of the potential. from the strong surface corrugation for these layers References: publications 20-21,24,28,68. dominate over the effects from the phonon inelastic- ity, in qualitative agreement with experimental ob- servations.

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A5: Surface reactions calculated cross sections are several orders of Persson and Bret Jackson are extending their previ- magnitudes too small, and (ii) that the polarization ous modeling in an restricted geometry of an Eley- experiments show qualitatively different results in Rideal surface reaction for , using time- comparison with the calculations. It is concluded dependent wavepacket calculations by keeping all that the substrate mediated mechanism must be of degrees of freedom of the molecule, but with a flat importance. surface potential. An important byproduct is the Hellsing collaborates with Vladimir P. Zhdanov development of a technique for doing wave-packet on a project considering the substrate mediated propagation in curvilinear coordinates. This task is mechanism ("hotelectrons") forphoto-induced proc- performed in close collaboration with the esses at surfaces. experimentalist C. Rettner and B. Kay. The possibility of "hot precursors" at surfaces, i.e. Bo Hellsing's research activity includes the stud- ballisticly moving hyperthermal adatoms, are im- ies of the photochemistry of O2 chemisorbed on portant for crystal growth and surface reactions. Pt(l 11). He has investigated the direct mechanism Recent STM data on dissociative adsorption of O2 for photo-induced desorption and dissociation of t>> on Al(lll) has been interpreted in terms of hot on Pt(l 11). Information about the local density-of- precursors. By performing stochastic trajectory cal- states is obtained from an embedded calcula- culations with realistic atom-surface potentials, tion. From an experimental point of view, different Christer Engdahl and Göran Wahnström have deep- aspects of the cross section has been studied, by ened the analysis and found the "hot-precusor" con- varying (i) photon frequency, (ii) polarization of the cept to have limited applicability for the O atoms on light, and (iii) angle of incidence of the light. In the Al surface. comparision with experiments it is shown (i) that the Engdahl has also continued the stochastic-trajec- tory calculations of (i) dissociative adsorption of Hi on Cu surfaces, further illustrating the importance of taking all degrees of freedom into account, and (ii) of the surface-temper; ture and angular dependence of the sticking coefficient of N2 on Ag surfaces, in order to reveal the orientational anisotropy of the physisorption interaction. References: publications 14,22-23,48-49,58-59, 77.

A6: Energetics of materials Kenneth Holmluiid and Uno Yxklinten have applied the effective-medium theory to the lattice dynamics of the high-Tc material YBaCuO, aiming at com- parisons with Raman-scatteringdata. Yxklinten stud- ies the energetics of various materials with the effective-medium theory (EMT) and other methods. The studied systems include adsorbates interacting with surfaces, e.g., H on Mg and Cl on K, metal- Figure 1. The time evolution of the trajectories with a metal interfaces, and ceramic superconductors certain initial condition for an oxygen atom on an (YBaCuO,...). The so-called one-electron-energy Al(lll) surface. The figure shows the lateral positions correction has been included in the EMT code, and of the oxygen atom for all 64 trajectories at consecu- user friendly interfaces to the computer programs tive times with a time step of 9 fs. The projection on the surface of the oxygen atom positions are marked have been developed. with crosses and the equilibrium surface atom posi- Recent studies of chemisorbed (metastable) oxy- tions are marked with dots. The total time interval gen on surfaces of noble and transition metalsdo not recorded is 0.45 ps and the length scale is given in agree on the role of the d-electrons in molecular Ångströms.

MATERIALS SCIENCF., 1993 MATERIALS AND SURFACE PHYSICS

adsorption. Hellsing, P. Nordlander, and Zwartkruis plan to resolve these and other questions by using the CASTEP computer package in a thin-slab calcula- tion. As a first step Zwartkruis has visited a summe r school entirely devoted to introducing this well written package. In order to calculate binding properties of sys- tems with strongly varying electron densities, e.g., in chemisorption, Zwartkruis is improving and mod- ernizing a Green's function code for cylindrical symmetric problems. One of the objectives for this is to analyse the effective-medium theory by making a detailed comparison with self-consistent computa- tions. interface and superlattice effects for layered me- (2100) tallic materials are being examined by Papadia in two studies. In particular, it was proposed in the CA B CC literature in a simplified model (with unrealistic parameters) that Friedel oscillations would give rise to oscillations in interface excess energy with layer thickness. Papadia and Zwankruis have performed self-consistent jellium calculations in a sandwich geometry with varying sandwich thickness and den- sity which reveal oscillating interface excess ener- gies of significant magnitude in these, more realistic, potentials. In a microscopic calculation employing thefull-potential linearmuffin-tin orbital (FP-LMTO) scheme, Papadia, K. Karlsson, P.O. Nilsson and T. Jarlborg has studied the change in elastic constants with superlattice period for Mo/V layers. The trends are compared to continuum-model predictions and discussed in the context of the so called supermodulus effect in metallic superlattices. References: publications 46-47,66,69,96.

A7: Computational materials theory Figure 2. (a) Potentiatenergy contours perpendicular During 1992 Thomas Mattsson has, together with to the surface (energy step 0.1 eV) for a single hydro- Wahnström, continued the work on quantum diffu- gen atom on a rigid Mg(0001) surface, (b) Potential- sion with application to hydrogen diffusion on a energy contours (energy step 0.1 eV) for a single hydrogen atom in subsurface positions in a plane nickel surface. The numerical method is based on the perpendicular to the Mg(000l) surface. Feynman path-integral formulation. At low tem- peratures this path integral is dominated by the so- called instanton solution. This occurs, when there is a transition from an essentially classical diffusion to a quantum-mechanical one. Wahnström has performed extensive molecular- dynamics calculations on the dynamics of a two- component atomic system. Two components are used to avoid crystal formation. The aim has been to

THE CENTRE FOR MATERIALS AND SURFACE PHYSICS test theoretical predictions and to make clear the B: Mesoscoplc Physics microscopic mechanism for relaxation processes on the timescale of nanoseconds. Bl: Uttrasrnall tunnel junctions Together with L. Lewis, Montreal, Wahnström New lithographic techniques and other technologi- has studied a more complicated molecular system cal progress have made possible the study of electron aimed to describe o-terphenyl, one of the most tunneling into ultrasmall conductors, into small clus- studied . The molecule is treated as a solid ters of atoms, and through very small Josephson body, and the equations of motion arc solved by junctions. The capacitance of these structures, being usinggeneralizedEuler angles, so-calledquatemions. proportional to the area of the tunnel junction, can be Their model gives a surprisingly good agreement made sufficiently small that the Coulomb energy with neutron-scattering data, and a secondary, slow corresponding to a single tunneling electron gives relaxation process is obtained. Studies of time-de- measurable effects. Wellknown charging effects in pendent quantities have revealed that this secondary ultrasmall tunnel junctions are the Coulomb block- process derives from strongly anharmonic motions ade and so called "single electron transistors". Mats of molecules that are trapped temporarily by the Jonson has recently studied the effect of the electro- surrounding molecules. magnetic environment on the Coulomb blockade Wahnström and Yinggang Li have studied hy- and charging effects injunctions driven by a micro- drogen diffusion in Pd at temperatures significantly wave field. In the linear transport regime Jonson and above room temperature, where a classical descrip- Robert Shekhter have for some time been active. tion is expected to apply. To make clear the impor- Results include Coulomb blockade effects in tunnel microtransport, the fundamental resistance tance of including the coupling to electronic quantization in point contacts and adiabatic excitations molecular dynamics has been combined microtransport in a magnetic field. with stochastic simulation. Studies of hydrogen dif- fusion in Nb are now performed in collaboration Magnus Gisselfalt is performing Monte-Carlo with Herbert Dosch, Miinchen. simulations of ultrasmall tunnel junctions coupled to Wahnström has been supervising diploma works transmission lines. A first aim is to study how the on the corresponding questions for hydrogen in bulk conductance of the junction is affected by the mag- metal (Björn von Sydow), on solving the three- nitude of the junction resistance and the impedance dimensional Schrödingerequation in an anharmonic of the electromagnetic environment A transi- potential that has to be determined self-cons stently tion from a Coulomb blockade-state to a conducting (Lennart Bengtsson), on hydrogen-induced recon- state is expected. He is also studying parity-induced structions of a tungsten surface (Anders Nilsson and suppression of the Coulomb blockade of Josephson Zhdanov), and on the sintering problem, i.e., on the tunneling. Software development for the computer growth of particleson surfaces (Per-Erik Skogholm). tool Materialia is also an important activity of his. Urban Engberg, in collaboration with Wahnström References: publications 37,39-40,78. and Yinggang Li, has used the Monte Carlo simulations of hydrogen diffusion in palladium to B2: Transport In constrained systems verify some basic assumptions of Transition State Jonson and coworkers have studied the influence of Theory. a magnetic field on the ballistic electron transport References: publications 4-5,7-13,15,93-94. through single and multiple microconstrictions and the eventual breakdown of quantized conductance A8: Interaction between large molecules and the corresponding crossover to the mesoscopic Jan-Olov Brånander has studied optical properties of regime as the length of a 10 channel is made longer. photosyntetic pigment system: "specially coupling Anna Grincwajg is working on problems related and edge effects. to the crossover from ballistic to diffusive transport References: publications 71-74. in laterally constrained two-dimensional electron systems. Peter Hessling is inverstigaing the transport prop- erties of quantum contacts together with Alexander Zagoskin and Shekhter. The objectives are to derive

MATERIALS SCIENCE, 1993 MATERIALS AND SURFACE PHYSICS the quantum kinetic equation for the carriers inside B5: Noise in hlgh-Tc superconductors the contact and to apply it to the problem of its Shekhter, Zagoskin, and G. Wendin have studied response to external electro-magnetic field, finite oxygen diffusion and dynamical disorder in high-Tc bias, the phonon and impurity scattering etc. superconductors, in particular low-frequency noise Thomas Swahn studies ballistic transport in later- in superconducting tunnel junctions. They show that ally constrained low-dimensional systems. He has the noise is "diffusion-like" and proportional to the been investigating non-ideal point contacts and square of the contact current-vol tageratio. The noise boundary scattering effectsin high mobility AlGaAs magnitude is sharply peaked near the maximal criti- structures. Most recently he has been working on cal temperature achievable for a given type of high- narrow ballistic wires and non-equilibrium proper- temperature superconductor by an optimal oxygen ties of quantum dots. Recent results show fluctua- doping. tions of the current on a new scale corresponding to The screen-oriented computer program a small fraction of the quantum unit of magnetic flux "NoiseScreen" is being constructed by Zagoskin to $0 = h/c. calculate and plot the characteristics of the noise in Zagoskin has performed research in several ar- different superconducting structures and to compare eas: The conductance of topologically nontrivial them with the experimental data. The first part, (doubly-connected) two-dimensional quantum con- describing low-frequency noise in a tunnel junction tacts in the magnetic field of a thin solenoid has been made of a high-temperature superconductor, based discussed. It is shown that ther? are two typesof these on the predictions of the theory developed by contacts, planar and cylindrical ones, with qualita- Shekhter, Zagoskin and G. Wendin, is in operation. tively different conductance dependence on the The second part of "NoiseScreen" is being made to magnetic flux. In the second case the magnitude of include Voss-Clarke theory of the low-frequency the conductance oscil'.ations equals 2e2/h and is noise superconductors. independent of the details of the system's geometry. References: publication 81. References: publications 30-33. 38, 82,87-88,95.

B3: Persistent current in a mesoscopic ring Publications Dror Lubin has studied the persistent current in a normal mesoscopic ring or cylinder, induced by a Ph.D. Dissertations time-dependent Aharonov-Bohm magnetic flux. The Gunnar Russbcrg, May 31,1989. Thesis: CATs, SETs and characteristic behaviour of the current is explained Maps. Modelling and Dynamics of Selected Nonlinear as a manifestation of localization in energy space. Systems. References: publication 76. Aarc Mällo, September 28,1990. Thesis: Modelling of interactions in metals. B4: Heavy fermiorts The non-linear temperature dependence of the Hall Björn Rudbcrg, February 1,1991. Thesis: Electron constant in heavy-fermion compounds has been tunneling in semiconductor structures - Scattering and explained by Zagoskin on the basis of the self- polarization effects. consistent temperature shift of the chemical poten- Charlotta Hcdcnäs, May 10,1991. Thesis: Wavcpackct tial, within the two-band hybridization model, with- calculations of scattering from surfaces. out explicit reference to any magnetic (Kondo) interaction. Licentiate Dissertations For certain heavy-fermion compounds Zagoskin Björn Rudbcrg, May 31,1989. Thesis: Scattering Mecha- has analyzed the dependence of therresistivity on the nisms in Resonant Tunneling. pressure and magnetic field over a wide temperature Charlotta Hcdcnäs, June 9 1989. Thesis: Panicle Scattering range. The experimental data are well explained by Against Rigid and Vibrating Surfaces - Quantum a free-electron two-band- hybridization model, pro- Mechanical Wavcpackct Propagation with Fast Fourier vided that a self-consistent calculation of the chemi- Transforms. cal potential is made. References: publications 89-92.

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Uno Yxklinlen, November 30,1990. Thesis: Total-energy 7. "A molecular dynamics study of a supercooled two- calculations with the effective-medium theory. component Lcnnard-Jones system", G. Wahnstrom, Phys. Rev. A 44,3752,1991. Stella Papadia, May 15,1991. Thesis: Electronic effects at metallic surfaces and interfaces: image slate formation 8. "Nonadiabauc effects in hydrogen diffusion in metals", and charge redistribution. Y. Li, and G. Wahnstrom, Phys. Rev. Lett. 68,3444, 1992. Christer Engdahl, May 15,1991. Thesis: Studies of dynamics of molecules on metal surfaces - trapping 9. "Relaxation of molecular at intermediate times", and dissociative adsorption. L J. Lewis, and G. Wahnstrom, Institute Report 92-25.

Kenneth Holmlund, March 24,1992. Thesis: High Tem- 10. "Molecular dynamics simulation of hydrogen diffusion perature Superconductors - Structure and Lattice in palladium", Y. Li, and G. Wahnstrom, Phys. Rev. B Dynamics of YBa2Cu3O7. , in press.

Carl Johan Setterlind, June 9,1992. Thesis: Desorption 11. "H motion in Pd and Nb: a molecular-dynamics study", Induced by Electronic Transitions - A Study with Y. Li, and G. Wahnstrom, in Materials Theory and Quantum Mechanical Wavepackct Propagation. Modeling, eds. P. Bristowc, J. Broughton, and J. M. Ncwsam, in press. Jan-Olov Brånander, June 10,1992. Thesis: Absorption and Adsorption Aspects in Photosynthesis and 12. "Numerical calculations for hydrogen in metals using Biocompatibility. quantum mechanical methods", B. von Sydow, Applied Physics Report 92-12. Thomas Mattsson, March 19,1993. Thesis: Transition state theory from path-integrals, applications to hydrogen 13. "Some tests of basic assumptions in transition state diffusion on Ni{100) theory for hydrogen diffusion in metals", U. Engbcrg, Y. Li, and G. Wahnstrom, J. Phys.: Condens. Matter, Diploma Work to be submitted. Björn von Sydow, November, 1992. Thesis: Numerical calculations for hydrogen in metals using quantum- 14. "The question about transient mobility in dissociative mechanical methods. chemisorption of O2 on Al(l 11)", C. Engdahl, and G. Wahnstrom, Surf. Sci., to be submitted. Reports and articles 15. "Diffusion of hydrogen in palladium and niobium", G. 1. "Rate Equations, Rate Constants and Surface Diffu- Wahnstrom, and Y. Li, invited review to Mod. Phys. sion", G. Wahnstrom, in Interaction of Atoms and Lett. B , in preparation. Molecules with Solid Surfaces, Eds. V. Bortolani, N.H. March, and M.P. Tosi, (Plenum, New York, 1990). 16. "Mean Free Path of Trapped Physisorbcd Hydrogen Molecule", M. Persson, L. Wilzén.and S. Andersson, Phys, Rev. B 41,5331,1990. 2. "Hydrogen motion on a rigid Cu surface: The calcula- tion of the site to site hopping rate by using flux-flux correlation functions", K. Haug, G. Wahnstrom, and H. 17. "Electron Rcsonaccs on Free-electron like Metals", S. Mctiu.J.Chcm.Phys. 92,2083(1990). Papadia, M. Persson, and L.-A. Salmi, Phys. Rev. B 41,10237,1990. 3. "Hydrogen Diffusion on Metal Surfaces - Nonadiabatic 18. "Vibrational Lineshapcs at Surfaces", D. Langrcth, and Effects", G. Wahnstrom, in Many-Atom Interactions in , eds. R.M. Nicmincn, M.J. Puska, and M.J. M. Persson, Phys. Rev. B 43,1353,1991. Mannincn (Springer-Vcrlag, Berlin, 1990). 19. "Anisotropy of the Physisorption Interaction between H2 and Metal Surfaces", S. Andersson, L. Wilzén, and 4. "Dynamic anomalies in a supercooled liquid: A M. Persson, Phys. Rev B 43,7003,1991. molecular dynamics study", G. Wahnstrom, Physica Scripta 44,166,1991. 20. "Possible electronic mechanism behind nanotribology of rare-gas monolaycr", M. Persson, Solid State 5. "Dynamic susceptibility in a supercooled liquid: A Commun. 80,917, 1991. molecular dynamics study", G. Wahnslröm, J. Non- Crystalline Solids , 131-133,109,1991. 21. "Inelastic scattering and sticking of hydrogen mol- ecules at adsorbed rare gas overlaycrs", CM. Hcdcnäs, 6. "Dynamics and statistics of surface diffusion at finite and M. Persson, Phys. Rev B 45,11273, 1992. coverages", G. Wahnstrom, and V.P. Zhdanov, Surf. Sci. 247,74,1991.

MATERIALS SCIENCE, 1993 MATERIALS AND SURFACE PHYSICS

22. "A quantum mechanical study of recombinative 35. "Interface roughness and asymmetry current-vottagc desorption of atomic hydrogen on a metal surface", B. characteristics in resonant tunneling", B.G.R. Rudbcrg, Jackson, and M. Persson, J. Chem. Phys. 96,2378, Semicond. Sci. Technol. 5,600,1990. 1992. 36. "Optical phonons in resonant tunneling", B.G.R. 23. "Vibrational excitation in recombinative desorption of Rudberg, Semicond. Sci. Technol. 5,328,1990. hydrogen on metal surfaces: Eley-Rideal mechanism", B. Jackson, and M. Persson, Surf. Sci. 269/270,195, 37. "Quantum fluctuations and charging effects in small 1992. tunnel junctions", K. Flensberg. and M. Jonson, Phys. Rev. B 43,7586,1991. 24. "Atomic Switch proves importance of electron-hole pare in processes on metal surfaces?", S. Gao, M. 38. "Breakdown of conductance quantization and Persson, and B.I. Lundqvist, Solid State Commun. 84, mesoscopic fluctuations in the quasi-ballistic regime", 271.1992. L.I. Glazman, and M. Jonson, Phys. Rev B 44,3810, 1991. 25. "Vibrational dephasing at surfaces: the role of cubic anharmonicity and Fermi resonances", K. Burke, D. 39. "Tunneling in a self-consistent dynamic image poten- Langketh, M. Persson, and Z.Y. Zhang, Phys. Rev. B, tial", B.G.R. Rudberg, and M. Jonson, Inst. Rep. 90-36. submitted (1992). 40. "Dynamic image potential and traversal time for a 26. "Anharmonic effects at the Ni(100) surface", Y. tunneling electron", B.G.R. Rudbcrg, and M. Jonson, Beaitfet, L. Lewis, and M. Persson, Phys. Rev. B, Phys. Rev B 43,9358,1991. accepted (1992). 41. "Towards a spin polarized effective medium theory", 27. "Anharmonic effects at the (100) and (110) surfaces of U. Engbcrg, Inst. Rep. 90-58, (Diploma work). Ni", Y. Beaudet, L. Lewis, and M. Persson, in Materi- als Theory and Modeling,, eds. P Brisiowc, J. 42. "Quantum mechanical wavepackct calculation of Broughton, and J. M. Newsam, in press. inelastic scattering of neon against Cu(100)", CM. Hedenäs, Inst. Rep. 9049. 28. "Sticking in the physisorplion well: Influence of surface structure", S. Andersson, and M. Persson, Phys. 43. "Electron tunneling through a double barrier with Rev. Lett., accepted (1992). electron-phonon interaction in the mean field approxi- mation - wavepacket simulation", CM. Hedenäs, and 29. "Surface barrier resonances on a simple metal", S. B.G.R. Rudberg, Inst. Rep. 90-50. Yang, R.A. Bartynski, G. Kochanski, S. Papadia, T. Fonden, and M. Persson, Phys. Rev. Lett. 70,849 44. "Theoretical aspects of adsorption", B.I. Lundqvist, in (1993). Physics of solids and : Interactions of atoms and molecules with solid surfaces, eds. V. Bortolani, N.H. 30. "Field-induced adiabalic transport in 2D ballistic March, and M.P. Tosi, Plenum Press (1990), pp.213- systems", L.I. Glazman, and M. Jonson, Phys. Rev. 254. Lett. 64,1186,1990. 45. "Direct determination of transformation coefficients in 31. "Globally adiabatic regime in quantum ballistic Gram-Schmidt, orthonormalization", Z.J. Tian, Inst. transport", L.I. Glazman, and M. Jonson, Phys. Rev. B Rep. 90-57. 41,10686,1990. 46. "Hydrogen- Interaction Energies", U. 32. "Quantum fluctuations and the single-junction Cou- Yxklinten, Z.J. Tian, A. Mällo, C Engdahl, and B.I. lomb blockade", S.M. Girvin, L.I. Glazman, M. Lundqvistjnst. Rep. 90-33. Jonson, D.R. Penn, and M.D. Stiles,Phys. Rev Lett. 64,3183,1990. 47. "Total-Energy Calculations with the Effective-Medium Theory", U. Yxklintcn, Licentiate thesis, 1990. 33. "Tunneling times in quantum mechanical tunneling", M. Jonson, in Quantum Transport in Semiconductors, 48. "Hydrogen dissociation on copper: importance of eds. D. Ferry, and C. Jacoboni, Plenum Press, New dimensionality in calculations of the sticking coeffi- York, (1990). cient", C. Engdahl, and U. Nielsen, J. Chcm. Phys., in print. 34. "Electron-phonon contribution to the thcrmopowcr of metals", M. Jonson, G.D. Mahan, Phys. Rev. B 42, 9350,1990.

10 THE CENTRE FOR MATERIALS AND SURFACE PHYSICS

49. "Multidimensional effects in dissociative 64. ""Up-hill" Diffusion and Hydrogen-Hydrogen Interac- chemisorption: H2 on Cu and Ni surfaces", C. Engdahl, tion in Palladium-Platinum Alloys . A. Mällo, and A. B.I. Lundqvist, U. Nielsen, and J.K. Norskov, Phys. Krozer, J. Less Common Metals 167,305-317,1991. Rev. B, in press. 65. "FEM Calculation of the Elastic H-H Interaction 50. "Computation of the Auger rate for a He+ ion ap- Energy for Hydrogen in Metals", A. Mällo, 168, J. proaching a simple metal surface", T. Fonden, and A. Less Common Mcials 168,361-375,1991. Zwartkruis,Surf. Sci. 269/270,601,1992. 66. "Electronic structure of metallic supcrlattices: Mo/V", 51. "Auger rates and spectra for simple models of He+ in S. Papadia, K. Karlsson, P.O. N .son, and T. Jarlborg, front of a metal surface", A. Zwartkruis, and T. Phys. Rev. B, 45,1857 (1992). Fonden, Surf. Sci., submitted. 67. "Electronic effects at metallic surfaces and interfaces: 52. "Analysis of Auger spectra from a Hc+-ion in front of a image state formation and charge redistribution", S. simple metal surface", T. Fonden, and A. Zwartkruis, Papadia, Licentiate thesis, 1991. Applied Physics Report 92-14. 68. "Desorpuon induced by electronic transitions studied 53. "Coulomb blockade in single tum.el-juncuons: quan- with a timcdcpcndcnt quantum mechanical method", tum mechanical effects of the electromagnetic environ- CJ. Scttcrlind, Surf. Sci. 269/270,175-179,1992. ment", K. Flcnsberg, S.M. Girvin, M. Jonson, M.D. Stiles, and D.R. Penn, Z. Phys. B 85,395,1991. 69. "Calculated chemisorption properties of Magnesium , Z.J. Tian, U. Yxklinten, B.I. Lundqvist, and K.W. 54. "Quantum mechanics of the electromagnetic environ- Jacobsen, Surf. Sci. 258,427-438,1991. ment in the single-junction Coulomb blockade", K. Flensberg, S.M. Girvin, M. Jonson, D.R. Penn, and 70. "Studies of dynamics of molecules on metal surfaces - M.D. Stiles, Physica Scripla T42,189,1992. trapping, and dissociative adsorption", C. Engdahl, Licentiate thesis, 1991. 55. "Auger decay of Surface Rydberg State", S. Gao, and B.I. Lundqvist, Prog. Theor. Phys. Suppl., 106,405, 71. "Optical absorption in pigment aggregates", J.-O. 1991. Brånander, P. Apell, and T. Gillbro, J. Biophysics, (1993), accepted. 56. "Two-dimensional Fermi Liquid in Surface Rydberg Stale; Limits set by Auger Decay", S. Gao, and B.I. 72. "Adsorption of Brownian particles on a solid-liquid Lundqvist, Solid State Commun. 84,147,1992. interface", J.-O. Brånander, last. Rep. 92-26.

57. "Wavepacket Calculations of Scattering from Sur- 73. "Optical absorption of one- and two-dimensional faces", CM. Hedenäs, PhD thesis, 1991. pigment aggregates", J. Hartford, and J.-O. Frånandcr, in preparation. 58. "Molecular Oxygen on Metals", B. Hellsing, and S. Gao, Chem. Phys. Lett. 187,137-142,1991. 74. "Absorption and Adsorption Aspects in Photosynthesis and Biocompatibilily", J.-O. Brånanccr, Licentiate 59. "Chemisorbed molecular oxygen on metals; interaction thesis, 1992. and charge transfer", B. Hellsing, and S. Gao, Inst. Rep. 91-45. 75. "Inelastic Hot Electron Scattering at GaAs(l 10) surface", S. Gao, Solid State Commun., in print. 60. "Effect of intra-atomic Coulomb repulsion on charge transfer in atom-metal surface scattering", B. Hcllsing, 76. "Persistent currents as an indication of localization in and V.P. Zhdanov, Surf. Sci., submitted (1992). energy space", D. Lubin, ITP 92-10.

61. "Kondenserad materias fysik - oväntade upptäckter 77. "The direct mechanism for photoinduccd desorption och nya vägar", M. Jonson, B.I. Lundqvist, and S. and dissociation of O2 on Pl(l 11)", B. Hcllsing, Surf. Lundqvist, Kosmos 1991, p. 109. Sci. 282,216,1993.

62. "Aspects of Molecule-Surface Interactions", B.I. 78. "Parity-induced Suppression of the Coulomb Blockade Lundqvist, Surf. Sci. 242,365,1991. of Josephson Tunneling", K.A. Matveev, L.I. Glazman, M. Jonson, and R. Shekhtcr, Applied Physics Report 63. "Calculation of the Force-Dipole Tensor for Hydrogen 92-5. in Palladium and Platinum", A. Mällo, and U. Yxklinten,Z.Phys.B 83,213-216,1991.

MATERIALS SCIENCE, 1993 11 MATERIALS AND SURFACE PHYSICS

79. "Point-contact of the elcctrcn-phonon 88. "1/f noise and clectron-phonon interaction in point interaction near metal surface and a planar defect", contacts", A.M. Zagoskin, I.O. Kulik, and A.N. Yu.A. Kolesnichcnko, and R.I. Shckhter, Proc. Int. Omelyanchouk, Proc. Int. Conf. on Point-Contact Conf. on Point-Contact Spectroscopy (PCS "91), Fiz. Spectroscopy (PCS '91), Fiz. Nizk. Temp., 18,665, Nizk. Temp. ,18,478,1992. 1992.

80. "Nonlinear effects in the case of transverse electron 89. "A non-Kondo maximum in electric resistivity of some focusing in metals", Yu.A. Kolcsnichenko, and R.I. heavy-fermion compounds and its dependence on Shckhtcr, Proc. Int Conf. on Point-Contact pressure and magnetic fields", A.S. Rozhavsky, I.G. Spectroscopy (PCS '91), Fiz. Nizk. Temp., 18,520, Tuluzov, and A.M. Zagoskin, Proc. Int. Conf. on Point- 1992. Contact Spectroscopy (PCS '91), Fiz. Nizk. Temp., 18, 529,1992. 81. "Oxygen diffusion and dynamical disorder in high-Tc superconductors: low frequency noise in superconduct- 90. "On the temperature dependence of the Hall constant in ing tunnel junctions", R.I. Shekhtcr, A.M. Zagoskin, some heavy-fermion compounds: a qualitative theory", and G.Wendin, To appear in: Proc. World Congress A.M. Zagoskin, and A.S. Rozhavsky, J. Phys. Cond. on , Munich, 1992. Matt. 4,7115,1992.

82. "Nonlinear electrical conductivity of ballistic quantum 91. "Influence of pressure and magnetic field on the contacts", A.M. Zagoskin, JETPLett., 52,436,1990. temperature-dependent resistivity of hcavy-fcrmion systems", A.S. Rozhavsky, A.M. Zagoskin, Yu.G. 83. "On the possibility of the direct observation of the Naidyuk, and I.G. Tuluzov, Phys. Rev. B , submitted difference between cyclic and zero boundary condi- (1992). tions", A.M. Zagoskin, and I.O. Kulik, J. Phys. Cond. Matt. 2,5271,1990. 92. "Magnetic field dependence of cyclotron masses in heavy fcrmion conductors in a two-band hybridization 84. "Transport of local pairs in metallic oxides: calculation model", A.S. Rozhavsky, A.A. Zvyagin, and A.M. of frequency and temperature dependence of conduc- Zagoskin, Physica B, submitted (1992). tivity", R.I. Shckhtcr, G. Wcndin, and I.O. Kulik, Phys. Rev. B 44,10215,1991. 93. "H diffusion on Ni (100), a quantum Monte Carlo simulation", T.R. Mattson, Applied Physics Report 93- 85. "Optical spectroscopy of localized states in metallic 8. oxides", R.I. Shekhtcr, Z. Crljcn, and G. Wcndin, Physica Scripta, submitted (1992). 94. "Transition state theory from path-integrals, application to hydrogen diffusion on Ni (100)", T. Mattson, 86. "Single-electron tunneling into randomly distributed Licentiate thesis, 1993. double-electron states: linear voltage and temperature dependence of the conductance of high-Tc tunnel 95. "Magnetic flux-induced conductance steps in junction", M. Hurd, R.I. Shckhtcr, and G. Wendin, microwires", E.N. Bogacheck, M. Jonson, R.I. Phys. Rev. B , submitted (1992). Shckhtcr, and T. Swahn, Applied Physics Report 92-9.

87. "Quantum interference in double-connected ballistic 96. "High Temperature Superconductors - Structure and contacts", A.M. Zagoskin, Proc. Int. Conf. on Point- Lattice Dynamics of YBa2Cu3C>7", Kenneth Holmlund, Contact Spectroscopy (PCS '91), Fiz. Nizk. Temp., 18, licentiate thesis, 1992. 637,1992.

12 THE CENTRE FOR Electronic Structure of Condensed Matter

Research Summary Staff Photoemission, inverse photoemission and other Senior Members techniques are used to study the electronic structure Lars liver civ.ing. of solid materials, including their surfaces and in- Janusz Kanski docent terfaces. The main tool is angle-resolved photoelec- Per-Olof Nilsson professor tron spectroscopy in the UV range, ARUPS. De- Hans Starnberg docent tailed information is obtained with this method about Graduate Students valence states in the volume, surface states and Hans Brauer fil.kand. resonances, chemical shifts of core levels and more. YousefKhazmi M.Sc. Some surfaces are prepared by cleaving, while oth- Örjan Olsson civ.ing. ers are obtained by epitaxial . For the latter purpose an MBE-system has been connected Secretary to a surface physics analytical chamber. RHEED and Ann-Marie Frykestig LEED can be applied. The whole complex is at- tached to the storage ring for synchrotron light at the MAX-facility in Lund. We should also mention that Major Instrumentation during the period a complete scanning Auger system • Angle-Resolved Photoelectron Spectroscopy. has been installed, enabling us to do mapping and The photoelectron spectroscopy facilities include depth profiling on e.g. the MBE samples. four units. One is an ADES 400 (Vacuum Gen- A central theme in the research activity concerns erators) system, where the radiation is generated surfaces and interfaces of semiconducting systems. by either a discharge lamp (21 -41 e V) or an X-ray By means of dispersion of valence states and core tube (1256 and 1487 eV). A spherical sector level shifts detailed geometric and electronic infor- analyser is movable in the horizontal plane. The mation is obtained. Examples of interest are surface system is further equipped with a band pass reconstructions, surface states and band offsets for photon detector and electron gun for inverse elemental, III-V and II-VI compounds. Another photoemission, LEED, sputtering ion gun, sam- example is the effect on the band structure of inter- ple manipulator with heating, sample introduc- calation in layered materials. tion chamber and gas inlet system. Another sys- The experimental research is supported by com- tem (in-house design) is equipped in much the putational physics. Recently a method for calcula- same way, except that the X-ray source is re- tion of partial, local density of states for realistic placed with a cylindrical mirror energy analyser semiconductor surfaces was developed. for Auger spectroscopy. A third system is con- nected to a McPherson monochromator (7-11 eV) and equipped with facilities for epitaxial Address growth of binary alloys. The fourth system for Department of Physics angle-resolved studies is used at MAX-lab in Chalmers University of Technology Lund (beamline 41). It is equipped with LEED S-41296 Göteborg, Sweden and an MBE system (see below). Phone+46 31 7723312 Fax+46 31 165176 • Scanning Auger Microprobe A UHV scanning Auger microscope (PHI model 590) is used for secondary electron or Auger

MATERIALS SCIENCE, 1993 13 ELECTRONIC STRUCTURE OF CONDENSED MATTER

electron imaging, as well a« point analysis. An B: Electronic structure of Interfaces and argon sputter gun is available for depth profile Overlayers on Semiconductors measurements. The instrument is operated with a Participants: L. liver, J. Kanski, Y. Khazmi, and P.O. primary electron energy up to 10 KeV and has a Nilsson spatial resolution of = 0.3 pm in the lateral Collaborators: C. Håkansson, Lund University, U.O. imaging. A sample handling system enable fast Karlsson, KTH, Stockholm, G. LeLay, CRMC2- loading of specimens into the instrument, but CRNS, Marseille, France, S.P. Svensson, Marietta gives no options for sample treatment except ion Laboratories, Baltimore, USA, bombardment. C: Layered Materials and intercalation Molecular Beam Epitaxy Participants: H. E. Brauer and H. Stamberg At the storage ring for synchrotron light at MAX- Collaborators: L. J. Holleboom, Lund University, lab, Lund an MBE-system and sample transfer H.P. Hughes, University of Cambridge, U.K., system has been connected to the photoemission chamber at beamline 41. The liquid D: Catalytic Oxidation of Semiconductor cooled system contains 5 effusion cells with Surfaces computer controlled shutters and RHEED. A Participants: H. Stamberg special UHV system has been constructed for Collaborators: K. M. Choudhary, University of Notre- sample analysis (e.g. Auger Spectroscopy) and Dame, USA, Z. Hurych, Northern Illinois Univer- used when the MBE system is not on-line the sity, USA, P. Soukiassian, CEA, Saclay, France MAX-ring. E: Implantation Damaged High Resolution X-ray Diffraction. Semiconductors The Philips HRD instrument is a five crystal Participant: J. Kanski diffractometer intended for characterisation of Collaborators: G. Petö, Central Research Institute semiconductor crystals. Ka-radian'on from a 2000 fo: Physics, Budapest, Hungary W Cu tube is collimated by a four crystal mono- chromator before reaching the sample. Using the F: Studies of Unoccupied Ge(440) reflection of the monochromator the Electronic States angular divergence in the beam is 0.0015°. The Participants: L. liver, J. Kanski, P.O. Nilsson, and H. sample is mounted in a computer controlled three Stamberg axis goniometer, with option for x-y translation. Collaborators: V. N. Strocov, International Institute A slit collimated detector is scanned together of Interface Interactions with the goniometer to obtain rocking curves with extremely high angular resolution. Informa- G: Many-body Effects in Solid State tion is obtained about lattice constant, compo- sition and lattice strain in heteroepitaxial Participants: P.O. Nilsson and H. Starnberg overlayers Collaborators: H.P. Hughes, University of Cam- bridge, U.K. and S.P. Svensson, Marietta Laborato- ries, Baltimore, USA Major Fields of Research H: Computational Physics - Electronic A: Electronic structure of Semiconductor Structure of Materials Surfaces Participants: K. Karlsson, Y. Khazmi, and P.O. Participants: L. liver, J. Kanski, Y. Khazmi, P.O. Nilsson Nilsson, and Ö. Olsson Collaborators: O. Gunnarsson and O. Jepsen, Max- Collaborators: C. Håkansson, Lund University and Planck-Institute, Stuttgart, Germany, R.J. Needs, A. U.O. Karlsson, KTH, Stockholm Qteish, and R.W. Godby, Cambridge, U.K., E. Sobczak, Institute of Physics, Warsaw, and T. Jarlborg, University of Geneva

14 THE CENTRE FOR ELECTRONIC STRUCTURE OF CONDENSED MATTER

Research Projects hv (eV) 20

A: Electronic structure of Semiconductor Surfaces Our work within this project has been focused on two subjects: investigations of surface core level shifts and mapping of bulk and surface valence states. Core level photoemission has become a very useful technique for surface characterisation due to its ability to give direct information about the num- ber of inequivalent surface sites and thereby provide useful test of current models of the surface geometry. We have employed this method to studies of com- pound as well as elemental semiconductors. As an example we have investigated the reversible phase transitions on the Ge(100) surface, reflected by different reconstructions in electron diffraction. Our results show that the 2x1 surface reconstruction is connected with formation of asymmetric surface dimers, and that this local dimer configuration is also present at the bw temperature c(4x2) as well as the high temperature lxl phases. Studies of surface and bulk valence band states Figure 1 has largely been motivated by the need of reliable (a). The band structure of CdTe derived from photoemission measurements at normal emission reference data for current and future investigations for a range of photon energies hv. An empirical of heterojunctions and superlattices. The work has LCAO band structure has been fitted to the experi- therefore been concentrated on the [ 100] surfaces of mental data. different semiconductors, e.g. Ge, InP, InAs and (b). Surface states and resonances deduced from AlAs. the angular dependence of photoemission data. References: 26,42,57,58 The surface projected LCAO band structure is shown as a shadowed region. For more details consult references 2 and 28. B: Electronic structure of Interfaces and Overlayers on Semiconductors Bl: Metal-Semiconductor Interfaces Core level photoemission has been widely applied of the predicted magnitude. This means that for studies of metal-semiconductor junctions during photoemission derived Schottky barrier heights on the last decade and much of the present knowledge n-type semiconductors are systematically overesti- about the microscopic development of Schottky mated by - 0.1 eV, while barriers on p-type semi- barriers is based on such data. We have pointed out conductors are correspondingly underestimated. that this approach may introduce errors to the esti- An independent test of the dielectric screening mated barrier heights of ~ 0.1 - 0.2 eV, due to model has been made by applying it to photoemission significant changes in the non-local electrostatic from noble gas adsorbates on semiconductors and on screening. To test these ideas we have performed metals. Good agreement has been found between experiments, in which the metal-semiconductor junc- experimentally observed and model predicted core tion is made on a layered semiconductor system. By level shifts, giving further support to the conclusions varying the thickness of a spaces layer, we have on Schottky barriers. found that effects of non-local screening are indeed References: 27,35,38,47,48.

MATERIALS SCIENCE, 1993 15 ELECTRONIC STRUCTURE OF CONDENSED MATTER

In an attempt to get around the mentioned inher- 3MLInAs:InP(100) ent limitations we have performed photoemission As(3d) experiments on a GaAs/Al As superlattice grown on 8=60° a stepped GaAs substrate. As an effect of the stepped hv=105eV structure and fractional layer MBE deposition, the growth results in a so called tilted superlattice, with the interfaces between the component materials reaching the physical surface. Assuming that the interface pinningmechanismsissignificantlystronger than surface state induced band bending, this confi- guration should be well suited for studies of interface ' ' ' ' I ' ' ' ' I As:InP<100) characteristics, e.g. the valence band offset. From As(3d) our experiments an offset of 0.4 eV was deduced between the valence band maxima of AlAs and GaAs. References: 34,39

C: Layered Materials and Intercalation

22 23 24 The collaboration with Dr. H. P. Hughes, University Kinetic energy (eV) of Cambridge, UK has continued. Ti 3d electronic states of TiS2, induced by intercalated excess Ti, has Figure 2 been studied by angle-resolved phptoemission The As 3d core level in InAs overlayers as obser- ved in photoemission. The lower panel refers to spectroscopy. The character of such states could be an lnP(110) substrate covered with one monolayer conclusively established by evaluation of their dif- of InAs. Two inequivalent As surface positions are ferent behaviour as the temperature was changed. observed demonstrating the formation of asym- An extensive study of the layered material VSe2, metric dimers. The upper panel shows the same for three monolayers InAs. Here an As signal from including thermal effects, led to the successful sepa- "the bulk" is also observed. Further information ration of direct transitions from the indirect spectral can be found in reference 34. component. By applying inverse photoemission spectroscopy (IPES), together with secondary elec- tron emission spectroscopy (SEES) and total current spectroscopy (TCS), we also obtained detailed in- formation about the unoccupied bands of VSe2, and B2: Heterojunctlons studied the enhancement of the secondary electron Due to the inherently limited probing depth in photo- yield induced by surface adsorbates. At MAX-lab electron spectroscopy it is in principle not possible to the intercalation of VSe2 by Cs was studied using use this method for studies of an interface between synchrotron radiation. A drastic transition from three- two semi-infinite media. Still, since the interface dimensional to two-dimensional behaviour was ob- electron structure is believed to be established for served, and this is presently being analysed and very thin overlayers, photoemission has become a compared to band calculation^ by Dr. L. J. Hilleboom very common tool. To test the validity cf this as- at the University of Lund. sumption we have undertaken systematic studies of References: 36,40,41,53,56 thedevelopment of the three-dimensional band struc- ture with increasing semiconductor overlayer thick- ness. From studies of InAs overlayers on InP we have concluded that even for 3 monolayers thick film the overlayer does not exhibit bulk characteris- tics.

16 THE CENTRE FOR ELECTRONIC STRUCTURE OF CONDENSED MATTER

D: Catalytic Oxidation plement to inverse photoemission spectroscopy of Semiconductor Surfaces (IPES) and is highly sensitive to structures normally not seen in IPES. By using a method developed by The studies of alkali-metal promoted oxidation of Dr. V. N. Strocov, International Institute of Interface semiconductor surfaces, in collaboration with North- Interactions, St. Petersburg, Russia it is possible to em Dlinois University, USA has continued. The determine the band structure without the uncertainty linearrelationship between oxide thickness and loga- about perpendicular wavevectors inherent in most rithmic oxygen exposure was found to be a general other techniques. In an initial study of VSe2 the TCS feature of alkali-metal covered surfaces of elemen- method was compared to IPES and secondary elec- tary semiconductors, while a different behaviour tron emission spectroscopy (SEES). The Cu(100) was observed for III-V semiconductors. The cata- surface has been extensively studied, and these data lytic nitridation of III-V semiconductors was also are being analysed. demonstrated, and the bonding of alkali metals at the The theoretical and experimental projects utilis- InP( 110} surface was studied by photoemission ex- ing IPES have continued. Cd(OOOi) was studied tended x-ray absorption fine-structure (PEX AFS) in both experimentally and theoretically and interband a collaboration with Dr. K. M. Choudhary, Univer- transitions, density of state effects and excitations of sity of Nctre-Dame, USA. surface states and resonances were identified. References: 4-11,21-24,52,54,55 References: 16,17,36,4,50

E: Implantation Damaged 6: Many-body Effects Semiconductors in Solid State Spectroscopies

The earlier reported anomalous amorphous state of 61: Temperature Dependence in Photoemission implantation damaged Ge has been subject to con- We have performed systematic investigations of tinued investigations. Gear similarities were found thermal effects as seen in photoemission spectra, between electron diffraction patterns from transmis- using UV-light. These effects, which may be crucial sion electron microscopy on the implanted Ge with in the interpretation of photoemission spectra, in- X-ray diffraction patterns on liquid Ge, supporting clude changes in positions, widths and heights of the idea that the implantation damaged material is spectral peaks, as well as appearance of new spectral significantly more disordered that obtained by eva- features. Of these the height changes usually domi- poration. The question of possible contamination nate, but they show irregular variations, which are stabilisation of the amorphous state has been ad- inconsistent with conventional Debye-Waller theory. dressed via self-implantation in UHV conditions. It A more recent theory suggests that valence-band was then found that the photoemission spectra of spectra are a complicated mixture of direct and such samples were essentially identical to those indirect contributions, of which the former are redu- obtained on Sb implanted ones. ced by Debye-Waller factors, while the latter in- References: 18,19 crease in intensity as the temperature is raised, and furthermore are strongly angle-dependent due to k- space weighting. Our measurements on Cu and F: Studies of Unoccupied States VSe2 surfaces essentially confirm this. In addition to this we have developed a procedure by which direct A project involving studies of unoccupied bands of and indirect contributions successfully can be sepa- metals and semiconductors - using Total Current rated. Our main conclusions so far are: Spectroscopy (TCS) - has been initiated. These - It is possible to enhance direct and indirect con- studies can provide information which is crucial to tributions by making linear combinations of the correct interpretation of photoemission data, and EDC's measured at different temperatures. offers possibilities to test theoretical models of the electronic structure of solids. The method is a com-

MATERIALS SCIENCE, 1993 17 ELECTRONIC STRUCTURE OF CONDENSED MATTER

- The indirect contributions are already at room Chemical shifts in copper oxides with different temperaturecomparable in size to the direct ones, formal valences were calculated. The results could and they are characterised by strong angular be used to get insight into the electronic structure of dependence. In general the indirect components the high Tc-material YBa2Cu306_5. are quite similar to the direct ones, but signifi- The one-step model for inverse photoemission cantly broader than typical direct transitions. was further developed to include the possibility of image state excitation by secondary beams. - The success of the decomposition procedure Photoemission spectra of Cd(OOOl) have been indicates that the temperature dependencies of calculated using a multiple scattering theory, which the direct and indirect components, respectively, among other thongs identifies surface states and are fairly uniform. resonances. We have also exploited thermal effects in photo- A computer program has been developed to emission in studies of impurity states in "self-inter- calculate the partial and local surface electronic calated" titanium disuJphide, Ti 1+XS2. structure of realistic semiconductorsurfaces, includ- References: 3,40,53,56 ing reconstructions and overlayers. References: 20,43-46,49,50. 62: Vale Auger Spectra fn nteonductc The L.WVV Auger spectrum of InP(l 10) has been investigated using synchrotron radiation as the exci- Publications tation source. All observed features could be iden- tified using a one-body theory involving convolu- Ph.D. Dissertations tions of partial, local density of states functions H. Qu, "Studies of the Electronic Structure of Some Clean a-d obtained from a band calculation and atomic transi- As-covcrcd Semiconductor Surfaces using Angle-Resolved Spectroscopy", 1991 tion probabilities. A quantitatively good agreement with experiment was obtained using an effective K. Karlsson, "Electronic Structure Calculations: Materials with Weak and Strong Correlations", 1992 Coulomb repulsion Ucff = 0.8 eV, which simulates the hole-hole interactions in the valence band. Fur- Diploma Work ther investigations (also considering surface effects) F. Prässlcrand U. Heydcnrcich, "Electron Energy Loss Fine should show whether our results are typical for III- Structure", 1992 V and II-VI semiconductor compounds. Ö. Olsson, "Anglc-rcsolvcd Photoclcctron Spectroscopy of Reference: 33 InSb(100)", 1992 H. Braucr, "Fermi Surface Studies with Angle-Resolved Ultraviolet Photoclcctron Spcctoscopy" H: Computational Physics - Electronic Structure of Materials Reports and articles 1. J.F. Morar, U.O. Karlsson, R.I.G. Uhrbcrg, J.Kanski, Artificial structures, such as semiconductor hetero- P.O. Nilsson, and H. Qu, Angle-resolved photocmission junctions and short-period superlattices, have been study of the As/Gc(100) interface Journal of Applied Surface Sciencc,41/42 (1989) 312 with investigated with respect to the band offset at their interfaces. A method for tuning the offset was 2. H. Qu, P.O. Nilsson, J. Kanski and L. Ilvcr, The Elec- proposed, whereby (n,m) was varied for the inter- tronic structure of CdTc(llO) as studied by anglc-rc- solvcd photocmissionJ'hys.Rcv. B39,5276 (1989) face GaAs/(AlAs)n(GaAs)m. The metallic superlattice Mo/V was studied with emphasis on 3. P.O. Nilsson, L. Ilvcr, H.I. Stamberg, and D. S.-L. Law, hydrogen storage. Anomalous Temperature Dependence in Pholocmission from Cu(l 11), JPhys.: Condcns. Matter 1,6159 (1989) The effect of final state screening on the Schottky barrier height, as deduced from core level shifts, was 4. K M Choudhary, P S Mangat, H1 Stamberg, Z Hurych, DKildayandPSoukiassian, Low-coverage alkali-mctal- investigated by model calculations using dielectric induccd surface structural changes in III-V semiconduc- functions e(q). It was found that such effects could be tors: Pholocmission extended x-ray absorption finc-struc- oftheorderofO.leV. lurc study of the Na/InP(l 10) interface, Phys. Rev. B 39, 759 (1989)

18 THE CENTRE FOR ELECTRONIC STRUCTURE OF CONDENSED MATTER

5. ZDHurych, HI Stamberg and PSoukiassian, Photon- 17. P.O. Nilsson, Direct and Inverse Phoioemission from stimulated desorpiion (PSD) study of H+ ions from clean Metals and Semiconductor Surfaces, Proc. Int. School on and oxygen-covered Cs/Si(100)2xl surfaces, Europhys. Surface Physics. Beijing 20-30 March, 1990, Editors: D- Lett. 8. 567(1989) S Wang and D-H Shen. World Scientific, Singapore, 1990 6. KMChoudhary,PSMangai,DKilday,GMargaritondo, P Soukiassian, HI Stamberg and Z Hurych, Low-cover- 18. G. Peiö, G. Kotai and J. Kanski, Surface regrowth of age metal-induced structural changes in the substrate at implantation damaged Ge(l 11), Vacuum 41,618 (1990) metal/InP(i 10) interfaces determined by phoioemission extended. X-ray absorption fine structure, J. Vac. Sci. 19. G. Peiö, L. Rosta, J. Kanski, A. Ban», E. Menelle and R. Technol.A7,2024(1989) Balissent, Indication ofan anomalous amorphous state of Ge induced by heavy ion implantation, J. Non-crysl Sol. 7. HIStarnberg,PSoukiassianandZHurych,Alkali-meta!- 125,258(1990) promoted oxidation of the Si(100)2xl surface: coverage dependence and nonlocalityJPhys. Rev. B 39, 1277S 20. K. Karlsson, RJ. Needs, A. Qtcish and R.W. Godby, (1989) Tailoring materials for quantum wells: band offsets at (001)-oricntcdGaAs/(AlAs)n(GaAs)minterfaccs,J.Phys.: 8. PSoukiassian, HI Stamberg and T Kcndclcwicz, Insula- Condensed Matter 2,5265 (1990) tor-semiconductor interface formation by electronic pro- motion using alkali metal and removal of the catalyst, 21. Z D Hurych, P Soukiassian and HI Stamberg, "Photon Appl. Surf. Sci. 41/42,395 (1989) stimulateddcsorption(PSD)of positive ions from cesiated semiconductor surfaces using synchrotron radiation", 9. P Soukiassian and H I Stamberg, Alkali metals and Phys.Scr. 41 (1990)935. semiconductor surfaces: Electronic, structural and cata- lytic properties in Alkali adsorption on metals and semi- 22. P Soukiassian, T Kcndelewicz, H I Siamberg, M H conductors .Ed.H.P. Bon/.cl, A. M. BradshawandG. Ertl Bakshi and Z Hurych, Catalytic nitridation of a III-V (Elsevier 1989). semiconductor using alkali metal, Europhys. Lett. 12,87 (1990) 10. HI Starnberg, P Soukiassian, M H Bakshi and Z Hurych, New aspects in the oxidation kinetics of alkali-metal 23. HIStambcrgandPSoukiassian,"Alkali metalpromoted promoted group IV and III-V semi-conductor surfaces. oxidalionof semiconductors: Oxidation kinetics",Vacuum Surf. Sci. 224,13 (1989) 41(1990)678.

11. PSoukiassian and HI Stamberg, Chemisorption of alkali 24. P Soukiassian, H I Stamberg, T Kendelewicz and Z metals on semiconductor surfaces, Vuoto 19,151 (1989) Hurych.Room-tcmperatureniLidau'onof gallium arsenide using alkali metal and molecular nitrogen, Phys. Rev. B 12. H.Qu,J.Kanski,P.O.Nilsson,andU.Karlsson,Valence 42(1990)3769. bands and surface states of CdTc( 110), J. Elcctr. Spectr Related Phenomena 51,149 (1990) 25. J.Kanski,P.ONilsson,U.O.Karlsson,andS.P.Svensson, Electron Structure Studies of the InP(100):As Surface, 13. J. Kanski, H. Qu, P.O. Nilsson, and U. Karlsson, Proc. of 20th Int. Conf. on the Physics of Semiconductors, PhcHoemission studies of the GaAs(100)-4xl surface, J. World Scientific 1990, Editors: E. M. Anastassakis and Electr. Spectr. Related Phenomena 52,133 (1990) J.D. Joannopoulos

14. H. Qu, J. Kanski, P.O. Nilsson, V.O. Karlsson, and J.F. 26. J. Kanski, P.O. Nilsson, U.O. Karlsson.andS.P. Svensson, Morar, Angle-resolved phoiocmission from CdTc(MO) Band mapping of MBE-grown AlAs(100), Solid State andCdo.65Mno.35Tc(110),PhysicaScripta,41,164(1990). Commun. 77,617 (1991)

15. H. Qu, J. Kanski, P.O. Nilsson and U.O. Karlsson, Va- 27. K. Karlsson, O.Nyqvist and J. Kanski, Final-state effects lence bands and surface state of CdTc(llO): A new in phoiocmission from metal-semiconductor interfaces, surface resonance in the GX azimuth, Vacuum 41,610 Phys. Rev. Lett. 67,236 (1991) (1990) 28. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson, 16. H.S.Chauhan,L.Ilvcr, P.O. Nilsson, J. Kanski and U.O. Anglc-rcsolvcd pholocmission studies of the CdTe( 110) Karlsson, The electronic structure of Cd(0001) as studied surface, Phys. Rev. B43,14 589 (1991). by phoiocmission, inverse phoiocmission and computa- tions, Vacuum 41,531 (1990) 29. Surface band structure of ZnTc(llO) studied by phoiocmission, H. Qu, J. K2->ski, P.O. Nilsson, and U.O. Karlsson, Surface Science 251/252,233 (1991)

MATERIALS SCIENCE, 1993 19 ELECTRONIC STRUCTURE OF CONDENSED MATTER

30. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson, 42. G. Le Lay, V. Yu. Aristov, J. Kanski, P.O. Nilsson, U.O Angle-resolved photoclcctron spectroscopy study of the Karlsson, K. Hricovini, and J.E. Bonnet, Electronic prop- surface electronic structure of ZnTc(l 10), Phys. Rev. erties of cleaved (110) and MBE-grown (100) InAs B43,9843 (1991) surfaces, clean and covered with an ultra-thin Ag ad- layer, Hague conf. -92 31. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson, Bulk and surface electronic structure of ZnSe(l 10), Phys. Rev. 43. K. Karlsson, O. Gunnarsson and O. Jepsen, Shape of the B44,1762(1991) Cu 2p core level photocmission spectrum for monova- lent, divalent and trivalcnt Cu compounds, J. Phys.: 32. H. Qu, J. Kanski, P.O. Nilsson, and U.O. Karlsson, Condens. Matter 4,2801 (1992) Surface electronic structure of InP(llO) studied with angle-resolved photoelectron spectroscopy. Surface Sci- 44. K. Karlsson, O. Gunnarsson and O. Jepsen, Chemical ence 225,237 (1991) shifts for monovalent, divalent and trivalcnt Cu com- pounds, LPhys.: Condensed Matter 4,895 (1992) 33. P.O. Nilsson and S.P. Svensson, The Phosphorus Auger L2.3V V Spectrum of InP( 110), Solid State Commun. 79, 45. O. Gunnarsson, K. Karlsson and O. Jepsen, Chemical 191(1991) shifts and core level line shapes for monovalent, divalent and trivalcnt Cu compounds, Particles and Held series 49; 34. J.Kanski,P.O.Nilsson,U.O.Karlsson,andS.P.Svensson, Synchrotron Radiation and Dynamic Phenomena, edited Photoemission study of a thin epitaxial InAs layer on by A. Bcswick (AIP new York, 1992) p. 550 InP(001), Applied Surface Science 56-58,604 (1992) 46. K. Karlsson, O. Gunnarsson, and O. Jepsen, Cu 2p 35. G. Le Lay, J. Kanski, P.O. Nilsson, and U.O. Karlsson, chemical shifts for YBa2Cu3Oö.5: Valence of the Cu Core-level spectroscopy study of the initial formation of atoms, Phys. Rev. B45,7559 (1992) tin-germanium interfaces, Applied Surface Science 56- 58,178 (1992) 47. J. Kanski, K. Karlsson, O. Nyqvist, P.O. Nilsson, U.O. Karlsson, M.C. Håkansson, and S.P. Svensson, Final- 36. H.I. Starnberg, P.O. Nilsson, and H.P. Hughes, Conduc- stateeffects in photocmission from metal-semiconductor tion band structure of VSc2 studied by inverse intcrfaces.Proceedings from the Tenth International Con- photocmission, secondary emission and total current, J. ference on Vacuum Ultraviolet Radiation Physics (VUV Phys.: Condens. Matter 4,4075 (1992) 10), Paris (1992)

37. Y. Khazmi, J. Kanski, P.O. Nilsson, Z. Lin, M.C. 48. K. Karlsson, O. Nyqvist, and J. Kanski, Differences in Håkansson,and U.O. Karlsson, Identification of surface final state effects for adsorbatcs on metal and semicon- states at the CdTc(l 10) surface by means of Cs adsorp- ductor surfaces, J. Vac. Sci. Technol. B10,1335 (1992) tion, Surface Science 269/270,844 (1992) 49. S. Papadia, K. Karlsson, P.O. Nilsson, and T. Jarlborg, 38. J. Kanski, K. Karlsson, P.O. Nilsson, S.P. Svensson, Electronic Struc tureof metallic supcrlatu'ces:Mo/V,Phys. M.C.Häkansson, and U.O. Karlsson, MetaJ-scmiconduc- Rev. B45,1857(1992) lor interfaces: Final-State Effects in Photo-emission, Pro- ceedings from the21st International Conference on Phys- 50. P.O. Nilsson, K. Karlsson, and J. Rundgren, Prediction of ics of Semiconductors, Beijing, 1992 image state excitation by secondary beams in inverse photocmission spectroscopy, Phys.Rcv B15 (1992) 39. Y.Khazmi,L.Ilver,J.Kanski,P.O.Nilsson,U.O.Karlsson, and S. P. Svensson, Photocmission studies of tilted GaAs/ 51. L. liver and P.O. Nilsson, Angle-Resolved UV AIAs superlattices, Proceedings from the 6th Interna- Photocmission from Single Crystals of AgPd Alloys, tional Conference on Supcrlatlices, Microstructurcs and Acta Physica Polonica A 82,723 (1992) Microdevices, Xian. 1992 52. P Soukiassian, T Kcndclcwicz, H I Stamberg and Z 40. H.I. Stamberg and P.O. Nilsson, Thermal effects in angle- Hurych, Rb- and K-promotcd nitridalion of cleaved GaAs resolved photoemission: is it possible to separate direct and InP surfaces at room temperature, Appl. Surf. Sci. 56- and indirect transitions? Surface Science 1992 58,772(1992)

41. H.I.Slamberg,P.O.Nilsson.andH.P.Hughes, Adsorbatc 53. HIStambcrg.PONilssonandHPHughcs.Photocmission induced enhancement of secondary electron emission study of the Ti 3d electron pockets in self-intercalated

from the layered compound VSc2 Surface Science 1992 TiS2, Mat. Sci. Forum 91-93,727 (1992)

20 THE CENTRE FOR ELECTRONIC STRUCTURE OF CONDENSED MATTER

54. HI Starnberg, P Soukiassian and T Kcndclewicz, GaP, 59. M.C. Håkansson.U.O.Karlsson,J.Kanski.P.O.Nilsson, GaAs, and InP nitridation at room temperature by N2 Y. Khazmi, and K. Hricovini, Dimer formation and adsorption on (110) surfaces modified by alkali metals, electronic structure on the Ge(IOO) (2xl):Sb surface, Surf. Sci. 269/270,915 (1992) Surface Science Letters 278, L2131 (1992)

55. HI Stamberg, P Soukiassian, S T Kim, A Papageorgo- 60. E.Sobczak,P.O.Nilsson,andK.Karlsson,Photoemission poulos and S Kapoor, Logarithmic exposure dependence of Cd(0001) using Synchrotron Radiation, Acta Physica in alkali-metal promotedoxidation of elemental semicon- PolonicaA82,337(1992) ductors. Surf. Sci. 269/270,934 (1992) 61. P.O. Nilsson, Photoelectron Spectroscopy by Synchro- 56. H I Stamberg, L liver, P O Nilsson and H P Hughes, tron Radiation, Acta Physica Polonica A 82,201 (1992) Thermal effects in photoemission from VSc2: Separation of direct and indirect contributions, Phys. Rev. B (1992) 62. P.O. Nilsson, Ultraviolet Photoelectron and Inverse Photoemission Spectroscopy, Proceedings 2nd Interna- 57. G. LeLay,J. Kanski, P.O. Nilsson, U.O. Karlsson, and K. tional Seminar on X-ray and Electron Spectroscopy, Hricovini, Surface core level shifts on Gc( 100): c(4x2) to Madralin, Poland, Sept. 4-7,1989, p. 48 Printed by Polish 2x1 and lxl phase transitions, Phys. Rev. B45, 6692 Academy of Sciences 1990. Editors: J. Auleytner andK. (1992) Lawniczak-Jablonska.

58. S.Wiklund,U.O. Karlsson,J.Kanski.andH.Qu,Surface shifts of the Se 3d and the Te 4d core levels of ZnSe( 110) and ZnTe(l 10), Phys. Rev. B, 1992

MATERIALS SCIENCE, 1993 21 Thermal Transport Properties of Materials

Research Summary Address The transport properties that are being studied by the Department of Physics research group include Thermal Conductivity, Ther- Chalmers University of Technology mal Diffusivity and Electrical Resistivity. From S-412 96 Göteborg, Sweden information about the thermal properties it is also Phone+46 31 772 3176 possible toestimate the Specific Heat of the material. Fax +46 31 3177 A wide range of materials have been studied many at the requests from outside research and development laboratories. However, recently our Staff interest has been focused on High Tc materials and Senior Members particularly the behaviour of the Thermal Conduc- Silas Gustafsson docent tivity at and around the transition temperature. Emest Karawacki docent As a complement to the previously developed transient methods (Transient Hot Strip and Pulse Graduate Students Transient Hot Strip) the TPS-(Transient Plane Bashir Suleiman M.Sc. Source)- method has been introduced. It is presently Tomas Hultgren fil.kand. being used for Thermal Conductivity and Thermal Diffusivity measurements from cryogenic tempera- Technical Staff tures up to about 1000 K. It is a convenient tool for Kerstin Gustafsson Ing. routine measurements, which makes it possible for us also to perform measurements at requests from outside research laboratories. The reason for con- Major Instrumentation tacting our group for assistance with measurements • Low Temperature Cryostat (Oxford Instruments) is because there are hardly any laboratories in the • Evaporation Unit (Edward's 306) country where measurements can be routinely per- • TPS-Measuring Units formed over a Thermal Conductivity range from • Specially designed furnace for Thermal Con- 0.02W/mKtolOOW/mK. ductivity measurements up to 1000 K. Recently studies with the Pulse Transient Hot • (One of the TPS-Measuring Units and the Strip (PTHS) method were initiated. The mi:—, furnace are frequently used for measurements strips used in this technique make it possible to study of thermal conductivity of new materials at the insulating layers of thicknesses down to and below requests of outside R & D laboratories) one micrometer. The reason for the growing interest in thin layers is that certain classes of materials are only used in or can only be produced in the form of thin layers. Earlier measurements made in our re- Major Reids of Research search group indicate that the thermal properties of insulating layers produced for instance by vacuum A: Thermal Conductivity (Bulk material) evaporation have thermal properties that are quite Participants: Silas Gustafsson, Ernest Karawacki, different from those of the corresponding bulk ma- Bashir Suleiman, Tomas Hultgren and Kerstin terial. Gustafsson

22 THE CENTRE FOR THERMAL TRANSPORT PROPERTIES OF MATERIALS

Collaborators: Asghari Maqsood (Associate Profes- A2: Thermal Conductivity of Composites sor) and Izhar-ul-Haq (Graduate Student) Depart- Over the last ten years we have had a rather close ment of Physics, Quaid-i-Azam University Islama- collaboration with the research groups at the Physics bad, Pakistan, N S Saxena (Associate Professor) Departments in Islamabad, Pakistan and Jaipur, Department of Physics University of Rajasthan, India, with the support from International Science Jaipur, India. Program in Uppsala. As part of this collaboration a graduate student Izhar-ul-Haq has recently spent B: Transient Methods for Measuring two years in our research group as part of a Ph D Thermal Conductivity sandwich program. In addition longer and shorter Participants: Silas Gustafsson, Ernest Karawacki, exchange visits have been arranged. Bashir Suleiman and Kerstin Gustafsson The measurements on composites in our group has been in support of studies performed for many C. Thermal Conductivity years at these other laboratories. The specific interest of Micrometer Layers in these systems is due to the interest in arranging Participants: Silas Gustafsson and Ernest Karawacki materials with low Thermal Conductivity particu- larly if the material if kept in panels at reduced pressure. Research Projects B: Transient Methods for Measuring Thermal Conductivity A: Thermal Conductivity (Bulk material) Bl: Transient Plane Source Method Al: Thermal Conductivity of Hlgh-Tc Materials In a paper from 1979 we outlined the Transient Hot One Yttrium- and one Erbium-based 1,2,3 High Tc Strip method; and in 1984 we published the first material have been studied within a temperature paper on the Pulse Transient Hot Strip method, range around the transition temperature. Both ther- which in contrast to the THS-method was designed mal conductivity and electrical resistivity have been for the study of insulating micrometer thick layers. measured. In continuation of this work the Transient Plane Studies of these materials have been performed Source (TPS) method was developed and published earlier but only with steady state methods. The in 1991. This method uses plane TPS-elements reason for taking up these studies was the possibility placed between the flat surfaces of two pieces of the to work with much smaller temperature differences sample material under investigation. The transient than in the steady state methods and then see if the measured properties would be influenced by the temperature differences that appear in the sample during the different measuring procedures. The results from the two different methods of measuring the thermal properties agree well. How- ever, there is one rather striking difference. From measurements with steady state methods there are reports on a an increase of the Thermal Conductivity just below the transition temperature of about ten per cent. However, with the Transient Plane Source method we have reported increases between 50 and 100 per cent, which means that we see a very dramatic increase in the transport properties just below Tc. This high thermal conductivity falls off rather quickly as the temperature is further lowered because of boundary scattering or the Casimir effect. "Hot dish".

MATERIALS SCIENCE, 1993 23 THERMAL TRANSPORT PROPERTIES OF MATERIALS recording of a TPS-experiment is limited in time so possible to place sensors anywhere inside a building, that there is no influence on the temperature increase building construction or insulating material with of the TPS-element from the outside boundaries of electrical leads attached and then connected to a the sample pieces. With such an experimental proce- centrally located measuring panel and from there dure it is obvious that the shape of the outside perform measurements and follow variations in the boundaries have no effect on the measurement. Thermal Conductivities at the various locations of This method uses a thin metal foil (incorporated the sensors. Because of limited resources this kind of in the TPS-element) both as heat source and tem- experiment has so far not been possible to arrange. perature sensor in the same way as in the THS- method. However, the conducting pattern is not in B4: Round Robin Measurements the form of a straight strip but can be given a rather and Requests from R & D Laboratories. arbitrary shape. The pattern design of the conducting The research group has participated in two Round material in the TPS-element used by us is mainly that Robin measurements. One series of measurements of a double spiral, which effectively reduces the heat was initiated by Cabannes (France) and Minges flow inside the sensor during a transient recording. (USA) and involved the study of Cecorite 130P, a The sensors are, for room temperature and cryogenic cordierite-based ceramic material provided by work, made of a 0.01 mm thick metal foil sand- Lafarge Company, France, and used for a COD ATA wiched between two sheets (thickness 0.025 mm) of measurement program. The results of these meas- Kapton. The sensors for temperatures above 500 K urements have been summarised in a paper pre- are insulated by sheets of a mica material. The sented at arecent Thermal Conductivity conference. sensors are produced in collaboration with Calesco The other study involved measurements on Foil AB. Corning 9606, a Pyroceram material. This study has Since the TPS-elements are electrically insulated not been summarised yet. it is possible to make measurements on both insula- At the requests of both Swedish and foreign R & tors and electrically conducting materials. D laboratories measurements of Thermal Conduc- The experimental techniques described above tivity have been performed over temperature ranges are presently used at twelve different research labo- up to about 1000 K on a large number of different ratories throughout the world. materials.

B2: Dynamic Plane Source Methods C. Thermal Conductivity The TPS-elements described above have also been of Micrometer Layers used as plane heat sources and temperature sensors in the recently published Dynamic Plane Source Cl: Development of the Pulse Transient Method, which in contrast to the TPS-method uses a Hot Strip Method one dimensional heat flow. In 1987 Aslam Chohan was awarded his Ph D degree These methods are very convenient whenever the from our group and the subject of his thesis was the heat losses from the sample boundaries can be Pulse Transient Hot Strip method. This method uses neglected. By using different parts of the voltage evaporated micro-strips for studies of layers with versus time recordings it is possible to estimate thicknesses down to and below one micrometer. The Conductivity, Diffusivity and Specific Heat inde- approximate dimensions of a typical micro-strip are: pendently. Length 0.5 mm, Width 0.01 mm and Thickness 50 nm. B3: Studies of Building Materials Thermal Conductivity measurements have been In collaboration with groups at "Statens Prov- performed on fused quartz and compared with ningsanstalt" studiesofbuildingmaterialshavebeen vacuum evaporated Silicon Dioxide. Studies have initiated. Since a TPS-element can be placed at a also been made on Gallium Arsenide and Liquid distance from the recording instrumentation (Volt- Crystals. meter, Power Supply, Bridge and PC) used for the Measurements with this method is just being experiments, the TPS-method can in principle be initiated after a recent development of the experi- used for field experiments. It would for instance be mental procedure, which will result in a significant

24 THE CENTRE FOR THERMAL TRANSPORT PROPERTIES OF MATERIALS simplification of the theory, which in the general "Dynamic Plane-Source Technique for Study of the case is rather complex. 1:. J measurements will also Thermal Transport Properties of Solids", E Karawacki and B M Suleiman, High Temp - High Pres 23 (1991) 215. include a renewed study of Liquid Crystals at the request by the group at the Physics "An Extension to the Dynamic Plane Source Technique for Department. Measuring Thermal Conductivity, Thermal Diffusivity, and The micro-strips will be produced with assistance Specific Heat of Dielectric Solids", E Karawacki, B M from the Nano-Meter Facility within the Physics Suleiman, I ul-Haq, and Bui-Thi-Nhi, Rev Sci Instrum 63 (1992)43901. Department. This very important facility will make it possible to produce micro-strips with a precision, "Thermal Conductivity of the Ceramic Cecorite 130P which will greatly improve the reliability of the between 88 and 280 K Measured Using the Transient Plane Thermal Conductivity measurements. Source Technique", Bashir M Suleiman, Izhar-ul-Haq, Ernest Karawacki and Silas E Gustafsson, J Phys D: Appl Phys25(1992)813.

Publications "Thermal Conductivity and Electrical Resistivity of the Y- and Er-substituted 1-2-3 Superconducting Compounds in the Vicinity of the Transition Temperature", B M Suleiman, Diploma Work I Ul-Haq, E Karawacki, A Maqsood and S E Gustafsson. Tomas Hullgren: "Konstruktion av instrument för bestäm- (Submitted for publication). ning av värmekonduktivitet hos fasta anisotropa material. (Fall semester 1991). "The Transient Plane Source Technique: Experimental Design Criteria". Silas E Gustafsson, Bashir Suleiman, Reports and artides Narendra S Saxena and Izhar-ul-Haq, High Temperature- "Temperature Dependence of Thermal Conductivities and High Pressure 23 (1991) 289. Thermal Diffusivities of Composites using Transient Hot- Strip Method", N S Saxena, S E Gustafsson, M A Chohan "Recent Work with and Developments of the PTHS-(Pulse and A Maqsood. Int. Journal of Energy Research 13 (1989) Transient Hot Strip) Technique", Silas E Gustafsson and 411. Ernest Karawacki, (manuscript).

"Anordning för mätning av tcrmiska egenskaper hos en "Simultaneous Measurements of Thermal Conductivity and provsubstai.s", Silas E Gustafsson, Swedish Patent No 461 Thermal Diffusivity of Insulators, Fluids and Conductors 177. American Patent No 5 044 767, Japanese and PCT Using Transient Plane Source (TPS) Technique", A Application No PCT-SE89-OO137. Maqsood, N Amin, M Maqsood, G Shabbir, A Mahmood and Silas E Gustafsson, Int J Energy Research (in press). "Transient Plane Source Techniques for Thermal Conducti- vity and Thermal Diflusivity Measurements of Solid Mate- "Thermal Conductivity and Diffusivity of KH2PO4 and rials". Silas E Gustafsson. Rev Sci Instrum 62 (1991) 797. NH4H2PO4 Polycrystallin Samples in the Neighbourhood of their Transition Temperatures", B M Suleiman, (manu- "Simultaneous Measurement of Thermal Conductivity and script). Thermal Diffusivity of Rock - Marbles Using Transient Plane Source (TPS) Technique", Izhar-ul-Haq, N S Saxena, "Thermal Conductivity and Thermal Diffusivity of a S E Gustafsson and A Maqsood, Heat Recovery Systems & Cordierite-Based Ceramic. Results of a COD ATA mea- CHP11 (1991)249. surement program", F Cabannes and M L Minges, High Temp - High Press 21 (1989) 69. "Thermal Transport in Building Materials", Silas E Gustafsson and Ernest Karawacki, Swedish Council for Communication at the Conference on Phonon Scattering, Building Research. Document D11:1991. Silas E Gustafsson, Cornell University, August 1992.

"Thermal Conductivity and its Temperature Dependence in Selected Steel Samples", N S Saxena, S E Gustafsson and Izhar-ul-Haq, (manuscript).

"Dynamic Plane Source Technique for Simultaneous Determination of Specific Heat, Thermal Conductivity and Thermal Diffusivity of Metallic Samples", E Karawacki and B M Suleiman, Meas Sci Technol 2 (1991) 744.

MATERIALS SCIENCE, 1993 25 Interdisciplinary Materials

Research Summary Staff Senior Members Mlcrostructure, Defects, Impurities, P.M. Fischer docent Atomic Transport M. Friesel tekn.dr The research may be roughly classified as applied A. Loading professor solid and liquid state physics; however with wide H. Odelius Ph.D contact areas and numerous overlaps to other areas U. Södervall tekn.dr of materials science. Particular accent is placed on: Graduate Students atomic binding and mobility in condensed matter, J.H. Wang. dipl. engineer point defects and extended defects; kinetics and L.G. Persson odontlit. distributions of impurities; surfaces and interfaces. Research is pursued on different classes of materials Technical Staff (solid and liquid metals; semiconductors; ceramics; E.U. Engström research engineer glasses; minerals; biological tissues) and aims to R. Sotkovszki technician (part-time) explain electrical, thermal and mechanical proper- Secretary ties of matter in relation to microstructure and H. Hast (part-time) microanalysis. Applications extend into numerous disciplines, ranging from basic solid state physics, physical metallurgy and semiconductor microelec- tronics, over chemical physics, analytical chemistry Major Instrumentation and nuclear engineering, into biomaterials, clinical • Interdisciplinary SIMS, Cameca-Geologie odontology, geo-cosmology and archaeometry. IMS-6F(1992). A significant part of the activities is devoted to • SIMS ion probe-microscope, Cameca IMS-3F/ development of advanced methodology in materials 4F(1983). characterization, especially as based on interactions • Talysurf Profilometer. between energetic ions and matter. The interdiscipli- • Edwards Evaporator. nary rcsearchgroupisresponsiblefortheGothenburg • High pressure experimental plant, 15 kbar - SIMS-Laboratory, with Scandinavia's major heavy 1500 K,Unipress (1991). instrumentation in multidisciplinarilyemployed sec- • Metallurgic anneal furnace equipment. ondary ions mass spectrometry, used as a "national • Specimen preparation equipment: lapping, resource" in materials research. Consequently very polishing, microtome. intensive interaction and collaboration exists with • Several PC computers (HP) other laboratories, at universities and industries in Sweden and abroad. Major Fields of Research A: Microstructure, element kinetics, Address corrosion of metals, ceramics, glasses Department of Physics Participants: U.Engström, A.Lodding, H.Odelius, Chalmers University of Technology O.Odawara, U.Södervall S-41296 Göteborg, Sweden Collaborators: Max Planck Institut fur Metall- Phone+46 31772 3430 forschung, Stuttgart, Germany; Inst. f. Metall- Fax 446 31 772 3436 forschung, Univ. Miinster, Germany, Inst. fiir Metallphysik, Techn. Universität Berlin, Germany;

26 THE CENTRE FOR INTERDISCIPLINARY MATERIALS

Dept. of Materials Sci. & Eng., Univ. of Florida; F: Secondary Ion Mass Spectrometry Savannah River Laboratory, Aiken, SC: Enrico (SIMS); mechanisms and Fermi Institute, Univ. of Chicago; Cameca SA, methodology Courbevoie, France; Laboratory for Superconduc- Participants: U.Engström, A.Lodding, H.Odelius, tors, Physics Dept.,ChalmersUniv. Tech.; Sv. Kärn- U.Södervall. bränslehantering AB, Stockholm. Collaborators: Cameca SA, Courbevoie (France); Dept. of Analytical Chemistry, Univ. of Antwerp, B: Semiconductors; dopants & defects, Belgium; Dept. of Electronic Chemistry, Tokyo Identification & kinetics Inst. of Technology; Dept. of Materials Sci. & Eng. Participants: M. Friesel, A. Loading, H. Odelius, U. Univ. of Florida, Gainesville, FL; Enrico Fermi Inst., Södervall. Univ. of Chicago; AEA Industrial Technology, Collaborators: Dept. of Solid State Electronics, Harwell, UK. Chalmers Univ. Tech.; Dept. of Physics & Measure- ment Technology, Univ. Linköping; Dept. of Solid State Physics, Univ. Lund; Max Planck Inst., Stutt- Research Projects gart, Germany; SiTek AB, Mölndal, Sweden. A: Microstructue, element kinetics, C: Geo-cosmology, Isotope geology corrosion Participants: U. Engström, A. Loading, H. Odelius, Al: Metals & alloys U. Södervall In a continuing project, tracer diffusion and point Collaborators: Dept of Geology, Chalmers Univ. defect studies have been performed on hep a-phases Tech.; Dept. of Marine Geology, Univ. of Göteborg; of Group IV metals in wide temperature ranges. Section of Mineralogy, Museum of Natural History, Secondary ion mass spectrometry is used for evalu- Stockholm. ation. Particular attention is given to isotope effects. Significant conclusions are drawn concerning in- D: Biomineralizations and trinsic as well as short-circuit type diffusion mecha- biocompatlble materials nisms. Participants: P.M Fischer, A.Lodding, H.Odelius Pilot microstructural and microanalytical investi- Collaborators: Biomaterials Group, Dept. of Han- gations have been made on phase kinetics, grain dicap Research, Univ. of Göteborg; Dept of Pedo- boundary phenomena and impurity effects in refrac- and Orthodontics, Univ. of Göteborg; Enrico Fermi tive metal composites, incl. tungsten heavy metals. Institute, Univ. of Chicago; Dept. of Material Continuing investigations are focused on atomic Technica, Univ. of Groningen, Netherlands; Medi- transport properties of liquid metals. Experiments cal & Dental Center, County Hospital, Halmstad, are conducted under gravity-free conditions Sweden; Inst. for Post-Graduate Dental Education, (Spacelab), producing convection-free diffusion data Jönköping, Sweden. of unprecedented accuracy. Measurements in wide temperature intervals are indicative of a cooperative E: Archaeometry, cultural environment; transport mechanism. The energetics of elementary materials characterization atom displacements are further illuminated by the Participants: P.M. Fischer, M.Friesel, A.Lodding, first ever obtained data on the isotope effect of H.Odelius diffusion in liquid metal. Collaborators: Scandinavian Archaeometry Center, Göteborg; Dept. of Musicology, Univ. of Göteborg; A2: Ceramics & glasses Dept of Pedo- and Orthodontics, Univ. of Göteborg. In systematic microstructural-microanalytic studies of high-Tc superconductors and related mixed ox- ides, careful quantitation has been performed for SIMS characterization of numerous oxide phases. Applications have been performed on thin supercon- ducting layers in interaction with production envi-

MATERIALS SCIENCE, 1993 27 INTERDISCIPLINARY MATERIALS p\.ment and substrate material under different con- lanthanide ratios in minerals & rocks; c) isotope ditions of heat treatment. Pilot studies have also been ratios of C and O in marine microfossils; and d) high made of oxygen diffusion and environmental corro- resolution element distribution mappingof phases in sion in oxide superconductors. minerals, incl meteorites. The collaborative project Extensive studies have been made (and are con- of several laboratories, centered onSIMS methodol- tinued) of oxidic glasses, corroded in aqueous envi- ogy, is of interest in petrogenesis, geothermometry, ronment. SIMS in-depth profiling of the concentra- hydrothermal transformations, ocean climatology, tion of up to 40 elements provides the tool to assess marine paleology, and cosmochemistry. the teachability of glasses of nuclear waste interest, and yields important information on the mechanism of corrosion in dependence of glass composition and D: Biomineralizations and leachant environment. Numerous such studies have Mocompatible materials been conducted for extended periods of time in Collaborative research with medical, surgical and laboratory as well as in geological burial environ- odontological groups in Sweden and Holland has ment. directly resulted in, or strongly contributed to, 4 doctoral dissertations during the three most recent years. By means of advanced SIMS, about 40 ele- B: Semiconductors; dopants & defects, ments in tooth and bone are charted 3-dimensionally identification & kinetics in concentrations down to 10 ppm or less. The work The structures and mobilities of dopants and impu- is directed on mineralization problems, with some rities have been investigated in silicon and germa- accent on the clinical role and kinetics of fluorine in nium. Diffusivities have been measured (by SIMS of dental material, as well as the kinetics and toxic stable isotopes) in very wide ranges of temperature effect of leakage elements from contact with (yielding activation energies), hydrostatic pressure biomaterials, such as surgical implants and dental (activation volumes) and diffusant mass (isotope fillings. effects). The concerted approach has yielded exten- Pilot studies have been made on interface mor- sive information on the point defect configurations phology, recovery phases and elemental interactions and energetics, indicating several differential trans- at prosthetic implants in bone. Significant results port mechanisms. While vacancies appear to domi- have been obtained particularly on the leakage of Al nate diffusion in Ge, several impurities in Si are seen and Ti from implant screws and on the topography of to diffuse interstitially and/or by the participation of the restoring tissues. self-interstitials. Pilot studies have been performed on polymer- Pilot studies are also being conducted on bonded base fluoridized filling composites in interaction Si layer structures and on stability in very highly with enamel and dentin; systematic investigaitons, doped Si layers. in-vivo as well as in-vitro, are in progress. The focus of interest is gradually moving to layered ni-V type semiconductor systems, incl dif- fusion effects at delta-layers and the mechanisms of E: Archaeometry, cultural environment; ohmic contacts. materials characterization The archaeological interest has been strongly stimu- lated by the unique potentialities of SIMS in sensi- C: Gee-cosmology, isotope geology tive elemental and structural characterization of Pilot studies have been performed to chart the capa- interdisciplinary materials. Within the program frame bilities of SIMS in mineral dating by Pb isotope of the Scandinavian Archaeometry Centre, the tech- study of zircons. With new and particularly qualified nique has been successfully exploited fordating and SIMS equipment (acquired in 1992), main interest provenance studies of materials from excavations in has been placed on geological effects as manifested Sweden, Greece, Cyprus and Jordan. in relatively light elements and isotopes (H, C, O, In acontinuing collaborative project, aimed at the lanthanides). Present research is focused on a) iso- construction of organ pipes closely reproductive of tope ratios of O and H in silicate minerals; b)

28 THE CENTRE FOR INTERDISCIPLINARY MATERIALS the tonal quality of famous baroque organs of North reproducible use of SIMS. The dependence of sec- Germany and Holland, the chemical, microstructural ondary ion yield, from different matrices, on ion and mechanical properties of Pb-Sn alloys are being energy, mass and other operational parameters has investigated. The studies include ancient organ ma- been charted. Considerable instrumental improve- terial from numerous churches as well as modem ments have been effectuated on existing instrumen- alloys, as-produced and aged. Particular accent is tation and subsequently also implemented on the placed on grain structures, distributions of impuri- latest acquisition; particular progress was reached in ties, and surface effects. Collaboration takes place suppressing the effects of charge build-up in quanti- with expertise in acoustics and musicology. tative SIMS profiling of insulating materials.

F: Secondary Ion Mass Spectrometry (SIMS) Publications

Fl: National resourceI n materials Dissertations characterization Ulf Södervall, "Quantitative Applications of Secondary Ion The SIMS-Laboratory of the Chalmers Univ. of Mass Spccttomctry", December 1991. Technology has for more than a decade been estab- Reports and articles lished as a major facility in materials research con- 1. "Accelerated Leach Tests of SRL-165 HLW Glass in ducted at universities and industries in Sweden and Deionizcd Water", H.Kamizono, D.E.Clark, abroad. Applications take place both in collaborative ALodding, J.NucI.Sci. & Tech. 26,1989, pp 441-448 ventures and in commercial contract work. The number of laboratories/industries involved on aregu- 2. 'Correlation of Laboratory and Stripa Leaching Studies". B.KZoitos, D.E.Clark, A.Lodding, G./G.Wicks, "The lar basis during 1989-92 was about 40. The interna- Scientific Basis for Nuclear Waste Management XII", tional status of the laboratory has brought involve- (Lutzc <& Ewing, Eds.), Mat.Rcs.Soc. 127,1989, pp ment in multinational collaboration and standardisa- 247-256 tion. The laboratory is presently coordinating a program on characterization of elements in soft 3. Effect of Topical F Solutions on Caries-Like Lesions at Root Surfaces, T.Dérand, L.G.Pctcrsson, A.Lodding, biological tissues (particularly Al in brain tissues, in Caries Res. 23,1989, pp 135-140 connection with senile pathology). The CEC-BCR supported project involves the participation of labo- 4. Fluorine Profiles in Human Enamel after In-Vitro ratories in Sweden, UK, Netherlands and Finland. Treatment with Dentifrices of Different Compositions In 1992 the laboratory has entered a stage of and Acidities, L.G.Pctcrsson, A.Lodding, M.Hakcbcrg, G.Koch, Swed.DentJ. 13,1989, pp 177-183 considerably expansive development, qualitatively as well as quantitatively, due to the acquisition of a 5. Analysis of GaP-GaAsP Layered Structures, second SIMS instrumentation, of a hitherto unique U.Södcrvall, M.R.Lcys, A.Lodding, L.Samuclsson, design and with renderings radically superior to Surf.Interf.Analysis 12,1989, pp 555-558 those of earlier types of SIMS. The equipment 6. Secondary Ion Mass Spectrometry of Cape York, (C meca-GéologieIMS-6F with "tailor-rmade" fea- E.U.Engström, Meteorilics 24,1989, pp 100-101 tures) was financed by a grant (ca 8 million SwCr) from FRN and the Wallenberg foundation. It is run 7. SIMS Studies of Teeth; a New Dating Technique?, and organized by the interdisciplinary materials P.M.Fischcr, A.Lodding "High Middle or Low research group under the administrative auspices of Chronology?" Stud. Mcditerr.Archaeol. & Litt. 80, 1989, pp 142-149 a CTH-GU Supervising Committee and a National Reference Group. 8. Diffusion in Liquid Metals under Microgravity, G.Frohbcrg, K.H.Kraatz, H.Wcvcr, A.Lodding, F2: Mechanisms of SIMS; methodology H.Odclius, Defect & Diffusion Forum 66,1989, pp Systematic studies have revealed several mecha- 295-300 nisms inherent in by sputtering, and thus have significantly contributed to quantitative and

MATERIALS SCIENCE, 1993 29 INTERDISCIPLINARY MATERIALS

9. Activation Volumes of Impurity Diffusion in Silicon, 20. Effect of High Pressure on Grain Boundary Diffusion U.Sodervall, A.Lodding, W.Gust, Defect & Diffusion during Dis-Conlinuous Precipitation in Cu-In, Forum 66,1989, pp 415-420 M.Friesel, W.Lpjkowski, W.Gust, B.Prcdcl Dcf. & Diff. Forum 75,1991, pp 229-237 10. Marker Study of Surface Layer Formation and Partial Dissolution, BJCZoitos, R.L.Schultz, D.E.Clark, 21. "Quantitative Applications of Secondary Ion Mass ALodding, "Nuclear Waste Management" (Mellinger, Spectrometry; Solid State Diffusion and Mass Fractio- Ed.), CeramTrans. 9,1990, pp 297-306 nation Study", U.Södervall Tekn.dr. Thesis, CTH, 1991

11. Quantitative Concentration Profiling and Element 22. SIMS Studies of Archaeological Materials, Balance in SRL Glass after 2 Years in W1PP, P.M.Fischer, H.Odelius, A.Lodding Laborativ Arkeol. ALodding, E.U.Engström, D.E.Clark, G.G.Wicks, 5,1991, pp 209-214 Nuclear Waste Management" (Mellinger, Ed.), Ceram.Trans. 9,1990, pp 317-334 23. Surface Analysis of SRS Waste Glass Buried for up to Two Years in Limestone in the UK, G.CNamboodri, 12. Atomic Transport of Trivalent Impurities in Silicon; SL.Mamboodn, G.G.Wicks, A.Lodding, L.L.Hench, Diffusion, Isotope Effects, Activation Volumes, DECIark, R.G.Newton, 'Ceramics in Nuclear & U.Södcrvall, M.Fricscl, A.Lodding J.Chem. Hazardous Waste Management", US Ccr.Soc., SocFaraday Trans. 86(8), 1990, pp 1293-1298 Cincinnau, 1991

13. Quantitative SIMS of Superconducting Oxide Systems, 24. Analysis of SRS Glass Buried in Granite in Sweden E.U.Engsttom, ALodding, O.Odawara "SIMS VII" and Salt in the United Slates, J.P.Williams, G.G.Wicks, (Benninghoven & at. Eds.), Wileys, NY, 1990, pp7O5- D.E.Clark, A.Lodding "Ceramics in Nuclear & 708 Hazardous Waste Management", US Ccr.Soc., Cincinnati, 1991 14. MIIT International In-Situ Testing of Simulated HLW Forms; Analyses of SRL165/TDS Waste Glass and 25. Surface Modification of Aluminosilicaic Metal Systems G.G.Wicks, A.Lodding, P.B.Macedo, Glasses Using Microwave Energy, D.Fathi, I.Ahmed, D.E.Clark, M.A.Molecke "High Level Radioactive J.H.Simmons, D.E.Clark, A.Lodding "Microwaves; Waste Management I", Las Vegas, 1990, pp 443-450 Theory & Application in Materials Processing" Ceram.Trans. 21,1991, pp 623-629 15. Secondary Ion Mass Spectromctry in the Study of Biomineralizations and Biomaterials, A.Lodding, 26. Characterization of Corroded Ceramics by SIMS, P.M.Fischer, H.Odelius, J.G .Norén, L.Synnerby, ALodding Ch. 4 in "Corrosion of Glasses, Ceramics C.B Johansson, J.M.Chabala, R.Levi-Sciti and Ceramic Superconductors" (Clark & Zoitos, Eds.), Analyt.Chim.Acta 241(2), 1990, pp 299-314 Noyes Publ., Park Ridge NJ, 1992, pp 103-121

16. International Round Robin Experiment for SIMS 27. Tissue Reactions in Ti-Al-V-AHoy, C.B Johansson, Quantification, F.G.Riidcnaucr, A.Lodding, T.Albrektsson, P.Thomsen, L.Sennerby, A.Lodding, USödervall & al. Pcriod.Polyiech. (Budapest) 34(1-3), ROdelius, EurJ.MuscoIoskel.Rcs. 5,1992, pp 135- 1990, pp 73-80 236

17. SIMS Applications on Nuclear Waste Form, 28. Isotope Effects of Atomic Transport in Metals, ALodding, D£.CIark, E.U.Engstrom, H.Odelius ALodding, J.NucI.Sci & Eng., 1992, pp 472-477 M.Schumacher, G.G.Wicks. B.K. Zoitos, "Ceramics Today - Tomorrow's Ceramics" (Vincenzini, Ed.), 29. In-Situ Testing of Simulated HLW Forms in Salt Elsevier, Amsterdam, 1991, pp 3121-3129 during 5 Year Burial, G.G.Wicks, A.Lodding, P.B.Macedo, D.E.Clark,, "Scientific Basis for Nuclear 18. High Quality YBCO Thin Films, Laser Deposition, Waste Management XV", 1992 Co-Evaporation, Device Fabrication, J. A. Alarco, G.Brorson, T.C.CIaeson, M.Danerud, E.U.Engström, 30. Long Term Field Leaching Studies of Nuclear Waste Z.G.Ivanov, P.A.NiIsson, H.OIin, D.Winkler Glass in Granite and Salt, R.L.Schukz, D.E.Clark, Phys.Scripta44,1991, pp 95-101 A.Lodding, G.G.Wicks,, "Scientific Basis for Nuclear Waste Management XV", 1992 19. Elemental Concentration Profiles in an Oxidized Silicon Nitride Material, BL.K.L.Falk, E.U.Engström J.Amer.Cer.Soc. 74,1991, pp 2286-2292

30 THE CENTRE FOR INTERDISCIPLINARY MATERIALS

31. Measurements of Isotopic Ratios; Influence of Instru- mental Variables, U.Sodcrvall, A.M.Adrcaens, AIxdding, E.U.Engström, H.Odelius, F.Adams, SIMS VIII" (Benninghoven & Al, Eds.), J.Wiley & Sons, NY, 1992, pp 81-84

32. Elemental Depth Profiling of Nuclear Waste Glasses after Two Years Burial in a Salt Geology, A.Lodding, E.U.Engström, B.ICZoitos, D£.Ciark, JAmer.Cer.Soc. 75,1992, pp 1238-1249

33. Volume Diffusion of Titanium in a-Hafnium Single Crystals., M.Köppers, Chr.Herzig, U.Sodervall, ALodding, DIMENTA, Japan, 1993, in press

34. A Swedish Nuclear Waste Glass after Eight Years of Leaching in the Stripa Mine, L.O.Werme, H.Odelius, A lidding, "In-Situ Testing of Radioactive Waste Forms and Engineered Barriers" (McMenamin, Ed.), CEC-EUR, 1993, in press

35. Leachabilities of International Waste Glasses in WIPP, ALodding, DJa.Clark, G.G.Wicks "In-Situ Testing of Radioactive Waste Forms and Engineered Barriers", (McMenamin, Ed.), CEC-EUR, 1993, in press

MATERIALS SCIENCE, 1993 31 Experimental Physics

Research Summary ductors has been interpreted in terms of conduction Research is conducted on a wide range of materials on fractal structures and fractal time processes. The with interesting optical, electrical and structural prop- experimental studies encompass a broad range of erties. The work iseitheroffundamental character or materials. Recently our dielectric studies have been oriented towards technical applications. extended to water saturated porous materials as well. The research is focused on solid state physics and Dielectric coatings, pigments, and other materi- also includes components of materials science with als are studied with the aim of developing materials emphasis on thin film coating technology. Certain for passive radiative cooling applications. projects embrace (electrochemistry, meteorology The ion transport has been studied in a number of and technology in a broad sense. Many of the projects materials; inorganic salts, polymer electrolytes and are chosen so that they elucidate salient issues related high-temperature superconductors. New high-tem- to energy efficiency and energy production and, at perature protonic conductors have been developed least in some cases, have led to the establishment of and fuel cells for the medium temperature range have new important materials, and new concepts, for been constructed. energy efficient architecture. Industrial aspects and Third World issues are relevant for some of the research. Address Coatings with selective optical properties, ob- Department of Physics tained through microstructural control, have been in Chalmers University of Technology focus for much of the research during the past several S-41296 Göteborg, Sweden years. Thus we have studied heavily doped oxide Phone+46 31 772 3345 semiconductors with spectrally selective transmit- Fax +46 31 3367 tance and established quantitative models for their properties. Coatings with angular-selective trans- mittance have been developed by exploiting special Staff (January 1993) thin film techniques with oblique incidence of the evaporated flux. Senior Members Much attention has been devoted to electro- Claes G Granqvist professor chromic materials and electrochromics-based de- Bengt-Erik Mellander docent vices. The latter work embraces electrochromic ox- Gunnar A Niklasson docent ide coatings with mixed conduction for ions and Anne A Andersson tekn dr electrons, purely ion conducting materials including Andris Azens PhD (Latvia) novel transparent adhesive polymer electrolytes, Bertil Stjerna fil dr and ion-storage coatings with some electronic con- Graduate Students ductivity. New materials with temperature-depend- Ingvar Albinsson civ.ing. ent semiconductor-metal transition have been Zhu Bin M.Sc. (China) investigated with the goal of obtaining coatings with Rafi Gått B.Sc. (Israel) thermochromic switchingaroundroom temperature. Abel Gutarra M.Sc. (Peru) Considerable effort has been devoted to basic Jan Isidorsson civ.ing. studies of disordered materials, with emphasis on Godfrey Mbise M.Sc. (Tanzania) their dielectric response (ac conductivity). A power Bo Nettelblad civ.ing. law behaviour of the ac conductivity of amorphous Torbjörn Nilsson civ.ing. semiconductors and insulators as well as ionic con- Steve Palmer M.Sc. (UK)

32 THE CENTRE FOR EXPERIMENTAL PHYSICS

Technics Staff • Complex impedance analysers, electrometer Sören Nasenius (50%)civ.ing. • High pressure equipment (gaseous pressures Secretaries up to 1 GPa) for electrical and thermal analysis Marita Ahlkvist (20%) measurements. Ingrid Riedl (50%) The equipment can be made available to external users by commercial agreement with CoAT AB, Datavägen 21B, 436 32 Askitn. Contact person: CG. Granqvist, 031-772 33 55. Major Instrumentation • Magnetron sputtering unit for thin film deposi- tion. (Substrates up to 5 x 5 cm2; rf and/or dc sputtering from up to four sources simultane- Major Fields of Research ously; non-reactive or reactive deposition with A: Optical Properties of Strongly Doped Semi- up to three individually regulated g?ses; ar- conductors: Spectrally Selective Thin Films. rangements for work with fluorine-containing Participants: CG. Granqvist, B. Stjerna. ; rotatable substrate fixturing; substrate heating up to 800°C; UHV-compatibility; B: Chromogenics. load-lock for easy and rapid access). Participants: CG. Granqvist, G.A. Niklasson, • Magnetron sputtering unit for thin film deposi- A.M. Andersson, A. Azens, A. Gutarra, 2 tion. (Substrates up to 50 x 50 cm ; rf and/or dc J. Isidorsson, S. Palmer. sputtering from up to two sources simultane- Collaborators: CoAT AB, Askim (Sweden), U. ously; non-reactive or reactive deposition with Guelph (Canada), U. Rome (Italy), U. up to three individually regulated gases; ar- Campinas (Brazil), UNI, Lima (Peru), U. rangements for work with fluorine-containing Rajshahi (Bangladesh) Tsinghua U. (China). gases; rotatable or linearly moving substrate fixturing; substrate heating up to 800°C for C: Electromagnetic Properties of Granular Matter small stationary substrates). and Fractal Structures. • E-beam evaporation unit for thin film deposi- Participants: G.A. Niklasson, CG. Granqvist, tion (up to 2 individually controlled sources; R. Gått, B. Nettelblad. facility for ion bombardment during deposi- Collaborators: ABB Research and Develop- tion; shared facility). ment, Dept. of Building Materials (CTH), • Film thickness monitor (Alfa-step R&D 200). Dept. of Theoretical Physics (CTH), Dept. of • Spectrophotometers for 0.2-2.5 |im wave- Geology (CTH). length with integrating sphere, specular reflect- ance attachments, polarizers. D: Ion Conductors and Materials for Fuel Cells. • Spectrophotometer for 2.5 - 50 )im wave- Participants: B.-E. Mellander, I. Albinsson, length with specular reflectance attachments, Z.Bin polarizers. Collaborators: U.Guelph (Canada), U. Pera- 4 4 • Dielectric spectrometer for 10 - 10 Hz deniya (Sri Lanka), U. del Valle (Colombia), frequency range. Dept. of Phys. and Chem. U. of Uppsala, DSIR • Electrochemical interface. (New Zealand), Oslo U. (Norway), Odense U. • Dry-lab (glove box). (Denmark). • Spectroradiometer (array detector). • Thermal analysis equipment; differential E: Materials and Devices for Radiative Cooling thermal analysis, differential scanning and Irrigation. calorimetry, dilatometer Participants: CG. Granqvist, G.A. Niklasson, • High temperature X-ray diffractometer T. Nilsson.

MATERIALS SCIENCE, 1993 33 EXPERIMENTAL PHYSICS

Research Projects ELECTROCHROMIC A: Optical Properties of Strongly DEVICE Doped Semiconductors: Spectrally Selective Thin Rims. Mi' Thin films of wide-bandgap semiconductors were produced by reactive evaporation and reactive sput- ter technology. Doping, up to several percent, was obtained by codeposition. Extensive studies were carriedoutforIn2O3:Sn,Zn0:Al,Sn0xandSn02(Sb, F), most recently with a focus on the Sn-based films. The materials were characterized by spectro- photometry in 0.2-50 nm wave-length range, elec- trical measurements, Hall effect determinations, Electrochromic device Mössbauer spectrometry, electron microscopy and X-ray diffraction. A consistent theoretical model properties have been formulated. A unique solvent- was formulated. It allowed quantitative calculations free Li+-conducting non-hygroscopic adhesive poly- of the optical properties. mer electrolyte was developed through cooperation With regard to applications, some of th • materials with the University of Guelph, Canad;1: v!ic material in this project give an unsurpassed combination of is based on acopolymerof polymethyl m^iiacrylate high short-wavelength transmittance and high long- and polypropylene glycol and is made ion conduct- wavelength reflectance (and concomitant low ther- ing by the addition of lithium triflate. An ion conduc- mal emittance and electrical resistivity). Hence they tivity as high as ~ 10"4 S/cm was recorded at room are useful as transparent electrodes - for example in temperature. electrochromic devices - as well as for window coatings that transmit solar energy with little emis- B2: Thermochromlc Materials sion of thermal radiation. Thermochromic thin films were studied with a focus on vanadium oxide-based materials. Pure VO2 un- dergoes a reversible metal-insulator transition, with B: Chromogenics an associated abrupt change of the optical properties, at 68°C. This material, as well as WyV^C^ and Bl: Electrochromic Materials and Systems VOxFy with depressed transition temperature, were The systems studied in this project include an prepared by reactive sputtering. Optical and electri- electrochromic layer in contact with an "electrolyte" cal properties were determined. The materials were and an "ion storage" layer. The electrolyte should characterized by electron microscopy and Rutherford have purely ionic conduction, whereas the other two backscattering. Fundamental issues connected with layers should have mixed conduction for ions and metal-insulator transitions, as well as potential win- electrons. The basic similarity to thin film batteries dow-related applications, have been investigated. should be noted. The configuration is placed be- tween transparent and electrically conducting layers suchasIn2O3:Sn(see project A). Among the electro- chromic materials, extensive work has been carried out for the oxides of tungsten, nickel, vanadium and niobium. Work has been begun for oxides of tita- nium and tin. These materials are characterized by spectrophotometry, cyclic voltammetry, impedance spectrometry, electron microscopy, X-ray diffrac- tion, Rutherford backscattering and nuclear reaction analysis. Detailed theoretical models of the optical

34 THE CENTRE FOR EXPERIMENTAL PHYSICS

C: Electromagnetic Properties of at an oblique angle of incidence. The columnar Granular Matter and Fractal microstructure has been characterized by high reso- Structures lution electron microscopy. The optical properties are qualitatively described by the theory for Cl: Optical Properties of MetaHnsulator anisotropic composites referred to above. Another Composites and Inhomogeneous study has concerned the optical properties of thin Metal Films metal network films close to the metal-insulator The dielectric permeability of a composite, with transition. inhomogeneities much less than the wavelength of electromagnetic radiation, can be described by ef- C2: Optical Properties of Materials fective medium theories. We have extended effec- with Large Inhomogeneities tive medium theories to include information on the The optical properties of materials with inhomo- pair and three-point correlation functions of the geneities comparable to or larger than the wave- inhomogeneities. Calculations of the optical proper- length of light can be described by multiple scatter- ties of fractal clusters have been performed. A theo- ing theory. We have shown that the four-flux theory retical framework for optically anisotropic absorb- is a useful and accurate approximation in many ing composites has also been developed. practical situations. An experimental programme on Experiments on metal-insulator composites, gas the optical properties of strongly scattering materials evaporated metal particles and thin metal films with is in progress. The specular and diffuse reflectance as a columnar structure are well described by these well as the direct and diffuse transmittance are being theoretical models. Analyses based on effective measured. We have studied quartz fibres immersed medium theories also has enabled us to shed light on in CCI4, pigmented polymers, water saturated po- the degradation of the absorption in solar collector rous glasses and inhomogeneous biological materi- surfaces, and lifetime predictions have become fea- als. Polymer foils containing inorganic pigments are sible as a result of this work. Retarded oxidation of interest for radiative cooling applications (See kinetics in cermet materials with ultrafine metal project E). particles has been discovered. Thin metal films with a columnar microstructure C3: Electrical Properties of dielectric Materials show angular selectivity of the optical properties and The electrical properties of ir ..ulating coatings were are of potential interest for applications on solar studied both from the basic physics point of view and control windows. Thin films of silver, aluminium because of applications in the field of electrical and chromium have been produced by evaporation insulation. We have measured the ac dielectric re-

ta) PAr» 0.25 Torr (b) PAf« 3 Torr (c) PAr«1O Torr

Gas-evaporated nickel particles. Note the different states of aggregation.

MATERIALS SCIENCE, 1993 35 EXPERIMENTAL PHYSICS sponse in the frequency range KH-107 Hz as well as tion of gas evaporated metal particles. It was found current-voltage characteristics and, in some cases, that aggregates of nonmagnetic particles had a fractal electroluminescence of visible light for a wide range dimension of 1.9-2, while aggregates of ferromagnetic of materials. They include CO-AI2O3 composites, Co particles showed fractal dimensions in the range amorphous AI2O3, SiO2 and SiOxNy coatings, an 1.35-1.6. These results are in qualitative agreement Agl-based composite ionic conductor, and pyroly zed with simulations using cluster-cluster aggregation. polyimide. The commonly observed power law behaviour of the dielectric permittivity has been interpreted in terms of conduction on fractal struc- D. Ion Conductors and Materials tures and fractal time processes. For cases where for Fuel Cells different dielectric response functions can be distin- guished, the Davidson-Cole expression appears to We have studied ion transport in inorganic com- give the best fit to our measurements. The dielectric pounds and polymer systems. A large number of spectroscopy technqiue has also been applied to the materials with high ionic conductivity have been study of electrochromic hydrated nickel oxide films studied. It has e.g. been shown that the increased as well as of ZnO based varistor materials, which are ionic conductivity in two-phase materials can be of interest for protection of electrical equipment related to the grain growth during the phase transi- against transient overvoltages. tion in eutectic or eutectoid systems. Computer simulations as well as experimental determination of C4: Electrical Properties of Porous Matelrais phase diagrams have also been performed. The A study of the ac electrical properties in the fre- transport-structure relation for ion conducting poly- quency range l(H-107 Hz of various cement mor- mers has been investigated by several techniques tars was carried out in collaboration with the Depart- and it has been shown that the ion association is an ment of Building Materials, CTH. Measurements important factor for the ionic conductivity in low were repeated periodically after the preparation of permittivity polymers. We have also determined the the samples. The dependence on water content was further studied by subjecting the samples to heat treatments. Our measurements gave evidence for a (A) percolation threshold at very low water contents. CH3 CH3 CH3 CH3 The frequency dependence of the dielectric response I I II was consistent with the assumption of a fractal pore H3C-Si-O-(-Si-O-)x-(-Si-O-)y-Si-CH3 surface. Structural parameters were extracted from I I adsorption isoterms. CH3 CH3 CH3 Presently the electrical properties of porous sam- ples of glass beads and sand glued together with epoxy are being studied in collaboration with the x = 6, y = 8, N = 7.5 Department jf Geology. The conductivity has been determined as a function of the conductivity of the salt solution introduced into the pores. (B)

C5: Characterization of Fractal Structures We have developed a method for determining the fractal dimension by measurements of the pair cor- relation function of aggregated particles seen in electron micrographs. The influence of projection effects has been modeled in collaboration with the Institute of Theoretical Physics at CTH. Further work on multifractal characterization is under way. One of the ion conducting polymers that have been These methods have been applied to study aggrega- produced is based on the polymer PECVPDMS(A) doped with Li CF3SO3; the anion is shown in (B).

36 THE CENTRE FOR EXPERIMENTAL PHYSICS electrical relaxation of the ion pair and discussed the Publications percolation effects on the ionic conductivity. The oxygen self-diffusion coefficient in RBa2Cu3(>7-5 Ph.D. Dissertations (R=Y, La, Nd,...) high-temperature superconductors A.M. Andersson, "Elcctrochromic Materials: Optical, has been determined using mechanical relaxation Electrophysical and Structural Properties", 1992. measurements of the oxygen hopping in the basal chain layer. The results offers a practical solution to W. Estrada, "Electrochromic dc Sputtered Nickel-oxide- based films: Optical Structural, and Electrochemical the problem of slow oxygen diffusion in single Characterization" (Lima, Peru, 1990; sandwich crystal and bulk materials such as wires and melt- program). textured monolithic bodies. Completely new types of proton conducting solid electrolytes have been K. Khan, "Electrical and Optical Properties of Vanadium developed and fuel cells using these electrolytes Dioxide and Vanadium Oxyfluondc Thermochromic Thin Films, and Their Applications to Energy Efficient have been constructed for use in the temperature Smart Windows" (U. Rajshahi, Bangladesh, 1989; range 500 to 800°G sandwich program).

B. Stjema, "Electrical and Optical Properties of Doped Tin E. Materials and Devices for Radiative Oxide Films", 1992. Cooling and Condensation Irrigation A. TaJIedo, "Vanadium Pcntoxide-bascd Thin Films: Optical, Structural, and Electrophysical Characteri- Passive radiative cooling is possible by infrared zation" (Lima, Peru, 1992; sandwich program). emission towards the clear sky. In earlier work we studied silicon oxynitride coatings, as well as certain Licentiate Dissertations gas layers, for this applica.ion. Presently, solar- A.M. Andersson, "Optical, Electrochemical and Structural reflecting infrared-transparent foil materials are be- Characterization of Elcctrochromic Thin Film Systems Based on Oxides of Nickel, Tungsten and Vanadium", ing developed by exploiting multiple scattering 1990. theory. In a more applied project, we investigate cooling devices for condensation irrigation in arid G. Mbise, "Angular-selective Window Coatings: Some regions. This project is performed in collaboration Theoretical and Experimental Studies" (M.Sc, U. Dar with groups in Africa. So far, up to -0.4 litres of es Salaam, Tanzania, 1989; sandwich program). water has been obtained per night, which is sufficient T. Nilsson, "Optical and Electrical Properties of Some for establishing growing plants. Inhomogeneous Materials Used for Energy Efficient Applications", 1990.

B. Stjema, "Electrical and Optical Properties of Non- stoichiometric Tin Oxide Films", 1990. Diploma Work A. Berg, "Diclcktriska egenskaper hos betong", 1989.

C. Edgrcn, "Värmcblockcrandc glas: Kupéklimaicts påverkan av spcktralselcktiva glas", 1991.

A. Lamm, "Tunna tellurfilmcr på polyeten som konvektionssköld för strålningskylning", 1991.

A. Books, compendia and proceedings volumes 1. CG. Granqvist, Spectrally Selective Surfaces for Heating and Cooling Applications (SPIE Opt. Engr. Press, Bcllingham, 1989), Vol. TT1,120 pages.

MATERIALS SCIENCE, 1993 37 EXPERIMENTAL PHYSICS

2. C.G.Granqvist and CM. Lampert, editors, Optical B. Reviews Materials Technology for Energy Efficiency and Solar 1. CG. Granqvist, Materials for Energy Efficiency and Energy Conversion VIII (SPIE Opt. Engr. Press, Solar Energy Conversion: Some Examples, in Work- Bellingham, USA, 1989), 208 pages. shop on Materials Science and the Physics of Non- conventional Energy Sources, eds. G. Furian, D. 3. CG. Granqvist and CM. Lampert, editors. Optical Nobili, A.M. Sayigh and B.O. Scraphin (World Materials Technology for Energy Efficiency and Solar Scientific, Singapore, 1989), pp. 1-44. Energy Conversion IX (SPIE Opt. Engr. Press, Bellingham, USA, 1990). 318 pages. 2. CG. Granqvist, Energy-Efficient Windows: Options with Present and Forthcoming Technology, in Electric- 4. C.G.Granqvist and G.A. Niklasson, Thin Film ity: Efficient End Use and new Generation Technol- Technology: Compendium for a Course given at ogy, and Their Implications for Electric Utility Plan- Chalmers University of Technolgy (1990), 307 pages. ning and Policy, eds. T.B. Johansson, B. Bodlund and R.H Williams (Lund University Press, Lund, Sweden, 5. CM. Lampert and C.G.Granqvist, editors, Large-area 1989), pp. 89-123. Chromogenics: Materials and Devices for Transmit- tance Control (SPIE Opt Engr. Press, Bcllingham, 3. CG. Granqvist, Kromogena Material i Smarta Fönster: USA, 1990), 606 pages. Möjligheter och Utmaningar (Chromogenic Materials in Smart Windows: Possibilities and Challenges), 6. CG. Granqvist, editor, Materials Science for Solar Byggforskning, November 1989, pp. 30-32; also in Energy Conversion Systems (Pergamon, Oxford, UK, Byggvarunylt 1/1990, pp. 16-18; excerpt in Mckanisten 1991), 203 pages. 1990:1, p. 60.

7. CM. Lampert and C.G.Granqvist, editors, Optical 4. B.-E. Mcllander, Polymer solid electrolytes, in Solid Materials Technology for Energy Efficiency and Solar State Physics-1, eds. M.A.K.L. Dissanayake, R. Attelc Energy Conversion X (SPIE Opt. Engr. Press, and K. Tcnnakone (Nova Science Publishcrs.Inc, New Bellingham, USA, 1991), 298 pages. York, 1989), p. 193-200.

8. A. Sobhan and CG. Granqvist, guest editors, Solar 5. CG. Granqvist, Optical Properties of Granular Materi- Energy Materials and Solar Cells, Vol. 28, No. 2 als: How to Model Coatings for Energy-efficient (1992), pp. 103-193. Windows, in Physical Phenomena in Granular Materi- als, edited by G.D. Cody, T.H. Gcballc and P. Sheng, 9. CG. Granqvist, Electrochromic Oxides: Thin Films MRS Symp. Proc. 195,37-52 (1990). and Devices (Elsevier, Amsterdam, The Netherlands) (to be published). 6. CG. Granqvist, Window Coatings for the Future, Thin Solid Films 193/194,730-741 (1990). 10. CG. Granqvist, A. Hugot-LcGoff and CM. Lampcrt, editors, Optical Materials Technology for Energy 7. CG. Granqvist, Solar Energy Materials: The Role of Efficiency and Solar Energy Conversion XI: Selective Research and Development, in Energy and the Envi- Materials, Reflectors, Concentrators, Transparent ronment into the 1990s, cd. A.A.M. Sayigh (Pergamon, Insulation and Super Windows, Proc. SPIE 1727 (to be Oxford, 1990), Vol. 3, pp. 1465-1475; also in Proc. published). Conf. on Energy and Environment, Riga, Latvia, 13-17 May 1991, pp. 352-362. 11. CG. Granqvist, A. Hugot-LeGoff and CM. Lampert, editors, Optical Materials Technology for Energy 8. CG. Granqvist, Chromogenic Materials for Transmit- Efficiency and Solar Energy Conversion XI: tance Control of Large-area Windows, Crit. Rev. Solid Chromogenics for Smart Windows, Proc. SPIE 1728 State Phys. Mater. Sci. 16,291-308 (1990); also in (to be published). Proc. Workshop on Materials Science arid Physics of Non-conventional Energy Sources (World Scientific, 11 CG. Granqvist, A. Hugot LeGoff and CM. Lampcrt, Singapore, 1991), pp. 143-199. editors, Optical Materials Technology for Energy Efficiency and Soiai Er.?nsy Conversion XI: Photovol- 9. CM. Lampert and CG. Granqvist, Introduction to taics, Photochemistry and Photoclectrochemistry, Proc. Chromogenics, in Large-area Chromogenics: Materials SPIE 1729 (to be published). and Devices for Transinittancc Control, eds. C.M. Lampert and CG. Granqvist (SPIE Opt. Engr. Press, Bcllingham, 1990), pp. 2-19.

38 THE CENTRE FOR EXPERIMENTAL PHYSICS

10. CG. Granqvist, Introduction to Materials Science for 21. CG. Granqvist, Electrochromic Coatings for Smart Solar Energy Conversion Systems, in Materials Windows: A Status Report, in Renewable Energy: Science for Solar Energy Conversion Systems, ed. Technology and the Environment, edited by A.A.M. CG. Granqvist (Pergamon, Oxford, 1991), pp. 1-6. Sayigh (Pergamon, Oxford, 1992), pp. 114-123.

11. CG. Granqvist, Energy-efficient Windows: Options 22. CG. Granqvist, Electrochromic Thin Films, in Optical with Present and Forthcoming Technology, in Materi- Interference Coatings, Optical Society of America als Science for Solar Energy Conversion Systems, ed. Technical Digest Series, Vol. 15, p. OMA 3-1/5 CG. Granqvist (Pergamon, Oxford, 1991), pp. 106-167. (1992).

12. C.G.Granqvist and T.S.Eriksson, Materials for 23. CG. Granqvist, Electrochromics and Smart Windows, Radiative Cooling to Low Temperatures, in Materials Solid State Ionics, to be published. Science for Solar Energy Conversion Systems, ed. CG. Granqvist (Pergamon, Oxford, 1991), pp. 168-203. 24. CG. Granqvist, Principles of Electrochromic Devices, Proc. Ini School of Materials Sci. Tcchnol., to be 13. CG. Granqvist, Materials for Energy-Efficient Win- published. dows: New Coatings with Spectral and Angular Selectivity, Proc. Workshop on Materials Science and 25. CG. Granqvist, Transparent Conductive Electrodes for Physics of Non-conventional Energy Sources (World Elcctrochromic Devices, Proc. Int. School of Materials Scientific, Singapore, 1991), pp. 87-141. Sci. Tcchnol., to be published; also in Appl. Phys., to be published. 14. CG. Granqvist, Semiconductor-based Coatings for Energy Efficiency and Solar Energy Applications, in 26. CG. Granqvist, Eleclrochromic Tungsten-oxide-based Semiconductors and Rare Earth Based Materials, eds. Thin Films: Physics, Chemistry and Technology, in CAJ. Ammcrlaan, F.F. Becker, JJ.M. Frånse, Nguyen Physics of Thin Films, cd. J. Vossen (Academic, San Van Hieu and Than Due Hien (World Scientific, Diego, 1993), to be published. Singapore, 1991), pp. 122-138. 27. G.A. Niklasson, Elektricitet och fraktaler, KOSMOS 15. G.A. Niklasson, Optical Properties of Inhomogeneous 1992: pp. 103-118. Two-phase Materials, in Materials Science for Solar Energy Conversion Systems, edited by CG. Granqvist (Pergamon, Oxford, 1991), pp. 7-43. C. Original Scientific Papers 1. A.M. Andersson, CG. Granqvist and J.R. Stevens, An 16. G.A. Niklasson and CG. Granqvist, Selectively Solar- Electrochromic LixWO3/polymer electrolyte/Li^Os absorbing Surface Coatings: Optical Properties and Device: Towards an All-solid-state Smart Window, Degradation, in Materials Science for Solar Energy Appl. Opt. 28,3295-3302 (1989). Conversion Systems, ed. CG. Granqvist (Pergamon, Oxford, 1991), pp. 70-105. 2. T. Farestam and G.A. Niklasson, Projection Effects in Electron Micrographs of Three-dimensional Fractal 17. B.-E. Mellander, I. Albinsson and J.R. Stevens, Ion Aggregates: Theory and Application to Gas Evapo- transport mechanisms in polymer electrolytes at normal rated Speciments, J. Phys. Cond. Matter. 1,2451-2463 and high pressure, in: Frontiers of High-Pressure (1989). Research, Eds. H.D. Hochhcimer and R.D. Etters (Plenum Press, New York, 1991), p. 17-23. 3. T. Farestam, G.A. Niklasson, A. Torebring, C. Larsson and CG. Granqvist, Fractal Structure of Gas Evapo- 18. CG. Granqvist, Elcctrochromic IR Coatings: Proper- rated Metal Aggregates, Physica A 157,49-52 (1989). ties, Prospects and Problems, Proc. SPIE Vol. CR 39, 156-178(1992). 4. K.A. Khan and CG. Granqvist, Thermochromic Sputter-deposited Vanadium Oxy fluorideCoating s 19. CG. Granqvist, Elcctrochromism and Smart Window with Low Luminous Absorptancc, Appl. Phys. Lett. Design, Solid State Ionics 53-56,479-489 (1992). 55,4-6(1989).

20. CG. Granqvist, Solar Energy Materials: Survey and 5. G. Mbise, G.B. Smith and CG. Granqvist, High Some Examples, in Surface Science: Lectures on Basic Resolution Studies of Columnar Growth in Obliquely Concepts and Applications, Springer Proc. Phys., eds. Deposited Metal Films on Glass, Thin Solid Films 174, F.A. Ponce and M. Cardona (Springer, Berlin, L123-L127(1989). Heidelberg, 1992), Vol. 62, pp. 237-248.

MATERIALS SCIENCE, 1993 39 EXPERIMENTAL PHYSICS

6. G. Mbise, G.B. Smith, G.A. Niklasson and CG. 19. B.-E. Mcllander and C.-A. Sjöblom, Computer aided Granqvist, Angular-Selective Optical Properties of Cr evaluation of the p-T phase diagram of Agl using Films Made by Oblique-angle Evaporation, Appl. thermodynamic data, High Pressure Research, 4,517- Phys. Utt. 54,987-989 (1989). 519(1990).

7. G.A. Niklasson, Applications of Inhomogencous 20. B.-E. Mellander, B. Granéli and J. Roos, Ionic conduc-

Materials: Optical and Electrical Properties, Physica A tivity of single crystal LiNaSO4l Solid State Ionics 40/ 157,482-488(1989). 41,162-164(1990).

8. G.A. Niklason, Comparison of Dielectric Response 21. B. Stjcma and CG. Granqvist, Electrical Conductivity Functions for Conducting Materials, J. Appl. Phys. 66, and Optical Transmittance of Sputter-deposited SnO, 43504359(1989). Thin Films, Solar Energy Mater. 29,225-233 (1990).

9. G A. Niklasson, Effective Medium Theories with Pair 22 B.Stjerna and C.G.Granqvist, Optical and Electrical and Three-Point Correlation Effects, Physica A 157, Properties of SnOx Thin Films made by Reactive RF 364-367(1989). Magnetron Sputtering, Thin Solid Films 193/194,704- 711(1990). 10. G.A. Niklasson, Fractals and the ac Conductivity of Disordered Materials, Physica D 38,260-265 (1989). 23. B. Stjcrna and CG. Granqvist, Transparent Conducting SnO, Films High-rate Reactively Sputtered onto 11. G.A. Niklasson, K. Brantervik and T.S. Eriksson, Polyester Foil, Appl. Opt. 29,447-448 (1990). Dielectric Properties of Disordered Insulators, Physica A 157,520-523 (1989). 24. B. Stjema, CG. Granqvist, A. Scidcl and L. Häggström, Characterization of RF Sputtered SnOx Thin Films by 12. G.A. Niklasson, T.S. Eriksson and K. Brantcrvik, Electron Microscopy, Hall Effect Measurement, and Dielectric Properties of Silicon Oxynitride Films, Appl. Mössbaucr Spcctrometry, J. Appl. Phys. 68,6241-6245 Phys. Lett. 54,965-967 (1989). (1990).

13. S. Passerini, B. Scrosati, A. Gorenstein, A.M. 25. A. Tallcdo, A.M. Andersson and CG. Granqvist, Andersson and CG. Granqvist, An Elcctrochromic Electrochromically Lithiated V2O5 Films: An Opti- Window Based on NiO/(PEO)g LiCIO4/WO3. cally Passive Ion Storage for Transparent Electro- J. Electrochem. Soc. 136,3394-3395 (1989). chromic Devices, J. Mater. Res. 5,1253-1256 (1990).

14. P.A. Svantesson, I. Albinsson and B.-E. Mellandcr, Ion 26. I. Albinsson, B.-E. Mellander and J.R. Slevens, Ionic conducting phases in the poly(propylcnc glycol) - conductivity in polyethylene oxide) modified poly(methyl methacrylaie) - L1CF3SO3 systems, Z. poly(dimelhyl siloxane) complcxcd with lithium salts, Naturforsch.44a, 1231-1233 (1989). Polymer, 32,2712-2715 (1991).

15. P.W.S.K. Bandaranayake and B.-E. Mcllandcr, Phase 27. A. Berg, G.A. Niklasson, K. Brantcrvik, B. Hedberg transitions and ionic conductivity of the Na2SO4- and L.O. Nilsson, Dielectric Properties of Cemen:

MgSO4 system, Solid State Ionics 40/41,31-33 (1990). Mortar as a Function of Water Content, J. Appl. Phys. 71,5897-5903(1991). 16. K. Brantervik, A. Berg, G.A. Niklasson, B. Hedberg and L.O. Nilsson, Percolation Effects in the Electrical 28. K. Brantcrvik and G.A. Niklasson, Circuit Models for Conductivity of Porous Cement Mortar, Europhys. Cement Based Materials Obtained From Impedance Lett. 13,549-554(1990). Spectroscopy, Cement Concr. Res. 21,496-508 (1991).

17. A. Gorenstein, F. Decker, W. Estrada, S. Passerini, S. 29. W. Estrada, A.M. Andersson, CG. Granqvist, A. Pantaloni and B. Scrosati, Electrochromic NiO,Hy Gorenstein and F. Decker, Infrared Reflectance Hydrated Films: Cyclic Voltammctry and ac Imped- Spectroscopy of Electrochromic NiO,Hy Films made ance Spectroscopy in Aqueous Electrolyte, J. Electro- by Reactive dc Sputtering, J. Mater. Res. 6,1715-1719 anal. Chem. 277,277-290 (1990). (1991).

18. U. Kreibig, K. Fauth, CG. Granqvist and G. Schmid, 30. B. Heed, B. Zhu, B.-E. Mellandcr and A. Lunden, 6s-Electrons in Stabilized Au55-Clusters, Z. Phys. Proton conductivity in fuel cells with solid sulphate Chem.N.F. 169,11-28(1990). electrolytes, Solid State Ionics, 46,121-125 (1991).

31. J. Håkansson and G.A. Niklasson, Multifractal Analy- sis of Gas Evaporated Metal Particle Aggregates, Z. Phys. D20,317-319 (1991).

40 THE CENTRE FOR EXPERIMENTAL PHYSICS

31 S.-J. Jiang, C.-B. Ye. M.S.R. Khan and CG. Granqvist, 45. 1. Albinsson, B.-E. Mellander and J.R. Stevens, Ionic Evolution of Thermochromism During Oxidation of conductivity in polypropylene glycol) complexed with Evaporated Vanadium Films, Appl. Opt. 30.847-851 lithium and sodium triflate, J. Chem. Phys. 96,681 -690 (1991). (1992).

33. M.S.R. Khan, K.A. Khan, W.Estrada and C.G. 46. N.H. Andersen, P.W.S.K. B2rtdaranayke, M.A. Granqvist, Electro-chromism and Thcrmochromism of Careem, M.A.K.L. Dissanayake, R. Kaber, A. Lunden, LixVO, Thin Films, J. Appl. Phys. 69,3231-3234 B.-E. Mellander, L. Nilsson, J.O. Thomas and C.N. (1991). Wijayasekera, Paddle-wheel versus percolation mechanism for cation transport in some sulphate 34. A. Lunden and B.-E. Mellander, On the electrical phases, Solid Slate Ionics, 57,203-209 (1992). conductivity and other transport properties of molten sodium sulphate, Solid State Ionics, 48,127-129 (1991). 47. M.Friesel, B.-E. Mcllander and J.Kubat, Phase transitions in poly(cthylene oxide) and polystyrene at 35. A. Lunden, B.-E. Mellander and B. Zhu, Mobility of high pressure, High Pressure Research 9.169-172 protons and oxygen ions in cubic lithium sulphate, (1992). Acta Chem. Scand., 45,981-982 (1991). 48. P. Jacobsson, I. Albinsson, B.-E. Mellander and JR. 36. G.A. Niklasson, K. Bramervik and L. Börjesson, Stevens, Ion association effects and phase separation in Conductivity Relaxation in Silver Iodide-Silver Borav poly(propylcne-oxide) modified poly(dimethylsilo- Glasses, J. Non-Cryst Solids 131-133,1096-1098 xanc) complexed with triflate salts, Polymer 33,2778- (1991). 2783 (1992).

37. G.A. Niklason, A. Berg, K. Brantervik, B. Hedberg 49. T.MJ. Nilsson, G.A. Niklasson and CG. Granqvist, A and L.O. Nilsson, Dielectric Properties of Porous Solar Reflecting Material for Radiative Cooling Cement Mortar Fractal Surface Effects, Solid State Applications: ZnS Pigmented Polyethylene, Proc. SPE Comm. 79,93-96 (1991). 1727,249-261 (1992); also in Solar Energy Mater. Solar Cells 28,175-193 (1992). 38. C.-A. Sjöblom and B.-E. Mellander, p-T phase diagrams of silver halides; A computer aided evalua- 50. J.L. Tallon and B.-E. Mellandcr, Large enhancement in tion using thermodynamic data, High Pressure Re- oxygen mobility in the superconductors RBa2Cu3O7 search, 7,111-113 (1991). with increasing rare-earth size, Science, 258,781-783 (1992). 39. J.A. Sotelo and G.A. Niklasson, Optical Properties of Fractal Clusters of Small Metallic Particles, Z. Phys. D. 51. I. Albinsson and B.-E. Mellandcr, Electrical relaxation 20,321-323(1991). in polymer electrolytes, to be published in: Fast Ion Transport in Solids, Ed. B. Scrosati (Kliiver Academic 40. B.Stjema and CG. Granqvist, Optical Properties of Publishers, Dordrecht, 1993). SnOj Thin Films: Theory and Experiment, Appl. Phys. Lett. 57,1989-1991 (1991). 52. I. Albinsson, B.-E. Mellandcr and J.R. Stevens, Ion association effects and ionic conductivity in polymer 41. A. Talledo, A.M. Andersson and CG. Granqvist, electrolytes, submitted to Solid State Ionics.

Structure and Optical Absorption of Liy V2O5 Thin Films, J. Appl. Phys. 69,3261-3265 (1991). 53. A.M. Andersson, C.G. Granqvist and Z.G. Ivanov, Superconducting Properties of Elcctrochemically Li+ 42 C.N. Wiyayasekera and B.-E. Mellandtr, Crystal Intercalated YiBa2Cu3C»7-S Thin Films, Mater. Sci. defects in the sodium sulfate rich pan of the sodium Engr. B, to be published. sulfate - lithium sulfate system; An ionic conductivity studv. Radiation Effects and Defects in Solids 119, 54. CG. Granqvist, Electrochromic Materials: Metal 981-^86(1991). Oxide Nanocomposiles with Variable Optical Proper- lies, Mater. Sci. Engr. B. to be published. 43. C.N. Wijayasekera and B.-E. Mellander, Ionic conduc- tivity and phase transitions of the lithium sulfate - 55. CG. Granqvist, Electrochromic Materials: Microstruc- lithium phosphase system, Solid State Ionics 45,293- turc, Electronic Bands, and Optical Properties, Appl. 298(1991). Phys.

44. I. Albinsson, P. Jacobsson, B.-E. Mellandcr and J.R. 56. B.-E. Mellander and B. Zhu, High temperature proto- Stevens, Ion association effects and ionic conduction in nic conduction in phosphate based salts, submitted to polyalkalene modified dimeuiyyioxanes, Solid Slate Solid State Ionics. Ionics, 53-56,1044-1053 (1992).

MATERIALS SCIENCE, 1993 41 EXPERIMENTAL PHYSICS

57. G.A. Niklasson and T.MJ. Nilsson, Relaxation 6. A.M. Andersson, A. Talledo, CG. Granqvist and J.R. Processes in Insulator Thin Films, J. Phys. Condcns. Stevens, Electrochromic Coatings and Devices for Matter, to be published. Large-area Transmitlance Control, in Proc. Symp. Electrochi-omic Matenals, eds. M.K. Carpenter and 58. G A. Niklasson, Adsorption on Fractal Structures: D.A. Corrigan, Proc. Vol. 90-2 (The Electrochemical Application to Cement Materials, Cem. Concr. Res., to Soc., Pennington, 1090), pp. 261-273. be published. 7. W. Estrada, A.M. Andersson, F. Decker and A. 59. C.-A. Sjöblom and B.-E. Mellander, Computer Gorenstein, "In Situ" Optical Mechanical and Electro- evaluation of p-T phase diagrams, submitted to High chemical Characterization of Electrochromic HyNiOx Pressure Research. Films, in Proc. Symp. Elcctrochromic Materials, eds. M.K. Carpenter and D.A. Corrigan, Proc. Vol. 90-2 60. Å.Wendsjö, J. Lindgren and B.-E. Mellander, The (The Electrochemical Soc., Pennington, 1990), pp. 54- phase diagram for the system PrXCFsSOjh - PEO, 69. Solid State Ionics, in press. 8. S.-J. Jiang, C.-B. Ye, M.S.R. Khan and CG. Granqvist, 61. S.-Y. Zheng, A.M. Andersson, B. Stjema and CG. Structural and Compositional Evolution during Granqvist, Optical Properties of Sputter-deposited Oxidation of Vanadium Coatings, Proc. SPIE 1272, Cerium Oxyfluoride Thin Films, Appl. Opt., to be 185-196(1990). published. 9. M. Kakihana, S. Schantz, B.-E. Mellander and L.M. 62. B. Zhu and B.-E. Mellander, Novel proton conducting Torell, Temperature dependence of the charge carrier ceramics for solid state fuel cells, submitted to J. generation in polymer electrolytes; Raman and conduc- Electrochem. Soc. tivity studicsof poly(propylcne oxidc)-LiClO4, in: Proceedings of the second international symposium on 63. B. Zhu and B.-E. Mellandcr, Proton conducting polymer electrolytes, ed. B. Scrosati, (Elsevicr, sulphate ceramics, submitted to Solid State Ionics. London, 1990).

64. B. Zhu, B.-E. Mellander and J. Chen, Cubic M3PO4 10. K.A. Khan and CG. Granqvist, Thcrmochromism of (M=Li, Na, K) polymorphs with high ionic conductiv- Sputter Deposited Vanadium Oxyfluoridc Coatings, in ity, submitted to Mat. Res. Bull. Large-area Chromogenics: Materials and Devices for Transmittance Control, eds. CM. Lampert and C.G. Granqvist (SPIE Opt. Engr. Press, Bcllingham, 1990), D. Conference Papers pp. 160-167. 1. K. Brantervik and G.A. Niklasson, Dielectric Proper- ties of Zinc Oxide Based Varistors, Proc. 3rd Intern. 11. G.A. Niklasson, Degradation of Solar Collector Conf. on Conduction and Breakdown in Solid Dielec- Coalings: Model Calculations for Nickel Pigmented trics, Trondheim, Norway, (IEEE, New York, 1989>, Aluminium Oxide, Proc. SPIE 1272,250-264 (1990). pp. 309-312. 12. G.A. Niklasson, Theoretical Model for the Durability 2. G.Mbise,G.B. Smith, G.A. Niklasson and C.G. of Solar Selective Absorber Coatings at Elevated Granqvist, Angular Selective Window Coatings: Temperatures, in Energy and the Environment Into the Theory and Experiment, Proc. SPIE 1149,179-199 1990s, (edited by A.A.M. Sayigh, Pcrgamon, Oxford, (1989). 1990), pp. 1372-1376.

3. G.A. Niklasson and T.S. Eriksson, Radiative Cooling 13. T.M.J. Nilsson and G.A. Niklasson, Comparison of with Pigmented Polyethylene Foils, Proc. SPIE 1016, Dielectric and Optical Properties of Nickel Oxide 89-99(1989). Based Electrochromic Coalings, Proc. SPIE 1272,129- 138(1990). 4. A.M. Andersson, W. Estrada, CG. Granqvist, A. Gorenstein and F. Decker, Characterization of 14. S. Passcrini, B. Scrosali, A. Gorcnstcin, A.-M. Electrochromic de-Sputtered Nickcl-oxidc-bascd Andersson and CG. Granqvist, Solid State Electro- Films, Proc. SPIE 1272,96-110 (1990). chromic Devices, in Proc. Symp. Elcctrochromic Materials, cds. M.K. Carpenter and D. A. Corrigan, 5. A.M. Andersson, C.G. Granqvist and J.R. Stevens, An Proc. Vol. 90-2 (The Electrochemical Soc., Penning- ton, 1990), pp. 237-245. Electrochvomic LixWO3/poIymer laminatc/LiyV^Os Device, in Large-area Chromogenics: Materials and Devices for Transmitlancc Control, eds. CM. Lampert 15. B. Sijcrna and C.G. Granqvist, Optical Properties of and CG. Granqvist (SPIE Opt. Engr. Press, Belling- SnOx Thin Films: Experimental Data and Theoretical ham, 1990), pp. 471 -481. Model, Proc. SPIE 1272,12-25 (1990).

42 THE CENTRE FOR EXPERIMENTAL PHYSICS

16. J.S.E.M. Svensson and CG. Granqvist, Sputter 23. J.C. Gustafsson, O. Inganas and A.M. Andersson, Deposited Nickcl-oxidc-bascd Electrochromic Coat- Conductive Polymers as Elcctrochromic Materials in ings, in Large-area Chromogenics: Materials and Solid State Elcctrochromic Devices, Proc. SPIE 1728, Devices for Transmittance Control, eds. CM. Lampert to be published (1992). and CG. Granqvist (SPIE Opt. Engr. Press, Belling- ham, 1990), pp. 285-297. 24. A. Lunden, B.-E. Mcllandcr and B. Zhu, Proton conductivity in oxyacid salts at high temperature, in 17. C.N. Wijayasekera, M.A.K.L. Dissanayake, M.A. Materials for High Temperature Fuel Cells, ed. B. Careem and B.-E. Mellander, On the irreversible phase Bergman,(Mcdiatcknik KTH, Stockholm, 1992), p. 131. transition in lithium phosphate; thermal analysis, X-ray diffraction and ionic conductivity measurements, 25. A. Talledo, A.M. Andersson and CG. Granqvist, Proceedings of the Sri Lanka Association for the Structure and Optical Absorption of Liy V2O5 Thin Advancement of Science, 46 (1), 123-124 (1990). Films, in Surface Science: Lectures on Basic Concepts and Applications, Springer Proc. Phys., eds. F.A. 18. W. Wixwat, J.R. Stevens, A.M. Andersson and C.G. Ponce and M. Cardona (Springer, Berlin, Heidelberg, Granqvist, An Adhesive Polymer Electrolyte for 1992), Vol. 62, pp. 315-316. Elcctrochromic Smart Windows: Optical and Electrical Properties of PMMA-PPG-LiCIO4, in Second Interna- 26. S.-Y. Zheng, A.M. Andersson, B. Stjema and CG. tional Symposium on Polymer Electrolytes, edited by Granqvist, Cerium Oxide and Oxyfluoridc Thin Films B. Scrosati (Elsevicr Appl. Sci., London. 1990, pp. for Energy efficient Windows, in Renewable Energy: 461465. Technology and the Environment, edited by A.A.M. Sayigh (Pergamon, Oxford, 1992), pp. 164-172. 19. Z.Q. Yin, B. Stjema and CG. Granqvist, Antireflcction Coatings of Sputter-deposited SnOxFy and SnNxFy, 27. S.-Y. Zheng, A.M. Andersson, B. Stjema and C.G. Proc. SPE 1536,149-157(1991). Granqvist, Optical and Electrochemical Properties of Cerium Oxyfluoride Thin Films, in Technical Digest of 20. T.MJ. Nilsson and G.A. Niklasson, Optimization of of 1992, Int. Conf. on Lasers and Optoelectronics Optical Properties of Pigmented Foils for Radiative (ICLOE'92),p.48. Cooling Applications: Model Calculations, Proc. SPIE 1536,169-182(1991). 28. B. Zhu, J. Chen and B.-E. Mcllandcr, Proton conduc- tion in phosphates, in Materials for High Temperature 21. A. Azens, A. Talledo, A.M. Andersson, G.A. Fuel Cells, ed. B. Bergman, (Mediateknik KTH, Niklasson, B. Stjcrna, CG. Granqvist and JR. Stevens, Stockholm, 1992) p. 159. W oxideftolymer laminate/ V oxide Elcctrochromic Smart Windows: Recent Advances, Proc. SPIE 1728, 29. G.A. Niklasson and B. Ncttclblad, Dielectric Properties 103-117(1992). of Porous Materials, IEE Conf. Publ., 363,450453 (1993). 22. R. Gatt, G.A. Niklasson and CG. Granqvist, Degrada- tion Modes of Cermet Based Selectively Solar Absorb- 30. B. Stjema and CG. Granqvist, Optical and Electrical ing Coatings, Proc. SPIE I727,87-101 (1992). Properties of Doped RF Sputtered SnG\ Films, Proc. SPIE 1727,178-193(1993).

MATERIALS SCIENCE, 1993 43 Materials chemistry

Inorganic Chemistry 46 Reaction Dynamics 58 Chemical Analysis - Swedish National Testing and Research Institute, SP 63

MATERIALS SCIENCE, 1993 45 Inorganic Chemistry, CTH/GU

Research summary Staff Much of the basic research at the department is Senior Members directly connected to materials science. There is a Lindqvist, Oliver prefekt, professor long tradition on solid state chemistry, especially Albertsson, Jörgen professor with respect to synthetic inorganic chemistry, struc- Ahlberg, Elisabet docent turalchemistrybasedondiffractionand spectroscopic Jagner, Susan docent methods, and relations between structure and prop- Johansson, Gunnar docent erties. Other important fields of basic research are Langer, Vratislav docent electrochemistry and heterogeneous kinetics. The Ljungström, Evert docent mentioned research fields are supported actively by Sjölin, Lennart docent expertise within quantum mechanical calculations. Stomberg, Rolf docent The applications within material research de- Berggren, Jan tekn.dr. scribed below are strongly connected to and based on Berghult, Bo tekn.dr. the basic research areas. Electrochemical applica- Börtin, Olle tekn.dr. tions are dissolution of metallic materials, mineral Eriksson, Sten fildr. flotation and material aspects of battery technology. Gobom, Sylvia fil.dr. Areas of application connected to solid state Håkansson, Mikael tekn.dr. chemistry are structure-property relationships in Idrestedt, Ingvar tekn.dr. ceramics and in high Tc-superconducting materials. Panas, Itai fil.dr. Another field is growth of large crystals and inves- Strömberg, Dan fil.dr. tigation of their properties. Svensson, Göran tekn.dr. Heterogeneous chemistry is applied within com- bustion relatedresearch,i.e.characteristicsofbiornass Graduate Students and coal fuels, of ash components and of FBC Alenljung, Roger fil.kand. additions. Main fields are atmospheric and high Andersson, Helge fil.kand. temperature corrosion involving important materi- Berastegui, Pedro filkand. als such as ceramics, metals, natural stones and Chen, Jiaxin fil.kand. paper. Elfströrn-Broo, Ann fil.kand. Surface reactions are studied in situ by tempera- Elfving, Pernilla fil.kand. ture controlled (180-1800 K) surface X-ray diffrac- Eriksson, Henrik civ.ing. tion and FT-IRAS spectroscopy. A specific field of Hallqvist, Mattias fil.kand. competence is structural research based on synchro- Heim, Maiken fil.kand. tron radiation research. Johansson, Anna fil.kand. Jäglid, Ulf fil.kand. Kassman, Håkan civ.ing. Address Karlsson, Rune civ.ing. Department of Inorganic Chemistry, CTH/GU Langer, Särka filkand. Chalmers University of Technology Lindstedt, Anja civ.ing. S-412 96 Göteborg, Sweden Lopes, Cesar fil.kand. Phone +46 317722850 Mattisson, Tobias fil.kand. Fax 446 31 167194 Miettinen, Heije fil.kand. Öländers, Birgitta civ.ing. Olsson, Lise-Lotte fil.kand.

46 THE CENTRE FOR INORGANIC CHEMISTRY. CTH/GU

Potter, Douglas fil.kand. DTA balance gravimeter, TA-1, Mettler, 1982, Shirazi, Ahmad Resa fil.kand. Contact person: Maiken Heim, tel. 772 2888 Snis, Anders fil.kand. FTIR- spectrometer, Perkin Elmer, 1800, Steenari, Britt-Marie civ.ing. 1986, Contact person: Pernilla Elfving, tel. Strandberg, Helena fil.kand. 7722860 Ström, Carin fil.kand. Ion chromatograph, HPLC-system, 1987, Svensson, Jan-Erik fil.kand. Contact person: Pernilla Elfving, tel. 772 2860 Tsai,Li-Chu filkand. Atomic absorption spectrometer, Philips, 1987, Tullin, Claes civ.ing. Contact person: Käthe Puromäki, tel. 772 2887 Wettström, Catarina civ.ing. Electrochemical instrumentation: Potentiostats Xiao, Zifan fil.kand. PAR 173/276, PAR 273A, Frequency response Åhman, Johan civ.ing. ana'yser Solatron 1255, Lock-in-amplifier PAR 5210. The instrumentation can be used Technical Staff for analyses, corrosion studies as well as for Abul-Milh, Miroslawa Ph.D. fundamental electrochemical research. Con- Forsberg, Roger techn. tact person: Elisabet Ahlberg, tel. 772 2879. Karlsson, Kajsa ing. Low Temperature Ashing, LFE Corp Model Kovacs, Janos ing. 302,1989. Contact person: Ahmad Resa Lagerqvist, Lars techn. Shirazi. Lundqvist, Eva ing. Nilsson, Ove civ.ing. Olsson, Solveig ing. Major Fields of Research Puromäki, Käthe Ph.D. A: Materials Research in Electrochemistry, Selander, Sören ing. participants: Elisabet Ahlberg, Bo Berghult, Väanänen, Esa techn. Ann Elfström-Broo, Ove Nilsson Wang, Jian civ.ing. collaborators: ABB atom, Sydkraft AB.

Secretary B: Reactivity of Ceramic Materials, Bergström, Britt participants: Jiaxin Chen, Maiken Heim, Oliver Lindqvist, Robert Pompe collabora- tors: Volvo Flygmotor AB, Swedish Ceramics Major Instrumentation Institute. • Single crystal diffractometers, Syntex, 1975, Contact person: Janos Kovacs, tel. 772 2855 C: Crystal Growth and Crystal Properties, • Single crystal diffractometer, Rigaku, 1989, participants: Jörgen Albertsson, Göran Contact person: Mikael Håkansson/Janos Svensson, Johan Åhman Kovacs, tel. 772 2856/2855 collaborators: MAX laboratory, Lund • Single crystal diffractometer, Enraff-Nonius, 1993, Contact person: Göran Svensson, tel. D: High-Tc Superconducting Oxides. 7722882 participants: Pedro Berastegui, Sten Eriksson, • Single crystal growth apparatus, Crystalox, Gunnar Johansson, Carin Ström 1993., Contact person: Göran Svensson, tel. collaborators: Department of Physics CTH/GU 7722882 • Powder diffractometers, Siemens D5000, E: Atmospheric Corrosion Research. 1992, Contact person: Vratislav Langer/Janos participants: Pernilla Elfving, Anna Johansson, Kovacs, tel. 772 2877/2855 Gunnar Johansson, Oliver Lindqvist, Helena • Medium frequency induction heater, Stanelco, Strandberg, Jan-Erik Svensson 1993, Contact person: Göran Svensson, tel. collaborators: Volvo AB, National Board of 7722882 Antiquities, STFI.

MATERIALS SCIENCE, 1993 47 INORGANIC CHEMISTRY, CTH/GU

F: Combustion related Materials Research, passivating oxide layers on the electrochemical re- participants: Oliver Lindqvist, Vratislav sponse. Langer, Käthe Puromäki, Ahmad Resi References: 1,2,3,29,30,31,32,33,34,53,54 76, Schirazi, Britt-Marie Steenari. 77,78,96,103,104,105. collaborators: ABB Carbon, Department of Energy Conversion CTH, Celsius. A2: Materials in Battery Technology The Department of Inorganic Chemistry has a tradi- tion in battery R&D, especially in the lead acid Research Projects battery. The increase of material utilisation of the porous PbO2 electrode without sacrificing the cycle A: Materials Research In life is a crucial problem. The research has been Electrochemistry directed towards thin electrodes and processes to oxidise lead foils to PrXVelectrodes. Al: Electrode kinetics The need for a better environment involves also During the last ten years the ELECTRO- the development and use of Electric Vehicles. One CHEMISTRY GROUP at the department of Inor- task we have undertaken in that area is the develop- ganic chemistry GU/CTH has worked with different ment of a bipolar, high power density battery in metal and mineral dissolution reactions. Mainly which the use of thin electrodes and minimum of electrochemical techniques have been used and the acid and inactive material is the main idea. The mechanistic interpretations performed are based on project also involves new methods to make these traditional evaluation of kinetic parameters like the electrodes. Tafel slope and the reaction order dependence from The future activities will involve also red-ox steady state measurements. In recent years we have batteries. The use of DS A electrodes or graphite will successfully used Impedance Spectroscopy in con- give such batteries a substantially increased life junction with polarization measurements in the in- compared to any other battery. terpretation of the kinetics of metal dissolution reac- Further, the research group will be enlarged to tions as well as adsorption/desorption phenomena. deal with material problems as well as electro- The metal systems most carefully studied by the chemical performance of Solid Oxide Fuel Cells. group are iion in acidic aqueous solutions and in The studies will centre around high temperature acetonitrile/water medium, lead in acidic electrolyte corrosion of ceramics and metals, ion conductivity providing both active dissolution and partial of ceramic materials and electrochemical activities passivation by the formation of small amounts of of perovskite. The applications we are aiming at are lead sulfate and zinc in slightly acidic aqueous flue gas abatement and power generation. solutions. In many practical applications metals References: 35,112. forming passivating oxide layers are used. The electrochemistry of sulphide minerals has been studied with the emphasis on the flotation and B: Reactivity of Ceramic Materials. leaching processes. Most sulphide minerals are good electric conductors or semiconductors and Bl: Oxidation/Corrosion of electrochemical models have successfully been used advanced ceramics composites and fibres for the interpretation of the~e processes. However, Advanced ceramic fiber composites (CMC) are for low conducting minerals the electron transfers considered for use in the burning chamber of jet taking place should be regarded as localised and engines, rocket engines and other applications re- because of the low mobility in the solid these reac- lated to more efficient energy conversion. These tionscan not be studied by traditional electrochemical applications involve operation temperatures up to methods. 1600 °C. Further studies will focus on the temperature The objective of the project is to investigate the dependence and the double layer effects of metal resistance to oxidation/corrosion of selected fibers dissolution reactions and on the influence of and ceramic matrix composites in oxidative and/or

48 THE CENTRE FOR INORGANIC CHEMISTRY, CTH/GU corrosive environment. The effect of constituents process which is sensitive to the structure of the present in exhaust gases such as H2O, SO2, hydro- diffusion medium. For the corrosion of the ceramics, carbons as well as salts will be examined to identify we have concluded that gaseous corrosion in the the mechanisms and kinetics governing the of simulated combustion environment which contains the corrosive attack. NOX, SO2/SO3, H2O, CO2, O2 etc. will be essen- Two types of composites will be studied: tially the same as oxidation in O2 or in air. For the hot a) dense (HIP - Hot Isostatic Pressed) specimens corrosion where a constant stream of NaCl vapour is based on Si3N4 matrix/SiC (C) fibres and SiC ma- introduced into a gaseous corrosion environment, trix/SiC(C) fibres exposed short time to high tem- however, the material surfaces undergo severe cor- perature and rosion damage due to the formation of a large b) porous composites (oxide and/or non-oxide ma- amount of low viscosity silicate. We have pointed trix/oxidic fibres) and their behaviour on long term out that the corrosion may be caused by the reaction exposure. between materials and NaOH(g) which is formed at Experimental techniques which are employed high temperature. Our future work will be to exam- include thermogravimetry and heat treatment in ine the O2 diffusivity in various sodium-containing specially equipped furnaces. The corrosion products silica materials so that we can predict the actual hot are identified using a wide spectra of analytical corrosion process. References: 38,55, 56. techniques such as XRD, XPS, AES, IR and RAMAN. These are combined with micro structural studies with TEM/SEM/EDS and spectro- C. Crystal Growth ellipsometry. References: 49,67,71,72,93. and Crystal Properties. Cl: Structure-property relations B2: High temperature oxidation & corrosion of inorganic materials of structural ceramics Crystal growth is of great importance in material Ceramic materialsarepromisingcandidatesfor many research. A crystal laboratory was started in Lund in high temperature applications. The evaluation of 1989 but will be moved to Chalmers University of their oxidation and corrosion behaviour becomes Technology in Göteborg in 1993. The main interest particularly important when the consequence of the is in crystal growth and characterisation of non- material failure is catastrophic. In cooperation with linear optical materials. The research is focused on Volvo Flygmotor AB and Department of Physics at experimental conditions that effects the crystal qual- Chalmers as well as Shanghai Ceramic Institute, we ity as e.g. shape and material of crucible, thermal have tested the oxidation- and corrosion resistance conditions, growth speed, impurities and dopand of some advanced ceramics, such as silicon carbide distribution. The crystals are characterised by dif- composite and hot isostatic pressed silicon nitride, in fraction methods, electron microscopy, etching, lu- severe corrosion environments at high temperature. minescence and others. To study the oxidation and corrosion mechanism of We are involved in several projects, but our main these materials, we have applied various surface interest is non-linear optical materials. Below fol- analytical techniques such as glancing angle X-ray lows a list of projects. diffraction, electron microscopy, infrared 1. Growth of germanium for a neutron detector. spectroscopy, X-ray photoelectron spectroscopy, (Dr. Roland Tellgren, Studsvik). Auger electron spectroscopy, and spectroscopic 2. Growth and characterisation of Co-doped ellipsometry. We have observed that on oxidation of LiGasOg for optical storage of data. (Dr. carbide and nitride, much more crystalline structures Stefan Kröll, Atomic Physics in Lund). of the oxide scales are formed than that on single 3. Growth of CsI/CsBr for calorimetric measure- crystal silicon, even though the final oxidation prod- ments in nuclear- and particle physics. This is a ucts on the materials have essentially the same collaboration between several laboratories in chemical compositions. Many peculiar oxidation Euiope called "Crystal Clear Collaboration" behaviour of carbide and nitride could be readily organised from CERN. (Dr. Leif Jönsson, understood in the light of this observation, because Particle Physics in Lund). the oxidation process is an O2 diffusion controlled

MATERIALS SCIENCE, 1993 49 INORGANIC CHEMISTRY, ClH/GU

4. Growth and characterisation of non-linear Polycrystalline materials are prepared by solid materials such as LiNbC^, LiTaO3, KT1OPO4 state sintering, vacuum line and high pressure meth- and KTiOAsO4. (Dr. Fredrik Laurell, The ods, polymerised complex routes, reaction in closed Institute for Optical Research in Stockholm systems and by use of precursor techniques. Moreo- and Dr. Rindert Bolt, Holland). ver, we also work with single crystal growth and thin 5. Other projects are studies of compounds such film fabrication. Due to the broad spectrum of pre- as CuCl, LaF3, HCN and DCN. parative methods used we are able to synthesise a large number of high-Tc materials such as Y-123, Y- C2: Structure-property relations 247, Y-124, Tl-2201, Tl-2212, Tl-1201, Tl-1212 for dielectric materials. and Bi-2201 just to mention a few. The microscopic origin of various dielectric and Aiming at an increased understanding for struc- magnetic phenomena are studied. A direct relation- ture- property relationshipsi n these and other cuprates ship, on the atomic level, between external action a vast number of doped materials have been prepared (changes in temperature, electric field, hydrostatic and structurally characterised. In this context we use pressure etc.) and polarisation has been developed diffuse neutron scattering and magnetic scattering to for several pyroelectric and ferroelectric crystals. obtain information concerning atomic disorder and Much information is also obtained from phase magnetic order, respectively. Our work on the so changes when crystal properties change and new called ortho II phase in the RE-123 system is one properties appear while others disappear. Our ulti- example of the problem of atomic disorder. Moreo- mate goal is to calculate tensor components describ- ver, a systematic search for new high-Tc supercon- ing electric, opdc and mechanical properties of ma- ductors among antiferromagnetic oxides with pro- terials. A thorough knowledge about how to grow nounced 2D character has been started. In for in- and dope the materials is of importance for any stance Y-123 and in the thallium cuprates there is a characterisation and future application. Materials of strong competition between superconducting and present interest in our investigations are the alpha antiferromagnetic behaviour. One state or the other and gamma phases of UIO3 related alkali metal can be stabilised by appropriate doping, a technique iodates and iodic acid, ZnO and other pyroelectrics that we have much experience in. with wurtzite structure and SrAlFs and related struc- References: 7,8,9,10,11,18,19,20,21,22,23,28, tural families of double fluorides. Among the latter 42,46,47,48,64,65,70,83,84,85,86,94,95,99, compounds most work has been with the ferroelectrics 100,101,102,106,107,108,109,110. Pb5M3F19,M=Cr,AlorFe.

E: Atmospheric Corrosion Research. D: Synthesis and structureproperty The atmospheric corrosion chemistry group studies relations In hlgh-Tc superconducting reactions that occur when metallic and non-metallic oxides. materials are exposed to humid atmospheres con- Our research on high-Tc cuprate superconductors taining traces of reactive air pollutants (e.g. NO2(g), was initiated in early spring 1987. We work with O3(g), SO2(g), Cl2(g), H2S(g) and NaCl(s)). In synthesis and characterise the materials by use of particular we study the combination effects that various diffraction techniques. Single crystals as occur when two or more corrosive micro-compo- well as polycrystalline materials are studied by x-ray nents interact on the surface. For example we have diffraction, the latter also by neutron powder diffrac- shown that NO2, which by itself is rather unreactive tion. Spectroscopic methods (NMR, Raman, X AFS, towards most materials, may accelerate corrosion XPS, Mössbauer) as well as wet chemical and appreciably in combination with SO2. We have gravimetric techniques also play an important role in found evidence for such a synergistic effect of SO2 our research. An extensive network of collaborators and NO2 with materials as diverse as marble, carbon has been developed on a national as well as an steel, copper, zinc and gold-coated brass (Johansson international basis and we are today highly competi- 1984, Eriksson and Johansson 1990, Svedung tive. Johansson and Vannerberg 1983, Johansson, Mangio and Lindqvist 1988, Svensson and Johansson 1989).

50 THE CENTRE FOR INORGANIC CHEMISTRY, CTH/GU

Similar effects occur when ozone is combined with 1) Real-time studies of the kinetics of deposition SO2 (Mangio and Johansson 1989, Eriksson and and formation of trace gases on materials. Johansson 1992, Svensson and Johansson 1993). It The consumption of SO2, O3 and NO2 and the is well known that small amounts of NaCl accelerate formation of NO and HNO2 on e.g. metal samples is the atmospheric corrosion of many metals. This is studied in a time-resolved manner. The sample is primarily caused by the increasing conductivity of exposed in a flow-reactor and the output gas is the surface electrolyte and by the enhancement of the analysed by the different gas analysers that have fast anodic reaction by chloride. However, the corrosive response and high sensitivity (about 1 ppb). The effect of combinations of NaCl with corrosive trace sensitivity of the analysers allows us to work at gases on metals and calcareous stones has not been ambient concentrations of SO2, NO2 and O3 (20 - thoroughly studied in the past. Our study on zinc 1 OOppb). The concentration changes that we register (Svensson and Johansson 1992) is the first system- are caused by reactions on the surface of the sample. atic work dealing with the complex interactions This experimental set-up is best suited for exposures between chloride and corrosive trace gases at sub- of short duration (< one week), for example studying ppm concentrations on a corroding surface. the initiation of atmospheric corrosion. We have also developed a fixed-bed reactor technique to Methodology investigate the kinetics of the reactions between the The most important experimental techniques in- different corrosion products and gaseous species clude the following: like SO2, NO2 and O3 without the influence of the metal. The gas analysis is supplemented by ion

SO2 analyser NO-NOX/O3 1 analyser Excess air Pressurized purified air

Mass flow regulators

Reactor 03-generator 0 s 28 mm

Permeation I Sample Humidifier tubes SO2/NOj

Thermostated water tank

Experimental arrangement for time-resolved study of the deposition and formation of SO2. NO, NO2 and 03 on solids.

MATERIALS SCIENCE, »993 51 INORGANIC CHEMISTRY, CTH/GU chromatography after the exposure. This type of F: Combustion related Materials study allows us to close the mass balance for the Research. corrosive substances, to determine reaction stoichiometries ai d to study the kinetics of the Fl: Coal Research reactions. The sulphur in coal is present as sulphides or sul- 2) Corrosion rate measurements phates, as organic compounds and as elementary In order to link the kinetic studies of the interaction sulphur. They are all sources for SO2 in flue gas. of corrosive trace substances on the zinc surface to Especially in pre-cleaning methods of coal it is the corrosion rate of the metal we will carry out long necessary to know the quantity and also the quality term exposures under controlled conditions. The of these compounds. By using an Electron Probe experimental set-up was developed at our labora- Micro Analyser and Automatic Image Analysis, e.g. tory. The corrosion rate is determined from the metal the content of pyrite, marcasite and pyrhotite in loss after exposure. In addition, mass gain measure- pyritic sulphur mineral has been determined, which ments are performed during exposure. The corrosion is not possible by using standard methods of analy- products formed are studied by XRD, and ion chro- sis. matography . In addition the corroded samples will The time of analysis is proportional to the amount be analysed by SEM-EDX and XPS. of particles which have to be counted for a pre-set accuracy. However, the analysis area can be reduced 3) FT-IRAS and-DRIFT measurements; Investi- by applying Low Temperature Ashing (LTA; LFE gations of the formation of reactive intermedi- Corp. model 302) before the analysis. In this process ates on the surface. a radio frequency generator ionises oxygen at ,ow A specular reflectance cell is used to study corrosion partial pressure and oxygen reacts with the coal products and adsorbed species formed on metal sample. Thus the mineral matter will appear more surfaces. We have access to a high performance readily available for the analysis. It has been possible FTIR-instrument with MCT detector (Perkin Elmer to lower the ashing temperature to 70° C by substi- 1800). Using this equipment, adsorption layers less tution of the oxygen for a mixture of oxygen and than a monolayer thick may be studied. The gradual helium (Very low temperature Ashing, VLTA). build-up of corrosion products and adsorbates dur- Thus the oxidation of the sulphides is avoided. ing the initial stages of corrosion is studied. In addition we use in-situ diffuse reflectance F2: Ash characterisation. spectroscopy to study adsorbates and compound Diffraction studies of ashes from different combus- formation on powdered substances, i.e. solid corro- tion processes are performed on this instrument. The sion products. qualitativeanalysisisdoneinteractivelyon the screen References: 5,6,15,16,25,26,27,37,40,41,43,52, with JCPDS databasis on-line. Quantitative analysis 57,58,63,68,69,81,82,92. of Ca-compounds has been developed. Department of Inorganic Chemistry GU/CTH was one year ago equipped with a new powder

Temperature controlled brast plate diffractometer, Siemens D5000. The specific fea- BaF windows 2 tures of the diffractometer are: high effect X-ray Sample generator and tube, scintillation and position sensi- tive detector (PSD), high and low temperature cells and a thin film attachment. The high temperature cell operates from room temperature up to 1600° C in vacuum and up to 1200° C in different atmospheres (Pt - heat element). i t I In connection with position sensitive detector, it is gas gas gas outlet inlet outlet possible to follow quick changes (reactions in situ under controlled temperature and atmospheric pres- Schematic view of the in-situ Fourier transform sure ) or phase changes (reversible or irreversible) specular reflectance cell. with temperature, scanning with PSD 160° diffrac-

52 THE CENTRE FOR INORGANIC CHEMISTRY, CTH/GU

tion angle within few minutes. The low temperature Ghardashkhani, S., Thesis: The Chemistry Behind the cell can be used for temperatures from -190 to +300° Sulfur Dioxide Removal by Oxide in Fluid- C in a similar manner. ized Bed Coal Combustion (1991). The thin film attachment is based on the fact that Mangio, R., Thesis: The Influence of Various Air Pollut- incident beam is touching the surface under very ants on the Sulfation of Calcareous Building Materials small angle, causing only surface material to diffract. (1991) 1-55. As diffracted radiation is divergent in this arrange- ment, long Soller slits and a flat secondary Munthe, J., Thesis: The Redox Cycling of Mercury in the Atmosphere (1991). monochromator are used to select diffracted X-rays to scanning scintillation detector. This results in Sjöberg, J., Thesis: On the Preparation and Structure of O'- magnification of the signal from the surface and the Sialonsn(1991). influence of the substrate can be minimalized. Of course, the thin film configuration can be used in Eriksson, P., Thesis: Effects of SOz and NO2 on melal surfaces: Atmospheric corrosion of copper and surface combination with both high and low temperature reactions on gold (1992). cells. References: 13,17,50,61,62,87,88,89,90,91,97, Hall, B., Thesis: An Experimental Study of Mercury 111. Reactions in Combustion Flue Gases (1992).

Wängberg, I., Thesis: An Experimental Study of some Nitrate Radical Reactions of Importance to Tropo- spheric Chemistry (1993). Publications Ph.D. Dissertations (1989-) Licentiate Dissertations Andersson, Y., Thesis: Gas-Phase Kinetic Studies of Elfstrom Broo, A., Electrochemical Studies on the Galena/ Relevance to Atmospheric Chemistry (1989). Xanthate System, Relationship to Flotation, ISSN 0283-8575, Report OOK 90:03,1-27. Carlström, E., Thesis: Defect Minimisation in Silicon Carbide, Silicon Nitride and Alumina Ceramics (1989) Hall, P., Reactions of Mercury with Flue Gas Components, 1-87. ISSN 0283-8575, Report OOK 90:06.

Cooper, D., Thesis: Some Aspects of NOx Control in Schagcr, P., The Behaviour of Mercury in Flue Gases, Fluidized Bed Combustion (1989). ISSN 0283-8575, Report OOK 90:07.

Eriksson, S., Thesis: On the structure and Properties of Tullin, C, Sulphur Capture in Pressurised Fluidised Bed some Doped Y-I23 Cuprate superconductors and Combustion, ISSN 0283-8575, Report OOK 90:04. Related Non-Superconducting Materials (1989) 1-107. Xiao, Z., Some Aspects of Mercury as a Pollutant in the

Friel, M.( Thesis: The Polarisation of Iron in Acidic Environment, ISSN 0283-8575, Report OOK 90:05,1- Acctonitrile-Watcr Solution (1989). 39.

Bcrghult, B., Thesis: Fundamental Electrochemical Elfving, P., Atmospheric Corrosion on Silane Treated Aspects of the Lead Electrode in Connection with the Stones, ISSN 0283-8575, Report OOK 91:04,1-57. Lead-Acid Battery (1990). Linsten, M., Some Properties of Hydrothermally Hclgcsson, G., Thesis: Dependence of the coordination Dealuminated Y-Zeolites, ISSN 0283-8575, Report number of silvcr(I) in crystalline halogcnoargcntatcs(I) OOK 91:02. on the nature of the cation (1990). Tsai, Li-Chu., Crystallographic Investigations of Wild Strömberg, D., Thesis: Some mercury Compounds Studied Type Azurin and Some Azurin Mutants from by Relativistic Quantum Chemical Methods (!990). Pscudomonas aeruginosa, ISSN 0283-8575, Report OOK 92:02. Tcgehall, P-E., Thesis: The Chemistry of Zinc Phosphaling of Steel (1990).

MATERIALS SCIENCE, 1993 53 INORGANIC CHEMISTRY, CTH/GU

Diploma Work 11. Y1Ba2.ySryCu3.xFexO7-

54 THE CENTRE FOR INORGANIC CHEMISTRY, CTH/GU

26. The Influence of Ozone on the Atmospheric Corrosion 40. Stone consolidation by tetraalkoxysilane treatment. A of Carrara Marble in Humid Atmospheres Containing case study on sandstone and limestone in medieval Sufur Dioxide; Deposition Studies of SO2 on Marble. churches on Gotland. Elfving, P. ISSN 0283-8575, Mangio, R. and Johansson, L.-G. Proc. 1 lth Report OOK 90:08. Scandinavian Corrosion Congress, Stavanger, F-45 41. Kisclsyraesterbaseradstenkonscrvcring. (1989) 1-6. Långtidsexponering på Gotländsk kalk- och sandsten. 27. A Laboratory Study of the Atmospheric Corrosion of Elfving, P. ISSN 0283-8575, Report OOK 90:09. Zinc: Synergistic effects of Trace Amounts of SO2, 42. The role of charge transfer and close packing in doped NO2 and NaCl(s). Svensson, J.-E. and Johansson, L.- Y-123 materials. Eriksson, S.G. ISIS- report, G. Proc. 1 lth Scandinavian Corrosion Congress, Rutherford- Appleton- Laboratory A50,1990. Stavanger, F-47 (1989) 1-7. 43. Synergistic effects of air pollutants on the atmospheric 28. Study of the effect of the substitution of O by F, S and corrosion of metals and calcareous stones. Johansson, CI on the superconductivity of YlBa2Cu3O7^. Yi, L., L.-G. Marine Chemistry 30 (1990) 113-122. Persson, M. and Eriksson, S.G. Z. Phys. B-Condcnscd 44. Bestämning av kapaciteten au absorbera svaveldioxid Matter 74 (1989) 423428. hos svensk dolomiL Jäglid, U. and Lindqvist, O. ISSN 29. Anodic Dissolution of Lead in Perchloric Acid Solu- 0283-8575, Report OOK 90:01. tions. Correction for Changes in Active Surface During 45. A Kinetic Study of Tetraethoxysilane in an Alkaline Potential Dynamic Sweeps. Ahlbcrg, E. and Bcrghult, Medium in Methanol Solution. Jäglid, U. and B. Electrochim Acta 35 (1990) 1213-1218. Lindqvist, O. Acta Chem. Scand. 44 (1990) 765-768. 30. Anodic oxidation of lead in sulphuric acid solutions. 46. Phonon characterisation of YBa2Cu3O7 doped with Al The effect of different pcrchlorate salts on planté and Ga by Raman spectroscopy. Kakihana, M., formation. Ahlbcrg, E. and Bcrghult, B. Journal of Börjesson, L. and Eriksson, S.G. Physica B165-166 Power Sources 32 (1990) 243-251. (1990) 1245. 31. The Polarization of Iron in Aqueous Pcrchlorate 47. Effect of Sr and Co doping on structure and phonon Solutions; The Effect of Quality and Purity of the Raman spectra of YBa2Cu3O7. Kakihana, M., Electrolyte. Ahlbcrg, E. and FricI, M. J. Electrochcm. Börjesson, L. and Eriksson, S.G. Physica B165-166 Soc. 137(1990)1196-1199. (1990) 1247. 32. The Anodic Dissolution of Iron Microclectrodes in 48. Evidence for charge transfer in Y-123. Kakihana, M., Acidic Water-Acetonitrilc Solutions. Ahlbcrg, E. and Eriksson, S.G., Börjesson, L. and Kall, M. Int. Conf. on FricI, M. Electrochimica Acta 35 (1990) 501-507. Superconductivity and its relating Character in Layered 33. An Electrochemical Investigation of the Corrosion Compounds, Yokohama, 1990. Behaviour of Sintered Stainless Steels. Ahlbcrg, E., 49. The development of microstructure in pressureless Engdahl, P. and Johansson R. Proc. of the PM'90, sintered Si2N2O bodies. O'Meara, C. and Sjöberg, J. Wembley, London, England (1990). Ceramic Transactions 7 (1990) 647-663. 34. The surface oxidation of pyrite in alkaline solution. 50. Investigation of grate combustion of biomass fuels in Ahlberg, E., Forssberg, K.S.E. and Wang, X. Journal an experimental furnace. Öländers, B, Report (1990). of Applied Electrochemistry 20 (1990) 1033-1039. 51. Ammonia Adsorption on Synthetic Zeolities. 35. Thesis: Fundamental Electrochemical Aspects of the Shambayati, P. Projektarbete 10 p. (1990). Lead Electrode in Connection with the Lead-Acid 52. A laboratory study of the atmospheric corrosion of Battery. Bo Bcrghult (1990). statue bronzes and copper. Strandberg, H., Johansson, 36. Bildningen av lustgas från kvävedioxid, svaveldioxid L.-G. and Lindqvist, O. Eurocare-Copal Report (EU och vattenånga. Börjesson, S. Projektarbete 20 p.. 316) (1990) 1-36. Institutionen för oorganisk kemi, Chalmers Tekniska 53. Anodic Dissolution of Lead in Perchloric Acid Solu- Högskola och Göteborgs universitet, 412 96 Göteborg tions: The Effect of Sulphuric Acid. Ahlberg, E. and (1990). Berghult, B. Electrochim. Acta 36 (1991) 197-201. 37. Luftföroreningarnas inverkan på byggnader och 54. Anodic polarization of galena in relation to flotation. monument. Ett söndervittrande Göteborg. Börjesson, Ahlbcrg, E. and Elfström Broo, A. Int. J. of Mineral S., Lindqvist, O., Lundgren, H. and Rosvall, J. Institute Processing 33 (1991) 135-143. of Conservation, University of Göteborg, Sweden, 55. The Rate-controlling Processes in the Oxidation of 1990:1 (1990). HIPpcd Si3N4 with and without Sintering Additives. 38. Oxidation of Silicon Nitride. Chen, J., Sjöberg, J., Chen, J., Sjöberg, J., Lindqvist, O., O'Meara, C. and O'Meara, C. and Pejryd, L. Proc. 1 lth Ris0 Sympo- Pejryd, L. Journal of the European Ceramic Society 7 sium on Metallurgy and Materials Science (cd. J J. (1991)319-327. Bentzen et al.) (1990) 439444. 56. The corrosion behaviour of HIP SJ3N4 and SiC/SiC 39. Electrochemical Studies on the Galcna/Xanthatc composite in simulated combustion environments. System, Relationship to Flotation. Elfström Broo, A. Chen, J., Sjöberg, J., O'Meara, C. and Pejryd, L. Proc. ISSN 0283-8575, Report OOK 90:03,1-27. 4th Int. Symp. Ceram. Mater. Eng. (cd. R. Carlsson) (1991).

MATERIALS SCIENCE, 1993 55 INORGANIC CHEMISTRY, CTH/GU

57. Atmospheric Corrosion on Silanc Treated Stones. 73. Neutron diffraction studies of Tl-2201 andTl-2212 Elfving, P. ISSN 0283-8575, Report OOK 91:04,1-57. doped with Lanthanum. Ström, C, Johansson, L.-G., 58. The formation of Sulfuric Acid, Nitrogen Monoxide, Eriksson, S.G., Kall, M., and Börjesson, L. Physica and Nitrous Acid on Gold in Air Containing Sub-ppm C185-189 (1991) 625. Concentrations of SO2 and NQ2. Eriksson, P. and 74. Neutron diffraction studies of Tl-2201, Tl-2212 and Y- Johansson, L.-G. J. Electrochem. Soc. 138 (1991) 123 doped with Strontium. Ström, C, Johansson, L- 1227-1233 G-, Eriksson, S.G., Kall, M. and Börjesson, L. Physica 59. Powder neutron diffraction studies of the structural C185-189 (1991) 623. changes induced by charge transfer substitutions in 75. Electrochemistry of carboxylic acids: mechanistic high-Tc superconductors of the types Y-123 and Tl- aspects of Kolbe-type reactions. Ahlberg, E. Supple- 2201. Eriksson, S.-G. and Ström, C. ISIS-report ment B: The Chemistry of Acid Derivatives 2, Ed. S. Rutherford-Appleton-Laboratory A42 (1991). Patai (1992) 1250-1270. 60. Neutron diffraction and Raman spectroscopic studies 76. Simulating Impedance Spectra from a Mechanistic of Y-123. Eriksson, S.-G., Johansson L.G., Ström, C, Point of View: Theory and Simulations. Ahlberg, E. Berastegui, P., Börjesson, L., Kali, M. and Kakihana, and Andersson, H. Acta Chem. Scand. 46 (1992) 1-14. M. Physica C185-189 (1991) 893. 77. Simulating Impedance Spectra from a Mechanistic 61. Thesis: The Chemistry Behind the Sulfur Dioxide Point of View: Application to Zinc Dissolution. Removal by Calcium Oxide in Fluidizcd Bed Coal Ahlberg, E. and Andersson, H. Acta Chem. Scand. 46 Combustion. Ghardashkhani, S. (1991) 1-73. (1992) 15-24. 62. Some aspects of calcium sulphite reduction with 78. General corrosion of alloy X-750 under BWR condi- carbon monoxide. Ghardashkhani, S. and Lindqvist, O. tions. Ahlbcrg, E. and Rcbensdorff, B. Water Chemis- Thermochim. Acta 190 (1991) 307-318. try of nuclear reactor systems 6,2 (1992), 278-285. 63. Reaction Rates of Trimethylethoxysilane and 79. Electrochemistry of sulphide minerals. Ahlberg,E., Trimethylmethoxysilane in Alkaline Alcohol Solu- Asbjömsson, J. and Elfström Broo, A. NUTEK B tions. Jäglid, U. and Lindqvist, O. Acta Chem. Scand. 1992:6,128-158. 45 (1*591) 887-891. 80. Corrosion of Water mains widi special respect to Iran 64. Fabrication and characterisation of highly pure and pipes. Bcrghult, B., Elfström-Broo, A., Hedberg, T. homogeneous YB^CirjOj. Kakihana, M., Börjesson, and Lind Johansson, E. Proc. 12:th Scan. Corr. Cong., L, Eriksson, S.G. and Svedlindh J. Appl. Phys. 69(2) Espoo Finland, May 1992,253-264. (1991). 81. Silanc Bonding to Various Mineral Surfaces. Elfving, 65. High-quality ceramics of YBa2Cu4C>8 from citrate sol- P. and Jäglid, U. ISSN 0283-8575, Report OOK 92:01. gel precursors sintered at one atmosphere oxygen 82. Thesis: Effects of SO2 and NO2 on metal surfaces: pressure. Kakihana, M., Kall, M., Börjesson, L., Atmospheric corrosion of copper and surface reactions Mazaki, H., Yasuoka, H., Bcrastegui, P., Eriksson, on gold. Eriksson, P. (1992). S.G. and Johansson, L.-G. Physica C173 (1991) 377- 83. Powder diffraction studies of substituted Y-124, Tl- 380. 2201 , Tl-2212 and (Ba,Nd)2(Nd,Cc)2Cu3O8-d. 66. Neutron diffraction and Raman spectroscopic studies Eriksson, S.-G., Ström. ISIS-report, Rutherford- of Y-123. K9II, M., Kakihana, M., Börjesson, L, Appleton-Laboratory A46 (1992). Ström, C, Johansson L.-G. and Larsson, T. Physica 84. Powder diffraction studies of the structural changes C185-189 (1991) 821. induced by charge transfer substitutions in high-Tc

67. Structural Changes in O'-Sialons, Si2.xAlxN2-xOi+x, superconductors of the types Y-123 and Tl-2201. 0-045xS040. Lindqvist, O., Sjöberg, J., Hull, S. and Eriksson, S.-G., Ström. ISIS-report, Ruthcrford- Pompe, R. Acta Cryst. B47 (1991) 672-678. Appleton-Laboratory A45 (1992). 68. Thesis: The Influence of Various Air Pollutants on the 85. Charge transfer and compression effects in Y-123. Sulfau'on of Calcareous Building Materials. Mangio, R. Eriksson, S.-G., Ström, C, Johansson L.-G. and (1991). Simon, A. Conference Proceeding, May 23-29,1992, 69. Structure and Properties of Calcium Sulfate Sulfiie Gaithcrsburg,USA.(1992).

Dodecahydrate. Mangio, R., Langcr, V. and Johansson, 86. A neutron diffraction study of YiBa2.ySryCu3.xMexO7. L.-G. Acta Chem. Scand. 45 (1991) 572-577. d (Mc= Co, Al, Fe), Eriksson, S.-G., Ström, C, 70. Mössbauer Study of the Site Preference for Fe Substi- Johansson L.-G., Simon, A. and Mattausch, Hj. tutions in Some YBa2Cu3<>7.y Compounds. Seidel, A., Conference Proceeding, May 7-10,1992, Nyborg, Häggström, L, Min, P., Eriksson, S. and Johansson, Denmark.(1992). L.-G. Phys. Scripta44 (1991) 71-73. 87. The influence of carbon monoxide on the reaction 71. Thesis: On the Preparation and Structure of O'-Sialons. between sulphur dioxide and calcium oxide. Sjöbcig.J. (1991). Ghardashkhani, S. and Lindqvist, O. Thcrmochim. 72. Refinement of the Structure of S12N2O. Sjöberg, J., Acia 195(1992) 113-128. Helgesson, G. and Idrestedt, I. Acta Cryst. C47 (1991) 88. The influence of O2 on the reaction between CaO and 2438-2441. SO2. Ghardashkhani, S., Lindqvist, O. and Tullin, C.

56 THE CENTRE FOR INORGANIC CHEMISTRY, CTH/GU

89. Snabb kvantitativ fasanalys av bränsleaskor. Langcr, 102. The effect of carrier concentration on structure and V. and Puromäki, K. Ptoc. Förpex-92,4-5 nov. 1992, Tc in TI-2212. The effect of carrier concentration on Chalmers University of Technology, Sweden. structure and Tc in TI-2212. S.- G. Eriksson, C. Ström 90. Characterization of ashes from wood and straw. and N. Winzek. Conference Proceeding, ICMAS-93, Öländers, B. and Steenari, B-M. ISSN 0283-8575, Paris-Mame-la-Vallee, France. Report OOK 92:03. 103. On the AC Impedance of the Amalgamated Zinc 91. Fasanalys och smällförlopp hos askor från bark/spän Electrode. Ahlberg, E. and Anderson, H., submitted for och halm. Öländers, B. and Steenari, B-M. Proc. publication. Förpex-92,4-5 nov. 1992, Chalmers University of 104. Simulating Impedance Spectra from a Mechanistic Technology, Sweden. Point of View: diffusion Effects in Metal Dissolution 92. Testmetoder för sten samt studie av några Reactions. Ahlberg, E. and Anderson, H. Acta Chem. konserveringsmedel för sten med hjälp av dessa Scand., submitted for publication. testmetoder. Ryberg, M. and Elfving, P. ISSN 0283- 105. Carbon Paste Electrodes in Mineral Processing: An 8575, Report OOK 92:05. Electrochemical Study of Galena. Ahlberg, E. and 93. Local structure of b'-sialons: an EXAFS study. Asbjörnsson, J. Hydrometallurgy, accepted for publica- Sjöberg, J., Ericsson, T. and Lindqvist, O. Journal of tion. materials Science 27 (1992) 5911-5915. 106. Polymerised complex synthesis of a pure 93 K 94. A neutron powder diffraction study of structural Y2Ba4Cu7Oi5.d superconductor without the need of changes in ^-xBaaCuOM and Tl2.xBa2CaCu2O8-d high oxygen pressure and additive catalysts. P. related to thallium and oxygen stoichiometry. Ström, Berastegui, M. Kakihana, H. Mazaki, H. Yasuoka, L- C, Eriksson, S.-G., Johansson L.-G. and Simon, A. G. Johansson, S.- G. Eriksson, L. Börjesson and M. Conference Proceeding, May 7-10,1992, Nyborg, Kail. J. Appl. Phys., accepted for publication. Denmark.(1992). 107. On the effect of thallium and oxygen stoichiometry 95. Neutron powder diffraction studies of structural in Tl-2201 and TI-2212 on structure and Tc. C. Ström, changes in Tl2.xBa2Cu0frd and Tl2.xBa2CaCu2O8.d S.- G. Eriksson, L.- G. Johansson, Hj. Mattausch, R. related to thallium and oxygen content. Ström, C, Kremer and A. Simon. Submitted for publication to Eriksson, S.-G., Johansson L.-G. and Simon, A. JSSC.

Conference Proceeding, May 23-29,1992, 108. Depression of Tc in Y-123 by a combination of Gaithersburg,USA.(1992). cobolt doping and oxygen depletion. S.- G. Eriksson, 96. Electrochemical study of surface oxidation and C. Ström and M. Kakihana. Physica C, submitted for collcctorless flotation of arsenopyrite. Wang, X.-H., publication. Ahlberg, E. and Forssberg, K.S.E. Journal of Applied 109. The influence of calcium and oxygen content on Electrochemistry 22 (1992) 1095-1103. superconducting properties in the Yj.yCayBa2Cu3. 97. An improved method of preserving and extracting xCoxO7.

72,(1993)125-131 110. Review on synthesis of cuprate based High-Tc 98. ^Tl NMR in oxygen depleted cuprate superconduc- superconductors by a polymerized complex method. tors Tl2Ba2CaCu2O8-dN. Winzek, Hj. Maliausch, S.- M. Kakihana, M. Yoshimura, H. Mazaki, H. Yasuoka, G. Erueson, C. Ström, R. Kremer, A. Simon and M. S.-G. Eriksson, P. Berastegui, C. Ström, M. Kail and L. Mehring. PhysicaC205,43 (1993) Börjesson. Jap. J. Appl. Phys., submitted for publica- 99. Charge transfer and compression effects of isomor- tion. phous substitutions in Y-123. M. Kakihana, S.-G. 111. Direct Quantitative Analysis of Mineral Matter and Eriksson, L.-G. Johansson, L. Börjesson and C. Ström. Different Pyritic Sulphur in Coal by Electron Probe Phys. Rev B47, march issue (1993) Micro Analyzer (EPMA) and Automatic Image

100. Control of carrier concentration in Y] .yCay Ba2Cu3_ Analyis (AIA). Shirazi A.R., Eklund L. and Lindqvist ,Co,07^. S.- G. Eriksson, C. Ström and M. Kakihana. O. To be published. Conference Proceeding, ICMAS-93, Paris-Mame-la- 112. Nilsson O. "A Bipolar, High Power Density, Lead Vallee, France. Acid Battery". To be published. 101. Structure and superconducting properties of

d, Yi .yCayBa2Cu3. 7.d. S.- G. Eriksson, C. Ström and A. Simon. Conference Proceeding, ICMAS-93, Paris-Mame-la-Vallec, France

MATERIALS SCIENCE, 1993 57 Reaction Dynamics

Research Summary 0.5 eV. This probably makes it the best electron The group has used extremely rapid desorption emitter available, giving experimental current densi- kinetics as a means of studying the dynamics of ties of >500 A/cm2 at 800 K. These experimental molecule-surface interaction, with the shortest results agree with theoretical quantum mechanical desorption time constants for alkali atoms measured predictions. down to 100 ns. In such a case, an atom jumps thermally on the average only 105 times before it leaves the surface. The alternative method of study- Address ing the dynamics of interaction between molecules Department of Physical Chemistry, GU and surfaces is to scatter a molecular beam off a Chalmers University of Technology surface. In the case of a heavy molecule and a light S-412 96 Göteborg, Sweden surface, like a graphite layer, the impinging mol- Phone+46 31 772 2832 ecule can not reverse its direction in one collision Fax+46 31 772 3107 with the surface. The dynamical insight gained in such experiments also made it possible to explain the long-standing problem of the rotational tempera- Staff tures of scattered molecules, often being much lower Senior Members: than the surface temperature. LeifHolmlid docent Under many conditions, electronically excited Jan Davidsson fil.dr. and thus easily field ionizable states like Rydberg Jan Pettersson fil.dr. states are formed in large densities in emission after diffusion through the bulk of graphite, or through a Graduate Students: thin surface layer of graphite on a metal. At low Jörgen Lundin civ. ing. densities, mainly ordinary Rydberg states are formed, Robert Svensson fil. lic. but at higher densities, electronically excited clusters Carina Åman civ.ing. are formed. Rydberg states are also formed at alkali Tony Hansson kemist promoted industrial catalyst surfaces at ordinary Elisabeth Wallin kemist operating temperatures, for example at the iron- Klas Engvall fil lic based ammonia catalyst. The new information on Bo Olsson kemist emission energies and kinetics of desorption of alkali from catalysts has even made it possible to deduce the detailed internal energetics for alkali in Technical Staff: Benny Lönn Research Engineer the catalysts. Thomas Hessel Technician From a material point of view, a very interesting development is the stabilization of an excited type of matter. This new type of matter is formed from Secretary condensing Rydberg states, and it is thus called Maj Levin (shared with the department) Rydberg matter. Macroscopic amounts of such a matter can be stabilized in vacuum for hours. Prop- erties like conductivity and work function have been studied. Rydberg matter has very special properties, as expected, for example the work function is below

58 THE CENTRE FOR REACTION DYNAMICS

Major Instrumentation C: Electronically excited matter • Surface scattering UHV apparatus with rotat- participants: J. Davidsson, L. Holmlid, B. able (120°) quadrupole mass spectrometer (m/ Olsson, J.B.C. Pettersson, R. Svensson, E. z 250), SIMS ion gun at 2.5 keV with Wallin, C. Åman, L. Lundgren rastering, three stage differentially pumped collaborators: Kurchatov Institute, Moscow; molecular beam source for 1 bar pressure with JSB Ingenjörsbyrå, Trosa chopper • Desorption and surface scattering UHV appa- ratus with rotatable detectors (360°): Research Projects Quadrupole mass spectrometer (m/z 200), A: Surface - molecule interactions Weak field ionization detector, Surface ioniza- Al: DesoiptkMi and diffusion kinetics tion detector, and a differentially pumped of alkali metals on graphite alkali metal molecular beam source with and metal surfaces chopper Ordinary pyrolytic graphite surfaces (basal surfaces) • Desorption apparatus with linear time-of-flight have many special properties compared to metal mass spectrometer for cluster studies, at time surfaces: they are extremely inert even at high tem- resolution of <1 ms peratures, they adsorb many molecules without dis- • Apparatus for surface desorption studies at sociating them, and they allow rapid migration into surface life-times down to 30 ns with the field the surface, eventually giving macroscopic interca- reversal technique lation. The complicated energetics for alkali atoms • Apparatus for cluster formation studies with on graphite surfaces has been studied with high quadrupole mass spectrometer resolution at extremely short desorption life-times. • Open thermionic energy converter (TEC) for Desorption from metal surfaces with small islands of surface and Rydberg matter (condensed graphite is studied, showing preferential desorption ) studies through the islands after diffusion on the surface • Pulsed Nd:YAG laser (8 ns), with frequency [10]. Laser desorption is used to study the desorption doubling processes at very low temperatures, giving together • Infra-red diode laser (lead salt laser) 6 orders of magnitude in the rate constants [311. With spectrometer for molecular spectroscopy, line- rapid kinetics and time-of-flight, it is shown that a width 0.001 cm-i large part of the ioniza tiontakin g place isdue to field ionization of Rydberg states, and not to surface ionization [17]. In fact, it is likely that the process Major Reids of Research believed to be surface ionization does not exist at all. A: Molecule-surface Interactions participants: T. Hansson, L. Holmlid, G. A2: Surface scattering from graphite surfaces Nyman, J.B.C. Pettersson The special vibrational properties of the basal sur- collaborators: Ecole Polytechnique, Paris; face of graphite and the energy transfer at the surface Fysikalisk kemi GU have been studied by surface scattering. In the case of a heavy molecule and a light surface, like a B: Electronic excitation of atoms graphite layer, the impinging molecule has to make and molecules at surfaces several jumps on the surface, which is seen in the participants: J. Davidsson, T. Hansson, L. scattering angular distributions for Xe and SF6 [6]. Holmlid, J. Lundin, A. Kotarba, B. Olsson, The much studied "rotational cooling" of NO mol- J.B.C. Pettersson, E. Wallin, C. Åman ecules scattered from graphite has been explained as collaborators: State University of Ghent; due to the very small lateral energy barriers on the Jagiellonian University, Cracow; Norsk Hydro surface coupled to angular momentum conservation a.s., Chemetall GmbH [8]. The angular distributions for argon and nitrogen cluster beam scattering from graphite have been measured in another laboratory. The clusters are

MATERIALS SCIENCE, 1993 59 REACTION DYNAMICS

heated at surface impact and fragmentize depending formation of Rydberg stateson industrial catalysts is on the available energy. This fragmentation process certainly coupled to the loss of alkali promoter in the has been studied with classical trajectory calcula- process [24], but maybe also to the promoter func- tions, and is well described by evaporation of small tion, as predicted previously [5]. Angular resolved fragments from the parent cluster [32]. desorption is used to identify also cluster formation and desorption from the catalysts [24,27]. Novel surface scattering features are observed, as well as B. Electronic excitation of atoms and angular patterns for ion desorption which resemble molecules at surfaces channelling, with lobes of a few degrees width [27,30]. Similar behaviour is also found for metallic Bl: Rydberg states of alkali and hydrogen catalysts. at graphite surfaces due to bulk diffusion The emission of alkali atoms from high temperature surfaces gives a large fraction of electronically ex- C: Electronically excited matter cited atoms, partly in Rydberg states [1]. This is expected since the surface-vacuum interface is not in Cl: Excited clusters of alkali metal thermal equilibrium. Also the ions are excited and and hydrocarbons even negativeexcited ionscan be formed [4]. Rydberg At higher densities of Rydberg states outside sur- atoms will interact strongly with surfaces, and they faces, the extremely large interaction potential be- will probably diffuse rapidly into the material. This tween the Rydberg states gives rise tocluster forma- type process was observed previously in kinetics tion. The masses of the field ionized clusters are studies, but is now observed in a beam-surface determined by time-of-flight mass spectrometry, experiment [28]. Also hydrogen molecules give and typical clusters obtained contain 4,000-10,000 Rydberg states in diffusion sources, and the tempera- Csatoms[7],ormassesof 10,000-200,000 a.u. in the ture dependence as well as the time dependence at case of hydrocarbon molecules [23]. The source the detector are studied [16,25]. The time constants used to form such clusters employs diffusion through of the field ionization process are measured, and a carbon foil [19]. Also the emission of alkali from turns out to be similar to ordinary radiation lifetimes metal oxides (heterogeneous catalysts) gives rise to [12]. Other excited states of cesium can also be formation of clusters [24,27]. formed under some conditions, giving Cs2+ in field ionization [2]. By forming surface layers from C2: Surface layers of condensed Rydberg states of alkali, it iseven possible to observe excited states (Rydberg matter) the ion H2. in a mass spectrometer [18]. This ion is If beams of Rydberg and other electronically excited not stable in its ground state, and thus the observed states like clusters impinge on surfaces, quite stable state must be in a Rydberg state, which can have a surface layers of excited states can be formed. Such much longer life-time. layers can be observed when they deexcite explo- sively, giving off visible light [11]. They can also be B2: Rydberg states of alkali promoter observed from the current given off to the support at catalyst surfaces when the impinging beam is cut off [25]. Further, Many commonly used heterogeneous catalysts are they can be employed to give surfaces with low work promoted with alkali. One very common class con- functions, which can transfer electrons to molecules tains metal oxides, and this type of porous catalyst is to give negative ions [18]. shown to emit large fluxes of Rydberg states at ordinary process temperatures. The first examples C3: Rydberg matter studied is an iron oxide catalyst used for styrene An excited form of matter can be formed by conden- production [9,14], and the vanadium oxide catalyst sation of Rydberg states, as predicted by theory. for SO3 production [15]. The complicated internal Macroscopic amounts, several mm3, of so called energetics for alkali in the complex and porous Rydberg matter can be formed easily and maintained catalyst material is studied in detail. Field ionization for many hours in experiments where excited states is used to identify the Rydberg states [22]. The of cesium are formed in contact with a carbon

60 THE CENTRE FOR REACTION DYNAMICS covered surface! 13]. Rydberg mattercan be formed 4. "Large fluxes of highly excited ions from a at temperatures of 500-800 K by this method, and it diffusion source". T. Hansson, C. Äman, J.B.C. Pettersson and L. Holmlid, J. Phys. B: At. Mol. Opt. can be observed and studied. The resistivity is low, 2 Phys. 23 (1990)2163-2171. of the order of 10- - 10-3 Q m [13]. The work function is very low, at least smaller than 0.7 eV and 5. "Alkali promoter function in heterogeneous catalysis: probably smaller than 0.5 eV [21]. These results possibility of interaction in (he form of Rydberg agree with theoretical calculations by a group at states", J.B.C. Pettersson, L. Holmlid and K. Möller, Appl. Surface Sci. 40 (1989) 151-154. Kurchatov Institute in Moscow. The potential distri- bution in a sheath of Rydberg matter has been studied 6. "Inelastic surface scattering of Xe and SF<, from [26] and agrees with the other results. A technical graphite surfaces at high temperatures", J.B.C. application of Rydberg matter is developed, and a Pettersson, A. Sigurdsson, G. Nyman and L. Holmlid, patent is applied for [20] in the form of an improved Surface Sci. 232 (1990) 329-338. thermionic energy converter. When Rydberg matter 7. "Field ionizablc cesium metal clusters from a foil is formed inside an electrode with small opening in diffusion source". C. Åman, J.B.C. Pettersson and L. it, Rydberg maner leaks out to the outer surface, Holmlid, Chcm. Phys. 147(1990) 189-197. giving very low work functions at high tempera- tures. This type of construction is intended for a 8. "Surface scattering of NO from graphite: a statistical novel electrode for use in magnetohydrodynamic description of energy distributions", G. Nyman, L. Holmlid and J.B.C. Pettersson, J. Chcm. Phys. 93 energy converters [29]. (1990)845-853.

9. "Mechanism of loss by dcsorplion from an iron oxide catalyst for the styrcne process", J. Lundin, K. Engvall, L. Holmlid and P.G. Menon, Catal. Letters Publications 6(1990)85-94.

Ph. D. Dissertation 10. "Rate constants for cesium desorption and lateral J.B.C. Pettersson, "Excitation of atoms and molecules at diffusion on indium with graphite islands: parallel surfaces: inelastic scattering and excited state emis- processes studied by field reversal", T. Hansson, J.B.C sion". (1990). Pettersson and L. Holmlid, Surface Sci. 253 (1991) 345-352. Licentiate Dissertations R. Svensson, "Highly excited states in an electronically 11. "Visible luminescence from panicles on surfaces: controlled thermionic energy converter". (1990). evidence of decxcilation of Rydberg matter", J.B.C. Pcttcrssson, H. Lindroth, C. Åman and L. Holmlid, J. Mat. Research 7 (1992) 100-104. K. Engvall, "Experimental studies of industrial alkali doped catalysts: emission of excited alkali species". (1992). 12. "Rydberg states of caesium from a diffusion source: pulsed field ionization and life-times", C. Åman and L. Reports and articles Holmlid, J. Phys. D.: Applied Physics 24 (1991) 1049- 1053. 1. "Rydberg states of cesium in the flux from surfaces at high temperatures", J.B.C. Pettersson and L. Hoimlid, 13. "A semi-conducting low pressure, low temperature Surface Sci. 211 (1989) 263-270. plasma of cesium with unidirectional conduction", R. Svensson, L. Holmlid and L. Lundgren, J. Appl. Phys. 2. "Sampling of a hot Cs plasma with a QMS in a 70(1991)1489-1492. thermionic energy converter", J. Lundin and L. Holmlid, "Advances in Mass Spcctromctry", Vol. 11A 14. "Comparative loss of alkali promotor by desorption (Ed. P. Longevialle), Heyden & Son, London, 1989, p. from two catalysts for the dchydrogenation of ethyl 204-205. benzene to styrene", K. Engvall, L. Holmlid and P.G. Mcnon, Appl. Catal. 77 (1991) 235-241. 3. "Surface ionizauon at atmospheric pressure. II. Particles of inorganic alkali salts and of sodium 15. "L iss of alkali promoter by desorpuon from promoted dodecyl sulphate", L. Holmlid and S. Wall, Langmuir 5 vanadium oxide catalysis", K. Engvall, L. Holmlid, H. (1989)1170-1175. Prinz and H. Hofmann, Catal. Letters. 11 (1991) 41 -48.

MATERIALS SCIENCE, 1993 61 REACTION DYNAMICS

16. "Excited states of hydrogen emitted from a graphite 25. "Highly excited Rydberg states of hydrogen from a diffusion source: Arrhcnius behaviour", E. Wallin and high temperature diffusion source", E. Wallin, T. L. Holmlid, Chem. Phys. 159 (1991) 313-319. Hansson and L. Holmlid, J. Phys.: Condensed Matter (9) (1992). 17. "Field ionization of cesium atoms diffusing out from an indium foil, studied by time-of-flighi mass 26. "Temperature studie 5 and plasma probing of a Rydberg spectrometry", E. Wallin, T. Hansson and L. Holmlid, matter collector in a thermionic energy converter", R. Int. J. Mass Spectrom. Ion Proc. 114 (1992) 3145. Svensson and L. Holmlid, Paper No. 929430,27rd Inicrsociety Energy Conversion Engineering Confer- 18. "Negative ions tormed at grid surfaces in a flux of ence, (IECEC 1992, San Diego), Society of Automo- excited Cs atoms and ions", J. Lundin and L. Holmlid, tive Engineers, Warrcndalc 1992, Vol. 3, p. 537-542. Int. J. Mass Spectrom. Ion Proc. 114(1992) 137-147. 27. "Dcsorption and emission of potassium Rydberg atoms 19. "Source for excited states of alkali atoms and clusters and clusters from iron oxide catalyst surfaces". C. using diffusion through a thin graphite foil", L. Åman and L Holmlid, Appl. Surface Sci. (1992). Holmlid, J.B.C. Pettersson, C. Aman, B. Lönn and K. Möller, Rev. Sci. Instrum. 63 (1992) 1966-1968. 28. "Large hysteresis effect in surface ionization of Cs due to bulk diffusion", T. Hansson and L. Holmlid, Surface 20. "Kollcktor med lågt uurädesarbetc för Sci. (1992). teimojonomvandlare". L. Holmlid and R. Svensson, Patent application nr 9102263-2. Accepted. 29. "High emissivity electrodes for MHD channels", R. Svensson, K. Engvall, L. Holmlid, J. Braun and L. 21. "Very low work function surfaces from condensed Lundgren, 1 lth International Conference on MHD excited states: Rydberg matter of cesium", R. Svensson electrical power generation, Beijing, 92-10-12-16. and L. Holmlid, Surface Sci. 269/270 (1992) 695-699. 30. "Field ionization of Rydberg alkali states outside iron 22. "Field ionization of excited alkali atoms emitted from oxide catalyst surfaces: peaked angular distributions of catalyst surfaces", K. Engvall and L. Holmlid, Appl. ions", C. Åman and L. Holmlid, Appl. Surface Sci. Surface Sci. 55 (1992) 303-308. (1992).

23. "Hydrocarbon clusters from a foil diffusion source", C. 31. "Rate constants for thermal cesium ion dcsorpiion on Åman and L. Holmlid, J. Cluster Sci. (1992). clean and graphite-covered indium studied by laser- induced desorption", T. Hansson and J.B.C. Pettersson, 24. "A new approach to loss of alkali promoter from Surface Sci. 269/279 (1992) 189-194. industrial catalysts: importance of excited states of alkali", L. Holmlid, K. Engvall, C. Åman and P. G. 32. "Dynamics of cluster scattering from surfaces", J.B.C. Menon, International Congress of Catalysis, Budapest Pettersson and N. Markovic', Chcm. Phys. Letten 1992. Oral presentation, to app&. < in proceedings (1992). volume.

62 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE Chemical Analysis

Research Summary Address The emphasis of R&D work at the department of Swedish National Testing and Research Institute Chemical Analysis is on the development of instru- Chemical Analysis mentation and methods that allow specific proper- Box 857 ties or compositions of materials and products to be S-50I 15 Boras, Sweden measured such that unambiguous interpretation of Phone+46 33 165000 the results can be made. Another theme is the close Fax+46 33 12 37 49 examination of some particular property of materi- als cr groups of products that influence the suitability for their end use. Staff The main areas of R&D may be referred to as Senior Members 'Indoor Air quality', 'Energy-Environment', 'Poly me- Björn Lundgren fil.dr., head of department ric Materials' and 'Building Materials' (inorganic). Karin Berglund ing. Measurements of emissions of organic compounds, Lars Cedheim fil.dr. in particular formaldehyde from e.g. chip board, and Hans Gustafsson apotekarex. VOC (volatile organic compounds) from e.g. floor- Lars Johnson fildr. ing materials, is a continuing contribution to efforts Margret Månsson docent for creating a sound indoorenvironment. Characteri- Claus R0yem fiLlic. sation of fuels of various types, lately in particular Lars Winnerstam civ.ing. gasoline and diesel fuels (e.g. its total content of polyaromatic hydrocarbons), is one theme related to Secretary considerations of the environment in general. An- Sonja Mozer-Rosell other theme that has been, and is focused on is the tracing of residues ot CFC from the manufacturing of polymeric foams. Major Instrumentation Life-cycle studies are becoming part of the R&D work. Also, characterisations other than determina- • ICP Emission Spectrometer, Chus R0yem tions of composition and ordinary physical proper- • WD-XRF, Lars Winnerstam ties are getting increasingly important for various • NMR, Lars Cedheim type residues as a basis for decisions on their safe use • Flame AAS, Graphite-Furnace AAS, in new applications rather than having to be paid for Claus R0yem as land-fill. • GC-MSD,GC-ECD,GC-FID, Lars Johnson Another R&D field for analytical chemistry is the • HPLC,GPC,IC,TLC, Lars Cedheim preparation of samples and/or preseparation of com- • Elemental analysers: C-H-N, C-S, S, ponents required before qualitative as well as quanti- Karin Berglund tative analysis can be made. In a number of p* ojects • Emission chambers (VOC, formaldehyde) 3 dealing with the characterisation of polymeric mate- 1 and 17 m , Björn Lundgren rials, e.g. in determinations of type and amount of • Bomb Combustion Calorimeter, plasticizers, fillers, antioxidants and other additives Margret Månsson to polymers, the design and checking of such pre treatment is the more demanding part. Only limited direct access for external users, but co- operative programs are possible.

MATERIALS SCIENCE, 1993 63 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - CHEMICAL ANALYSIS

Major Fields of Research Al: Held and Laboratory Emission Cell - FLEC Development of a small, easy-to-handle emission cell for measurement of volatile organic compounds A: Indoor Air Quality emitting from planar materials. The cell is designed Participants: Björn Lundgren, Hans Gustafsson, for use in the laboratory, on site in buildings, and for Ingrid Isaksson, Lars Johnson, Bengt Jonsson, Lars product developmentandproductioncontrolofbuild- Roseli ing materials. The construction of the cell ensures a Collaborators: CTH, KTH, SBI (Denmark) and uniform air velocity over the enclosed surface of the Groups in Europe test material. A protocol for measurements with FLEC has been defined. Developed in co-operation B: Energy - Environment with AMI and SBI in Denmark. Participants: Bjöm Lundgren, Margret Månsson, Karin Berglund, Lars Cedheim, Jolanta Karlsson, A2: European Investigation on the Comparability Peter Marstorp, Karl-Axel Olsson, Lars Winnerstam of Large Chamber Tests on Formaldehyde Emissions from Wood Based Panels C: Polymeric Materials This is one example of joint efforts at the European Participants: Bjöm Lundgren, Lars Cedheim, Per level to establish to what extent experimental condi- Blomqvist, Per Lindberg, Margret Månsson tions in terms of chamber volume, material of Collaborators: CTH construction of the chambers, dimensional propor- tions, air velocity, technical handling etc. lead to significant differences in the results obtained. Large Research projects chamber volumes vary e.g. between 12 and 80 m3. Other European projects aim at establishing correla- 3 A: Indoor Air Quality tions between results obtained using 'small' (1 m or A number of projects can be referred to under this less) and between small and large chambers. heading. They represent a) development/compari- sons of equipment and techniques for measuring A3: Characterisation of Chemical Emissions from Concrete Admixtures chemical emissions from products or materials, b) This project is a study of whether and to what extent studies of various types of emissions from groups of concrete admixtures contribute to indoor air che- products and c) examinations of amounts and types mical emissions from building materials. of organic compounds in indoor air. - Also, consult list of publications. A4: The Effect on Flooring Materials from Damp Concrete FLEC - Sampling for measurements A study of how and to what extent damp concrete of emissions of VOC. effects P.ooi" covering materials. The measurements at SP are concerned with the effects on the chemical emissions from the flooring materials. Three types of vinyl flooiing and one linoleum material are in- cluded in the study. The concrete moisture levels chosen are those corresponding to 95 %, 85 % and 50% RH, respectively. Measurements (FLEC) are planned for 54 combinations of material-'moisture level'.

A5: Experiences from the Development of Low-Emission Building Materials In this project available general knowledge and experience from the development of low-emission materials and constructions is to be summarised for

64 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - CHEMICAL ANALYSIS

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g 0,2 ^ • • • r •EBB» • 0,1 J " • " " •

n * 1 1 1 h 1 1 1 —1 1 1 0.1 0.2 0.3 0A 0,5 0.6 0.7 0.8 0,9 oJrchanges per hour

TVOC as a function of the degree of ventilation for the individual home. the benefit of the 'users' (architects/designers, build- B: Energy - Environment ers, building contractors etc.). Efficient ways of distributing this information between various Bl: Polyaromatic Hydrocarbons in Diesel Fuels branches of the building industry and producers of For environment/tax purposes diesel fuels are as- building material are to be developed. signed to different classes depending on among other things their content of polyaromatic hydrocar- A6: Air quality In residential housing bons (PAH). In this project a method for measuring A survey of indoor air quality in 40 to 50 one-family the total amount of PAH was designed. The method houses built in the period 1983 - 1990. The study in fact also defines what is meant by "total PAH includes determinations of the total amounts of content". The determinau'ons had to be reasonably volatile organic compounds (TVOC) with identifi- .ample to carry out. The uncertainty of the measure- cation of major components and measurements of ments must of course be small enough to allow the actual ventilation for comparison with the regu- proper differentiation according to the classification latory values for this type of houses. system for the fuels.

MATERIALS SCIENCE, 1993 65 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - CHEMICAL ANALYSIS

10 15 20 30 35 PAH in diesel fuels - HPLC method: D = PAH, reversal of flow at R. (A- aliphatic, B- benzene and C- naphtalene type hydrocarbons).

B2: Calorimetrfc Determinations of Energies/ C: Polymeric Materials Enthalpies of Combustion (Calorific Values) Bomb calorimetric measurements is an area where Cl: Chromatographic Preseparation of Chemical analysis has a lot of experience from Components in Polymeric Materials measurements of high accuracy toroutine determina- Equipment was installed and tested, and strategies tions on liquid and solid fuels. Lately, projects were designed for the separation of components concerned with the revision/rewriting of standard prior to analysis of products based on polymeric methods (ISO 1928; solid fuels) and devising in- materials. The chromatographic techniques utilised struction material for this type of measurements on are TLC, HPLC, SEC and open column chromatog- materials other than fuels (Nordtest; building mate- raphy. -An optical densitometer and equipment for rials) have been carried out. quantitative TLC-analysis were added to the exist- ing analysis system.

C2: Methods of Analysis for Trace Amounts of CFC In Polymeric Foams When restrictions in Sweden on the use of CFC in the manufacturing of polymeric foams were comple- mented by import restrictions on CFC-manufactu- red foams, analytical methods for tracing CFC residues were required to make such legislation meaningful. It had been shown in a previous project that trace amounts of CFC could be traced also in foams with open cells where CFC has only been a manufacturing aid and not an intended component of the product.

66 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - CHEMICAL ANALYSIS

7. "CFC in Polymeric Foams, Tracing CFC Residues Publications from the Manufacturing" Mats Olsson, Margret Månsson Björn Lundgren, Nordic Council of Minis- Diploma woik ters, Miljörapport 1989:3. Ellen Ekelund: "Bestämning av svavel, fosfor och bly i bensin med plasmaemissionsspektroskopi (ICP)", SP-AR 8. "Methods of Analysis for Trace Amounts of CFC in 1992:20. Spring 1992. Polymeric Foams" Olle Jacobson, Margret Månsson, Mats Olsson, Nordic Council of Ministers, Nord Reports and articles 1991:17. 1. "Building Materials Identified as Major Sources for Indoor Air Pollutants - A Critical Review of Case 9. "Nedbrytning av glykoler i värmepump och Studies" Hans Gustafsson, Byggforskningsrådet, solvärmesystem. Laboratorieundersökning" Lars D10:1992. Cedhcim, Ulla Blume, Björn Lundgren, Byggforskningsrådet, R107:1988. 2. "Byggnadsmaterial och emissioner" Hus & Hälsa - Kunskapsbas: U6.1992, BFR. Björn Lundgren, Hans 10. "Fysikalisk-kemiska studier av tillsatsmedel i polymera Pettersson m fl. material" Lars Cedheim, SP Report 1989:30.

3. "Field and Laboratory Emission Cell: FLEC" P. 11. "Förlaga till reviderad ISO 1928 för kalorimetriska Wolkoff, P.A. Clausen, P.A. Nielsen, H. Gustafsson, bestämningar av värmevärdct fär festa bränslen" B. Jonsson, E. Rasmusen, Conf. Proceedings 'Healthy Margret Månsson, Värmeforsk, SVF438. Buildings' Sept. 4-8,1991; p 160-165. Washington, D.C.USA. 12. "Determinations of Calorific Va'ues of Building Materials - A Guide" Margret Månsson, Nordtest 4. "Review of Small Scale Devices for Measuring proj.871-90,SP Report 1991:15. Chemical Emission from Materials" Hans Gustafsson, Bengt Jonsson, SP Report 1991:25.5. "Formaldehyde 13. "Miljörclatcradc egenskaper 'ios eldningsoljor. En Contents in Swedish Chipboard. A Comparison kvalitctsundcrsökning" Karin Berglund, Elisabeth between Different Laboratories" Rune Ziethén, Bengt Ekberg, Margrel Månsson, Mats Rignell, Jonsson, SP Report 1989:25. Naturvårdsverket Rapport 4013.

6. "Materialval och kemiska emissionsdata" Hans Gustafsson, AMA-NyU Mark • Hus 2/92, p 40 - 43.

MATERIALS SCIENCE, 1993 67 Polymers and fibres

Materials Physics 70 Polymer Technology 78 Polymeric Materials 87 Polymer Technology and Surface Protection/Corrosion - Swedish National Testing and Research Institute, SP 95 The Swedish Institute of Fibre and Polymer Technology, IFP-TEFO 102 The Swedish Institute of Fibre and Polymer Technology, IFP-PGI 106

MATERIALS SCIENCE, 1993 69 Materials Physics

Research Summary Address Our research program concerns structure and dy- Department of Physics namics of disordered systems (glasses, polymers, Chalmers University of Technology ceramics, etc.) especially energy related materials S-412 96 Göteborg, Sweden (ion conducting glasses, polymeric electrolytes, high Phone +46 31 772 3176 temperature superconductors, etc.) using laser light Fax+46 31 772 3177 and neutron scattering methods. The light scattering investigations are performed at Chalmers using advanced Fabry-Perot-, Raman-, and photon corre- Staff lation techniques. Neutron scattering is performed at Senior Members the international facilities at ISIS (Oxford) and ILL Lena M. Torell professor (Grenoble). Lars Börjesson docent Seeking to explain the dynamics of the glass Staffan Schantz fil. dr (-90) transition we investigate various glassformingmate- Per Jacobsson fildr 12 rials over the enormous time range of 10- s to Is. David Sidebottom dr We show that by changing the network forming ability of the glass, the dynamics is changed in a Graduate Students systematic way, as reflected in the relaxation func- Staffan Schantz filkand. (-89) tion (non-exponential in time, non-Arrhenius in Mats Elmroth fil.kand. temperature). Comparisons are made to recent theo- Mikael Kall civ.ing. ries for the liquid-glass transition, e.g. hierarchical vs Jan Swenson fil.kand parallel relaxation theories, mode-coupling etc. Rikard Bergman fiLkand It is found that ion conducting glasses exhibit Britta Matsson civ.ing strong correlations in the intermediate range order. Dennis Engberg civ.ing This suggests that the dopant salt forms a percolating Abdel Hassan M.Sc. network which is decoupled from the host glass and proposed to be fractal. Such an interconnected sub- structure may provide the conduction path way which Major Instrumentation allows for the anomalously high ionic conductivity. • Lasers: Spectra Physiscs Ar-lasers, He-Ne lasers In the work on polymeric electrolytes we inves- and dye lasers, equipped for single-mode tigate structural properties for an optimized charge operation. transport. We demonstrate that the unfortunate and much debated conductivity drop at large salt concen- • Fabry - Perot Interferometers: Pressure scanned trations is due to crosslinking phenomena which single-pass interferometer (model Hilger & Watts); Piezo electrically scanned triple-pass result in reduced ionic mobility. interferometer (model Burleigh); Piezo electri- Raman experiments on high-Tc superconductors cally scanned six-pass tandem interferometer reveal direct correlations between Tc and the lattice (model Sandertock). vibration frequency of the bridging oxygen atoms between CuO2 superconducting planes and CuO • Raman spectrometers. Spex double monochro- chains in samples of YBa2Cu3O7-d subject to oxy- mator equipped with third monochromator. gen deficiency or selective substitution. 1 he results Spex triple spectrograph. strongly support recent charge transfer m xlels for high temperature superconductivity. • Raman Microprobe (Nikon Instruments)

70 THE CENTRE FOR MATERIALS PHYSICS

Photon Correlation Equipment. ALV 5000 E: High temperature superconductors photon correlator. Participants: Lars Börjesson, Mikael Kall, Alexander Litvinchuk (Dr MPI, Stuttgart, Detectors. 2-dim CCD-detectors (Wright Germany), Girsh Blumberg (Dr Estonian Instruments); cooled photomultiplier-detectors. Acad. Sci ), Hoang Van Phuong Cryostats (4K-700K)/furnaces (300-1500K) (M.Sc., Hanoi Univ. Vietnam), Lee Van Hong Oxford instruments developed for light scatter- (Dr. Hanoi, Univ. Vietnam), Masato Kakihana ing. (Prof, Tokyo Inst. Techn., Japan) Collaborators: Robert McGreevy (Clarendon Lab, Oxford, England), Niels Hessel Andersen Major Fields of Research (Risö National Lab., Denmark), Gunnar A: Structural glasses and the glass transition. Johansson (Dr, Inorganic Chemistry, CTH), Participants: Lena Torell, Lars Börjesson, Mats Peter Svedlind (Dr, Teknikum, Uppsala Un.) Elmroth, Dennis Engberg, Abdel Hassan David Sidebottom (Dr, Kansas State Univ., USA), Matthias Fuchs (Dr. Univ. Munich, Research Projects Germany) A: Structural Glasses and the Collaborators: Austen Angell (Prof, Arizona Glass Transition St. Univ., USA) Aldo Fontana(Prof, Trento Univ., Italy) Al: LJght Scattering Our main interest in glassforming liquids concerns B: Polymers structural relaxation processes of liquid state mo- Participants: Lena Torell, Lars Börjesson, tions, and how the out of these motions is Rikard Bergman, Per Jacobsson, Mats Elmroth, causing the glass transition. The variation in relaxa- Jim Stevens (Prof, Guelph Univ., Canada) tion times, observed during of liquids Collaborators: Alexander Brodin (Dr, Univ. which fail tocry stallize, is enormous, some 15 orders Kiev, Uraina), Spencer Howells (Dr, ISIS, U.K.) of magnitude. To follow processes over such a broad C: Fast ion conducting glasses time range a wide variety of experimental techniques Participants: Lena Torell, Lars Börjesson, Mats are needed. We combine different light scattering Elmroth, Abdel Hassan, Jan Swenson methods; Raman (10-'5-10-i2s), Brillouin (10-'2- 7 2 Collaborators: Aldo Fontana (Prof, Trento Univ., 10-9s), and photon correlation (10" -10 s). Elect- Italy), Reneé Vacher (Prof, Univ. Montpellier, rical and mechanical spectroscopies are performed France), Robert McGreevy (Dr, Clarendon by our collaborators over a wide frequency range. Lab., Oxford, U.K.), Spencer Howells (Dr, We find that the structural relaxation time vs ISIS, U.K.), Kurt Sköld (Prof, Studsvik, temperature is independent of the detailed micro- Sverige) scopic liquid structure-, data from different materials of the same group of glassforming systems fit the D: Polymeric electrolytes same curve when using the glass transition tempe- Participants: Lena Torell, Lars Börjesson, rature as a scaling parameter. However, systematic Staffan Schantz, Dennis Engberg, Britta differences occur when changing the intermediate Matsson, Greger Pedersén, Per Jacobsson, Jim range connectivity as observed in studies of a wide Stevens (Prof, Gueiph Univ., Canada), Masato range of materials from "strong" network glass- Kakihana (Dr, Tokyo Inst. of Techn, Japan) formers of covalent bondings via "intermediate" Collaborators: Bruno Scrosati (Prof, Rome polymeric glasses of entangled networks to "fragile" Univ., Italy), Michel Armand (Prof, ENSEEG, molecular and ionic glasses held together by weak France), Colin Vincent (Prof, Univ. St. Aidrews, van der Waals or Coulomb forces. The experimental U.K.), Michel Smith (Prof, Lisbon Univ., data have been used förtests of recent theories for the Portugal) liquid glass transition especially the so called mode- mode-coupling theory recently proposed by prof.

MATERIALS SCIENCE, 1993 71 MATERIALS PHYSICS

A. Sjölandei (CTH) et al. and by prof. W. Götze C: Fast Ion Conducting Glasses (Miinchen Univ.) et al. The model gives a com- Cl: light Scattering pletely new scenario for glass formation for both The increasing interest in vitreous FICS (fast ion structural glasses and spin glasses. conducting solids) is due to favourable properties as solid electrolytes in various technical applications, A2: Neutron Scattering especially as candidates for microbatteries devel- The neutron scattering project on glasses aims at oped for future 3D integrated circuits. The project investigating the dynamics around the glass tran- concerns studies of structure and dynamics of ion sition from studies of simple model systems. As conducting glasses, especially the mechanism for discussed above (Al) this is currently a hot topic of ion diffusion. Also, two level system (TLS) relaxa- experimental as well as theoretical interest (mode- tions at low temperatures (<10K) are investigated. coupling-, percolation-, parallel vsconstrained mod- In vitreous FICS, a remarkable decoupling of the els etc). So far quasi-elastic scattering studies have modes of motion of the mobile ions from those of the been performed on molecular glasformer, propylene ions, which make up the solid glassy matrix, has carbonate and iso-propylbenzene (at ISIS, Oxford). occurred. This is demonstrated by the decoupling of An ionic glassformer Ca-K-N(>3 has been investi- the structural relaxation time of the glassforming gated by the neutron spin-echo technique (at ILL, matrix from the relaxation time due to fast ion Grenoble). The observations support the suggestion diffusion, which both have been determined over a of a"new"critical temperature for glass formation in wide time range from 10-'] s to hundreds of seconds. accordance with mode-coupling predictions. The decoupled ionic motion can be explained by the existence in the glass of a sub-network of the dopant B: Polymers salt (see C2 below). It is this substructure which may Theproject concerns studiesof elastic propertiesand supply a connected network for ionic diffusion. mechanical stability in relation to crosslinking, polymerization, polymer mixing etc. The short time C2: Neutron Scattering and dynamics is investigated on the microscopic level to Computer Simulations relate the local intrachain flexibility of the polymer For the neutron scattering program we use the interna- backbone (microscopic viscosity) to the overall tional facilities at ISIS (Oxford) and ILL (Grenoble). mechanical stability (macroscopic elasticity). From Our diffraction studies show a feature in fast ion investigations of polymers of increasing molecular conducting glasses which now is much discussed; a weight we find that despite changing the macro- strong and anomalous diffraction peak at very low q icopic behaviour from a fluid to an elastomer by in the doped (conducting) glass, which is absent in increasing the chain length, the elastic properties the undoped (nonconducting) glass. The effect im- (sound velocity,compressibility,elasticmoduliietc.) plies strong structural correlations in the conducting are unchanged and seem to depend exclusively on glass. It may be attributed to an interconnected the local molecular mobility within the polymer network of the dopant salt, which is decoupled from chain. In contrast it is found that stabilizing a low the glassy matrix and which supplies the conducting molecular weight fluid of the same polymer by pathways for the fast ion transport. Percolation and/ crosslinking then the sound velocity increases rap- or fractal effects of such a structure are currently idlyandmonotonically with thenumber ofcrosslinks. investigated. Extensivecomputersimulations, using From studies of the structural dynamics we show the experimental data as constraints, are also per- that one can define a monomer viscosity which formed. behaves like the viscosity of a"fragile" glass former. The classification of glassformers based on a corre- D: Polymeric electrolytes lation of structural fragility with distribution of re- The research field of polymeric electrolytes is a laxation times (non-exponentiality of relaxation pro- relatively new area, which is rapidly expanding. This cess) relevant for non-polymeric liquids is being is mainly due to applications such as thin film solid extended to polymers. state batteries for electrical vehicles. The light scat- tering studies on ion conducting polymers are aim ing at investigating the two most essential properties

72 THE CENTRE FOR MATERIALS PHYSICS for a solid electrolyte, namely the mechanical stabil- We have been particularly interested in metal ion ity and the ion mobility. This includes structural as well as dynamical measurements. The project is the and Tl based cuprate superconductors. This offers bases for a Brite-Euram collaboration program. opportunities for selective studies of the roles of the So far polyethers (PPO and PEO) of various CuCVplanes, the charge buffer layers (CuO chains, molecular weights complexed with different alkali BiO or T1O planes and the CuO chains) and inter- metal salts have been investigated. Dramatic changes mediate layers for the superconducting properties. of the elastic properties are observed with increasing Among the most interesting results is that Raman salt content. It is found that the dissociated salt ions experiments give strong indications of a charge act as crosslinking centers. As a result the viscosity transfer mechanism; e.g. in YBa2Cu3O7-d the CuO is dramatically increasing and the ion mobility is chains act as charge reservoirs and provide the decreasing. We show that it is this effect which superconducting planes with holes through a charge causes the much discussed drop in the conductivity transfer involving lattice vibrations. Any disturbance at large salt content. Another effect influencing the of the chains by atomic substitutions (Co, Fe, Al) or conductivity is ion pairing phenomena. We demon- oxygen deficiency alters the delicate charge balance strate that the amount of free ions, ion-pairs and between the chains and the planes and destroys the multiple aggregates can be quantified by Raman efficiency of the charge transfer and therefore scattering. It is found that the temperature behaviour depresses superconductivity. of the ion-ion associations are strongly dependent on The superconducting gap is probe by electronic the cation valency of the dopant salt. It is contrary to Raman scattering or by phonon self energy effects. what existing models suggest. In YBa2Cu4Og samples where Y is partly substituted by Pr it is found that Tc is directly proportional to the E: Hlgh-Tc Superconductors size of the gap. The project is directed towards an understanding of the basic physical properties of high-Tc supercon- ductors. Our main interest concerns light scattering (Raman and Brillouin) studies of phonons, magnons and electronic excitations. Many complementary experimental techniques (including sol-gel prepa- ration techniques, chemical analysis, neutron- and x- ray diffraction, magnetic and resistivity techniques) are applied to the same samples. The program is part of an EC project (SCIENCE program).

New batteries are needed for the electrical car and the polymer battery is a strong Free Li candidate. The figure demonstrates the presence of "free" solvated ions and aniorv cation pairs in the polymer electrolyte LiBr (PEO)io- The amount of solvated ions should be maximised to obtain a large number of charge carriers and a high ionic conductivity. LiBr pair New polymer electrolytes, designed within an EC-program, are characterised on the molecular scale by the Materials Physics Group at Chalmers using laser light, neutron scattering, and computer simulation techniques. FreeBr

MATERIALS SCIENCE, 1993 73 MATERIALS PHYSICS

Publications 8. L.M. Torell and S. Schantz, Light Scattering in Polymer Electrolytes, in Polymer Electrolyte Reviews-2, eds. J Jt. MacCallum and C.A. Vincent, (Elsevier, London PH.D. Dissertations and New York 1989) p. 1. S. Schantz, Light Scattering in Polymer Electrolytes, (1990) 9. J. Sandahl, S. Schantz, L. Börjesson, L.M. Torell and J.R. Stevens, Elastic and Dynamic Properties of Licentiate Dissertations Polymer Electrolytes; a Brillouin Scattering Study of S. Schantz, Raman and Brillouin Scattering Studies of Ion Poly (Propylene Glycol) - NaCF3CF3 Complexes, J. Conducting Polymers, (1989) Chem.Phys.,91,655, (1989)

Diploma Works 10. M. Kakihana, J. Sandahl, S. Schantz and L.M. Torell, Mats Johansson, PerPedersen: Ramanspridning frän Optical Spectroscopy in Polymer Electrolytes, Proc. jonledande polymerer (1989) 2nd InL Symp. on Polymer Electrolytes, Elsevicr, (1989). Nils Addim-Addo, Peter Josefsson: Brillouin spridning från polymera etectrolyter (1991) 11. M. Kakihana, S. Schantz, B-E Mellander and L.M. Ola Stenlund, Optimization of lens systems (1991) Torell, Temperature Dependence of the Charge Carrier Dennis Engberg, Uppbyggnad av ett Raman microprobe Generation in Polymer Electrolytes; Raman and system (1991) Conductivity Studies of Poly (Propylene Oxide)- L1CIO4 Proc. 2nd Int. Symp. on Polymer Electrolytes, Reports and articles Elsevier, (1989). 1. L. Börjesson, U. Dahlborg, W.S.Howells and L.M. 12. M. Grimsditch and L. M. Torell, Opposiie ;r. reme Torell, Evidence of anomalous intermediate- range structural relaxation behavior in glassformcrs; a ordering in superionic borate glasses from neutron Brillouin scattering study of B2O3 and Cao.4 K0.6 diffraction., Phys. Rev. B39,3404 (1989). (NOj)i.4, in Dynamics of disordered materials, eds. D. Richter, A. J. Dianoux, W. Pctry and J. Tcxcira, 2. S. Schanlz, Thesis, (1990), Light scattering in polymer (Springer Proc. in Physics, 37, Springer 1989) p. 196. electrolytes. 13. M. Kakihana, L. Börjesson, S. Eriksson, P. Svcdlindh 3. L. Börjesson, M. Elmroth and W. S. Howells, Interme- and P. NorJing, Raman spectra, superconductivity and diate range structural ordering in silver-halide doped structure of Co-substituted YBa2Cu3O6+d., Phys. Rev. oxide glasses, In "Basic features of the glassy state", B40,6787, (1989). Eds. J. Colmenero and A. Alegria (World Scientific, Singapore 1989)p. 93. 14. M. Grimsditch, R. Bhadra and L. M. Torell, Shear waves through the glass-liquid transformation., Phys. 4. L. Börjesson, L.M. Torell and W. S. Howells, Brillouin Rev. Lett. 62,2616 (1989). scattering and neutron diffraction in ion-conducting glasses., Philosophical Magazine B59,105, (1989). 15. S. Eriksson, L-G. Johansson, L. Börjesson and M. Kakihana, Oxygen content and structural properties of 5. M. Elmroth, L. Börjesson and L.M Torell, Structural some Ba-Cu oxides, PhysicaC 162-164,59-60, (1989). relaxation in glassforming liquids, u* "Static and Dynamic Properties of Liquids", eds. M. Davidovic 16. S. Eriksson, L-G. Johansson, L. Börjesson and M. and A. K. Soper, (Springer Proc. in Physiscs 40, Kakihana, Investigations on oxygen content and Springer-Verlag, Berlin 1989) p. 118. ordering in Yl(Ba,Sr)2(Cu,Co)307-5 superconductors by means of wet chemical analysis, x-ray and neutron- 6. L. Börjesson, Low frequency light scattering in lithium diffraction techniques, Phy sica C162-164,73-74, (1989). borate glasses; A cross-over from phonons to fractons? Springer Proceedings in Physics, Vol. 37 Eds. D. 17. M. Kakihana, L. Börjesson, S. Eriksson, P. Svedlindh Richter, A. J. Dianoux, W. Petry and J. Texeira and P. Norling, Synthesis of highly pure YBajCujOy-d (Springer-Verlag 1989)p.316. superconductors using a colloidal processing tech- nique, PhysicaC 162-164,931-932, (1989). 7. L. Börjesson, L.M. Torell and J.R. Stevens, Reply on "Comment on Brillouin scattering study of structural 18. M. Kakihana, L. Börjesson, L. M. Torell and S. G. relaxation in poly(propylene-glycol) 10000., Polymer Eriksson, Phonon Raman scattering and structure of Co 30,370,(1989). substituted YBa2Cu3O6+5,PhysicaC 162-164,1245- 1246,(1989).

74 THE CENTRE FOR MATERIALS PHYSICS

19. M. Kakihana, L. Börjesson and S. G. Eriksson, Raman 31. S. Schan x. On the ion association at low salt concen- scattering and x-ray diffraction in Ni and Zn substituted trations ,n polymer electrolytes; a Raman study of YBa2Cu306+6, Phys. C162-164,1251-1252, (1989). NaCF3$O3 and LiClO4 dissolved in poly(propylene oxide), J. Chem. Phys., 94 (1991) 6296. 20. M. KJ;hana, L. Börjesson and S. Eriksson, The influence of oxygen variation on Raman scattering and 32. S. Schantz, J. R. Stevens and L. M. Torell, Ion pairing x-ray diffraction from BaCuO2-5, Phys. C 162-164, effects in poly (propylcnc glycol)-salt complexes as a 1253-1254,(1989). function of molecular weight and tempcrturc; a Raman scattering study using NaCF3SO3 and LiClO4., 21. L. Börjesson and W. S. Howells, Intermediate range J. Chem. Phys., 94 (1991) 6862. structural ordering in Agl doped supcrionic glasses: A neutron diffraction study. Solid State Ionics 40/41, 33. L. M. Torell, L. Börjesson and M. Elmroth, On the 702-704, (1990). non-exponentiality vs non-Arrhcnius behaviour of the structural relaxation in glassforming liquids., J. Phys. C 22. M. Kakihana, S. Schantz and L.M. Torell, Raman 2,207(1990). spectroscopic study of ion-ion Interaction and Its Temperature Dependence in a PPO-Bascd NaCF3SQ3- 34. P. Jacobsson, L. Börjesson and L. M. Torell, When is a Polymcr Electrolyte, J. Chem. Phys., 92,6271, (1990). polymer a polymer? A light scattering study of crosso- ver from viscous fluidlikc behaviour to chain con- 23. J. Sandahl.L. Börjesson, J. R. Stevens and L. M. Torell, strained dynamics, J. Non-Cryst. Solids, 131-133 Elastic and dynamic properties of a poly (propy Icne (1991)104. glycol)-Lithium perchloratc electrolyte: A Brillouin scattering study, Macromolecules (1990) 23,163. 35. M. Kakihana, L. Börjesson, S. Eriksson and P. Svcdlindh, Fabrication and characterization of highly 24. M. Kakihana, S. Schantz, J.R. Stevens and L.M. Torell, pure and homogeneous YBa2Cu3O7-5 from sol-gel Dissociated Ions and Ion-ion interactions in Poly derived powders, J. Appl. Phys., 69,867, (1991). (Ethylene Oxide) based NaCFsSQj Complexes., Solid State Ionics, 40/41,641-644, (1990). 36. M. Kakihana, L. Börjesson and S. G. Eriksson, Phonon characterization of YBaiCi^Oy-S doped with Al and 25. L.M. Torell, S. Schantz and P. Jacobsson, Raman study Ga by Raman spectroscopy, Physica B 165 & 166 of free volume effects on ion pairs in polymer electro- (1990)1245-1246. lytes, Proc. MRS-Socicty Fall Meeting, Boston, (1990). 37. M. Kakihana, L. Börjesson and S. G. Eriksson, Effect 26. S. H. Chung, K. R. Jeffrey, J. R. Stevens and L. of Sr and Co doping on structure and phonon Raman Börjesson, Dynamics of silver ions in (Agl),, (Ag2 O.n spectra of YBa2Cu307-5, Physica B 165&166 (1990) 8203)1-x glasses: A'°9 Ag nuclear magnetic resonance 1247-1248 study, Phys. Rev. B41,6154, (1990). 38. J. R. Stevens and P. Jacobsson, A comparison of 27. M. Kakihana, L. Börjesson, L. M. Torell and S. acetone and poly (propylcnc glycol) as solvents for Eriksson, Raman scattering from metal (Co, Ni and lithium inflate and lithium pcrchloratc, Can. J. Chem., Zn)- substituted YBa2Cu3O7-S., Physics and Materials 69,1980(1991). Science of High Temperature Superconductors, eds. R Kossowsky et al. (Kluwer 1990), p. 581-593. 39. L. Börjesson, M. Elmroth and L. M. Torell, Neutron and light scattering study of relaxation dynamics in a 28. S. Schantz, M. Sandberg and M. Kakihana, NMR glass-forming fragile molecular liquid, Cheni. Phys. study of a polypropylene oxide) - NaCF3SQ3 polymer 149,209(1990). electrolyte, Solid Stale Ionics 40/41,645-647, (1990). 40. G. A. Niklasson, K. Brantcrvik and L. Börjesson, 29. L. M. Torell and S. Schantz, Structural relaxation and Conductivity relaxation in silver iodide - silver boralc chain flexibility in polymeric ion conductors, J. Non- glasses, J. Non-Cryst. Solids, 131 (1991) 10%. Cryslalline Solids, 131-133, 981-989,(1991). 41. L. Börjesson and W. S. Howells, Incoherent 30. C.A. Angell, L. Monncric and L.M. Torell, Strong and quasiclastic neutron scattering of propylcnc carbonate fragile behaviour in liquid polymers, Symp. Mat. Res. in the glass instability range, J. Non-Cryst. Solids, 131 Soc., Ed. J. M. O'Reilly, 215,3 (1991). (1991)53.

42. L. Börjesson, M. Elmrolh and L. M. Torell, A Brillouin scattering study of an extremely "fragMc" molecular glassformcr, J. Non-Cryst. Solids, 131 (1991) 139.

MATERIALS SCIENCE, 1993 75 MATERIALS PHYSJCS

43. L. Börjesson and W. S. Howclls, Incoherent Quasiclas- 55. D. Sidcbottom, R. Bergman, L. Börjesson and L.M. tic Neutron Scattering Study of the Dynamics around Torell, Photon correlation study of liquid-glass transi- the Glass Transition in iso-Propylbcnzcnc, ISIS Annual tion in poly (propylcnc glycol), and Polym. Report 1990,(Rutherford-Appleton Laboratory, Sci. (in press). England, 1990). 56. P. Jacobsson, G. Pctersen, L. Börjesson and L.M. 44. L. Börjesson and W. S. Howclls, Neutron Diffraction Torell, Structural relaxation characteristics of super- study of Supcrionic Glasses, ISIS Annual Report 1990, cooled polymeric liquids. Colloid and Polym. Sci. (in (Ruthcrford-Appleton Laboratory, England, 1990). press).

45. S. H. Chung, K. R. Jeffrey, J. R. Stevens and L. 57. A.K. Hassan, L.M. Torell, L. Börjesson, and H. Börjesson, Non-Exponential Dynamics of Silver Ions Doweidar, Structural changes of B2O3 in the liquid- in Silver Iodide Doped Silver Borate Glasses Through glass transition range ; A Raman scattering study, NMR, Solid Slate Ionics 40/41,279-283 (1990). Phys.Rcv.B, 45,12797 (1992).

46. M. Kakihana, M. Kall, L. Börjesson, H. Mazaki, H. 58. M Kakihana, S-G. Eriksson, L. Börjesson, L-G. Yasuoka, P. Berastegui, S. Eriksson and L-G. Johansson and C. Ström, Charge transfer and compres- Johansson, High-Quality Ceramics of YBa2Cu4Og sion effects of isomorphously substitutions in from Citrate Sol-Gel Precursors Sintered at one 8, Phys. Rev. B (in press). Atmosphere Oxygen Pressure, Physica C 173,377-380, (1991). 59. M. Kakihana, H. Mazuki, H. Yasouka and L. Börjesson, Polymerized Complex Synthesis and 47. L. Börjesson, The Structure of Salt Doped Superionic intergranular coupling of Bi-Pb-Sr-Ca-Cu-O supercon- Oxide Glasses by Neutron Diffraction, Solid State ductors, characterized by complex magnetic suscepti- Ionics, Volume 210, (1991). bility, J. Appl. Physics, 71,3904 (1992).

48. L. Börjesson and R. McGrccvy, Disorder in Co doped 60. M. Kakihana, H. Mazaki, H. Yasouka, L. Börjesson, YBa2Cu3O7, ISIS Experimental Report, (Ruthcrford- M. Kail and S. Eriksson, Effect of carrier concentration Appleton Laboratory, England, 1991). on the superconductivity properties of Bi2Sr2Cuj- 4, Physica C (in press). 49. L. Börjesson and R. McGrccvy, Network breaking and structure modification in alkali silicate glasses, ISIS 61. S-G. Eriksson, L-G. Johansson, C.Siröm, L. Börjesson, Experimental Report, (Rutherford-Applcton Labora- M. Kall, M. Kakihana, Neutron diffraction and Raman tory, England, 1991). spcciroscopic studies of Y-123, Physica C 185-189, 843,(1991). 50. 1. Albinsson, P. Jacobsson, B-E Mcllandcr, and J. R. Stevens, Ion association effects and ionic conduction in 62. M. Kall, L. Börjesson, M. Kakihana, C. Ström, L-G. polyalkalcne modified polydimcthyl siloxancs, Solid Johansson, S. Eriksson and T. Larsson, Changes in the State Ionics (in press). apical oxygen vibrational frequency and Tc due to Sr doping for Ba in YBa2Cu3C*7-y, T12Ba2CuO6-y and 51. L. Börjesson, W.S. Howclls and R. McGrcevy, Fractal Tl2Ba2CaCu2Og-y superconductors, Physica C 185- aspects of supcrionic glasses from Reverse Momc 189,821,(1991). Carlo simulations, Phil. Mag. 65,261, (1992). 53. C. Ström, M. Kall, L. G. Johansson, S-G. Eriksson and 52. M. Kakihana, M. Yoshimura, H. Mazaki, H. Yasuoka L. Börjesson. Neutron diffraction studies of Tl-2201, and L. Börjesson, Synthesis of cupratc based High-Tc TI-2212 and Y-123 doped with strontium, Physica C superconductors by polymerized complex method, !85-189,623,(1991). Mat. Res. Soc. Symp. Proc. (in press). 64. C. Ström, M. Kall, L. G. Johansjon, S-G. Eriksson and 53. L. Börjesson and W.S. Howclls, Quasictastic neutron L. Börjesson, Neutron diffraction studies of Tl-2201 scattering study of the Ag+ diffusion in a superionic and TI-2212 doped with lanthanum, Physica C 185- boratc glass, ISIS Ann'ial Report, (Ruthcrfoid- 189,625,(1991). Applcton Laboratory, England, 1991). 65. L. Börjesson, R. L. McGrccvy and J. Wicks, The 54. D. Sidcbottom, R. Bergman, L. Börjesson, and L. M. structure of supcrionic glasses frooi neutron diffraction Torell, Observation of scaling behaviour in the liquid- and Reverse Monte Carlo simulations, J. Phys (Paris), glass transition range from dynamic light scattering of (in press). poly(propyleneglycol), Phys. Rev. lett.,68,3587 (1992).

76 THE CENTRE FOR MATERIALS PHYSICS

66. K. Kakihana, M. Yoshimura, H. Mazaki, H. Yasuoka, 75. S. Schantz and L.M. Torell, Evidence of dissolved ions S. Nishio, Y. Suzuki and L. Börjesson, Structural and and ion pain in dilute poly(propyleneoxidc)-salt physical properties of rare earth (R) substituted solutions, Accepted for Solid State Ionics. RBa2Cu(Og-S superconductors, J. Metals and Alloys (in press). 76. P. Bcrastegui, M. Kakihana, H. Mazaki, H. Yasuoka, L-G. Johansson, Eriksson, L. Börjesson, M. Kail, and 67. L. Börjesson, R. L. McGreevy, L. M. Torell, W.S. M. Yoshimura, Polymerized complex synthesis of a Howells, Diffuse neutra scattering studies of disorder pure 93-K YzBajCuvOis-g superconductor without the in high-Tc superconductors, Physica B 180-181,443, need of high oxygen pressure and additive catalysts, J. (1992). Appl. Phys. (in press).

68. A.K. Hassan, LM. Torell and L. Börjesson, A Raman 77. P. Berastegui, L-G. Johansson, M. Kail and L. study of B2Q3 through the liquid-glass transition range, Börjesson, Structure of Y(Pr)Ba2Cu4Og; A neutron J. Phys. (Paris) (in press). diffraction study, Physica C (in press).

69. M. Elmroth, L. Börjesson and L.M. Torell, Observa- 78. P. Jacobsson, I. Albinsson, B-E. Mcllandcr, and J.R. tion of a dynamic anomaly in the liquid-glass transfor- Stevens, Ion association effects and phase separation in mation range by Brillouin scattering, Phys. Rev. Leu. polypropylene oxide) modified poly(dimcthylsiloxanc) 68,79,(1992). complexcd with triflatc saks. ftalynKsr, 33,2779, (1992).

70. G. Petersen, P. Jacobsson and L.M. Torell, A Raman 79. L. Börjesson, L. Van Hong, M. Kall, M. Kakihana, and study of ion-polymer and ion-ion interactions in low P. Bcrastegui, The effects of Co substitutions for Cu in

molecular weight polyethcr - LiCT^SQ} complcxe, YBa2Cu3O6+x on the phonon Raman spectrum, J. Electrochimica Acta, 37,1495 (1992). Metals & Alloys (in press).

71. L.M. Torell, P. Jacobsson, D. Sidcbottom and G. 80. L. Ben-Dora, M. Szerera, G. B.'umberg, A. Givana, Petersen, The importance of ion-polymer crosslinks in L.V. Hong and L. Börjesson, Physical Charactcrizaton polymer electrolytes, Solid State Ionics 53-56,1037 and vihrational spectroscopy of Bi(Pb) cupratc 2212 (1992). ceramics prepared by the sol-gel method, Physica C 200,418,(1992). 72. M. Andersson, L. Börjesson, T. Jarlborg, H. V. Phuong and ö. Rapp, Relations between Cu(l) - 0(4) distance 81. N.H. Andersen, J.V. Andersen, L. Börjesson, R.

and Tc in Yi.2xCaxThxBa2Cu3O7-5: Raman scattering Hadficld, M. Kakihana, R.L. McGrccvy, O.G. and calculation of the electron phonon interaction, Mourilsen and H.F. Pouslen, Structure and conductivity

Phys. Rev. B 46,6501, (1992). in Co, Fc, Al doped YBa2Cu3O6+x., •>• Mclal and Alloys (in press). 73. S-G. Eriksson, C. Ström, L-G. Johansson, L. Börjesson and M. Kakihana, Powder diffraction studies of 82. J.D. Wicks, R.L. McGrccvy, and L. Börjesson, The

substituted Y-124, Tl-2201, Tl-2212 and determination of the structure of (AgI)x(AgPC»3)i.x by ,3aJ4d)2(Nd,Ce)2Cu3Og+8, ISIS, Annual Report 1992 a combination of X-ray and neutron diffraction data, J. (Rutherford-Applelon Lab. England 1992). Non-Cryst. Solids (in press).

74. L.M. Torell, P. Jacobsson and G. Peterson, \ Raman 83. M. Kakihana, M. Yashima, M. Yoshimura, M. Kali study of ion soivau'on and association in polymer and L. Börjesson, Invited review paper: "Application electrolytes, Accepted for Polym. Advanced Techn. of Raman spectroscopy in phase characterization of (PAT), "Special Issue on Ion Co ductivity in Polymer" advanced ceramic materials: High-Tc superconductors (in press). and zirconir. ramies", To appear in 'Trends in Applied spectroscopy" (World Scientific).

MATERIALS SCIENCE, 1^93 77 Polymer Technology

Research summary related to specialized use of bulk polymers, such as The general theme of the research within the depart- polyethylene, polypropylene and PVC. One exam- ment concerns relations between macromolecular ple is crosslinking by pero\ides or silanes, which structure and physical properties, and problems re- increases mechanical properties at increased tem- lated to production, processing ai.d end-use are peratures. We are also studying PVC with increased investigated. We continously work to increase our heat stability, which may lead to decreased u?- of resources for and competence on characterization of heat stabilizers containg heavy metals. To obtain polymer structure, e.g. characterization of different polyethylene with specific properties copolymcrs parameters by GPC, NMR, FTIR and ESCA. With with functional groups are investigated. relation to physical properties we have specific competence in relaxation, both on molecular (NMR, dielectric spectroscopy) and macroscopic (dynamic Address mechanical spectroscopy) levels. In many cases the Department of Polymer Technology research is performed in close cooperation with Chalmers University of Technology industry concerning more fundamental aspects of S-412 96 Göteborg, Sweden industrial relevant problems. Phone+46 31 772 3420 The activities can be grouped in three different areas. Fax+46 31 772 3418 One concerns synthesis and modification to obtain functional polymers. For such polymers the me- chanical properties are not the most important, but it Staff is instead other properties such as optical or electrical Senior members that are of interest. We are studying electrically B. Helgeé fil.dr. conducting polymers, in particular processable sys- P. Gatenholm docent tems, e.g. poly(3-alkyl thiophenes) and related poly- T. Hjertberg prof. mers. The work concerns both aspects related to CKhoo Ph.D processing (stabilty, degradation, blends) and more F. Maurer prof. fundamental aspects (structure, photoluminescence). S. Schantz fil.dr. We are also involveo in synthesis of liquid crystal- R. Shishoo adj. prof. line polymers of the side-chain type, for which properties such as ferroelectricity and piezoelectric- Graduate students ity are of interest. The second area is related to L-E. Ahlstrand fil.kand. surface properties of polymers, in particular the P. Bjellheim civ.ing. effect of molecular interactions across interfaces and C. Bonnerup civ.ing. mobility of interphases influences on the properties T. Chih.- ii civ.ing. of the whole system. This is studied both in 2- H. Eklind civ.ing. dimensional (laminates, lacquering of polymes) and J. Felix civ.ing. 3-dimensional (polymer blends, composites) sys- C. Frennfelt civ.ing. tems. The activities on blends and composites are I. Gustavsson civ.ing. done as an interdisciplinary cooperation within the L-K. Kulin fil.kand. materialsconsortium Interfacial Interactions in Poly- N. Ljungqvist civ.ing. meric Materials. The kno^l "*dge obtained is applied A. Nihlstrand civ.ing. in a project on recycling of polymers. The third area M. Palmlöf civ.ing. concerns more fundamental studies of problems M. Rogestedt civ.ing.

78 THE CENTRE FOR POLYMER TECHNOLOGY

M. Sandberg civ.ing Dynamic mechanical spectrometer for torsion A. Schmid civ.ing mesurements on solid samples and melts; S. Sigurdursson civ.ing temperature range -150 - +500°C; frequency A. Smedberg civ.ing range 0,001-500 Hz. K. Strandqvist civ.ing Contact person: Frans Maurer. A. Strålin civ.ing Positron annihilation lifetime spectroscopy for M. Svensson civ.ing free volume hole size (1-10 Å) determination. L. Ulrén civ.ing Contact person: Frans Maurer. M. Wallenius civ.ing Technical staff M. Björklund Major Reids of Research A. Mårtensson A. Rempling A. Polymer synthesis C. Sjögren participants: B. Helgeé, T. Hjertberg, N. Ljungqvist, A. Wendel M. Sandberg, A. Schmid, M. Wallenius. M. Ågren collaborators: Dept. of Physics and Measurement Secretary Technology, Linköping University; Research Inst. M. Huldén for Polymers and Textiles, Tsukuba, Japan; Liquid C. Meyer Crystal Group; CTH; Dept.of Organic Chemistry, CTH; Dept. of Chemical Technology, Trondheim UniversityofTechnology;CorporateResearch,Neste Major Instrumentation Oy, Finland. • GPC for determination of molecular weight distributions; 2 systems with on-line viscosity B. Surface properties of polymers and light scattering detectors (solvents: TCB at participants: C. Bonnerup, H. Eklind, J. Felix, P. 140°C and THF at 25°C); three smaller room Gatenholm, T. Hjertberg, C. Khoo, F. Maurer, A. temperature systems. Nihlstrand, S. Schantz, A. Strålin, Contact person: Lars-Inge Kulin. collaborators: Dept. of Polymeric Materials, CTH: Polymer Group; Lunds University; Dept. of • 300 MKz NMR spectrometer, besides solution Macromolecular Science; Case Western Reserve measurements the instrument is also equipped University, Cleveland, USA; Ecole Polytechnique for high resolution solid state NMR (CP-MAS Montreal, Montreal, Canada; Neste Chemicals, Fin- NMR) at variable temperature. land and Belgium; Granges Teknik, Finspång; Contact person: Staffan Schantz. TetraPak, Lund; Teknisk Utveckling, Volvo, • hi IK spectrometer, transmission and reflectane Göteborg; measurements (ATR, RAS, DRIFT); tensile tester for in-line orientation. C. Bulk polymers Contact person: Anders Mårtensson. participants: L-E.Ahlstrand, T. Hjertberg, L-I. Kulin, F. Maurer, M. Rogestedt, A. Smedberg • ESCA for surface analysis (shared with dept. collaborators: Neste Polyeten, Stenungsund, Swe- of Engineering Metals). den; Norsk Hydro, Stenungsund, Sweden, Porsgrund, Contact person: Anne Wendel. Norway • DSC (calorimeter) and TGA (thermobalance) for thermal ananlysis. Contact person: Lars-Inge Kulin.

MATERIALS SCIENCE, 1993 79 POLYMER TECHNOLOGY

Research projects Chemical and polymeris characterization is car- ried out using NMR, FTIR, DSC (differential scan- A. Polymer synthesis ning calorimetry) and SEC (size exclusion chroma- tography). Al: Conducting polymers The aim of this project is to synthesize stable and A3: Polymer gels processible electron conductive polymers, and to A polymergel consists of polymerchains connected study applications for these materials. The work is together in a network. The crosslinks may be of directed towards different 3-substituted polythio- either physical or chemical nature, e.g. crystallinity phenes. Alkyl groups introduce flexiblity, which e.g. or covalent bonds, respectively. The aim of this allow melt processing. This will, however, also lead project is to study separation properties of porous to a rapid conductivity loss at increased tempera- polymer gels. Mainly, the work hasconcemed chemi- tures, thermal undoping. At present, we are synthe- cally crosslinked networks based on trimetylol- sising polythiophenes with different substituents propantrimetacrylate (TRIM). By applying differ- and substitution patterns, which shows that it is ent comonomers orderivatization different surface possible to combine processiblity and stability in proeprties are also obtained. these polymers. Another part of the project concerns The gels are characterized with respect to their processing blends of these polymers and non-con- porosity and the pore size distribution. Apart from ductive matrix polymers. The main issues are to normal techniques such as mercury intrusion and learn the relation between the morphology and the nitrogen absorption, information about the pore struc- conductivity, and to be able to control the phase ture is also obtained by studying the separation effect structure via the interactions between the phases. in size exclusion chromatography. Gels modified by The project is a direct collaboration with the depart- chelating groups are evaluated for protein separa- ment of Organic Chemistry, also including close tion. By cooperation with prof. John Ugelstad in cooperation with Neste Corporate Research, Fin- Trondheim we are also evaluating monodisperse land, and the department of physics and measure- particles in SEC. ment technology, LiTH. B. Surface properties A2: Side chain liquid crystalline polymers This project on liquid crystalline polymers (LCP) is Bl: Surface modification of polymeric materials focused on ferroelectric LCP:s and is a joint project The projects concerns surface modifications of pri- between the department of PolymerTechnology and marily polyolefin based materials by use of primers, the Liquid Crystal Group at the physics department. wet chemistry methods and plasma treatment and Synthesis and characterization of both starting and plasma polymerization. Surface modifications of polymeric materials 'akes place at the department of polymers are important for designing specific sur- PolymerTechnology, while the evaluation of prop- faces which might be crucial in many applications. erties like electro-optic effects, piezo- and The project is directed towards two different appli- pyroelectricity and the like, is carried out at the cations where the surface properties is an essential Liquid Crystal Group. factor, lacquering of termoplastic elastomers based LCP:s with polysiloxanes as backbone polymers on polypropylene and biocompatibility of polymer have been synthesized and systems based on materials used in the medical area. Changes in the polyacrylates, polymetacrylates and polyesters will surface structure are studied by methods such as also be made. One objective of the project is to ESCA, SIMS, FTIR and contact angle measure- synthesize self supporting LCP systems with either ments. The project involves collaboration with the linear or crosslinked backbone polymerchains. When Institute of Surface Chemistry and Volvo Technical it comes to the mesogeneic groups the aims are to Development. synthesize units that give rise to high spontaneous polarization in the chiral smectic C phase.

80 THE CENTRE FOR POLYMER TECHNOLOGY

B2: Laminates between polyethylene polymer blends. This is done by studying thin poly- and aluminium mer films, 50-800 Å thick, with e.g. FTIR, DMTA Within this project the effect of molecular interac- and NMR. The mechanical properties can then be tions across the interface on the adhesion is studied explained by the properties of the interphase and an for laminates between polyethylene and aluminium. ultimate goal is to achieve custom-made properties Polyethylene is nonpolar and does not contain any of a blend by controlling the properties of the groups that can form specific interactions with the interphase. The project is a part of a material consor- aluminium oxide on the metal surface. The adhesion tium, Interfacial Interactions in Polyn.sric Materi- is therefore very low, but still this assembly is used als, consisting of members from Chemical Technol- in large quantities for packaging. It is a good example ogy at Lund Institute of Technology and the depart- that properties of two materials can be used in a ments of Polymer Technology and Polymeric Mate- synergistic way, in this case the barrier properties of rials at Chalmers University of Technology. The the aluminium foil and the sealing capacity of the co'.sortium hasongoingcooperation with Max Planck polymer. In the industrial production of these lami- Institute for Polymer Research, Mainz, Germany, nates the surface of the polymer is oxidised by high and Dept. of Macromolecular Science, Case West- temperature procssing in order to solve the problems ern Reserve University, Cleveland, USA. with adhesion. The oxidation creates a surface layer with several different groups containing oxygen B4: Adhesion between cellulose and polymers such as hydroxyl, carboxylic acid, ketone and alde- Interfacial interactions and their influence on the hyde, which can form stronger interactions with adhesion between cellulosic materials and synthetic aluminium. It has not been known to what extent polymers are investigated in this project. Common different groups contribute to the increased adhe- applications for these multicomponent systems are sion. found in the packaging industry and automotive Using FTIR reflection absorption spectroscopy industry. The major aim is to elucidate important (RAS), we are studying the formation of specific adhesion mechanisms and to optimize and evaluate molecular interactions across the interface between methods for increasing interfacial interactions. In the materials. Systems giving different kind of inter- order to fully understand the interaction balance, a actions are investigated. To introduce specific groups thorough surface characterization of all components at the polymer surface ethylene copolymers with has to be carried out. We use ESCA and FTIR for polar and reactive groups are utilised, and to further determining surface chemistry; static and dynamic control the interaction the alunrr.ium surface is contact angle measurements for studying surface modified in different ways. It has been possible to energetics; and inverse gas chromatography to de- correlate the delamination force with the strength of termine the dispersive/specific character of the sur- the moelcular interactions. faces. The polymer crystallizr'ion and morphology at the interface are studied using optical microscopy. B3: Interfacial interactions in polymer blends Surface properties are related to interfacia' adhesion Blending of polymers is an attractive way to obtain as measured specifically, using a single-fiber frag- new polymeric materials. The ultimate goal is to mentation test, which involves tensile testing under achieve an optimal material by combining favour- microscope. able properties from the starting materials. As most The project is part of the research programme polymer pairs are incompatible, the properties of the "Cellulose Based Multicomponent Systems" fi- complex material will be strongly influenced by the nanced by NUTEK. Collaboration has been estab- interactions between the phases. The interdiffusion lished with École Poly technique, Montreal, Canada; layers, or interphase, between the phases in a immis- Dept. of Chem. Eng., University of West Virginia, cible polymer blend is considered as a third phase Morgantown, USA; Division of Forestry, Institute and has its own characteristic properties. A strong for Surface Chemistry, Stockholm, Sweden, and interphase thus leads to better mechanical properties Dept. of Polymeric Materials, CTH. of the blend. We use different experimental and theoretical methods to characterize the interphase in

MATERIALS SCIENCE, 1993 POLYMER TECHNOLOGY

C: Bulk polymers D. Characterization

Cl: Thermal stability of PVC Dl: Molecular mobility in polymeric materials The thermal stability of PVC is not determined by The aim of this project is to establish and develop the nominal structure but the presence of a few solid state NMR techniques to study relations be- irregular structures having lower thermal stability. tween molecular mobility and properties of poly- The most important are chlorine on branch carbon mers. At the department we use a 300 MHz NMR and allylic chlorine associated with internal double spectrometerfor solid state high resolution CP-MAS bonds. Theircontents are quite low, typically 1 -2 and (cross polarization magic angle spinning) NMR. 0-0.2 per 1000 monomer units, respectively. For a With this technique we can study site-specific mo- long time if was not possible to determine these lecular mobility in the~kHzand -MHz region, using structures and thus obtain relations between stability the relaxation signals from various nuclei (mainly and defect structures. Using 13C-NMR we have 13C and 1H). In addition, relaxation times can be been able to obtain such correlations and also to find used to determine the size of heterogeneities in the out in what way the polymerization conditions influ- range ~5-5O0O Å (for studies of multi-phase sys- ence their formation. The present work is directed tems, e.g. polymer blends). The project involves towards methods to avoid the formation of thermally implementation of both one- and two-dimensional labile structures, and techniques to minimize their pulse techniques as .veil as solid state NMR methods negative influence. The latter include introduction of other than CP-MAS, such as wideline and multipulse reactive groups, capable to interfere with the deg- NMR spectroscopy. radation process, onto the polymer chains. The application part of the project is done in close cooperation with applied projects both within and C2: Functional polyethylene outside the department and mainly in the following Polyethylene is the most produced polymer and it is fields; polymer blends (material consortium); elec- used in a number of everyday applications. In order tron conducting polymers (Organic chemistry, CTH); toobtain materials with increased value, polyethylene ion conducting polymers (Experimental Material producers try to find speciality qualities. In this Physics, CTH); liquid crystalline polymers (Liquid project we study functional polyethylene, i.e. poly- Crystal Group, Physics, CTH). ethylene containing small amounts of a comonomer which gives a special property to the material. One example is comonomers with crosslinkable groups and we are investigating the mechanism of cross- linking ethylene copolymers containing trimethoxy silane and vinyl groups, respectively. The mecha- nisms are quite different but in both cases the crosslinking leads to materials with improved prop- erties at increased temperatures. Polyethylene con- taining stabilizing groups is another example. In contrast to their low molecular weight analogs these stabilizers should not leak out from the polymer, which allow 'jse under more severe conditions. On the other hand the decreased mobility may give reduced reactivity in the stabilizing reactions.

82 THE CENTRE FOR POLYMER TECHNOLOGY

Publications 1990 -1992 Mats Ganrot, Polymcrdispcrsion for Blending with Con- crete, 1989 Ph.D. Dissertations Ingrid Gustavsson, Hydrophilic Gels Based on Polyurct- Håkan Johansson, Blocked Polyurcthancs as Matrix hancUrca, 1990-05-18 Material in Composites, 1989

Mats Sandberg, Conducting Polymers - Structure and Maria Härsjö, Functionalization of Polyurethene-urea,1989 Properties, 1991-03-18 Peter Rydin, IPN of Epoxy and Polyurethane, 1989 Thami Chihani, Surface Modification of Polymer Materials - The Influence of the Mold Surface, 1992-06-10 Madeleine Nilsson, Synthesis, characterization and Use of Functional Polymers with Biocid Activity, 1989 Maria Wallenius, Synthesis and Characterization of Functional Polymers Based on Trimcthylolpropane Håkan Kassman, Crosslinking Reactions of Ethylcne Vinyl TrimcthacryalteandGIycidyl Mcthacryiate, 1992-10-02 Silanc Copolymcrs at Processing Conditions, 1989

Andrea Schmid, Synthesis and Characterization of S EC- Nils Ljungqvist, Synthesis and Polymerization of 3(1,4,7- packings Based on Trimcihylolpropanc Trimcthacrylate, lrioxo-8,8,8-triphcnyl octyl thiophene), 1990 1992-10-16 Margareta Ncméth and Carin Sylvandcr, Simulation of Ucenciate Dissertations Mold Flow with Rubber, 1990 Laila Ulrén, The Effect of Different Functional Groups in Ethylcne Copolymcrs on the Adhesion to Aluminium, Kent Hermansson, Polymer Blends with Poly(3-octyl 1989-02-09 thiophcnc), 1990

Magnus Palmlöf, Crosslinking of Ethylcnc Vinylsilanc Maria Andersson and Inger Fransson, Catalysts for Copoiymcrs, 1989-12-15 Crosslinking of Ethylcnc Vinylsilanc Copolymcrs, 1990

Kersti Strandqvisl, Computer Simulation of Polymer Eva Österberg, Environmental Influence on Stress Crack- Rcactiors, 1990-02-09 ing and Tens )c Strength of Modified Polystyrenes, 1990

Clacs Frcnnfclt, Adhesion Between Paint and Modified Anna Johansson, The Optimum Conditions for a Reactive Polyolcfins, 1991-05-03 Coalcsccnt in ;i Watcrbascd Paint, 1991

Marie-Louise Lagerstedt-Eidrup, Structure and Properties Anna Sultan, Methods for Determination of Lamellar of Poly(3-Alkyl Thiophcnc), 1991-05-30 Thickness in Polyethylene, 1991

Margareta Arwidsson, Microstructurc and Enzymatic Anders Frit/, Modification of Epoxy Surfaces with Water Stability of elhyl-O-(Hydroxycthyl)-Ccllulosc, 1991-06-06 Soluble Functional Polymers, 1991

Peter Bicllhcim, Electric Breakdown Strength of Aromatic Peter Fchcr, Modification of Epoxy Surfaces with Fluori- Polymers, 1992-06-09 natcd Carboxylic Acids, 1991

Chris Bonnerup, Molecular and Topographic Aspects of Anna Nihlstrand, Characterization of Copolyrncrs with Adhesion Between Coatings and Polyolcfin Substrates, SEC, 1991 1992-10-29 Robert Luttu, Characterization of Polycthylcnc/PVC Diploma Work Blends, 1991 Asa Eliasson, New Hydrophilic Microfiltration Membranes Based on Polypropylene, 1989 Roger Johansson, Stabilization of HDPE Produced with a Phillips Catalyst, M) Michael Hansson, The Influence of the content of stabilizer on the degradation of HDPE, 1989 Hans Jönsson, Modification of Polymer Surfaces with Polymcrizablc Surfactants, 1991 Roger Carlsson and Martin Bcmtsson, Laqucring of Modified Termoplastic Polyolefins, 1989 Wcnche Jensen, Investigation of IPN Based on PUR and Water Soluble Polymers, 1991 Per-Ola Nilsson, Crosslinking of Polyamides, 1989 Ann Björling, Measurement of Friction on Monofilament, 1991

MATERIALS SCIENCE, 1993 83 POLYMER TECHNOLOGY

Hans Eklind, Characterization of Electrically Conducting P. Gatcnholm, C. Bonncrup, E. Wallstrom: Wetting and Polymer Blends Containg Poly(3-octylthiophcnc), 1991 Adhesion of Water-borne Printing Inks on Surface Modi- fied Polyolcfins. J. Adhesion Sci. Techno!., 10,817 (1990) Mats Ryrberg, Water Permeability Through Films Of Acrylate Paint and Paint Systems, 1992 J. M. Felix, P. Gatcnholm: Evaluation of Surface Treat- ments for Cellulose Fibers and Interfacial Interactions in Lisbcth Jansson and Jeanette Magnesson, Simulation of Composites in: "Controlled Interfaces In Composite Mold Flow with Rubber, 1992 Materials (ed. H. Ishida), pp. 266 Elscvier Science Publ., 1990 Elisabeth Staaf, Copoplymers of Maleic Anhydride and Ethyl Acetate - Structure and Effect on Cellular Plastics, I. Gustavsson, P. Flodin: Synthesis and Characterization of 1992 Waier-Swcllable Polyurcthanc Urea Gels Containing Allyloxy Groups. I. React. Polym., 12,297 (1990) Annika Smedberg, Ethylenc Copolymcrs, 1992 L-I. Kulin, P. Flodin: Monosized Polymer Particles in Size Urban Wecke, A Study of Polymer Fibers with Bound Exclusion Chromatography. I. Toluene as Solvent. J. of Superabsorbent Particles, 1992 Chromatogr., 514,1(1990)

Madclcne Andersson, Synthesis and Characterization of A K. Jönsson, P. Flodin: Modelling of Urcthanc Formation Liquid Crystalline Polymer, 1992 Br. Polym. 1,23,71(1990)

Paul Zachrisson, A Study of Adhesion Between Different M. Wallcnius, P. Flodin: Reaction of the Epoxide Groups Polyolefins and Ethylcne Copolymers, 1992 of the Copolymer Trimethyiolpropane Trimcthacrylate- Glycidyl Mcthacrylate with Aliphatic Amino Compounds. Hans Hallberg, Manufacturing of Powder Resin Based on Br. Polym. J., 23,67 (1990) Urea and Formaldehyde, 1992 T. Hjcrtbcrg, M. Palmlöf, B-Å. Sultan: Chemical Reactions Åsa Lennartsson and Christin Roscnlöf, Improved Adhe- in Crosslinking of Copolymers of Ethylene and sion Between LDPE and Aluminium In Extrusion Coated Vinyltrimetoxysilanc. J. Appl. Polym. Sci., 42,118* (1991) Laminates, 1992 M. Palmlöf, T. Hjertberg, B-Å. Sultan: Crosslinking Jörgen Balogh, Preparation and Characterization of New Reactions of Ethylene Vinyl Silane Copolymers. Microlitographic Resists, 1992 J. Appl. Polym. Sci., 42,1193 (1991)

Fredrik Andersson, Characterization of Oriented Polymers T. Hjcrtbcrg, R. Dahl: Cooperation between Chemical and with DMTA Techrology, 1992 Physical Networks in Crosslinkcd and Plasticized PVC. J. Appl. Polym. Sci., 42,107 (1991) Paul Koch, Effect of A1CI3 on Thermal Degradation of PVC, 1992 M. Andersson, P.O. Ekcblad, T. Hjcitbcrg, O. Wenncrstiöm, O. Inganäs: Polylhiophenc with a Free Amino Acid Side Chain. Polym. Comm., 32,546 (1991). Reports and articles J.F. Rabek, J. Lucki, H. Kcrcszti, T. Hjertbcrg, Q.B. Jun: G. Gustavsson, O. Inganäs, W.R. Salancck, J. Laakso, M. Catalytic Dehydrochlorination of Solid PVC in the Pres- Loponcn, T. Taka, J.E. östcrholm, J.E. Stubb and T. ence of Aluminium Chloride (Friedcl-Crafts) Catalyst: Hjcrtbcrg: Proccssible Conducting Poly(3-alkyllhiophcncs). Studies of the Structure by Spcctroscopical Methods. in "Conjugated Polymers", Kluwcr Academic Publishers, J. Appl. Polym. Sci., 39,1569 (1990) Dordrecht, 1991, p. 315-60.

L. Ulrén, T. Hjertbcrg, H. Ishida: An FTIR Sudy on B-Å. Sultan, E. Sörvik: Thermal Degradation of EVA and Intcrfacial Interactions in Ethylcnc Copolymcrs/Aluminium EBA - A Comparison. I. Volatile Decomposition Products. Laminates in Relation to Adhesion Properties. J. Adhesion, J. Appl. Polym. Sci., 43,1737 (1991) 31,117(1990) B-Å. Sultan, E. Sörvik: Thermal Degradation of EVA and T. Hjertbcrg, T. Hargitai, P. Rcinholdsson: A 13C CP-MAS EBA - A Comparison. II. Changes in Unsaturation and Side NMR Study on Content and Mobility of Double Bonds in Group Structure. J. Appl. Polym. Sci., 43,1747 (1991) Poly(trimethylolpropane trimcthacrylatc). Macromolcculcs, 23,3080(1990) B-Å. Sultan, E. Sörvik: Thermal Degradation of EVA and EBA - A Comparison. III. Molccualr Weight Changes. J. Appl. Polym. Sci., 43,1761 (1991)

84 THE CENTRE FOR POLYMER TECHNOLOGY

E. Jensen, P. Galenholm, S. Nanguneri, L. Mathias: Effect M. Welander, F.H.J. Maurer: Effect of Sorbed Water and of Chemical Structure of Allyl Ethers on Polymerization Amide Content on the o-Ps Lifetime in Polyamides. Mater. and Properties of Multifunctional Acrylatc Systems Sci., Forum Vols. 105-110 1815 (1992) J. Appl. Polym. Sci., 42,2681 (1991) P.A.M. Steeman, J.F.H. Baetscn, F.HJ. Maurer: Tempera- J. Felix, P. Galenholm: The Nature of Adhesion in Com- ture Dependence of the Interfacial Dielectric Loss Process posites of Modified Cellulose Fibers and Polypropylene. in Glass-bead-filled Polyethylene. Polym. Hng. Sci., 32, J. Appl. Polyin. Sci., 52,689 (1991) 352(1992)

I. Gustavsson, P. Flodin: Synthesis and Characterization of G. Scott, H. Ishida, F.HJ. Maurer Rubber-Filler Inter- Water-SwellaWe Polyurcthane Urea Gels Containing action Effects on the Solid State Dynamic Mechanical Allyloxy Groups. II. J. Macromol. Sci. - Chem., A27,1477 Properties of Polyethylenc/EPDM/Calcium Carbonate (1991) Composites. Polymer Composites, 13,237 (1992)

I. Gu; 'vsson, P. Flodin: Modification of Polyurethane E. Jensen, P, Gatcnholm, C. Sellitti: An ATR-FTIR Study Ureas Containing Allyloxy Groups. React. Polym., 14,103 on Penetration of Resins in Wood. (1991) Macromol. Chem., 200,77 (1992)

I. Guslavsson, P. Flodin: Functional Polyurcthane Ureas P. Gatcnholm, J. Kubat, A. Mathiasson: Biodegradable Containing Carboxylic Acid Groups. React. Polym., 14, Natural Composites. I. The Effect of Processing on Proper- 119(1991) ties. J. Appl. Polym. Sci., 45,1667 (1992)

A. Schmid, L-I. Kulin, P. Flodin: Porosity Determination of P. Gatenholm, J. Felix, C. Klason, J. Kubat: Cellulose- Poly(trimcthylolpropane trimethacrylate) gels. Macromol. Polymer Composites with Improved Adhesion. Contempo- Chem., 192,1223 (1991) rary Topics in Polymer Science, Vol. 7, ed. J.C. Salamone, p. (1992) A. Schmid, P. Flodin :Hydrophilic Gels of Poly(trimcthylol- propane trimethacrylate-co-acrylamide). C. Klason, J. Kubät, »'. Gatcnholir- Wood Fibre-Reinforced React. Polym., 15,49 (1991) Composites ACS Symposium Scries No. 489, pp. 82 (1992)

K. Jönsson, P. Flodin Vulcanization of Rubber. Kinetic A. Schmid, M. Wallenius, P. Flodin: Mechanical Stability Parameters for SBR and Simulation of Vulcanization in a of Trimmethylolpropanc Trimethacrylate-Based Polymers. Mold. J. Appl. Polym. Sci., 43 (1991) J. Appl. Polym. Sci., 45,1995 (1992)

B. Helgeé, P. Bjellheim: Electric Breakdown Strength of A. Schmid, P. Rodin: Porosity Determination of Aromatic Polymers. IEEE Trans. Electr. Insul., 26,1147 Poly(trimethylolpropanetrimethacrylatc-co-methyl (1991) mclhacrylate) Gels. Makromol. Chem., 193,1579 (1992)

A. Strålin, T. Hjertberg: A FTIR Study of Interfacial M. Wallcnius, L-I. Kulin, P. Flodin: Synthesis and Charac- Interactions between Ethylene Copolymcrs and Hydraicd terization of Copolymcrs of Trimethylolpropane Trimet- Aluminium. J. Adhesion Sci. Tcchnol., 6,1233 (1992) hacrylalc and Glycidyl Mcthacrylalc in Toluene. Pan I. React. Polym., 17,309(1992) M. Rogcslcdt, T. Hjenberg: Degradation of Poly(vinyl chloride) with Incrc cd Thermal Stability. Macromolc- M. Wallenius, P. Flodin: Reactive Carriers for the Immobi- cules.25,6332 (1992) lization of Copper Ions. J. Chromatogr., 604,5 (1992)

P.A.M. Stecman, F.HJ. Maurcr An Intcrlaycr Model for B. Hclgec, P. Flodin: Preparation and Properties of Block the Complex Dielectric Constant of Composites: An Copolyamide Fibres. Polymer, 33,3616 (1992) Extension to Ellipsoidally Shaped Particles. Colloid Polym. Sci., 270,1069 (1992) M. Andersson, Q. Pei, T. Hjertberg, O. Inganäs, O. Wenncrström and J.E. Östcrholm: Synthesis of Soluble P.A.M. Stceman, F.H.J. Maurcr: Dielectric Properties of Poly(alkylihiophcncs) which arc Thermally Stable in the Polyamidc-6,6. Polymer, 33,4236 (1992) Doped slate. Synt. Met., accept.

M. 'iVelander, F.HJ. Maurer: Decrease in o-Ps Formation Q. Pci, O. Inganäs, G. Gustavsson, M. Granström, M. in Polymers During Positron Lifetime Measurements. Andersson, T. Hjertberg, O. Wcnnerström, J.E. östcrholm, Mater. Sci., Forum Vols. 105-110,1811 (199".) J. Laakso and H. Järvincn: The Routes towards Processiblc and Stable Conducting Poly(thiophcnes). Synt. Met., accept.

MATERIALS SCIENCE, 1993 85 POLYMER TECHNOLOGY

N. Ljungqvist and T. Hjertberg: Compatibility and Phase- T. Chihani, P. Flodin, T. Hjertberg: Surface Modification of Structure Dependence on the Conductivity in Blends of Epoxy Copolymcrs with Different Perfluoroacids. Poly(3-octyllhiophene). Synt. Met., accept. J. Adhesion Sci. Technol., accept.

S. Schantz and N. Ljungqvist: High-Resolution Solid-State T. Chihani, P. Flodin, T. Hjcrtbcrg: Modification of Epoxy 13C NMR Study of POT-PPO Blends. Synt. Met., accept. Surfaces with Different Polyvinylalcohol Polymers. J. Apr' ''j'.ym. Sci., accept. A. Strålin, T. Hjertberg: Adhesion between Hydrated Aluminium and Ethyiene Copolymers Containing Methoxy . lix, P. Gatenholm: Characterization of Ccllulosic Silanc Groups. J. Appl. Polym. Sci., accept. • Yocrs Using Inverse Gas Chromatography. Nordic Pulp & Paper J., accept. A. Strålin, T. Hjertberg: An FTIR Study of Imerfacis* Interactions between Hydraled Aluminium and Pr ' J. Felix, P. Gatenholm, H. Schreiber: Controlled Interac- Groups in Ethyiene Copolymers. Surf. Interf. A .-, sis, tions in Cellulose-Polymer Composites. I. Effect on accept Mechanical Properties. Polym. Eng. Sci., accept.

M. Rogestedt, T. Hjertberg: Structure • ' -'^gradation of P. Gatenholm, H. Bertilsson, A. Mathiasson: The Effect of Commercial Poly(viny) chloride) Obt ...ed at Different Intcrphasc on Dispersion of Cellulose Fibers in Plastics. Temepratures. Macromolecules, accept. J. Appl. Polym. Sci., accept.

M. Rogestedt, T. Jonsson, T.Hjertberg: Effect of Polymeri- C. Bonncrup, P. Gatenholm: Physical Modification of PP/ zation Initiator on Early Colour of Poly(vinyl chloride). EPDM Surfaces I. Determination of Surface Composition J. Appl. Polym. Sci., accept. ans Surface Order by FTIR-ATR. J. Polym.Sci. Phys. Ed., accept T. Chihani P. Bergmark, P. Flodin: Surface Modification of Ethyiene Copolymers Molded Against Different Mold C. Bonncrup, P. Gatenholm: The Effect of Surface Surfaces 1. Surface Enrichment by Functional Groups. Energetics and Molecular Intcrdiffusion on Adhesion in J. Adhesion Sci. Technol., accept. Multicomponcni Polymer Systems. J. Adhesion Sci. Tcchnol., accept. T. Chihani, T. Hjertberg: A XPS Study of Different Polyvinyl Alcohol Films Surface Composition. P. Bjcllheim, B. Hclgeé: Aromatic Polyimidcs: Synthesis, J. Appl. Polym. Sci., accept. Characterization and Evaluation of Electric Strength. J. Appl. Polm. Sci., T. Chihani, P. Bergmark, P. Flodin, T. Hjertberg: Surface Properties of an Anhydride-epoxy Resin Cured Against Different Mold Surfaces. J. Adhesion Sci. Technol., accept.

86 THE CENTRE FOR Polymeric Materials

Research Summary Anders Persson 1 Atpresentourresearch activities are centered around Thomas Rundquist the following topics. Hans Walter* Bjarne Moursund2 A: Mechanical properties, viscoelasticity and JanWahlbergi ageing. Ion Postoaca1 B: Physical properties of polymeric systems. 1 In collaboration with Lund Institute of Technology C: Rheology and processing. 2 D: Recycling of polymers. In collaboration with Norsk Hydro and Nordisk Industriforskerkomité In the following, our activities in these areas will be commented on briefly. Major Instrumentation • Tensile testing machine Address • Rheometers (rotational and capillary for melts, Chalmers University of Technology hot-melts and liquids) S-412 96 Göteborg, Sweden • High precision relaxometers Phone-^46 31 772 1310 • Equipment for stress dilatometry Fax+46 31 772 1313 • Instrumentation for advanced dynamic-me- chanical spectroscopy • Dielectric characterization (time domain Staff spectrometer) Senior staff • Equipment for thermal analysis (DSC, TGA) CarlKlason Professor, • Equipment for measuring interfacial tension of Head of Department polymer blends in molten state Josef Kubät Professor emeritus • SEM equipment with tensile stage Hans Bertilsson Ph.D., lecturer, • Equipment for measuring noise and frequency Deputy HeadofDepartment analysis Rodney Rychwalski Ph.D., guest researcher, • Compunding machines (Brabender kneaders, lecturer Buss kneader, twin-screw extruder) Per Bengtsson Ph.D. • Two single screw extruders Johan Becker Ph.D. • Two injection moulding-machines Anders Mathiasson Ph.D. • Moulding press Jan Åbom Senior research assistant TecMcaJ staff Kristina Thomeby Secretary Financial Support Ulla Engström Secretary (part time) 1. Swedish National Board for Industrial Devel- opment, NUTEK Graduate students 2. Swedish Research Council for Engineering Mohsen Safari Sciences, TFR Reza Ebrahimzadeh 3. Swedish Council for Planning and Coordina- Mats Delin tion of Research, FRN Henrik Larsson 4. The Swedish Natural Science Research Council, Lena Kvist NFR

MATERIALS SCIENCE, 1993 87 POLYMERIC MATERIALS

5. Carl Trygger Scientific Research Foundation D: Recycling of Polymers 6. Chalmers Research Foundation Participants: C Klason and H Bertilsson 7. Jacob Wallenberg Research Foundation Collaborators: Chemical Environmental Science, 8. Axel och Margaret AX:son Johnson Foundation CTH, Department of Polymeric Materials, CTH, Plastics and Rubber Institute (PGI), Gothenburg, and Swedish National Testing and Research In- Major Fields of Research stitute (SP), Borås.

A: Mechanical Properties, Visco- elasticity and Ageing In Polymers Research projects Participants: C Klason, J Kubåt, H Bertilsson and R Al: Volume Flow and Physical Ageing W Rychwalski. of Solid Polymers Collaborators: J M Hutchinson, Aberdeen Univer- It is well-known that glasses ana semicrystalline sity, F Maurer, Department of Polymer Technology, polymers age physically and the ageing is accompa- CTH, S Andersson, Chalmers Industriteknik, Z nied by a change of properties (dimensional stability, Sobotka, Czechoslovakia Academy of Sciences, rheological properties, oensification, etc.). A slow Institute of Mathematics, Prague, S Uggla, Depart- densification from non-equilibrium toequilibrium is ment of Numerical Analysis, CTH, Ch Högfors, observed also in transient flow. The possible simi- Centre for Biomechanics, CTH, B Edberg, Depart- larity of physical ageing and transient flow with ment of Textile Technology, CTH. regard to the accompanying, evolving volume is the starting point of a study on strain induced physical B: Physical Properties ageing. of Polymeric Systems The volumetric analysis is carried out experimen- Participants: C Klason, J Kubåt, H Bertilsson and R tally and theoretically. A liquid stress dilatometer of W Rychwalski. higher stability (< 2.5 x 1(H ml/h) and non-disturb- Collaborators: T Kitano, Research Institute of Poly- ing clip-on inductive extensometers have been built. mers and Textiles, Tsukuba, Japan, O Quadrat, Great attention is given to the elimination of tem- Institute of Macromolecular Chemistry, Prague, perature effects and the indentation of extensometer' s Czech Republic, P Säha, Technical University of measuring piobes. The developed experimental tech - Brno, Zlih, Czech Republic, A Ponomarenko, Insti- nique enables measurements of very small volume tute for Synthetic Polymeric Matenals, Russian changes even in the demanding condition of stress Academy of Sciences,Moscow, Russia, Th Hjertberg, relaxation, on soft-rubbery specimens, over many F Maurer, P Gatenholm, Department of Polymer decades of time (measured volume changes are Technology, CTH. typically 0.3-0.4 mmtydecade of time, or change of diameter is approx. 0.5 micron/decade of time). C: Rheoiogy and Polymer Processing Theoretical analyses within the framework of Participants: C Klason, J Kubåt and H Bertilsson linear viscoelasticity and free volume theory are Collaborators: T Kitano, Research Institute of Poly- used. These include: mers and Textiles, Tsukuba, Japan, P Säha, Techni- • calculation of volume strain using the differen- cal University of Brno, Zh'n, Czech Republic, V V tial representation of linear viscoelasticity with Jinescu, Polytechnic Institute, Bucharest, Romania, special interest given to strain rate effects P Gatenholm, Departmeiit of Polymer Technology, • calculation of volume strain proceeding from a CTH, B Edberg, Deptartment of Textile Technol- spectrum of volume retardation times ogy, CTH, B Wesslén, Department of Chemical • calculation of volume strain using the WLF/ Engineering, University of Lund and J-E Ståhl, Kovacs theories with the shifting single relaxa- Department of Production and Materials Engineer- tion time ing, University of Lund. • calculation of volume strain using the KAHR- model with the shifting discrete spectrum of relaxation times

88 THE CENTRE FOR POLYMERIC MATERIALS

• analyses of shift factors lar orientation, appear to be highly interesting from • predictions from stretched exponential formula. this point of view. The planned project activities aim A range of measurements and predictions are at at reducing present uncertainties about the time present carried out in the department of Polymeric dependent behaviour of the fibres in question. Materials, CTH, and in the department of Polymer Technology, KTH. It has been measured at small Bl: Polymer Blends: Whiskeis In Immiscible strains for low density polyethylene that volume vs. Polymer Blends time behaviour in stress relaxation is similar to the Polymer alloys from incompatible polymer combi- stress decay. On the other hand a comparison of nations are compatibilized by adding small amounts volume-stress plots measured in straining at a %,on- of block- or graft copolymers. The compatibilizing stantrateof strain and in stress relaxation are dissimi- effect from fillers and fibers have been reported in lar, and are also different for linear and branched literature but so far have not been systematically LDPE. Simultaneously the time dependence of studied or understood. The basic idea is that two (or contractional ratio has been measured. It has been more) polymers, should compete with each other to established from volumetric studies in creep of PC cover the surface of the filler and thus the morphol- and PMMA that a ratio of transverse and longitudi- ogy achieved during the compounding should be nal strain rates is more indicative for volume flow stabilized at the same time as the filler and not the processes in solid polymers than the contractional weak polymer-polymer interfaces are transfering ratio (Poisson's ratio). The volumetric measure- the mechanical stresses. The degree of dispersion ments are carried out in parallel with rheological necessary to achieve interesting mechanical proper- characterization. ties lies in the range of 1 ^m or less for the diameter A long-term cooperation with the Department of of the dispersed phase. The size of the filler particles Engineering, Aberdeen University (UK), Institute of must be of the same magnitude which excludes the Mathematics, Czechoslovakian Academy of Sci- use of common fibres. The use of whiskers is more ences (Czech Republic), Department of Numerical promising since they have diameters of the appropri- Analysis, CTH, has been established. Implementa- ate size and still an attractive aspect ratio giving a tion of Positron Annihilation Life-time Spectroscopy high surface to volume ratio. The use of whiskers is (PALS) for structural observations is here of interest commonly restricted by high cost but we have found and this is planned in collaboration with the Depart- an aluminum borate whisker which can be produced ment of Polymer Technology, CTH. at the price of carbon fibres. A range of incompatible polymer pairs has been A2: Time Dependent Mechanical Properties successfully studied using whiskers (in amounts of 5 of Advanced Textile Fibres -15 vol.%) as compatibilizer. An illustrative exam- Textile materials and products for advanced engi- ple is presented in figures 1 and 2 showing a SAN/ neering applications represent a steadily growing PA6 70/30 blend. The volume content of whiskers sector of the textile industry. The lack of available equal 10 % drastically changes the crack propaga- information on the viscoelastic behaviour is particu- tion from following-the-weak-polymer-polymer- larly pungent with the new generation of fibres used interfaces to proceeding right-through-the-material. in engineering applications. The present project will As expected the strength and stiffness was substan- focus on such problems and will include creep and tially improved by the whiskers but more interesting relaxation characterization of a number of advanced is that the elongation at break also increased. This fibre materials used in industrial textile products. was explained by a closer view on the morphology. The data will be supplemented by dynamic-me- In fig. 3, showing the same blend as in fig. 2, the SAN chanical measurements. Special interest will be de- matrix has been removed by a solvent and the voted to the both scientifically and technically im- remaining minority polymer and the whiskers form portant phenomenon of accelerated flow under con- a continuous phase. This interesting morphology ditions of periodically changing humidity of the was obtained by first compounding the whiskers surrounding atmosphere. The result will be analyzed with SAN, and then introducing PA6 in a second in terms of established theoretical models. Fibrous step. The interaction PA6 versus whiskers is much specimens, representing an extreme case of molecu- stronger than SAN versus whiskers. We have found

MATERIALS SCIENCE, 1993 89 POLYMERIC MATERIALS

Fig 1: Fracture area of SAN/PAG 70/30 blend. Fig 2: Fracture area of SAN/PAG 70/30 blend with 10% by volume of whiskers.

Among important areas for thi s compatibilization technique is the alloying of high temperature resist- ant polymers where blocks and grafts cannot be used due to thermally weak block links. Blends of liquid crystalline polymers with common engineering poly- mers suffer from inadequatecompatibilization routes and weak interfaces. Compatibilizaticn with whisk- ers will open up new possibilities in this context. Morphology control per se is important in cases where continuity of a dispersed minority phase is Fig 3: The same blend as in fig 2 where the SAN desired. We have recently obtained promising re- matrix has been removed by dissolving. sults concerning the dispersion of an electrically conductive polymer in matrices of common engi- neering polymers. that the morphology isdetermined by the differences The activities concerning the whiskers in poly- in polymer-whisker interaction and by the viscosity mer blends are parts of the NIWNUTEK consor- ratio of the polymers. The polymer-whisker interac- tium programme "Interfacial interactions in poly- tions have so far been qualitatively characterized by meric materials". dynamic mechanical analyses but a more quantita- tive characterization using inverse gas chromatogra- B2: Noise, Relaxation and Ageing Phenomena phy is running at present. in Polymeric Systems So far only completely immiscible pairs have There is a growing interest for measurements of the been considered. For polymer pairsshowing smaller, spontaneousconductancefluctuations(conductance but yet positive interaction parameters, still more noise) in technological materials with some degree interesting phenomena are to be expected. Accord- of microscopic disorder, such as polymers and high- ing to results of prof. Lipatov, Ukraina, the polymer- Tc superconductors. This is because measurements polymer interaction parameter can be substantially of conductance noise represent one of the most reduced, and become even negative, at the surface of powerful methods of studying the influence of mi- a filler to which both polymers exhibit some interac- croscopic disorder in materials. The reason for this is tion. This opens up the possibility for a third miscible well-known; the measured conductance noise am- polymer phase in a system of immiscible polymers plitude is the sum of cross-terms, originating from and the whiskers. different sub volumes of the material, and these terms are proportional to the square of the local current density.

90 THE CENTRE FOR POLYMERIC MATERIALS

Similarly, measurements of noise phenomena conditions. A method of studying the noise in con- during stress relaxation and physical ageing of poly- ducting polymers has been developed. The basic mers can be expected to be a far moie powerful idea behind the noise measurements is the notion that method of investigating the underlying mechanisms spectral analysis of the noise may provide useful than the measurement of the bulk behaviour. The physical information about the underlying molecu- same applies toother typesof time dependent behav- lar mechanisms. The object of the current research iours of solid polymers where, basically, the mecha- project is to study the temperature dependence of the nisms responsible for the macroscopic behaviour resistivity of conducting polymers, and how the type remain largely unexplained. This idea is the starting of filler and its content will influence the electrical point of the present project. Since common polymers and dielectrical properties of the composite. Also, do not possess a sufficient degree of conductivity in the noise method will be used to study flow phenom • order to allow the fluctuations of the charge carriers ena and structure of polymer solutions and gels. The to be determined directly, the systems to be investi- problems under study relate not only to flow proper- gated have to consist of polymer based composites ties of solutions, but also to melt flow instabilities, containing suitably selected conducting particles. rheology of melts and flow behaviour and properties This project is carried out in collaboration with of reinforced polymers. the Department of Solid State Physics at Uppsala The rheology and processing of thermoplastics University. has earlier been experimentally studied in coopera- tion with Dr. P Sdha at the Faculty of Technology, 33: Dielectric Properties of Polymers and BmoUniversity in Czech Republic. Also in thisarea, Polymer Based Composites the frequency analysis (noise method) has been used ft s project consists of two parts, all relating to the to study melt flow instabilities, and a flow visualiza- V< lectric behaviour of polymers and polymer based tion method has been developed to study the melt a mposites. The first part aims at quantifying a process in a single screw extruder. Recently a col- f irticutor similarity between the time-domain di- laboration in this area has been established with Prof. lectric behaviour of polymers and the kinetics of Jinescu of the Polytechnic Institute in Bucarest, stress relaxation, physical ageing, and similar proc- Rumania. The project deals with simulation of flow esses. in mixers (in single screw extruders). The second part is focused on polymeric composi- Polymer-polymer interfacial tension is a critical tes with high valuesof dielectric constant for absorp- parameter determining processing and performance tion of high frequency electromagnetic radiation. characteristics of multicomponent polymeric sys- tems. A recently developed method of the Imbedded Fibre Retraction (IFR) allows the evaluation of the Cl: Rheology of Filled Polymers interfacial tension between high polymers at el- The objective of this research project is to create a evated temperatures. IFR is based on the analysis of broadened basic understanding of the Theological the transitional shapeevolution of a short fibre of one behaviour of filled engineering plastics and their materia! imbedded in a matrix of a second. time dependent mechanical properties. The pro- The uniqueness of the method is related to its cessability of filled polymers, and hence the proper- ability to provide a value for the interfacial tension ties of the finished products, is closely related to the between high-viscosity materials over a relatively Theological properties of tne polymeric materials in short period of required experimentation. This project the molten state, and to the properties of the interface is in collaboration with the Dow Chemical Com- between the filler and the matrix. Studies of the pany, Midland, Michigan, USA. compatibiltyofmixedplasticscontainingmicrofibrils Mould design is critical in all processing tech- of cellulose is part of this project. niques. The object of this project is to use porous Another field of interest is carbon black filled metal in order to improve the venting of the mould polymers and the influence of processing on the during filling and to improve the tempering of the electrical properties. These polymers are of special moulds using a gas cooling technique. This project is interest in heating devices due to a positive thermal supported by Perstorp AB. coefficient of resistivity (PTC-effect) under certain

MATERIALS SCIENCE, 1993 91 POLYMERIC MATERIALS

Dl: Recycling of Polymers routes for recycling. SP (Boras) is working with This project started during the autumn -92 with the problems concerning specifications for the recycled aim to establish an interdisciplinary consortium in materials and, they are interested in finding the the area based on the following groups: synergistic effects from reprocessing and ageing. - Department of Chemical Environmental The other activity within the recycling programme Science, CTH at our department concerns composites based on - Department of Polymer Technology, CTH paper and plastic waste. The aim of this part is to - Department of Polymeric Materials, CTH create structural composites with good mechanical - Plastics and Rubber Institute (PGI), Göteborg properties and good long-term exposure properties - Swedish National Testing and Research from recycled materials containing polymer and Institute (SP), Borås cellulose fibers. A prerequisite for the project is through knowledge of the origin of the waste, its Two activities within the programme are carried out composition and possible treatment. The surface at the Department of Polymeric Materials; recyclirg properties of the fiber and its possibility to interact of engineering thermoplastics and composites based with different functional groups in the polymer is a on paper and plastics waste. The idea behind the crucial factor, both for dispersion of the fibers in the former mentioned activity is to implement knowl- melt during processing and the interfacial strength edge and techniques from polymer alloying in the between the two components. Another factor that upgrading of recycled engineering thermoplastics. will be investigated is reprocessing. To improve The prices of engineering thermoplastics are 4 - 5 dispersion and adhesion, compatibilizers and treat- times (or more) higher than those of commodity ments will be selected for fibre treatment prior to materials and thus there are possibilities to end up compounding o- in a one-step process. The obtained with attractive prices for the recycled materials even composite materials will be evaluated with respect to with necessary allowances for upgrading processes. mechanical properties, environmental ageing as well The conventional route for material recycling has as recyclability. Studies of the rheology and flow been, so far, to recycle a specific thermoplastic after properties as well as optimization of the processing upgrading, to the same thermoplastic again, even parameters are other areas of interest. sometimes to the same product. In the future, when streams of different engineering thermoplastics for recycling are expected to appear, the technology of mixing them properly in order to achieve the best positive synergistic effects will play a great role. The materials of interest so far are ABS, ASA, SAN, PC, PBT, PET, PA and PP. If recycled SAN is mixed with recycled PC, for example, very good properties can be found even at moderate levels of PC. Very small amounts of PCL has been found to be a powerful additive for morphology control. Since SAN is the matrix in ABS and ASA the same idea is used for them, giving high impact strength in used ABS, where the impact modifier is destroyed by ageing. Concerning polyesters like PET and PBT, transesterification processes during compounding shall be studied in order to obtain desired morphol- ogy (property control in blends with PC and PA, for example). The cooperation with other involved research departments is important. The Department of Che- mical Environmental Science is in a position to evaluate our ideas of recycling versus alternative

92 THE CENTRE FOR POLYMERIC MATERIALS

Publications 11. Kitano T, Klason C and Kubät J: Flow properties of liquid crystalline polymer and its fibre filled system PhJ>. Dissertations 1988 -1992 melt, Reports on Progress in Polymer Physics in Japan, Björn Franzén, "Mechanical properties of some polymeric XXXII (1989) 71 alloys and composites", 1989 Maria Welander, "Ageing and viscoelasticity of filled 12. Lindberg K A H, Vescly D and Bertilsson H: Electron HDPE", 1989 beam damage of some chlorine containing polymers Johan Becker, "Unstable flow of molten polymers", 1992 and PVC blends, J Mat Sci, 24 (1989) 2825 Per Bengtsson, "Electrical properties of carbon black-filled polymers", 1992 13. Klason C, Kubät J and Quadrat O: Excess thermal Anders Mathiasson, "Cellulosic fillers in thermoplastics", noise generated by the capillary flow of alkalinized 1992 latex dispersions carrying carboxyl groups, Rhcol Acta, 30(1991)180

Reports and articles 14. Klason C, Kubät J and Quadrat O: Electrical noise 1. BengtssonP,Klason C, KubälJam!McQueenDH: generated during the capillary flow of polyethylene Electrical Noise Characteristics of Carbon Black-Filled oxide) solutions. The influence of the solvent power, Chloroprene, Rubber Journal of Physics D, 22 (1989) Polymer, 33 (1992): 7,1464 1736 15. Kubät D G and Klason C: Stress relaxation in wood 2. Bertilsson H.Franzén B and KubétJ: Creep and (Scots pine veneer) 2. Quantitative cor parison with Volume Dilatation in PC/PBT Blends, Plastics and the prediction of a cooperative flow model, J Mat Sci, Rubber Processing and Applications, 11 (1989) 167 26(1991)5261

3. Welander M: Effect of high stress on the ageing beha- 16. Klason C, Kubät J and Gatenholm P: Wood fiber- viour of high density polyethylene, Polymer, 31 (1990) 64 reinforced composites, ASC Symposium Series 489, Viscoelasticity of Biomaterials, Eds. Glaser, Hata- 4. Bengtsson P, Klason C, Kubät J and McQueen DH: keyama, American Chemical Society, Washington DC, Positive temperature coefficient effects in carbon 1992, p. 82 black-filled chloroprene rubber, Plastics and Rubber Processing and Applications, 15 (1991) 257 17. Brostow W, Cook R and Kubät J: Molecular dynamics and Monte Carlo simulations of polymeric materials: 5. Becker J, Bengtsson P, Klason C, Kubäl J and Sana P: Chain relaxation dynamics, Integral Methods in Science Pressure oscillations during capillary extrusion of high and Engineering -90, Eds.: Haji-Shcikh, Corduneanu, density polyethylene, Inter Polymer Processing, VI Fry, Huang and Payne, Hemisphere Publ. Co., (1991): 4,318 Washington DC, 1991, p. 24

6. Becker J, Klason C, Kubät J and Sana P: 18. Bcrtilsson H, Franzén B, Klason C. Kubät J and instability phenomena in polymer extrusion, Plastics Kitano T: The influence of processing on fibre orienta- and Rubber Processing and Applications, 14 (1990) 77 tion and creep in short carbon-fibre reinforced low density polyethylene and polycarbonate, Polymer 7. Becker J, Klason C.KubatJ and Sana P: Melt strength Composites, 13 (1992): 2, p. 121 and rupture frequency in LDPE film blowing, Plastics and Rubber Processing and Applications. 14 (1990) 23 19. Gatenholm P, Klason C and Kubät J: Cellulose-polymer composites with improved properties, Polymer Science, 8. Becker J, Klason C, Kubät J and Sana P: Frequency 7 in Contemporary Physics, Ed. J Salomonc, Plenum analysis of pressure fluctuations in a single-screw Publ. J992 extruder, Inter Polyrer Processing, VI (1991): 4,326 20. Scrtilsson H, Kubät D G, Kubät J and Uggla S: A 9. Bertilsson H ami kindberg K: Morphology of polya- simplified cooperative model of stress relaxation and mide 6 - polybuladiene multiblock copolymers, J Mat other consolidation processes in solids, Rhcol Acta, 31 Sci, 26 (1991) 4383 (1992) 390

10. Lindberg K, Johansson M and Bertilsson H: Effects of 21. Kubat D G, Berulsson H, Kubät J and Uggla S: A the addition of a multiblock copolymer to an incompa- modified cooperative model of relaxation and ageing tible blend, Plastics and Rubber Processing and Appli- kinetics, J Phys: Condensed Matter, 4 (1992) 7041 cations, 14 (1990) 195

MATERIALS SCIENCE, 1993 93 POLYMERIC MATERIALS

22. Klason C, Kubat J and Quadrat O: Electrical noise and 32. Klason C, Kubåt J and Skov H R: Hydrolytic treatment streaming potential generated during capillary flow of of plastics waste containing paper in "Plastics Materi- poly(ethulcne oxide) solutions, J AppI Phys, 72 (1992) als Recycling", Ed. E P La Mantia, Chcm Tec Publ., 3219 Toronto, Canada, 1992

23. Kubdt M J, Jansson J F, Delin M. Kubai J. Rychwalski 33. Kuzel R, Kubät J, Krivka I, Prokes J and Nozar P: New R W and Uggla S: Some phcnomcnological relaxation polymeric composites, Proceedings of 12th General rate equations based on B-E similar kinetics, J AppI Conference of the Condensed Matter Division, Prague, Phys, 72 (1992) dec. Czechoslovakia, 1992, p. 105

24. Kuzel R, Krivka I, Stefan O, Kubåt J. Hrovat M, Rafaja 34. Krivka I, Stefan O, Kuzel R, Kubäl J and Rafaja D: D, Pesicka J, Prokes J and Broukal J: Problems with Glass composites - Hetcrogcnous systems, Proceedings resistive paste preparation, J Microelectronics, Elec- of 12th General Conference of the Condensed Matter tronic Components and Materials, 21 (1991)4,195 Division, Prage, Czechoslovakia, 1992, p. 141

25. Bertilsson H, Delin M, Kubät J, Kubåt M J, Rychwalski 35. Kubat J, Prokes J, Kuzel R, Krivka I and Stefan O: R W and Sobotka Z: Modelling volume strain during Diclcctric properties of polymeric composites, Procee- flow of solid polymers, Theoretical and Applied dings of 12th General Conference of the Condensed Rhcology, Eds.: Moldcnaers P, Keunings R, Proceed- Matter Divison, Prague, Czechoslovakia, 1992, p. 105 ings Xlth International Congress on Rheology, Brus- sels, Elsevier Sci Pubi B.V., 1992, p. 793 36. Prokes J, Kubat J, Kuzcl R, Krivka I and Stefan O: Frequency measurements on some polymeric compos- 26. Kuzel E, Kubät J, Keivka I, Prokes J, Klason C and ites, Proceedings of 34th IUPAC International Sympo- Stefan O: Heterogeneous systems based on precious sium on Macromolcculcs, Prague, Czechoslovakia, metal powders and polymers, Proc. EMRS 1992 1992, p. 4-P42 Spring Meeting, International Conference on Electro- nic Materials, Strasbourg, France, 1992, p. C-VII/P4 37. Kubät J, Bengtsson P, Krivka I, Prokes J, Kuzcl R and Stefan O: Carbon black-filled polyethylene and 27. Kubåt J, Kuzel R, Krivka I, Bengtsson P, Prokes J and chloroprcnc rubber, Proceedings of 34th IUPAC Stefan O: New conductive polymeric systems, Proc. International Symposium on Macromolcculcs, Prague, EMRS 1992 Spring Meeting, International Conference Czechoslovakia, 1992, p. 4-P43 on Electronic Materials, Strasbourg, France, June 1992, p. E-IV/P6 38. Kuzei R, Kubat J, Krivka I, Klason C, Stefan O and Prokes J: Polymeric composites filled with precious 28. Blonski S, Brostow W and Kubåt J: Computer simula- metal conductive powders, Proceedings of 34th tion of stress relaxation, Amer Chcm Soc Polym Paper, IUPAC International Symposium on Macromoleculcs, 33(1992): 1,625 Prague, Czechoslovakia, 1992, p. 5-P92

29. Klason C, Kubät J and Quadrat O: Flow properties and 39. Kuzcl R, Kubät J, Prokes J, Krivka I, Klason C and electrical noise generated during capillary flow of Stefan O. Polymeric materials and composites for Newtonian liquids, Theoretical and Applied Rheology, microelectronics, Proceedings of 28th Symposium on Eds.: Moldcnaers P, Keunings R, Proceedings Xlth Devices and Materials, SD 92, Portoroz, Slovenia, International Congress on Rhcology, Brussels, Elscvier 1992, p. 443 SciPublB.V.,1992,p.481 40. Kuzcl R, Kubat J and Votruba Z: Polymeric compos- 30. Klason C, Kubät J and Quadrat O: Relation between ites for thick film resistor preparation, Proceedings of electrical noise generated during capillary flow of 28th Symposium on Devices and Materials, SD 92, aqueous poly/ethylene oxide solutions and streaming Portoroz, Slovenia, 1992, p. 349 potential, Proceedings of Noise in Physical Systems and 1/f Fluctuations, Kyoto, Japan, Eds. T Musha, S 41. Gatenholm P and Mathiasson A: Environmentally Sato, M Yamamoto, Ohmsha Ltd. 1991, p. 141 dcgradable composites, Polymeric Materials Science and Engineering, 67 (1992) 361. Proceedings of the 31. Gatenholm P, Kubät J, Mathiasson A: Biodegradable American Chemical Society, Division of Polymeric natural composites. I. Processing and properties, J AppI Materials: Science and Engineering Polym Sci, 45 (1992) 1667

94 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE Polymer Technology and Surface Protection/Corrosion

Research summary Address The research activities of the department of Polymer Swedish National Testing and Research Institute Technology and Surface Protection/Corrosion are P.O. Box 857 mainly focused on increasing the understanding of S-501 15 Boras, Sweden how materials are degrading due to the application in Phone+46 33 165000 which the material is supposed to be used. Heat, U V- Telex 36252 testing S radiation, humidity, corrosive gases, mechanical Fax+46 33 13 55 02 stress etc are examples of factors which can seriously reduce the service life of a certain material. Investi- gations of the degradation mechanisms of different Research Staff materials exposed to various climates constitutes a Antal Boldizar Dr. Eng. Sci. basis for the development of methods for predicting Bo Carlsson Docent, Head of Surface Pro- service life of materials, products and systems. tection/Corrosion Division This research concept also demands activities Lennan Carlsson Docent regarding mixing and processing of materials since Lars Cedheim Ph.D. this step often is of crucial importance regarding the Else-Hanna Elgåsen M.Sc. final properties of tiie manufactured product Peter Eriksson Ph.D. Physical-chemical analysis methods, i.e. spectro- Thomas Gevert Ph.D., Head of Department scopy, thermoanalysis, chromatography, SEM etc, Ame Holmström Docent are used for investigations on the molecular level Ignacy Jakubowicz Ph.D., Head of Polymer while mechanical testing equipment are used to Technology Division deduce the macroscopic properties. Ulrika Johansson M.Sc. Ann-Sofie Lindgren M.Sc. The research activities within the department are Kenneth Möller Dr.Eng.Sci. divided into eight major programs: Monica Markinger M.Sc. A: Durability and long-term performance of Elvan Nilsson B.Sc. materials - degradation mechanisms and Marie Louise accelerated ageing. Samuelsson Ph.D. B: The effect of air pollutants and other aggres- Leo Spilg M.Sc. sive chemical environments - methods for Karin Wemstähl M.Sc. testing and evaluation. C: Recycling/destruction of polymeric materials. D: Analysis and characterization of polymeric materials. Major Instrumentation E: Processing of polymeric materials. • Spectroscopy: FTIR (IR-microscope, ATR, F: Quality- and reliability technique. DRIFT etc), UV-VIS-NIR (integrating G: Mechanical properties of advanced ceramic. sphere), NMR, MS, atomic absorption H: Physical keeping of documents. spectrometer, ICP, EDX. • Thermal Analysis: DSC-, TMA-, and TGA- equipment, Leco TG.

MATERIALS SCIENCE, 1993 95 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE. Polymer Technology and Surface Protection/Corrosion Chromatography: TLC (with densitometer), Major Fields of Research GOGCMS,HPLC,GPC. A: Durability and long-term performance of Microscopy: SEM equipped with EDX, materials - degradation mechanisms and stereomicroscope, phase contrast microscope. accelerated ageing Participants: B. Carlsson, K. Wemståhl, K. Processing and Reology: Injection moulding Möller, E-H Elgäsen, I. Jakubowicz, Th. machine Klockner Fcnomatic Oocking force 80 Gevert, AS. Lindgren tons), Brabender extruder, laboratory calendar, Collaborators: Dept.of Polymer Technology, form press, Struers thermopress, Monsanto Chalmers University of Technology, vulcanization simulator, melting index testers. Fraunhofer Institut, Freiburg, Switzerland, Mechanical Testing: Five tensile testing ma- ITR, Rapperswil, Switzerland, TNO, Nether- chines for static and dynamic testing with a lands, DTH, Lyngby, Denmark, Volvo capacity up to 100 kN max. load, and with Personvagnar AB, SAAB-Scania AB, Paint- possibility to choose testing climate within the industry in Sweden, IVF, Göteborg, FMV, temperature range of -70-+200°C. Impact Stockholm, Hydro Plast AB, Stenungsund, testers, falling dart impact tester, tear tester, De BASF, Germany, Atlas AG, Germany. Mattia fatigue tester, abrasion tester, double folding tester, Lupke-pendulum, equipment for B: The effect of air pollutants and other aggres- determination of brittle temperature, flex point, sive chemical environments - methods for elastic rejection, Vicat and HDT, compression, testing and evaluation relaxation etc. Participants: P. Eriksson, K. Möller, L. Cedheim, U. Johansson, I. Jakubowicz, Th. Equipment for durability tests: Approx. 100 Gevert. heating chambers, of which some are explo- Collaborators: ICT, Karlsruhe, Germany, sion proof, air manoeuvred etc. More than 20 Dept.of Inorganic Chem., Chalmers University climate chambers are equipped with program- of Technology. mable control equipment, 3 ozone cabinets with externally controlled UV-analyzer. C: Recycling / destruction of polymeric materials Weatherometers: 5 Xenotests, Suntest, Atlas Participants: A. Boldizar, Th. Gevert, M. (SR-35, UV-CON UC-1R, DMC, XW-WRC) Markinger, I. Jakubowicz. and Weiss global UV. Furthermore, there are Collaborators: Dept.of Polymer Technology, salt-fog boxes, chambers equipped with gas- Dept.of Polymeric Materials, Chemical Envi- meter, muffle furnaces, cell-type ovens, auto- ronmental Science, Chalmers University of claves etc. Technology, PGI, Mölndal, Ecole Polytech- nique Federate de Lausanne, Switzerland, Eidgenössische Materialpriifungs- und Financial Support Versuchsanstalt, Dubendorf, Switzerland. Ministry of Industry NUTEK D: Analysis and characterization of Polymeric BFR (Swedish Council for Building Research) materials AFR (Swedish Waste Research Council) Participants: Th. Gevert, K. Möller, I. NORDTEST Jakubowicz, L. Cedheim. Swedish Rescue Services Board Collaborators: Dept.of Polymer Technology, Swedish National Archives Chalmers University of Technology.

E: Processing of polymeric materials Participants: A. Boldizar, M. Markinger. Collaborators: Dept.of Polymeric Materials, Chalmers University of Technology.

96 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE, Polymer Technology and Surface Protection/Corrosion

F: Quality and reliability technique Thefollowing sub-projects ate included Participants: L Spilg, L Jakubowicz, Th. Gevert in the project: Collaborators: Industry - Exterior automotive paints - Paints for wood preservation G: Mechanical properties of advanced ceramics - Selective absorber materials for solar collectors Participants: L. Carlsson - Rust protective paints Collaborators: Swedish Ceramic Institute, - Plastic coven for solar collector Volvo Flygmotor AB, ABB Cerama AB, - Durability of impact modified PVC United Turbine AB, Institute of Technology, - Physical-chemical properties of polymeric Linköping University, NIST, USA, Japan Fine films Ceramic Center. - Long-term durability of polymeric building materials H: Physical keeping of documents - Life-time predictions for rubber Participants: ML Samuelsson, E. Nilsson Collaborators: Swedish National Archives Examples of publications: - An FTIR, impact strength and thermal analysis investigation of a PVC window frame natu- Research Projects rally aged for 20 years. Jakubowicz, I. and Möller K., Polymer Degr. and Stab. 36 (1992) 111-120. A Durability and long-term performance - Accelerated life testing of solar energy materi- of materials-degradation mecha- als. Carlsson, B., Möller, K., Frei U., (ITR, nisms and accelerated ageing Schweiz), Köhl, M., (Fraunhofer Inst. for Solar The demands for high reliability and a minimized Energy Systems, Tyskland). IEA-report, Task time duration from idea to the manufacturing of a X. new product are markedly increasing. It is therefore a big need for development of quanutive accelerated B The influence of air pollutants and ageing tests. The results from these tests can consti- other aggressive chemical environ- tute a basis for the determination of the lifetime of ments on degradation of materia:» - different materials before they are used in different testing methods applications. Air pollutants such as sulphur dioxide have been Investigations have to be performed in order to recognized since a long time as powerful accelera- find methods for ageing as well as methods for the tors of degradation/corrosion of the common basic characterization of different climatic parameters. metals, especially steel. As a consequence, dumping Knowledge of the mechanisms which are responsi- of sulphur has been strongly reduced during the last ble for the degradation processes induced by the years and has caused a decreased rate of corrosion environment must be gained. Methods for extra- mainly in densely built areas and industrial areas. polation of the results from accelerated tests in order Sulphur dioxide in combination with nitrogen tc fit results from "in-use"-conditions must be im- oxides has during the past time been attentioned as a proved. big environmental problem and is considered to be The project aim is to develop test methods for the reason for the accelerated degradation of histori- evaluation of long-term properties of materials based cal building monuments. Big international research on knowledge of the degradation mechanisms. The programs are carried out today in order to make a different subprojects concerns several different ma- survey of the proportions of the problem and suggest terials but the technique for artificial ageing, analysis counteractions. and characterization of the materials are almost Concerning materials, such as plastics, paints and similar. Several projects runs in cooperation with varnishes, there is very little known about how air the industry and other research institutes. pollutants and other chemical aggressive environ- ments influence their degradation or protective abil- ity. Some negative effects on the durability of this

MATERIALS SCIENCE, 1993 97 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE, Polymer Technology and Surface Protection/Corrosion type of materials have, however, been reported. For C Recycling/destruction of polymeric electronic components consisting of both polymeric materials materials and metals, the need of the development of Polymeric materials have become an integrated part testing methods has been judged as great for the of today's society, and they are used as cost effective evaluation of the significance of air pollutions on and functional materials in many applications. Poly- their function. mers have also come into the focus in the environ- Present R&D programs' goal is to contribute to mental debate, and as a result recycling has become map the importance of various environments on the an important issue, both for the public opinion and in durability of various materials such as plastics and the environmental policy. various paints and varnishes. The goal is also to This project focuses on the recycling of poly- develop relevant environmental test methods and a meric materials for large scale use in applications technique for studying changes in materials caused with some demands. This implies that it is important by the influence of various types of mechanical that their quality can be guaranteed. The properties stresses. of mixed polymers depend to a large extent on the morphology of the multiphase system formed, which Projects included: will be influenced by both composition and process- - The influence of air pollutions on polymeric ing conditions. Another problem in some potential materials such as plastics, paints and varnishes. applications,e.g. in the building industry, is the long- - Methods for testing of electronic components term stability. Any processing imposes a stress on under the influence of air pollutions. the material, and it is well known that repeated - SCC testing in H2S saturated solutions-deve- processing may lead to not wanted degradation and lopment of methods. deteriorated properties. It is also known that long- - Investigation of durability in alkaline environ- term use induces degradation by thermo- or photo- ment - part 2. oxidation. To protect the polymers from negative - Water vapour permeability as a function of consequences stabilizers are normally added. In the water content. case of recycled materials the situation becomes - Durability of plastic packing. even more complicated. Thermal history and the - Glass fibre reinforced plastics for transpor- original stabilization may vary, it is also probable tation of dangerous goods. that repeated cycles of processing and ageing will have a negative synergistic effect on the degree of Examples of publications: degradation. There are, however, very little knowl- - Plastics - accelerated ageing in alkaline envi- edge on these combined effects. The project is ronment. Jakubowicz, I., Andersson, K, and directed towards this issue. (Fig.l) Hägg, A., SP-report 1992:31. - Effects of sulphur dioxide on the degradation Elongation at break - number of cycles of selective nickel pigmented aluminium oxide solar absorber coatings. Möller, K., Carlsson, B., Eriksson, P. Proceeding at the 12th Scandinavian corrosion congress and Eurocorrosion '92.

* Cyclei 6 Figure 1 - Elongation at break for a nominally unstabi- lized LDPE vs number of cycles of extrusion, ageing, and combined extrusion and ageing. The standard deviations were ±8 % of the given values or less. The extrusions were performed with a conventional labora- tory extruder, according to recommended parameters. Each cycle of accelerated thermooxidative ageing was chosen to correspond to one year or more at 25°C.

98 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE, Polymer Technology and Surface Protection/Corrosion

Example of puMcation: - Repeated processing and ageing of LDPE. Boldizar, A., Gevert, Th., Jakubowicz, I., Bogren, M .*, Linde, M.*, Hjertberg, Th.**. Proceeding to be presented at Re '93 (Interna- tional recycling trade fair, with congress), Geneva 1993. * Dept. of Polymeric Materials, Chalmers University of Technology ** Dept. of Polymeric Technology., Chalmers University of Technology

-t -is -i -ts 0 as i is t D Analysis and characterization of StsUece. i. fnm tie m4*e.,'lie six* {mm/ polymeric materials This project is very tightly connected to the other Figure 2 - By using a film stacking technique, where projects. The aim of the activities within the project polymeric films doped with a diffusant are placed in is to develop and improve the sensitivity of different the middle of a stack of pure films, the diffusion spectroscopic analysis techniques. coefficient of the diffusant can be determined. The figure exemplifies the concentration profiles of an Sensitive techniques are of crucial importance antioxidant in a film stack of polyethylene (LDPE) after when it comes to investigation of minor changes in heat treatment at 50°C for 0,36 and 72 hours respec- the structure of materials. Very often severe deterio- tively. The antioxidant in this case was the dodecylester ration of the macroscopic properties are caused by of 2,&d'itertbutyl phenolpropionate (hindered phenol). Three doped films were used in order to obtain an small changes in the polymer due to chemical and/or appropriate total amount of antioxidant without exceed- physical degradation. The project is concentrated on ing the solubility of the antioxidant. qualitative and quantitative determination of additi- The solid curves represent theoretical values ves in polymeric materials, such as stabilizers, lubri- according to Rck's laws of diffusion under the bound- cants etc. ary conditions given. They were obtained by using a least square curve fitting procedure for best fit be- tween the experimental points in the figure and the The following sub^rojects form the prefect: theoretical expression. The circles, squares and - Diffusion - desorption of antioxidants in triangles represent experimental values, obtained by LDPE(Fig.2) FTIR spectroscopy, for the experimental conditions - Analysis of lubricants in PVC given above. As can be seen, there is a very good fit - Analysis of antioxidant activity in polymers between the experimental data and the theoretical curves. Moreover, the calculated diffusion coefficients also agree very well for the two different duration of Example of publication: time. The difference in the value of the diffuston - Diffusion of phenolic antioxidants in LDPE coefficients is less than 4%. Möller, K., Gevert, Th., to be published in J. of The results above indicate that the diffusir Appl. Pol. Sci. process is very well described by Fick's laws of diffu- sion with constant diffusion coefficients.

MATERIALS SCIENCE, 1993 99 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE, Polymer Technology and Surface Protection/Corrosion E Processing and rtteology G Mechanical properties of polymeric materials of advanced ceramics Almost all currently applied processing of poly- In many high-temperature structure applications such meric materials are based on transport and forming as in gas-turbines and reciprocating engines, parts of a melt. For understanding and prediction of the will be subjected to cyclic loadings. Only recently it courst and outcome of processes, the importance of has been accepted that a brittle ceramic such as rheology for polymer melts is generally accepted. silicon nitride can be sucseptible to cyclic fatigue. One of the problems is that there is no single This area has been studied at SP during the last three comprehensive model describing the complex years with the principal interest in fractography of rheological behaviour occurring in real processes. fatigued samples. All existing rheological models may be regarded as Participation takes place in an EA round-robin special cases of a particular rheological phenomena, between USA, Japan, Germany and Sweden regard- such as shear-flow or elongational flow. ing mechanical testing of silicon nitride. Our intention is first of all to achieve up-to-date Participation also takes place in a VAMAS round- information about the developments on the field of robin regarding fractography of ceramics. The re- theoretical and experimental rheology. We will fur- sults will probably form the base for a new standard thermore also contribute to the development of inCEN. understanding of rheology and its appropriate appli- cations. Examples wf puMcations: - Cyclic Fatigue of HIP Silicon Nitride at Room Ongoing prefects: Temperature. Carlsson, L. The American - Constitutive equations describing rheological Ceramic Society 92nd Annual Meeting, Dal- properties for polymeric melts. las, Texas. 1990. - Flow Rate Ratio (FRR), a rheological testing - Cyclic Fatigue at Room Temperature of Y- method for thermoplastics. TZP and HPSN. Carlsson, L. Proceedings of the 1 lth Risö International Symposium on Metallurgy and Materials Science, Risö, F Quality and reliability technique (1990), 225. The demand forquality systems in industry have led to an increased activity when it comes to formulating quality levels, documentation regarding processes H Physical keeping of documents and other activities, calibration etc. Round-robin Properties of materials and methods used for infor- tests gain information regarding accuracy of differ- mation storage are investigated. Both conventional ent test methods and could be a very useful tool to materials, e.g. paper and recording materials such as harmonize the different steps in the testing perform- pens and copying machines, as well as materials ance. used in modern techniques such as vidoe tapes and This project focus on round-robin tests and has as optical disks, are studied. a goal to support Swedish industry in their quality Our main interests are connected with the perma- assurance activities. nence of the information, i.e. the ability of the document to resist changes over long periods of time Two projects are running for the moment: and/or the possibility tocopy or convert the informa- - Abrasion tests of cables tion to other data carriers. - Round-robin-test on thermo-analythical inves- tigations of polymers Projects: - Permanence and durability of recordingo n Examples of publications: paper - Jämförande provning - gummimaterial, del 1- - Accelerated ageing of paper 12. Magna, A.C., Nilsson, K., Spetz, G., et al. SP-reports 1985-1988.

100 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE, Polymer Technology and Surface Protection/Corrosion Examples of publications: - Natural Ageing of Paper. Swedish Papers 1908-1988. Samuelsson, Marie Louise, Sorrier, K., R/. T-projektet för papperskonservering Rapport nr 4. Stockholm 1990. - Investigations of Video Tape and Audio Tape. Mechanical and Coating Properties. Nilsson, E. SP report 1991:56. Boras 1991.

MATERIALS SCIENCE, 1993 101 The Swedish Institute of Fibre and Polymer Technology, IFP-TEFO Formerly Swedish Institute for Textile Research, TEFO

Introduction Staff The sphere of activities of TEFO is regulated by an Managing Director: agreement between the Swedish Government,repre- Nils-Bertil Furvik, Tekn.lic. sented by NUTEK, the Swedish National Board for Director of Research: Industrial Technical Development and the Trade Roshan Shishoo, Tekn.dr., Prof. Association for Textile Research. TEFO's objective is to undertake R&D pro- Heads of Department: gramme of work dealing with the chemistry, physics Roshan Shishoo (Fibre Technology) and mechanics of fibres and fibrous materials as well Harald Åsnes (Fibre Chemistry) as the technology related to their production and use. Bemt Johansson (Textile Testing) Håkan Damberg (Information/Documentation) Areas of competence Scientific staff: 21 Chemistry, physics and mechanics of fibres and Number of employed PhD's and Licentiates: 11 fibrous materials and technologies related to their Technical staff: 15 production and use. Number of researchers from Chalmers University of Technology that spend part of their working week at Special equipment TEFO in the Science Park: 2 FTIR, Contact Angle tester, Density gradient Col- Total employees: 50 umn, Particle Counter, Viscosimeter», Yarn Shrink- age Tester, Static and Dynamic tensile Compression Annual turnover (1992): Testers, Photo Stereo Microscope, SEM, Tester for ca. 20 MSEK Bond Strength, KawabataTesters (for measurement of tensile, shear, bending, compression and shear properties of fabric films, paper and other sheet Research projects materials.) Structure and physical/mechanical properties of fibres and fibrous materials Address Studies of the basic mechanisms related to the influ- ence of physical and chemical treatments on fibres TEFO and fibrous materials and interactions with their Box 5402, Origovägen 6 structures. S-402 29 Göteborg Phone:(031)824000 Studies of heat setting and desettlng properties Fax:(031)831319 of synthetic fibres and yams Branch office: The shrinkage force of synthetic yarns as a function TEFO Boras, Box 55061, S-500 05 Borås of temperature and simultaneous extension has been Phone:(033)136430 determined for 30 different types. Variations in shrinkage forces have been measured on continu- ously fed yarn and frequency analysis have been carried out for some yam types.

102 THE CENTRE FOR THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-TEFO

By meansofanalysisof shrinkage force measure- and polyester fibres has been investigated with the ments on continuously fed yam it was possible to microbond technique developed by the Textile Re- distinguish different yarn batches. That was not the search Institute of America (TRI). case with standard tensile test for yarn. Liquid adsorption/sorption In fibrous systems. Analysis of heat transport mechanisms Studies of interactions between liquid adsorption/ In upholstery sorption mechanisms on one hand and structural The newly developed method of measuring heat parameters of fibres and fibrous products on the transport is using a shaped indentation device. The other. This work is relevant to absorbent products geometric shape is that of TEFOs mechanical testing and wet processing of textiles. device for sitting comfort. The heat flow in the surface layer is measured in a compressed state Analysis of fibrous absorbent structures. Work has corresponding to actual use. Both transient and been concentrated on small scale studies of the steady-state heat transport is measured. absorption properties of fibrous networks. This has The method has been shown to be sensitive been facilitated by the installation of an apparatus for enough to estimate the influence on comfort of dry forming of absorbent core samples on a labora- various components upholstery layers. tory scale. The systematic variation of absorbent structures has been guaranteed through changing the Water vapour transport in fibrous assemblies fluff and textile fibre combinations. A modified indentation device intended for measur- Additionally, an apparatus to determine dynamic ing the water vapour transport properties of fibrous contact angles and a viscositymeter have been pro- assemblies has been built. A computer controlled cured. These specifically define the surface tension water vapour generator supplies known quantities of and viscosity of test liquids used in the study of vapour to a shaped indentation device. liquid-fibre transport interactions.

Surface properties and surface modification Textile structures for fibre-reinforced composites of fibrous materials Studies have been made of the functional design of In many application areas the surface properties of fibrous reinforcing structures for different compos- fibrous material are of much greater importance than ites as well as studies on interfacial adhesion be- the bulk properties. The surface properties deter- tween matrix and fibres in end products. mine e.g. dyeing, adhesion between reinforcing fi- Fibrous structures for use as reinforcement in bres and matrix in composites, and adhesion be- fibre composites. Textile structures which are spe- tween a coating and a fibrous substrate. The surface cially designed to have high modules and long properties also affect the soiling and soil release lifetime are used as reinforcement in composites of properties of fibrous systems. hard as well as flexible character. These composites are used for products which satisfy high demands, e.g. extreme and corrosive environment combined Research programs with high temperatures and loads.These structures Studies of interfacial adhesion in fibrous materials. are often fabricated of highly performing fibres such This work includes studies of interactions between as aramid, carbon or PEEK fibres. fibre surface, characteristic of fibres and critical A Ph.D. work involving elastomer composites, parameters of adhesives and binders, with the aim to their fabrication and properties is under way. The improve the interfacial adhesion. matrix flow through nonwoven fibrous mats has Studies of relationship between surface proper- been studied according to a newly developed method. ties of fibrous materials and their soiling and soil The work has already got large international atten- release properties. tion. Studies of bonding mechanisms between ther- moplastic fibres and fibrous substrates and plastic coating. The bonding between PVC and polyamid

MATERIALS SCIENCE. 1993 THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-TEFO

The analysis of mechanical properties of light- tional processes of adhesion followed by plastic weight wool febrics relevant to garment making deformation or local fracture, damage. The dust is The tailorability of lightweight wool fabrics and the thus formed by the peak loading. interaction between the ease of tailorability and the performance characteristics of these fabrics has been undertaken on a qualitative/quantitative basis. To achieve trouble-free tailoring of garments made Publications from the above material, the role of the mechanical/ OH Andersson physical properties in the making-up process needs Comments on "Effects of Strain Rate and Gauge Length on to be fully understood. the Failure of Ultra-High Strength Polyethylene Fibers". TRJ, vol 59, no 9, sept 1989

Lost yam preforming and split film based weft insert warp Objectives: co-knitting, new routes for composite materials preforming. (a) To investigate the tailorability properties of light- Verbundwerkstoffe und Wekkstoffverbunde, Chemniz 17- weight wool fabrics using production-line studies 19 juni 1992 according to TEFO's time and motion analysis Thermal residual stresses in short fibre alumina reinforced method. al-alloy matrix. ICCM 8,15-19 juli 1991, Honolulu

(b) To characterise the relevant mechanical and Vibration excitaUxi low-pressure casting, a new route to physical properties of wool fabrics which are impor- produce metal matrix composites. ICCM 8,15-19 juli tant for ease of tailoring of lightweight wool fabrics. 1991, Honolulu H. Damberg The emphasis of this work is placed on the practical Current Situation in the Swedish Textile and Clothing analysis of the tailorability of difficult lightweight Industry. Textile Horizon, vol 9, no 1,49-50 (1989) wool fabrics with subsequent solutions for the mak- ing up of such fabrics. In addition to tailorability T. Dartman, C-H. Andersson analysis of overall garment production, analysis of Adhesion Mechanisms in Joints of PVC-coated Fabrics of part-processes such as sewing, feeding and handling Polyester and Nylon. The International Journal for the Joining of Materials, Vol 2, No 3, Sept. 1990 was done usingTEFO'sCMA-analysis mcthod.The results were also analysed in terms of the relevant S. Posner, A-C Ericsson mechanical and physical properties of the test fab- Control of dye-baths in dyeing processes by neans of fiber rics. The properties have been evaluated using both optical sensors. TEXTRANET-Symposium, 31 mars-1 KES and FAST sets of instruments. april 1992, FoTiO, Portugal R. Shlshoo Formation, transport and eliminating of dust from Fabric properties and making-up processes. Textile Asia, processing fibres, preforms and composites February 1989. Methodology and an apparatus to simulate the me- chanical stress build up in the handling of continuous Gcgcnscitige Beeinflussung von Gcwcbceigenschaften und fibres have been developed from first principles of Konfektionsprozessen. Bcklcidung & Wäsche 7/1989 solid mechanics and geometrical principles of textile Interactions between Fabric Properties and Garment machinery. This apparatus is used in conventional Making-up Processes. Lenzinger Berichte 67/1989. mechanical testing machines. It is encapsulated, works with a flow of pure nitrogen and is integrated Absorbency Mechanisms in Fluff Assemblies Containing with equipment direct counting instruments and Superabsorbcnt Polymers. ACS 63rd Colloid and Surface filters to sample the emitted dust for analysis of Science Symposium. Seattle, Washington, June 1989. morphology by scanning electron microscopy, SEM. Analyses of Mechanical and Dimensional Properties of As expected from the adhesional theory of fric- Wool Fabrics Relevant to Garment Making, fhe 8th tion, the stress build up during textile fibre handling International Wool Textile Research Conference. was found to be of stick-slip type, indicating fric- Christchurch, New Zealand, February 1990.

104 THE CENTRE FOR THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-TEFO

Research in Automation of Clothing Manufacture in Geometrical-Mechanical Properties of Polyester Knitted Relation to Fabric Properties. Symposium on Technical and Fabrics. Abstract of the 21st Textile Research Symposium Industrial Textiles. New South Wales, Australia, February (Mt Fuji) p. 173 (1992). 1990. Use of Objective Measurements in Garment Production and Product/Process Development Using Fabric Objective Design. Abstract of the 21st Textile Research Symposium Measurement Technology. Awtomcc Seminar, Australia, (Mt Fuji) p. 176(1992). February 1990. Analysis of Mechanical Properties of Lightweight Wool Interaction Between fabric properties and garment making. Fabrics Relevant to Garment Making. Proceedings of the Apparel International No 3 March 1990. 2nd International Clothing Conference, Univ. of Bradford, 7-9 July 1992. Investigation of Degree of Set and Deset for PET and Nylon 6.6 Yams. Lectures 15th IFATCC Congress, Lucern A New Process for Fabricating Nonwoven Fibrous- Switzerland, June 1990. reinforced Elastoner Composites. J. Appl. Polymer Sci., Accepted for publication. Relation between fabric mechanical properu>s and garment design and tailorability. International Clothing Conference, Material development for high functional clothing in the Bradford, July 1990. 90's. Proceeding of Int. Symposium on Textiles and Composites '92, Tampere, 1992. Relation between fabric mechanical properties and garment design and tailorability. Int J. of Gothing Science and Analysis of Structure - Absorbcncy Relationships in Technology vol. 2 (1990)3/4 pp.4047. Disposable Hygienic Products. International Conference on Nonwovens, Decemlxv 9-11,1992, New Delhi, India. Relation between fabric mechanical properties and garment design and tailorability. Int. FAMOS(EUREKA) Workshop Analysis of Physical and Mechanical Properties of on Flexible Automation in Textile and Apparel Industries. Nonwovens for Use in Protective Garments. International Oporto, Portugal, nov. 1990. Conference on Nonwovens, December 9-11,1992, New Delhi, India. Fabric Tailorability. Textile Asia, dec.(1990) pp.64-69. R. Shlshoo, M. Epstein Use of the Kawabata Evaluation System of Fabrics (KES- Fabrication methods for latex-based clasiorricd composites F) in the clothing industry. reinforced with long disconu'nous Fibers. Journal of Applied 30th International Man-Made Fibres Congress Dombirn/ Polymer Science, vol 44, no 2, jan. 1992. Austria, 12-14 juni 1991. B. Stenemur Enduse opportunities for viscose rayon fibres. Fascrvlicsbindung mit Polymerdespcrsionen. Conference Progress in Cellulosic Man-Made Fibres, arr. Chcmiefascm/Textilindustrie, vol 39/91,294-298 (1989) Berol Nobel, 10-12 september 1991, Arken Göteborg Vliessioff - Forschung in Schweden. Chcmiefascm/ Textilindustrie, vol 39/91,299 (1989) Fabrication Methods for Latex-Based Elastomer Compos- ites Reinforced with Long Discontinuous Fibres. Journal of Method and device for monitoring Tiber orientation distri- Applied Polymer Science, Vol 44,263-277 (1992). bution and web uniformity on running sebs of paper and npnwovcns based on light diffraction phenomenon. Inda Relation between fabric mechanical properties and garment Journal of Nonwuvcns Research, vol 4, no 2., 1992. design and tailorability. 'Textile Objective measurement and automation in garment manufacture",Ed G. Stylios. G. Waldert, H. Åsnes Publisher Ellis Horwood. Tumble Drying Acrylic, Modacrylic or Polypropylene Fabrics, American Dyest;iff Reporter, vol 79, no 2, Febr. Consumer demands and technical challenges for 1990. nonwoven-based protective clothing. EDANA's 1992 International Nonwoven Symposium 12 and 13 May J. Wang, H. Åsnes Munich. One-bath dyeing of wool/polycstcr blends with acid and disperse dyes. Part 1 and 2, Journal of the Society of Dyers New process for fabricating nonwoven fibrous reinforced and ColourisLs, 107 (1991) 274-279 and 314-319. elastomere composites. 4th International Techtexiil Sympo- sium June 1992.

MATERIALS SCIENCE, 1993 105 The Swedish Institute of Fibre and Polymer Technology, IFP-PGI Formerly Swedish Plastics and Rubber Institute, PGI

TheSwedishPlasticsandRubber Institute, PGI.isan Staff independent research organisation sponsored by the General Manager Rolf Ericsson, Ph.D. industry and the Swedish government via NUTEK CAE Jan-Erik Rosenberg, Ph.D. (Swedish National Board for Industrial and Tech- Processing Per Albihn, Ph.D. nical Development). More than 80 Scandinavian Material and industries are members of the institute. Recycling Ingrid Gustafsson, Ph.D. The Institute was founded in 1977 and has today Consultant work Staffan Ek, M.Sc. 17 employees. The average educational level of the employees is high, with 5 Ph.D., 5 Masters and 4 engineers. Besides most of the staff has a long industrial experience from different kinds of poly- Major Instrumentation mer and manufacturing industries. Simulation and Calculation • 2. HP 9000-730 PVRX work stations. Presently PGI is active in three main areas of re- • 1. HP 9000-360 SRX work station. search: • SDRC IDEAS for Plastics: Solid geometry - Computer aided engineering for polymer based program for CAD, linear FEM with processing and analysis complete rubber and plastics design and - Processing and production methods production analysis including mould design - Materials and recycling and warping of finished parts. PGI carries out industrial research and development • Abaqus, linear and nonlinear FEM program. work for the participating industries. The open re- • Moldflow, Moldfill, moldfilling simulation search projects are proposed and directed by repre- programs fcr plastics. sentatives from the industry. The results from these projects are presented in PGI-reports. Multiclient Production machinery research projects for a smaller group of industries are • Demag D 152-452 Injection moulding machine also undertaken. for rubber and plastics. Locking force 1500 kN. PGI also performs consultant work for all typesof • Brabender DSK 42/7 twin screw compounding industries. The results of that work are strictly con- extruder. fidential and no financial support is given by NUTEK. • Brabender internal mixer for rubber and plas- PGI annually arranges courses and conferences tics, capacity 400 g. in connection with on-going projects and other ac- • Roller mill for rubber. tivities. The institute also participates in education at • Instrumented injection moulding tools for different levels within our member companies and in rubber and plastic. the education at Swedish Universities. Mechanical test equipment Address • 6 MTS servohydraulic testing rigs for dynamic PGI and static tests. Max load 25-50 kN. Frequency Krokslätts Fabriker 30 .01-150 Hz. Climate chamber. S-431 37 Mölndal, Sweden • Monsanto TensometerlO tensile tester for Phone+46318635 80 rubber. Max loadlOkN. Climate chamber.

106 THE CENTRE FOR THE SWEDISH INSTITUTE OF FIBRE AND POLY MER TECHNOLOGY, IFP-PGI

• Instron tensile tester, max load 10 kN. Major Reids of Research • Computerized pendulum impact tester with time/force registration A: CAE - Computer Aided Engineering for • PGI computerized falling weight impact tester Polymer Processing and Analysis Dr Jan-Erik Rosenberg with time/force registration. • Zwick hardness tester for plastics. B: Processing of Rubber and Thermoplastics » Wallace hardness and microhardness tester for Dr Per Albihn rubber. C: Materials and Recycling • PGI creep rig with temperature chamber. Dr Ingrid Gustafsson Rheologlcal characterisation • Bohlin CS-melt dynamic rotation viscosimeter for creep and relaxation Research Projects • Bohlin Visko 88 rotation viscosimeter for liquids. A: CAE-Computer Aided Engineering- • Shimadzu CFT-500 Capillary Viscosimeter for for Polymer Processing and Analysis melts and powders. • CEAST 6540/010 Melt Index tester. Al: Optimization of design, mould and process • Davenport 423 Capillary Viscosimeter. For the design of polymer parts it is important that the • Monsanto Rheometer 100 for rubber vulcani- material's unique properties are used as effectively sation. as possible. Insufficient knowledge of the rheological and mechanical properties of polymer parts often Thermal and material analysis results in unsatisfactory designs and moulds. In • PerkinElmerDSC7andTAC7. order to achieve good results, the most effective • Polymer Laboratories DMTA Mk II. combination of geometry, material, mould design • JEOL JSM T100 SEM and sputter JST 1100 and manufacturing parameters is needed. PGI is for gold coating. currently working at gathering knowledge about the • AGEMA Thermovision 870 heat camera and development process of a part, and at optimizing the video recorder. manufacturing process by using CAE-technique. The demands on the process related to a finishing Other facilities treatment, laquering, is also considered. • Ovens for accelerated heat ageing. • Ozone testing chamber. A2: Quality control in the production • Climate chambers. of moulded parts • Weather simulators. For manufacturers of injection moulded parts, qual- • Microwave vulcanization plant. ity has to an ever increasing extent become an • Computer programs for evaluation of ageing, important tool in competion. The future will bring factory layout, databases for material selection. about higher demands on the manufacturers and call All instrumentations are in principal available for active quality control of every single produced for external users. Contact person, Staffan Ek, part. This involves automatic control of the part at the tfn 031-86 35 80. production stage, and if quality demands are not met, immediate rejection. This requires a large amount of measurements, both of the process and of the pro- duced parts, in order to find the mathematical con- nections used as input in a quality control system. The objective of the project is toestablish the advan- tages with an active quality control system. A basis for minimizing the time and cost consuming work to gather input to the quality control system will also be formed.

MATERIALS SCIENCE, 1993 107 THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-PGI

A3: Mechanical straight - wekflines B: Processing of Rubber and Higher demands are now also made on the end Thermoplastics product. Product properties are often not the same as in tests specimen, for example weld lines are weak- Bl: Rheology of Rubber ening factors in many products and the properties are The rheology of rubber polymers and finished rub- also influenced by flow length. In this project, prop- ber compounds is studied. The influence on process- erties of injection moulded parts with weld lines are ing behaviour of the polymer molecular structure studied, and relations between process parameters and different types of carbon black is investigated. and weld line properties are established. The aim is EPDM and SBR rubbers are caracterised for varia- to give instructions as how to dimension parts with tion in molecular structure (long chain branching) weld lines. and molecuiiu weigth and molecular weigth distri- bution using NMR, IR and SEC. P heological behav- A4: Knowledge based systems iour of the polymers and compounds are measured In many companies today there are problems with on capillary and rotational viscosimeters and corre- taking care of all the information, know-how, guiii- lated with industrial processing (compounding in ered during different development projects. The internal mixers and injection molding). purpose with this project is to develop a knowledge A study has shown that present standards and based system. This system will include know-how in instrumentation can not predict processing behav- order to facilitate future developments and to in- iour even for well standardised material while se- crease product quality. The system will also make lected rheological data were able to correlate with sure that continuity in the development process is processing performance. maintained and that the influence of personnel and The project aims to develop a standard reheologi- reorganizations is minimized. cal measurement for raw materials, processing rub- ber compounds and process control. A5: Compounding, designing and processing rubber parts B2: Practical rheology-evaluation of rheological One of the purposes with this project is to develop a characterisation of rubber material knowledge based system where the methods of Many different rheological methods and instrumen- experienced compounders will be implemented. The tation are used by the rubber industry. The project advantages with such a system is, for example, will study which type of rheological data that best simpler recipes, standardization possibilities and describe the processing ability of compounded rub- time reductions. For the company using the system ber material. Selected modem rheological instru- it is also a good way to take advantage of different mentation will be evaluated and measurement re- persons'knowledge. sults will be related to actual process performance for The calculations of strains and deformations in different processing operation. the designs of rubber parts can be very difficult since the rubber material model is complicated and de- B3: Multilayer Injection moulding of rubber formations, extensions and interferences between PGI has developed a method to produce a three layer rubber and surrounding walls are substantial. As a rubber product in one moulding operation. Contrary result, the calculations are highly non-linear and to thermoplastics, multilayer injection moulding of therefore considerably more complex to handle than rubber products is a stepwise process, one material the linear calculations used for dimensioning metal being injected at each step using moving parts in the parts. The purpose is to compare calculated and mould. measured static stresses and to evaluate the results. The flow behaviour of rubber in the mould is PGI has also begun a cooperation with a software industrial know-how and is not reported in the supplier to increase the possibilities for calculations litterature. on rubber materials. The aim is to develop a software The rheological and geometrical conditions that that makes it possible to analyze the mould filling controls the multilayer formation will be investi- process of rubber parts. The software is expected to gated. The processing conditions (mainly tempera- be commercially available during spring 1993. ture, injection speed and pressure) that controls the

108 THE CENTRE FOR THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, IFP-PGI multilayer formation will be evaluated for several The project will study the influence of the pro- rubber materials. To further promote adhesion be- cessing conditions on properties of finshed part in tween different rubber materials coupling agents selected advanced materials. will be used. The project aims at a complete indus- trial process and to produce finshed multilayer prod- B7: Effective start-up of injection moulds ucts in one moulding operation. Each new injection mould has to be run in. The setting of the production parameters are usually done 1. E Vos, H. Meijer, G Peters, Multilayer Injection by earlier experience. The process can take several Moulding: Intern. Polymer Processing IV (1991) I s hours. With the use of modem statistical methods 42-50. this can be speeded up and a higher quality of the product be assured. B4: Injection moulding technique The project is a multiclient study of how to make The project studies quality in injection moulding best use of commercially available statistical pro- using the latest machinery and instrumentation. grams for opimization of mould start up and quality Computer control of the injection process is nor- assurance of injection moulding. mally done by controlling the injection unit. Ad- Joint project with IYF, Swedish Institute for vances in computer technology now enabels process Production Research. control by sensors in the mould. Heat transfer in moulds also contributes to pro- 1. P Karlinger. E Biirkle. Von Qaulitetsmerkmalen duct quality. Temperature distribution in finished zu Einstelldaten. parts and in moulds are studied using heat camera Kunststoffe 82 (1992) 3 s 175-179. technique. B8: injection moulding of long fibers B5: Gasinject The fiber reinforcement of injection mouldable Injection of compressed gas in the melt during thermoplasics are made up of relativly short fibers, injection moulding is a novel method that have normally 0,1-1 mm long. Some materials with longer several advantages. Parts with a hollow interior have fibers are commercially available but in many app- lower weight, and a uniform wall thickness can lications the fibers are damaged by the injection eliminate sink marks. The gas distributes pressure moulding process. better and machines with lower clamping force can The project will study the interfacial mechanisms be used. The process also faciliates new construction of the fiber polymer bonds during the moulding solutions for many parts. operation. The surface treatment of the fibers (the PGI will evaluate the advantages and limitations siiane coupling agents) will be optimized for of the process together with industrial companies rheological properties during moulding as well as that are using the process. mechanical strength of finished parts. Joint project with YKI, Swedish Institute for 1. H Eckhard. KontinuierlicherGasinnendruck beim Surface Chemistry. SpritzgieBen, Kunststoffe 82 (1992) 10.

B6: Precision Injection moulding C: Materials and Recycling Many advanced materials such as LCP-polymers, These projects fall into three main categories; Dura- high performance blends and special compounds bility test of polymeric materials, Environmental require special processing conditions for optimum related projects and Recycling. performance. The products that are produced in these materials are ofen used in complicated applica- Cl: Durability tests of polymeric materials tions with high demands on product quality. The Degradation of polymeric materials is a very com- influence of processing conditions on material pro- plex process, which makes it difficult to predict the perties are often limited, even from the raw material lifetime for engineering polymers. PGI has during a producers. long period studied several methods of determining

MATERIALS SCIENCE, 1993 109 THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY, 1FP-PGI expected lifetime of plastic and rubber materials. functional unit are studied. Depending on the system Thereby several different methods have been evalu- boundaries surrounding conditions may have to be ated. assumed and rules for allocation may have to be A very comprehensive study was made on rub- decided to be able to calculate the environmental bers and thermo-plastic elastomers. The degradation impact in waste handling processes or processes was studied in air, water and oil and was performed with several products. during five years. The durability of mineralfilled polypropylene C3: Recycling has been studied extensivly in the last five years. If recycling of polymeric materials should be suc- Accelerated aging in oven at 125°C was performed cessful many problems must be solved within dif- and the lifetime of the material was determined ferent fields. If recycling should be used on a large as the impact properties decreased below fifty per- scale in applications with high demands it is neces- cent of the original values. It was found that the sary that the quality of the recycled material is lifetime of the mineral-filled polypropylenes varied sufficient. To garantee long-term properties for re- from two weeks to over one year depending on cycled material becomes even more difficult than which mineral the material was composed of. for virgin material. Studies are now performed to relate accelerated It is known that long-term use induces degra- aging in oven to other more quicker methods. The dation by thermo-oxidation or photo-oxidation. To oxygen induction time (OFT) is measured in a dif- protect polymers from this, stabilizers are normally ferential scanning calorimeter and related to the added. With recycled material the situation becomes results from accelerated aging in ovens. very complex. The thermal history and the original The remaining amount of different antioxidants stabilization may vary. Repeated cycles of process- are studied in aged materials by using supercritical ing and ageing may have a negative synergistic fluid extraction (SFE) on line with effect on the degree of degradation. However there chromatogranhy (SFC). Both qualitative and is very little knowledge on these combined effects quantitative measurements are performed using a and PGI is using SFE-SFC technique to study how flame-ion detector. to restabilize recylcled material to be able to improve the long-term properties of these materials. C2: LJfecycle assessment (LCA) LCA studies are made to analyse and assess the C4: Recycling of polymer blends environmental impact of a material, product or ser- The best way to get good properties for the recycled vice throughout the entire life cycle. LCA should be material is to separate the waste after polymeric composed of four different steps; goal definition, identity. However it is not always possible todo this. inventory analysis, impact analysis and valuation/- Sometimes it can be economically more favorable to improvement analysis. reuse the material as a polymeric blend. LCA can have various purposes: Most polymer combinations are however incom- - To calculate the environmental impact for patible and they give a multiphase material with poor specific life cycles. mechanical properties. It is widely known that the - To compare alternative products, processes or presence of certain blockcopolymers, compatibi- services. lizers, can increase the miscibility of different poly- - To identify parts of the life cycle where the mers. Suitably chosen it will alter the interfacial greatest improvements can be made. situation leading to improved mechanical proper- ties. PGI is working with the inventory analysis for PGI is studying the possibility to upgrade the plastic and rubber materials. One of the difficulties mechanical properties of recycled polymer blends encountered during the inventory is to find all the by using commercially available compatibilizers. necessary data about the processes and transporta- tion in the life cycle. On a methodological level questions defining the system boundaries and the

110 THE CENTRE FOR THE SWEDISH INSTITUTE OF FIBRE AND POLYMER TECHNOLOGY. IFP-PGI

Publications

Diploma ?.ork C Grönvall eL al., "Mould filling simulations of thermo- plastic parts", 1990

L Jansson, J Magnusson, "Mould filling simulations of rubber parts", 1992

L Lekscll eL al., "Warpagc and shrinkage - An evaluation ofl-DEAS Plastics", 1992

N Alveby, "Study of the compatibilizing effect on polypropylcnc/polyamidc blends", 1993

Reports and articles "Mould Tilling simulations of thermoplastic parts", C Grönvall et. al., PGI-report no 104,1991.

"Warpage and shrinkage - An evaluation of I-DEAS Plastics", L Leksell CL al., PGI-report no 111,1992.

"Ihc use of Swedish minerals as fillers in thermoplastics", G Mälhammar, PGI-report no 81,1988.

"Swedrh minerals as Tillers in thermoplastics", G Mälhammar, PGI-report no 98,1990.

"Minerals in polymeric systems", I Gustafsson, G Mälhammar, PGI-report no 109,1992.

"The effect of mineral fillers on impact and tensile proper- ties of polypropylene", L Jilkén et. al., Polymer Testing 10, (1991),329-344.

"Degradation of rubber materials and thcrmoclasiics in air, water and oil", Å Eliasson, H Tjömvik, PGI-rcport no 113, 1992.

"A comparison of process-techniques for SBR 1500 materials from four different suppliers", T Hjertberg et. al., PGI-report no 96,1989.

"Simplified production control during injection moulding of thcrmo-plastics", C Bengtsson, O Krugloff, PGI-report no 70,1987.

"Polymer melt rheology - an introduction", B Hagström, H-E Strömvall, PGI-report no 105,1991.

MATERIALS SCIENCE, 1993 111 Biomaterials

Surface Physics 114

MATERIALS SCIENCE. 1993 Surface Physics

Research Summary Address The group's research comprises basic research and Department of Applied Physics applied research within the field of surface science Chalmers University of Technology and chemical physics. The basic research is focused S-41296 Göteborg, Sweden on dynamics and kinetics of surface processes, espe- Phone+46 31 772 3370 cially molecule-surface interactions. Two Fax+46 31 772 3134 reoccurring, important issues are: i) description of individual steps (adsorption, desorption, surface re- actions etc.) forming the reaction sequence and ii) Staff what do the potential energy surfaces which govern Senior members the reaction dynamics look like? Surface processes Bengt Kasemo professor involvingchargetransferduringmoleculardissocia- IgorZbric PhD. tion (accompanied by light and electron emission), Jukka Lausmaa fil.dr. replacement type reactions, photo-induced reactions Anatole Krozer tekn.dr. and catalytic reactions are typical playgrounds were Dinko Chakarov Ph.D. the above issues are explored. Kinetics of surface catalyzed processes as well as the description of Secretary catalytic ignition are also of central interest. Appli- Anne-Christine Lindbom cation oriented research is focused around kinetic Graduate students studies of car exhaust catalysts and metal-oxide Bjöm-Owe Aronsson civ.ing catalystsfor catalytic combustion of methane. A link Julie Gold M.Sc. has been established between the basic research on Lars Hellberg fil. kand. model catalysts (single crystals) in ultra high vacuum Per Hjort fil.kand. (UHV) and applied work on supported catalysts, Patrik Johansson fil.kand. either underUH V conditions or at higher pressure (1 Staffan Lundgren fil.kand. (at AB Volvo) atm). This link also comprises industry collabora- Peter Lööf civ.ing tion. Bengt Olsson civ.ing (at AB Volvo) A multidisciplinary research within the field of Mats Rinnemo civ.ing biomaterials has grown rapidly within our group Michael Rodahl civ.ing, M.Sc. containing both basic and applied components and Per Salomonsson civ.ing (at CIT) industrial collaboration. The basic research aspects Claes Åkerlund fil.kand. are focused on issues related to the interaction be- Lars Österlund fil.kand. tween water, simple biomolecules (amino acids), and proteins with model bioimplant systems. On the applied side, issues of controlled growth of oxide Major Instrumentation surfaces on bioimplants and the role of surface • Molecular beam scattering apparatus for structure on the adsorption of biomolecules are studies of reactive molecule-surface scattering examined. Microfabricated surfaces down to the (incl. LEED, rotatable mass spectrometer, high nanometer level and chemically modified surfaces energy beam) are central in this research. • Molecular beam scattering apparatus for studies of surface chemiluminescence (incl. photon counting facility, sticking measure- ments on reactive species)

114 THE CENTRE FOR SURFACE PHYSICS

Surface analysis system (facility for UPS, XPS, Collaborators: profs S. Andersson, B.I. Lundqvist, AES, ISS studies of surfaces with sample load A. Rosen, (CTH), W. Ho (Cornell), V. P. Zhdanov lock system) (Institute of Catalysis, Novosibirsk, Russia), Emis- Combined UHV-high pressure apparatus for sion Teknik AB, Volvo AB, EKA Nobel AB., T. studying catalytic and other surface reactions Griffin (ABB, Heidelberg) (includes AES, HREELS, TPD, MS, LEED, UV photon beam) D: Catalytic Ignition Molecular beam mass spectrometer Participants: Mohammad Fashihi, Mats Rinnemo, Equipment for plasma preparation of materials Bengt Kasemo, Karl-Erik Keck Flow reactor with on line mass spectrometry Collaborators: V. P. Zhdanov (Institute of Catalysis, Combined UHV-high pressure apparatus for Novosibirsk, Russia) studies of metal hydrides (AES, XPS, QCM, MS) Thermal desorption spectroscopy equipement E: Kinetics and Thermodynamics Equipement for hydration-dehydration studies of Metal Hydrides of various materials at atmospheric pressure Participants: Per. Hjort, B. Kasemo, A. Krozer STM and AFM for topography and imaging of Collaborators: prof. L. Schlapbach (Fribourg, various surfaces. Switzerland) V. P. Zhdanov (Inst. of Catalysis, Novosibirsk), prof. E. Karlsson's group, Uppsala University

Financial Support F: Biomaterial Surfaces and Blocompatibilrty • Nutek Participants: Bjöm-Owe Aronsson, Julie Gold, Patrik • TFR Johansson, Bengt Kasemo, JukkaLausmaa, Michael • NFR Rodahl • Knut and Alice Wallenberg Foundation Collaborators: Prof. I. Lundstrom's group at the • Industry Laboratory of Applied Physics, Linköping Univer- sity; The Nanometer Laboratory, CTH; Department of Anatomy, Göteborg University; Medical Scien- Major Reids of Research ces Research Institute, USA; Nobelpharma AB, Several orthopaedic and other clinics A: Dynamics and Kinetics of Surface-Molecule Collisions G: Micronics Participants: Lars Hellberg, Bengt Kasemo, Igor Participants: Bjöm-Owe Aronsson, Julie Gold, Zone, Claes Åkerlund Michael Rodahl, Anatole Krozer, Peter Lööf, Collaborators: profs. B. Cooper and W. Ho, Cornell Mohammad Fassihi University, USA, profs. B.I. Lundqvist and S. Collaborators: Prof. I. Lundstrom's group at the Andersson (CTH) Laboratory of Applied Physics, Linköping Univer- sity; The Nanometer Laboratory, CTH; Department B: Reactivity of Caibon Surfaces of Anatomy, Göteborg University and Photoinduced Surface Processes Participants: D.Chakarov, Bengt Kasemo, Karl-Erik Keck, Lars österlund Research Projects Collaborators: C. Janiak, Frie Universität, Berlin, prof. R. Hoffman, Cornell University, USA A: Dynamics and Kinetics C: Catalytic Reactions Related of Surface-Molecule Collisions to Energy and Environment Participants: Bo Hellsing, Bengt Kasemo, Karl-Erik Al: Charge Transfer Reactions Keck, Staffan Lundgren, Peter Lööf, Per and Surface Chemlluminescence Salornonsson This project is concerned with the reaction of halo- gen molecules and atoms with alkali metal surfaces

MATERIALS SCIENCE, 1993 115 SURFACE PHYSICS

(e.g. CI2 on a potassium surface). The choice of about kinetics and dynamics of the particular surface reactants can be regarded as a model system for process under study. charge transfer at surfaces, where parameters are e.g. A search for the Eley-Rideal reaction mechanism the work function, electron affinity levels, and den- has been conducted in processes involving CO im- sity of states at the Fermi level. As a consequence it pinging on CO, O2 or NO adsorbed on Pt(lll) is possible to observe phenomena like emission of surface 43. A search for CO2 produced in a direct charged particles and light. This is more rarely seen pick-up process, for different beam energies, incom- in other systems where charge transfer is also known ing angles and degrees of vibrational excitation was to be important, such as molecular dissociation on carried out Upper limits for these particular reaction transition metals. probabilities were found to be very low (<10-5). An The motivation to perform these experiments is explanation for these low values was related to twofold. On the one hand, the phenomena observed symmetry properties of the reactant HOMO and are very interesting as such and are well worth to LUMO orbitals as well as to their position within the study. On the other, we believe that important new Pt conduction band. knowledge will emerge which will be possible to A second surface reaction studied was the re- generalize on other surface (catalytic) reactions. Our placement of O2 on Pt(l 11) surface by incident CO initiated studies on photoinduced desorption are molecules 48. We have studied this particular proc- conceptually and theoretically closely connected ess as a function of O2 coverage, CO kinetic energy with this project (see B below). and surface temperature. Furthermore, we have also A new molecular beam scattering apparatus has measured the associated CO coverage and energy been constructed for these studies. It was initially and coverage dependence of the CO sticking coeffi- used to study various aspects of the atomic light cient. The main findings include a strong variation of emission from the K4p-4s transition observed in the the replacement cross section with incident energy CI2 gas + K solid reaction. At later stage a facility to and O2 coverage. These results are contrasted by the measure the absolute sticking coefficient and an absence of O2 removal from the surface when ex- Auger Electron Spectrometer were added in order to posed to a beam of Ar atoms or O2 molecules having characterize the surface composition. The latest the same energy as the CO mole .ules. These results modifications have recently been used to measure suggest a dynamic energy transfer between the in- the sticking coefficient of CI2 on a clean potassium coming CO molecule and the adsorbed O2 as a surface. In general the equipment is designed for candidate for the replacement mechanism. studies of the different branches in e.g. in alkali- metal/halogen gas interactions such as, surface B: Reactivity of Carbon Surfaces and chemiluminescence, photon-, electron-, and ion Photoinctaced Surface Processes emission, and excited particle emission. The technological background for this project is the known influence of additives on the reactivity of A2: Reactive Molecular Beam Scattering carbon materials towards oxidizing molecules. Pure The main scientific goal of this project is to under- carbon in graphitic form is remarkably resistant to stand surface reactions on the atomic level. This is oxidation. In contrast alkali metals may enhance the best achieved once the details of the potential energy oxidation rate in O2 by several orders of magnitude. surface (PES) topology are established. Particular This phenomenon has implications for carbon gasi- regions of the PES, called activation barriers play fication (e.g.. fuel production), carbon combustion, very important roles since their size and location in soot combustion in diesel particle filters, etc. the reaction coordinate space determine reaction In this project the reactivity of carbon surfaces rate, as well as the energy degrees of freedom of the with additives is studied by a combination of kinetic reactant which is most effective in getting them methods, primarily Thermal Desorption Spectro- "over" the barrier into the product region. The ex- scopy, and spectroscopic methods. Specifically, we perimental method used to probe PES consists of a study coadsorbates of potassium with O2, H2O, supersonic beamofreactantsimpingingon the model CO2, or NOX, respectively on graphite. catalyst surface. The analysis of the reflected, stuck, Examples of recent results are that dissociative and reacted fraction yields valuable information sticking of O2 on graphite 59 is enhanced by > 103

116 THE CENTRE FOR SURFACE PHYSICS times by as little as O.OS monolayer of potassium. reactions, heat, and mass transfer, has been devel- Several KOX surface precursor complexes preced- oped. The model iscapableof a quantitative descrip- ing CO2 formation from O2 + graphite, have been tion for the ignition sequence in the H2/O2 system on identified by high resolution electron energy loss Pt over wide range of parameters. In particular the spectroscopy 5!. These results have stimulated theo- transition from the low temperature, kinetically lim- retical work by Dr. C. Janiak and Prof. R. Hoffman ited reaction to the high temperature, primarily mass at Berlin and Cornell University, respectively. Re- transport limited reaction is now well understood 52. cently we have also started a study of photochemical This project also contains a subproject aimed at reactions involving visible-UV light irradiation of computer modeling of kinetics of primarily catalytic potassium and potassium complexes with O2, H2O, reactions. The model system has from the beginning CO2, and NOX on graphite. been the H2/O2 reaction on Pt and connects the activities under A2 and C above. Basically, the C: Catalytic Reactions Related approach is to construct a kinetic model involving to Energy and Environment the known or assumed steps of the reaction, to This project involves active industry collaboration. calculate (i) surface coverages of participating spe- The common theme is catalytic oxidation of hydro- cies and intermediates, and (ii) calculating the rates carbons and/or H2, either for car exhaust emission of individual steps. This requires knowledge about reduction or forcombustion of primarily methan t. In sticking coefficients (including their coverage de- the former case noble metal catalysts are studied, in pendencies), rate constants and activation barriers the latter metal oxide catalysts. For car exhaust (including also their coverage dependencies) and so catalysts modifications of catalyst properties due to on The interplay with experiments, probing the support interaction has been studied37-69 (Pt and/or calculated quantities is vital. In the collaboration Rh on AI2O3 and COX respectively). Recently the with Ame Rosen's group the H2/O2 reaction has sintering of small Pt particles on these supports, as been explored using calorimetry to measure the influenced by H2,02 and NO has been studied 57. absolute PbO production rate, and laser induced Combustion catalysis of CH4 combustion are fluorescence to measure the simultaneousdesorption studied with respect e.g. to activity, oxygen capacity rate of the intermediate OH in the reaction (for and reaction mechanisms. The kinetic studies are pressures 1 - 1000 mTorr and temperatures 900 - combined with surface spectroscopic characteriza- 1300 K). This has resulted in a currently fairly tion of the catalysts. accurate model, within the so called mean field approximation, (for the H2/O2 reaction on Pt). The D: Catalytic Ignition same model predicts correctly the OH desorption and klnetik modeling from pure H2O and H2O+Oa mixtures on Pt 53, and The questions addressed in this project has a basic also accounts for the ignition of H2/O2 mixtures science component and an applied one. The central discussed above. issues include critical conditions, transients and in- stabilities in catalytic reactions like ignition, extinc- E: Kinetics and Thermodynamics tion, oscillations and chaotic behavior. Combined of Metal Hydrides theoretical and experimental efforts have advanced In this project we have studied the formation kinetics the understanding of the ignition phenomenon in the and electronic properties of (mainly) MgHx. Mg - H2+O2 reaction on Pt at 1 atm 7 •. The experimental hydride is a possible candidate for hydrogen storage approach consists of measuring pre-ignition kinetics in certain technological applications, e.g. heat pumps, and the ignition temperature for water production on catalytic combustion (as internal hydrogen source), Pt as a function of H2/O2 mixing ratioat atmospheric etc., and may also serve as a model material to study pressure, gas flow parameters, surface temperature the problem of hydrogen embrittlement. The project etc. In this pressure range surface kinetics, heat was naturally divided into two stages. balance and mass transfer are responsible jointly for In the first stage we investigated the kinetics of the observed catalytic ignition. A computational uptake and the phase diagram of hydrogen by Pd program for calculations of the time dependent coated Mg films15. The samples were prepared by coupled equations describing kinetics of surface

MATERIALS SCIENCE, 1993 117 SURFACE PHYSICS

UHV-evaporation on a sensitive quartz crystal cally upon hydriding; thus confirming that the alka- microbalance and hydrided in-situ at pressures 10-3 line earth hydrides are insulators. The bandgap (as -10 Torr in a hydriding cell attached to the UHV- obtained from UPS measurements) is 3.4 eV wide system The main findings are: There is a pressure- for Mg and 2.2 eV wide for Ba. The valence band of temperature regime (nigh p - low T) where thermo- Mg-hydride is centered around 5.4 e V and its FWHM dynamic equilibrium between the H2 gas and Pd is 2.4 e V. The valence band of Ba-hydride is centered covered Mg sample cannot be reached due to inter- around 4.3 eV and its FWHM is 2.9 eV. face hydride formation at the Pd-Mg interface. The The resistivity of Pd covered Mg films, hydrided interface hydride grows until it coalesces and blocks in the equilibrium region of the phase diagram, further hydrogen diffusion towards the (unhydrided) increases linearly by approximately 0.5 pQcm/aL%H, interior of the sample. This was inferred from the in the region of concentrations [H/Mg] < 1. Irrevers- observed kinetics, and proved by nuclear micro- ible resistivity shifts are generated by cycling the analysis measurements performed by Prof.. Erik hydriding dehydriding process. These shifts are gen- Karlsons group, Uppsala University. erally about a few percent of the total resistivity A theoretical model describing the formation and change and are supposed to be related to hydrogen growth of the interface hydride developed in col- embrittlement. laboration with Prof.. V. Zhdanov, Novosibirsk 61. The model agreed semiquantitatively with the ex- F: Biomaterial Surfaces perimental results. The model is applicable not only and Btocompatibllity to the H - Mg system, but describes the kinetics of The biomaterial related research within the group is any 1st order phase transformation which is driven carried as part of the Biomaterials Consortium, one by the (surface) source term. of 11 Interdisciplinary Research Consortia in Mate- There is also a p - T regime Qow p - high T) where rials Science and Materials Technology, funded by equilibrium can between H2 gas and MgHx can be NUTEK/NFR. The Biomaterials Consortium con- established. In this regime we have measured the sists mainly of our group at CTH and Ingemar hydrogen absorption anddesorption isotherms, and Lundstrom's research group at Linköping Univer- associated kinetics, at 105 times lower pressures sity, and also includes several projects in collabora- than reported before. The results are in excellent tion with groups from biology, medicine, and the agreement with the reported high temperature, high clinical disciplines. Our own activities consist of the pressure data. following major projects: In the second stage of the project one of us (A. Krozer) has studied hydrogen induced electronic Fl: Preparation and properties changes occurring during the formation of Mg - surface oxides on Ti hydride (and of Ba - hydride) by UPS and XPS. Surface oxides on pure Ti and Ti6A14V alloy are Currently we are studying the resistivity changes in prepared by different methods (thermal oxidation, Mg films as a function of hydrogen uptake. The electrochemical methods, plasma oxidation etc.) former experiments were performed in Fribourg in and analyzed by surface spectroscopies, electron collaboration with the group of Prof. L. Schlapbach microscopy, and STM/AFM. The objective is to 40-42,47. The main findings are: There is aconsid- develop methods for producing Ti surfaces with erable chemical shift (1.7 eV) of the Mg 1 s core level systematically varied properties (microstructure, upon hydriding. Ba 3d core levels show only minor roughness, chemical composition,...). The Ti sur- chemical shifts. Part of Mg samples used remained faces are used as model materials in biological metallic at the experimental conditions used, while experiments where the influence of specific surface Ba was hydrided fully at the same conditions. The (oxide) properties on biological response is studied structure of losses accompanying core lev- by collaborators. Results from this project have led els of metallic Mg (and of metallic Ba) changes to a broad surface spectroscopic and electron micro- drastically upon hydriding; the levels shift in energy, scopic characterization of oxides prepared by differ- broaden (i.e. experience larger damping) and the ent methods on pure Ti and Ti6A14V alloy '.3-5, number of losses decreases. The density of states at 8 - 10,12,14,21,22,26 - 28,35,36,39,44,46,54,56,62,64, the Fermi level of both Mg and Ba decreases drasti- 66,68,76-78

118 THE CENTRE FOR SURFACE PHYSICS

F2: Qowdtecnarge plasma preparation logical experiments (cell cultures, bacterial of surfaces adhesion)54 Glow discharge preparation is used as a method for Future developments in this subproject will include: controlled preparation and modification of (i)extendingthe range of microfabricated surfaces to biomaterial surfaces. One important goal is to map include structures and/or lateral chemical variations out the surface properties of plasma prepared sam- on the submicron scale, (ii) incorporation of the use ples as a function of plasma parameters (pressure, of self-assembled monolayer techniques for prepar- gas, current density, etc.). DC-plasmas are used for ingsurfaceswithcontrolledchemical functionalities. cleaning, oxidation, and chemical modification (nitriding, carbiding, etc.) of metal surfaces. The F4: Preparation, modHlcatlon preparation is carried out in a UHV-equipment, and properties of biomaterial surfaces which allows several preparation steps to be carried In this project different preparation methods out without any intervening exposure to uncon- (electrochemical methods, PVD, glow discharge trolled ambient. Results include: plasma, nano- and microfabrication, self-assembled • The current-voltage-pressure characteristics of monolayers) are developed for preparing samples argon DC glow discharge with cylindrical with systematically varied surface properties. The geometry has been studied. surfaces are analyzed using different techniques • Procedures for controlled cleaning of Ti (surface spectroscopy, electron microscopy, and surfaces using an Ar glow-discharge have been scanning probe techniques), and subsequently used established. in different biological experiments, which are mainly • Oxides with different properties have been carried out by collaborators. The aim of this project prepared in 02-plasma. is to find correlation between surface properties • Different plasma prepared surfaces (oxides, (structure and/or chemical composition) and bio- nitrides, etc.) have been analyzed by surface logical response. Some results from this subproject spectroscopies 62, electron microscopy, and are: STM/SFM44. • Ti implant, with different surface oxide proper- Within this project we also intend to develop proce- ties (thickness, roughness, and microstructure), dures for transferring UHV-prepared surfaces to have been evaluated with respect to bone biological experiments without exposure to uncon- response at the Department of Anatomy, GU. trolled ambient. Thicker and rougher surface oxides tend to heal in faster than smooth and thin ones %>. 68, F3: Nano-and mlcrofabricated surfaces wrth • Ti oxide surfaces have been used in plasma controlled mlcroarchrtecture protein adsorption studies at the Laboratory of and/or chemical composition Applied Physics, LiU. The different Ti oxide In this project nano- and microfabrication methods surfaces show differences in protein adsorption (optical and electron lithography, PVD, dry and wet behavior. chemical etching, etc.) are used for preparing model • Microfabricated surfaces, with controlled surfaces for biological experiments. The objective is lateral variation in chemical composition to develop surfaces with variations in micro- (10x10 fim domains of Ti, Al, or V), have been architecture and/or chemical composition, on a well- used in bacterial adhesion studies. Bacteria defined size scale. Materials used include Si, Ti, Al, show a binding preference in the order V > Ti V, Pt, and Au. This project utilizes the Nanometer >A154,66 Laboratory at the Department of Physics, CTH. • A method for preparing intact oxide-tissue • Surfaces with well-defined microarchitecture interface sections for TEM analysis has been and/or variations in chemical composition on developed in collaboration with the Depart- the \tm scale have been produced. The surfaces ment of Anatomy, GU 22. have been characterized by surface spectro- scopies, electron microscopy and STM/AFM 66 and are used in a number of different bio-

MATERIALS SCIENCE, 1993 119 SURFACE PHYSICS

F5: Model experiments of Gl: Sintering of highly dspersedPt on AJ203 biomolecule«unace interactions This study 37> 57- w was undertaken to primarily In this project the interaction of H2O and/or simple investigate the stability of highly dispersed Pt parti- biomolecules with solid surfaces is studied by sur- cles on porous AI2O3. The parameters of interest face science methods, in order to obtain an increased were temperature and gaseous environment. The understanding of the microscopic details of the inter- effects of the latter were striking. In noble gas or action between material surfaces and biological sys- reducing atmospheres no sintering, i.e. no loss of Pt tems. Initial experiments have been carried out on surface area, was observed up to 700°C. In contrast, H2O and glycine (co)adsorption on an oxidized Ti when the gaseous atmosphere contained O2 signifi- surface, usingthermaldesorpnonspectroscopy(TDS) cant sintering was observed down to 500°C. Nitric as the analytical technique. Results include: oxide, NO, had an even larger effect on the sintering, • Water adsorbs in at least three different bind- which was then observed down to 200°C. ing states in the first monolayer on the We have also developed a simple model which polycrystalline TiO2 surface, with desorption has been successful in describing the sintering peaks in the range 350-170 K. The two peaks behavior mathematically 52. The model is based on at higher temperature correspond to a coverage that emission of an atom or molecule from a sup- ~O.l ML. and are believed to represent bond- ported catalyst particle is the rate limiting step in ing and dissociation at defect sites (grain sintering and that the stability of a particle depends boundaries and oxygen vacancies). on adsorbed gases and on the size of the particle. • Multilayers of intact glycine molecules form at Emission T<350 K. No intact glycine molecules desorb Diffusion from the first monolayer, either because of \ dissociative adsorption and/or thermal decom- position (T >500 K). The results demonstrates the stability problem with • Coadsorption induces only minor changes in nm structures on supports and how important the the desorption spectra of H2O and glycine, influence of various properties is for the stability. respectively, independently of the sequence of adsorption. No change in glycine desorption is G2: QCM measurements of water and protein adsorption observed. For H2O the high-temperature peak This study 73«74 was initiated with the following long decreases in intensity, with a corresponding term goals increase in the medium-temperature peak. (i) to explore the possibility to use the QCM for Future studies in this project will include: (i) various protein adsorption studies, spectroscopic (XPS and UPS) characterization of (ii)to investigate the influence of different surface the adsorbed species, (ii) use of new surfaces (Pt, and preparations on the protein adsorption behavior single crystal TiO2) and additional amino acids, and (2D or 3D adsorption, absolute coverage at (iii) incorporation of interesting coadsorbates, such different protein solution and surface condi- as atomic H and alkali atoms. Another aim is to tions etc.) develop the TDS method as a "finger-print" tech- (iii) to eventually develop the QCM technique nique for characterizing biomaterial surfaces. for kinetic studies in liquids. So far steps (i) and (ii) have been realized. Using the G: Mlcronlcs immersion-washing-drying technique developed for studies of adsorption of silica sol particles we inves- The objective of this project is to use the group's tigated the saturation coverage of ferritin at different expertise about surfaces, surface processes, and sur- ferritin concentrations and on different surfaces. The face preparation and analysis to prepare and investi- main results are: With increasing protein concentra- gate properties and processes of submicrometer tion the saturation coverage increases monotonically particles/structures particularly those of interest for until aclose packed layer of ferritin is approached for catalysis and biomaterials. hydrophilic ozone cleaned Au surfaces. Step (iii) has just been initialized as a collaboration with the

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Department for Biophysics. We are building a liquid Jukka Lausmaa, GU, "Surface Preparation and Analysi of cell for the QCM which allows us to do simultaneous Titanium Implant materials," June 8,1988 measurements of protein adsorption, capacitance, Mohammad Fassihi.GU, "Catalytic Oxidation of H2 on Pt," and laser induced electron transfer processes in situ June 1,1991 and in real time. These results were compared to results obtained Diploma Work, CTH with oxidized Ti surfaces and with Au, prepared by Joakim Ramberg, "Testing of an Open Polymer High- preadsorption of thiols. The results showed signifi- Voltage Cable Ending," 1988 cant differences in surface coverage as the surface Bengt Olsson, "Influence of Mcthanol on the Tribological status was changed. These exploratory measure- Behaviour of Steels," 1988 ments will be extended to other proteins and to more precisely defined surfaces. Magnus Hurd, "Kinetic Modelling of 2NO + 2H2 & N2 + 2H2O on Palladium Surface," 1989 G3: Biomaterial related micronics projects Göran Rådegran, "Preparation of Thin Oxide Windows on There is a substantial overlap between the micronics Titanium forTEM Analysis and Protein Adsorption," 1989 project and the biomaterials projects. Within the micronics program we have acquired an atomic Johan Landin, "Preparative Techniques for the Study of force microscopy (AFM) and scanning tunneling Protein Adsorption," 1989 microscopy (STM). These methods are excellent tools for characterizing topography of biomaterials Martin Dahlberg, "Evaluation of Fuel Sensors for Alcohol Content measurements," 1990 44,68,72. The objective of this study is to, as precisely as possible, characterize the topography of implants Johan Strömqvist, "Numerical Calculations of Ion Trajecto- and try to understand how it influences the biological ries Inside a Quadrupolc Mass Spectrometer Analysis of response. As mentioned above AFM and STM have Detection Efficiency," 1991 also been used to characterize nano- and micro- Per Hovcrstam, "A Computerized Pulse Counting Detec- fabricated surfaces. In the future we expect an even tion System for Mass Spcctrometry - Installation, stronger connection between the micronics and the Syncronization, and Testing," 1991 biomaterials programs. Gudrun Spicss, "Sulphur Storage and Hydrogen Sulphide Release from Car Aged Catalysts," 1992

References 1988-1992 Project Work at GU Lars-Olof Torbcrntsson, "Calcium Doping of Anodic Oxide Ph.D. Dissertations Films on Titanium, 1989 Analolc Krozer, CTH, "Hydrogen Adsorption on Pd-coalcd Mg: Kinetics and equilibrium H/Mg ratios" May 26,1989 Claes Åkerlund, "Production and Size manipulation of Alkali Clusters on Alkali Halidc Surfaces," 1991 Dag Andersson, GU,"K+C12 Surface Chemilumincscencc: Molecuar Beam Scattering Apparatus, Spectra and Kinet- Patrik Johansson, "Theoretical and Experimental Studies of ics"; Nov 10.1989 a DC Glow Discharge Plasma," 1992

Jukka Lausmaa, GU, "Surface Oxides on Titanium: Books Preparation, characterization and biomaterial applications," 1. "Preparation, Surface Spcctroscopic and Electron June 4,1991 Microscopic Characterization of Titanium Implant Materials" J. Lausmaa, B. Kascmo, U. Rolander, L.M. Peter Sjövall, CTH, "Adsorption, Dcsorption and Reaction Bjurstcn, L.E. Ericson, L. Rosander and P. Thomscn in of Oxygen Containing Molecules on Clean and Potassium Surface Characterization of Biomaterials B.D. Ratncr, Covered Carbon Surfaces," May 21,1992 Editor. 1988,Elscvicr: New York. p. 161-174. 2. "Improved insight into catalytic reactions by kinetic Ucenclate Dissertations modelling and LIF detection of intermediate species" Mikael Ask, GU, "Composition and Structure of Surface E. Fndell, B. Hcllsing, S. Ljungström, T. Wahnström, Oxide Films on Ti6AI4V," May 31,1988 A. Rosén and B. Kasemo in Laser Spcctroscopy IX M.S. Fold, A. Mooradian, and J.E. Thomsas, Editor. 1989, p. 424.

MATERIALS SCIENCE, 1993 121 SURFACE PHYSICS

3. "Preparation and analysis of Ti and alloyed Ti surfaces 17. "An experimental study of the kinetics of OH and H2O used in the evaluation of biological response" J. formation on Pt in the H2+O2 reaction" S. Ljungström, Lausmaa, M Ask, U. Rolander and B. Kasemo in B. Kasemo, A. Rosén, T. Wahnström and E. Fridell, Biomaterials and biomedical devices J.S. Hanker and Surf. Sci. 216.1989,63. B.L. Giammara, Editor. 1989, Material Research 18. "Oxygen storage capacity of noble metal car exhaust Society: p. 647-653. catalysts containing Ni and Ce" P. Lööf, B. Kasemo 4. "The biomaterial-tissue interface and its analogues in and K.-E. Keck, Journal of Catalysis 118,1989,339- surface science and technology" B. Kasemo and J. 348. Lausmaa in The bone-biomaterials interface J.E. 19. "A Surface Spectroscopic Study of Reaction Layers in Davies, Editor. 1991, University of Toronto Press: Alcohol-Fuelled Diesel Engines" L. Mattsson, H. Toronto, p. 19-32. Abramsson, B. Olsson, H. Ekberg, P.H. Nilsson, G. 5. B. Kasemo and J. Lausmaa. Biomaterials from a Wirmark and B. Kasemo, Wear 130,1989,137. surface science perspective, in Symposium on Surface 20. "Unusual kinetics in Mg/Pd sandwiches, studied by Analysis of Biomaterials. 1988., Ann Arbor Michigan, hydrogen profiling and quartz crystal microbalance June 21-24,1987: Elsevier, Amsterdam. measurements" J. Rydén, B. Hjörvarsson, T. Ericsson, E. Karlsson, A. Krozer and B. Kasemo, J. Less Journal Articles Common Metals 152,1989,295. 6. "Kinetic model study of OH desorption during H2O 21. "Microstructure and morphology of surface oxide films production on Pi" B. Hellsing and B. Kasemo, Chem. on Ti6AMV" M. Ask, U. Rolander, J. Lausmaa and B. Phys. Leu. 148,1988,465. Kascmo, J. Mäter. Res. 5,1990,1662-1667. 7. "The island model of a Langmuir Hinshelwood 22. "Method for ultrastuetural studies of the intact tissue- reaction" B. Hellsing and V.P. Zhdanov, Chem. Phys. metal interface " L.M. Bjurstcn, L. Emanuclsson, L.E. Leu. 147,1988,613. Ericson, P. Thomsen, J. Lausmaa, L. Mattsson, U. 8. "Biomaterial and implant surfaces; on the role of Rolanderand B. Kasemo, Biomaterials 11,1990,596- cleanliness, contamination and preparation procedures" 601. B. Kasemo and J. Lausmaa, J. Biomed. Mater. Res.; 23. "Determination of the activation energy for OH Applied Biomaterials 22.1988,145-158. desorption in the catalytic H2 + O2 reaction on Pi" E. 9. "Biomaterials and implant materials: A surface science Fridell, B. Hellsing, B. Kasemo, S. Ljungström, A. approach" B. Kasemo and J. Lausmaa, The Interna- Rosén and T. Wahnström, Vacuum 41,1990,732. tional Journal of Oral & Maxillofacial Implants 3, 24. "Hydrogen uptake by Pd-coated Mg; absorption 1988,247-259. decomposition isotherms and uptake kinetics" A. 10. "Surface spectroscopic characterization of the separa- Krozer and B. Kasemo, J. Less Common. Metals 160, tion of plastic-embedded tissue and titanium implants" 1990,323-342. J. Lausmaa and L. Linder, Biomaterials 9,1988,277- 25. "Hydrogen interaction with Pd covered Mg- 280. equillibrium uptake and kinetics at low pressure and 11. "Weighing monolayers of colloidal silica particles with temperature" A. Krozer and B. Kasemo, Journal of the a quartz crystal microbalance" S.-A. Nordin and B. Less Common Metals 160,1990,323. Kasemo, Progress in Colloid & Polymer Science 76, 26. "Surface Spectroscopic Characterization of Titanium 1988,51. Implant Materials" J. Lausmaa, B. Kasemo and H. 12. "Preparation and Surface Spectroscopic Characteriza- Mattsson, Applied Surface Science 44,1990,133-146. tion of Oxide Films On Ti6A14V" M. Ask, J. Lausmaa 27. "Multi-technique surface characterization of oxide and B. Kasemo, Appl. Surface Sci. 35,1988-89,283- films on electropolishcd and anodically oxidized 301. titanium" J. Lausmaa, B. Kascmo, H. Mattsson and H. 13. "Electronic mechanism for alkali promoted oxidation Odelius, Appl. Surface Sci. 45,1990,189-200. of semiconductors" B. Hellsing, Phys. Rev. B 40, 28. "A Surface Spectroscopic Study of Nitrogen-Implanted 1989,3855. Ti and Ti6AI4V Wear against UHMWPE" J. Lausmaa, 14. "Ultrastructural Differences of the Interface Zone T. Röstlund and H. McKcllop, Surf. Interface Anal. 15, Between Bone and TOA14V or Commercially Pure 1990,328-336. Titanium" C. Johansson, J. Lausmaa, M. Ask, H.-A. 29. "NO2 adsorption on graphite at 90 K" P. Sjövall, S.K. Hansson and T. Albrektsson, J. Biomed. Mater. Res. So, B. Kascmo, R. Franchy and W. Ho, Chem. Phys. 11,1989,3-8. Lett. 171,1990,125-130. 15. "Equilibrium hydrogen uptake and associated kinetics 30. "Laser-induced fluorescence studies of rotational slate for the Mg-H2 system at low pressures" A. Krozer and populations of OH desorbed in the oxdidau'on of B. Kasemo, J. Physics. F. Condensed Matter 1,1989, hydrogen on Pt" T. Wahnström, S. Ljungström, A. 1533. Rosén and B. Kasemo, Surf. Sci. 234,1990,439-451. 16. "Determination of the activation energy for OH 31. "Hydroxyl desorption from plalimum in the catalytic formation in the H2+O2 reaction on polycrystalline formation and decomposition of water" E. Fridell, B. platinum" S. Ljungström, E. Fridell, B. Hellsing, T. Hcllsing, B. Kasemo, S. Ljungström, A. Rosén and T. Wahnström, B. Kascmo and A. Rosén, Surf. Sci. 223, Wahnström, J. Vac. Sci. Tech. A 9,1991,2322. 1989.L905-L912.

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32. "A gas inlet system for quantitative mass 47. "Hydrogen diffusion in thin Mg films studied by XPS" spcctroscopy" J. Hall, S. Lundgren, K.E. Keck and B. P. Spatz, H. Aebisher, A. Krozer, A. Fischer and L. Kascmo, Int. J. Ion and Mass Spcctromctry 108,1991, Schlapbach. to appear in Zcitscrift fur Physikalischc 1-21. ChcmicNF 33. "Measurement of position-dependent detection efficiencies for two quadropole mass spectrometers Submitted manuscripts with electron-impact ion sources" J. Hall, M. Rinncmo, 48. "Replacement of 02 by CO on Pt( 111) surface" C. I. Zone and B. Kasemo, Rev. Sci. Instr. 62,1991,1-6. Åkerlund, I. Zoric, J. Hall and B. Kascmo, submitted to 34. "Reaction scheme for catalytic oxidation of hydrogen Journal of Chemical Physics 1992. on platinum" B. Hcllsing, B. Kasemo and V. Zhdanov, 49. "The reaction between CI2 and evaporated K films. II. Journal of Catalysis 132,1991,210-228. Surface chcmilumincsccncc and negative particle 35. "Wear of ion-implanted pure Ti and Ti6A14V alloy emission intensities vs. CI2 exposure" D. Andersson against UHMWPE" J. Lausmaa, T. Rostlund and H. and B. Kascmo, submitted to Surf. Sci. 1992. McKcllop, Surf. Eng. 7,1991,311-317. 50. "The reaction between CI2 and evaporated K Films. I. 36. "Wear of ion-implanted pure titanium and Ti6A14 V Mass uptake rates vs. C12 exposure for various film alloy against UHMWPE" J. Lausmaa, T. RösUund and thicknesses" D. Andersson, B. Kascmo and A. Mällo, H. McKellop, Surface Eng. 7,1991,311-317. submitted to Surf. Sci. 1992. 37. "Influence of Ceria on the Interaction of CO and NO 51. "The interaction of potassium with oxygen on graphite with Highly Dcspersed Pi and Rh" P. Lööf, B. as studied by high resolution electron energy loss Kascmo, S. Andersson and A. Frestad, J. Catalysis 130, spcctroscopy and thermal dcsorption spcctroscopy" w 1991,181-191. D.V. Chakarov, P. Sjövall and B. Kascmo, submitted 38. "Up-hill diffusion and hydrogen-hydrogen interaction to Journal of Chemical Physics 1992. in Pd-Pt alloys'' A. Mällo and A. Krozcr, Journal of the 52. "Catalytic ignition in the hydrogen-oxygen reaction on Less Common Metals 167,1991,305. platinum" M. Fassihi, V.P. Zhdanov, M. Rinncmo, K.- 39. "Preparation of ultra-thin oxide windows on titanium E. Keck and B. Kascmo, submitted to Journal of for TEM analysis" G. Rådegran, J. Lausmaa, U. Catalysis 1992. Rolandcr, L. Mattsson and B. Kasemo, J. El. 53. "OH formation in H2O and H2O + Oa mixtures" E. Microscopy. Techn. 19,1991,99-106. Fridell, B. Kascmo and A. Rosén, submitted to 40. "Mg on Mg(l 11): the formation of local order ob- Langmuirl992. served by photoclectron diffraction" R. Fascl, J. 54. "Site-specific adhesion of S. cpidcrmidis in Ti-Al-V Osterwalder, A. Fischer, A. Krozer and L. Schlapbach, metal systems" B.L. Gabriel, J. Gold, A.G. Grisiina, B. Physical Review Letters 1992, Kascmo, J. Lausmaa, B. Nilsson, C. Mroczck and Q.N. 41. "Plasmon losses in thin Mg films - a new method for Myrvik, submitted to Science 1992. thickness determination" A. Fischer, A. Krozcr and L. 55. "Layer by layer growth of 5-50 nm silica-sol particles Schlapbach, Physical Review B 1992, studied by quartz crystal microbalance measurements" 42. "Mg/Pd and Ba/Pd interfaces and without hydrogen" A. Krozcr, S.A. Nordin and B. Kascmo, submitted to A. Fisher, A. Krozcr and L. Schlapbach, Surface Journal of Colloid and Interface Science 1992. Science 269/270,1992,737. 56. "Bone healing around titanium implants with different 43. "Reaction of fast CO molecules with CO, NO, or 02 surface oxides" C. Larsson, P. Thomscn, J. Lausmaa, presorbed on Pt(l 11) surface; a search for Elcy-Ridcal B. Kascmo and L.E. Ericson, submitted to 1992. reaction mechanism" J. Hall, I. Zoric and B. Kasemo, 57. "A TDS and TEM study of the influence of different Surface Science 269/270,1992,460-464. gases on the sintring rate of nm Pt-particles on AI2O3" 44. "Scanning Tunneling Microscopy of Oxidized Tita- P. Lööf, B. Stenbom, H. Norden and B. Kascmo, nium Surfaces in Air" H. Olin, B.O. Aronsson, B. submitted to Journal of Catalysis 1992. Kascmo, J. Lausmaa and M. Rodahl, Ultramicroscopy 58. 'Time and space resolved measurements of gas 42-44,1992,567-571. compostion and temperature in catalytic reactions. Equipment design and results for H2 oxidation and Pi" Accepted for publication S. Lundgren, K.-E. Keck and B. Kascmo, submitted to 45. "Vibrational spectra of KOx complexes on graphite" Journal of Catalysis 1992. D.V. Chakarov, P. Sjövall and B. Kascmo, to appear in 59. "A TPS study of oxygen, water, and carbon dioxide Surface Science coadsorplion with potassium on graphite" P. Sjövall 46. "A histomorphomctric study of the bone tissue re- and B. Kascmo, submitted to Surface Science 1992. sponse to untreated and nitrogen-ion implanted c.p. 60. "Thermal desorption from multiple stages of potassium titanium and Ti6A14V" C.B. Johansson, J. Lausmaa, T. intercalated graphite" P. Sjövall and B. Kascmo, Rostlund and P. Thomscn, to appear in J. Maler. Sci.. submitted to Physical Review Letters 1992. Materials in Medicine

MATERIALS SCIENCE, 1993 123 SURFACE PHYSICS

61. "Kinetics of the interface hydride formation by Pd- 70. "CO disproportionation on cobolt" S. Lundgren, B. coatcd Mg" VP. Zdhanov, A. Krozcrand B. Kasemo, Kascmo and K.-E. Keck, 1992 (manuscript in prepara- submitted to Physical Review B 1992. tion). 71. "On the critical condition for catalytic ignition; H2/O2 Manuscripts in preparation on Pt" M. Rinnemo, M. Fassihi and B. Kascmo, 1992 62. 'Titanium oxides formed in a DC glow-discharge (manuscript in preparation). plasma" B.-O. Aronsson, J. Lausmaa and B. Kasemo, 72. "Charcterization of natural oxide and electropolishcd 1991 (manuscript in preparation). titanium implants with different oxide thickesscs with 63. "A molecular beam scattering apparatus for surface AFM" M. Rodahl, 1992 (manuscript in preparation). chcmiluminesccncc studies. Preliminary results for 73. "Water adsorption measuremcts of various surfaces by emission of excited K atoms" D. Andersson, L. a quartz crystal microbalancc" M. Rodahl and B. Hellberg and B. Kasemo, 1992 (manuscript in prepara- Kasemo, 1992 (manuscript in preparation). tion). 74. "Quartz crystal microbalance studies of ferritin 64. "The behaviour of inflammatory cells close to the adsorption onto various surfaces" M. Rodahl, A. implant surface studied ultrastructurally during the first Krozcrand B. Kasemo, 1992 (manuscript in prepara- week after insertion of titanium and polytetrafluoro- tion). ethylcne implants in soft tissue" L.E. Ericson, P. 75. "Photodesorption of NO2 from graphite at 90 K" P. Thomson, L.M. Bjursten, J. Lausmaa and B. Kascmo, Sjövall, W. Ho, B. Kascmo and S. So, 1992 (manu- 1992 (manuscript in preparation). script in preparation). 65. "A simple model of sintering of supported catalyst 76. "The ultrastructure of the intact interface between particles in various atmospheres" M. Fassihi, P. Lööf tissue and implants of aluminium, gold, titanium and and B. Kascmo, 1992 (manuscript in preparation). zirconium" P. Thomsen, L.M. Bjursten, J. Lausmaa, B. 66. "Model systems for studying site-specific bacterial Kasemo and L.E. Ericson, 1992 (manuscript in adhesion in Ti-Al-V metal systems" J. Gold, B.L. preparation). Gabriel, B. Kascmo, J. Lausmaa, A.G. Gristina, C. 77. "Controlled microsurface preparation for analysis of Mroczck and Q.N. Myrvik, 1992 (manuscript in cell-implant interactions" P. Thomsen, J. Lausmaa, E.- preparation). K. Andersson and B. Nilsson, 1992 (manuscript in 67. "Kinetics of interface hydride formation in Pd preparation). precovered Mg films" A. Krozcrand B. Kasemo, 1992 78. "Morphomctry of the interface between bone and gold, (manuscript in preparation). titanium and zirconium implants" P. Thomson, J. 68. "Bone tissue response to surface modified implants in Lausmaa, L. Scnncrby, L.M. Bjursten, B. Kasemo and rabbit. Part 1. Studies on clcctropolishcd titanium L.E. Ericson, 1992 (manuscript in preparation). implants with different oxide thicknesses" C. Larsson, P. Thomsen, J. Lausmaa, B. Kasemo, L. Ericson and M. Rodahl, 1992 (manuscript in preparation). 69. "CO disproportionation on supported noble metal car exhaust catalysts" P. Lööf and B. Kascmo, 1992 (manuscript in preparation).

124 THE CENTRE FOR Clusters and fine particles

Molecular Physics 126 Engineering Chemistry 139

MATERIALS SCIENCE, 1993 125 Molecular Physics

Research Summary reactivity of clusters of Fen, CON and CUN clusters, The research activities within our group consist of a with N=10-55. An electric arc evaporation set up has theoretical programme for investigations of the also been built for macroscopic production of electronic structure of atoms, free molecules, atomic fullerenes and a time of flight (TOF) spectrometer clusters and surfaces and an experimental pro- for analysis of solids, surfaces, gases and volatile gramme for studies of clusters, fullerenes and prob- liquids using ion sputtering and laser ionization. lems in surface science and catalysis using laser spectroscopy. Qose interaction between the experi- mental and theoretical research programmes is em- Address phasized. Department of Physics The theoretical research involves both the devel- Chalmers University of Technology opment and the application of computational meth- S-412 96 Göteborg, Sweden ods for non-relativistic and relativistic calculations Phone +46 31 772 3295 for molecules, clusters and fullerenes based on the Fax+46 31 772 3496 Local Density Approximation. X-ray Absorption Near Edge Structure (XANES) and photoionization cross-sections have been evaluated for small metal Staff clusters. The electronic structure, ionization ener- Senior Members: gies, electron affinities, absorption spectra, linear Arne Rosén professor and non-linear optical properties have been calcu- John Persson PhD April91,UCLA lated for Ceo and COO doped with different atoms. A scheme has been developed for evaluation of Graduate Students: the electronic structures of the bulk, stoichiometric Mats Andersson civ.ing. and non stoichiometric surfaces of ionic crystals Alf-Peter Elg fil kand. such as CaF2 and BaF2 using small clusters embed- Erik Fridell fil.lic. ded in an external crystal potential. This scheme has Fredrik Gudmundson civ.ing. been used for interpretation of laser induced en- Henrik Grönbeck fil. kand. hanced electron and ion emission and SHG genera- Lotta Holmgren civ.ing. tion for these surfaces. Johan Mellqvist civ.ing. Laser-induced fluorescence (LIF) is used for the Erik Westin tekn.lic. identification and characterization of intermediate Bo Wästberg civ.ing. species in catalytic reactions, and particularly to- Daniel Östling fil. kand. wards studies of the reaction intermediate, OH, in the oxidation of hydrogen and decomposition of water Technical staff: on different transition element catalysts, such as Pt, Leif Johansson engineer Pd, Rh. Ir and Ni. Measurements of the yield of OH Heinrich Riedel chemist (part time) (from LIF) and the rate of H2O production (from calorimetry) have been combined with kinetic model Secretary: calculations by Prof. Bengt Kasemo in the Chemical Eva Eriksson (Dart time) Physics Group. A new set-up for production of clusters of any solid elements with the laser method has been built and used for measurements of the

126 THE CENTRE FOR MOLECULAR PHYSICS

Major Instrumentation Wilhelm and Martina Lundgren's Scientific Contact peisons: Foundation Ame Rosén tel 031-7723295 Adlerbertska Foundation Leif Johansson tel 031 -7723297 • High vacuum system for studies of catalytic reactions at pressures of 10*3 -1 Torr using Major Reids of Research LIF and mass spectrometry. A: Calculations for free molecules, clusters and • UHV-system with AES and LEED for studies surfaces of surfaces of single crystals, catalytic reac- participants: Henrik Grönbeck, Ame Rosén, tions using LIF, mass spectrometry, SHG, SFG Erik Westin, Bo Wästberg and Daniel Östling andDFG. collaborators: Sven Larsson, Manuell Braga, • Excimer laser, Lambda Physik EMG102 Phys Chem CTH., Don Ellis, Nortwestern (XeCl) Two dye lasers, Lambda Physik University Evanston Illinois USA , Bengt FL2002E Lindgren, Uppsala University, Uppsala., • Excimer laser, Lambda Physik LPX2101 Burkhard Fricke, Dirk Heinemann, University (ArF) of Kassel, Kassel, Germany, Eckart Matthias, • Nd: YAG laser ns, ps, Quantel International Freie Universität Berlin, Germany, Peter YG 671 C-10 Dye laser ns, TDL 51, Dye laser Apell, Dept of Theoretical Physics CTH ps, PTL 10, IR-generation, These lasers are shared with Lars Walldén B: Laser spectroscopic studies of catalytic reac- • TOF spectrometer for laser ionization mass tions and kinetic modelling spectrometry participants: Alf-Peter Elg, Erik Fridell, • Set-up for production and spectroscopy of free Fredrik Gudmundson, and Arne Rosén clusters collaborators: Bo Hellsing and Bengt Kasemo, • CCD camera Spectroscopy Instruments Chemical Physics, Dept. of Applied Physics, • Nd: YAG laser ns, Continuum YG 661-10 CTH/GU. • Workstations SUN SLC and ELC • Different MAC and IBM computers C: Laser Ionization Mass Spectrometry participants: Mats Andersson, John Persson and Arne Rosén. Financial Support The Swedish Natural Science Research Council D: Experimental Studies of Clusters (NFR) participants: Mats Anderssoi, John Persson The National Swedish Board for Technical Devel- and Arne Rosén opment (NUTEK) collaborators: Participants in the Consortium The Swedish Board for Technical Development "Clusters and Ultrafine Particles", Wolgang (STUF) Krätschmer, Max Planck Institut Heidelberg The Swedish Council for Planning and Coordina- tion of Research (FRN) E: Calculations for atomic systems Material Science Consortium "Clusters and participants: Arne Rosén Ultrafine Particles" (NFR/NUTEK) collaborators: Burkhard Fricke, University of Swedish Research Council for Engineering Kassel, Kassel, Germany. Sciences (TFR) National Energy Administration (STEV) F: Related projects Ema and Victor Hasselblad Foundation participants: Johan Mellqvist and Ame Rosén Knut and Alice Wallenberg Foundation collaborators: Bo Galle, Swedish Environ- Carl Trygger's Foundation mental Research Institute, Håkan Axelsson and Ollie and Elof Ericssons Foundation for Scientific Annika Johansson, Vattenfall, Engineering Research AB, Göteborg and Älvkarleby, Svante Höjer,

MATERIALS SCIENCE, 1993 127 MOLECULAR PHYSICS

Dept of Optoelectronics CTH , Magne Alpsten has been developed for 36 finite double point groups Dept of Radiation Physics GU, Olle Larkö (6) and used to study the electronic structure of Dept of Dermatology Sahlgrenska Hospital element 105 (7). GU In recent years, there have been an increasing interest in the use of numerical methods for the self- consistent solution of the Schrödinger and Dirac Research Projects equations for molecules as a complement to standard basis set oriented approaches i.e. MO-LCAO. We A: Calculations for free molecules, have used the finite element method (FEM) for clusters and surfaces calculations of potential energy curves for diatomic The calculations for free molecules, clusters and molecules within the restricted Hartree Fock Slater fullerenes performed within our group are mainly (HFS) approximation using the FEM method in based on the local density approximation, LDA, calculations of spin polarized HFS (3) and restricted which implies that the exchange and correlation Hartree Fock (HF) potentials (4). The potential parts of the electron-electron interaction are replaced energy curves are determined with a numerical with a local potential. The calculations are oriented accuracy of better than 10^a.u. i.e. 0.03 meV. These towards studies of electronic, linear and non-linear type of very accurate potential energy curves have optical properties. The molecular wavefunctions also been used for optimization of basis-sets used in and potentials evaluated with our programs have MO-LCAO calculations (5). also been used as input to other programs for evalu- A2: Electronic structure for free molecules, ation of XANES spectra and photo-ionization cross clusters, fulllerenes sections for small clusters. The computer programs The electronic structures of small cobalt and nio- developed for studies of the electronic structure of bium clusters, Coi.j3 (8), Nbi-n (9,10) have been free molecules, and small clusters are also very t calculated within the local spin density approxima- suitable for studies of problems related to surface tion using the LCAO method. The possibilities of science and catalysis. Of particular interest is the fact using XANES for determination of the geometrical that our computational methods can be used for structure of clusters has been tested in calculations of studies of surfaces of metals and insulators including theoretical K-edge XANES cross sections for some metal clusters and molecules adsorbed onto the dimers and trimers as Fe2, Ni2, M3, Mn2 and C02 surfaces, which are of great interest in basic surface (11,12). The calculated cross-sections for the dimers science and applied catalysis. predict broad resonantstructure s atthe threshold and weak Is transitions to unoccupied valence orbitals Al: Development of computational methods giving a shoulder at the threshold. The resonance The molecular wavefunctions are of Molecular Or- structure at the threshold of Ni3 appeared to be bital Linear Combination of Atomic Orbital, MO - sensitive when varying the apex angle of the trimers LCAO, form with atomic basis functions on a nu- from a linear shape to an equilateral triangle. merical grid generated with an atomic self-consist- In spite of very successful research for studies of ent-field (SCF) program for free atoms or ions. The experimental ionization potentials, electron affini- matrix elements in the secular equation are evaluated ties, abundances for neutral and negatively charged by use of three dimensional numerical integration clusters asdetermined from mass spectrometry meas- methods as the Discrete Variational Method, DVM, urements on supersonic cluster beams, very little is and more recently a method developed by P. M. known about the nature of the photoionization cross Boerrigter, G. Te Veide and E. J. Baerends (Int. J. sections of such clusters. We have in to order to Quant. Chem. 3_3_,87(1989)). The multiple scatter- analyze such problems performed some calculations ing, MS, method has been generalized for general of the photoionization cross section forclusters of Na non-muffintin potentials of molecules with an arbi- and K and have evaluated the U V and especially 5- trary geometrical shape and tested in calculations on + 15 eV photoelectron cross sections of Na2-s and K2. H2 and CO( 1,2). Furthermore, acomputerprogram K clusters (13-15) using the continuum multiple- for generation of symmetry adapted basis functions scattering method combined with starting potentials

128 THE CENTRE FOR MOLECULAR PHYSICS calculated with our molecular programs using the LDA method. The most striking feature of these calculations is the resonant behavior of all Kx clus- SURFACE CLUSTERS (MX2 13 atoms) ters between 5-10 eV and the absence of resonances M centred X centred for the Nax clusters. These resonances could be understood as shape resonances i. e. trapping of the outgoing photoelectron by a potential barrier in the effective potential. Surface plane The development of an efficient method [W. Kratschmer, L.D. Lamb, K. Fostiropoulos and D.R. Huffman, Nature 347 (1990) 354 - 358. ] for large scale productionof the early discoveredfootball-like carbon cluster COO also referred to as "Buckminsterfullrene" [ H. Kroto, J.R. Heath, S.C. Crystal cross section Point ions O'Brien, R.F. Curl, and R.E. Smalley, Nature 318 (1985) 162 - 163 ] has during the last two years initiated a boom of experimental and theoretical studies. Our earlier predictions from 1987 (16) of Figure 1. Geometry oi the planar clusters used to represent the (111) surface cf CaF2 and BaF2. optical transitions for Qj has been found to be Our model of the crystal ^rvironment is crucial when Krätschmer et al developed the electric schematically shown. M = Ca or Ba and X = F. arc evaporation technique for macroscopic method for production of fullerenes, (see project D2). These calculations have been extended to the evaluation of self consistent field calculations. This technique has the optical spectra for the negative and positive ions been used in analysis of the electronic structure of of COO and for polycyclic aromatic hydrocarbons different models of ionic surfaces of CaF2 and BaF2 PAH (17,18). Furthermore, many of our earlier and in particular of how the non-stoichiometry influ- predictions of ionization energies and electron af- ences the local surface electronic structure and hence finities for Qo have been found to be in good the interaction mechanisms with exterior distur- agreement with recent UPS measurements. Calcula- bances. We have so far discussed laser interaction tions have also been done for the neutral, positively (30-35) and compared our results with experimental and negatively charged clusters of Qo and metal EELS data for CaF2. The study of laser induced containing clusters as MQo .where M= La, Li, Na, processes at ionic crystal surfaces also include analy- K, Rb, Cs, Ca, Sc, and for K2Q0 and K3Q0 (22-27). sis of second harmonic generation, SHG, where we have worked out phenomenological expressions A3: Electronic structure of solids and surfaces governing this process (36) and evaluated the wave- The electronic structure and bonding processes for length dependent hyperpolarizabilities (37). molecules adsorbed on surfaces and especially CO adsorption on Ni, C1. Pd and Pt surfaces has earlier A4: Studies of linear and nonlinear optical been analyzed. We have more recently focussed our properties for fullerenes work on analyzing the composition of the 2p* state In this project, single particle wavefunctions deter- of CO adsorbed on the Pt(llO) surface (28). mined from ground state LDA calculations for An overview of our method for evaluation of the fullerenes are used for evaluation of dipole matrix electronic structure of surfaces of ionic crystals elements which combined with a sum over state surfaces is given in the fig. 1 and discussed in (30-35). approach yield linear and non-linear microscopic Briefly, a local molecular cluster is embedded in an polarizabilities gO) and gO), respectively. Lorentz external potential derived from frozen ionic charge local field factors, as well as a simple RPA type distributions and a sufficient number of exterior correction are introduced to facilitate comparison point ions (33,36). Molecular eigenvalues, wave- with the dielectric function e(w) determined from functions and charge densities are then obtained by films of C«). Reasonable agreement is found with

MATERIALS SCIENCE, 1993 129 MOLECULAR PHYSICS

results from linear optical response experiments i.e. Bl. Studies of OH, H2O formation and H20 ellipsometric and EELS measurements on C^n in decomposition on model catalysts as Pt, solid or solution form after screening has been Pd, Rh, Ir included as obtained from the RPA (38-41). Second We have in this project focussed our research on a Harmonic Generation, SHG, Third Harmonic Gen- study of the simplest heterogeneous catalytic model- eration, THG, and Degenerate Forward Mixing, reaction, that includes OH-radicals, which is the DFWM, experiments yield values close to the oxidation of hydrogen to water on a metal catalyst. unscreened result, while invoking a RPA screening The OH radical is formed at the surface of the results in a non-resonant value about 2 orders of catalyst when molecular hydrogen and oxygen first magnitude lower than most experiments. dissociate at the surface and then recombine to OH, which is then consumed in the water formation. If the A5: Studies of surface in fullerenes catalyst is kept at a high temperature (> 1000 K) there Studies of the U V absorption and EELS experiments is a small possibility that the OH radicals desorb have shown very strong resonances which have from the catalyst before beingconsumed in the water similarities to the collective resonances found in production. The OH radical has been detected and graphite. We have in cooperation with Peter Apell characterized with respect to its yield, activation modeled the electronic structure of Qo as a spherical energy for desorption and rotationalenerg y using the shell of electrons and used classical electrodynamic laser-induced fluorescence technique (LIF). Since theory for discussing the collective resonances the oxidation of hydrogen is exothermic the dissi- (42,43). A very good agreement has been found with pated chemical energy can be utilized to determine EELS experiments. Work is now in progress to the water formation rate (microcalorimetry). By apply the same formalism to the recently discovered combing the two techniques, LIF and "carbon onions" and "carbon tubes". These new microcalorimetry, we thus follow a short-lived inter- material are spherical and cylindrical multilayers of mediate radical as well as the final product. graphite and we expect that our predictions of optical We perform the experiments in two different properties will be valuable in the the characterization vacuum chambers: a high-vacuum chamber for ex- of these new types of carbon species. periments in the pressure range * mTorr to 10 Torr and a newly constructed UHV- system, containing LEED and AES for surface analysis, for studies with B: Laser spectroscopic studies of single crystals at lower pressures. catalytic reactions and kinetic modelling Studies of the H2 + O2 —> H2O reaction on polycrystalline Pt foils have shown that H2O forma- This project in catalysis is focussed on studies of tion proceeds mainly via OH + H —> H2O at high certain model reactions and identification of possi- temperature and that the OH-Pt bond strength is ble intermediate species, which are probed using the about2.0eV.Theexperimentally obtained resultson laser induced fluorescence, LIF, technique. Infor- H2O formation and OH desorption as a function of mation on the existence and yield of intermediate pressure, surface temperature and gas mixture are species in catalytic reactions gives a better under- well described by a kinetic model (47,48 and B. standing compared with when only the reactants and Hellsing, B. Kasemo and V. P. Zhdanov, J. Catal., final product(s) are followed. A molecule that is 132,210 (1991)). Besides the kinetic and energetic present in all oxidation of hydrocarbon, and prob- aspectsof catalytic reactions, achieved in the already ably important in initiating combustion in catalytic mentioned measurements, we have also studied the burners via desorption from the catalytic wall mate- population of different rotational levels of the rial into the gas-phase, is the OH-radical. The experi- desorbed OH and OD radicals or the rotational mental results are correlated with kinetic model temperatures of desorbed OH (48). Extrapolating calculations done in the Chemical Physics group at these data to zero pressure showed that the rotational CTH. energy distribution is a Boltzmann distribution with a rotational temperature of about 80 % of the catalyst temperature for OH and 96 % for OD. At higher pressures a strong cooling of the rotational tempera-

130 THE CENTRE FOR MOLECULAR PHYSICS ture wasobservedduetocollisions with thereactants The experiment indicate that the detected OH radi- and water . cals are formed at the surface and subsequently In order to understand this reaction further and to desorb and that they are not formed in gas phase test the kinetic models the reaction H2O +1/2 O2— reactions outside the catalyst —> 2OH, i.e. decomposition of water to OH radi- cals, has been studied (50,53,57). Gaseous water B3. Studies of murtfphoton prorssses flows into the vacuum system and the OH desorption It is in studies of catalytic reactions of interest to is monitored at different total pressures, different develop new measurement techniques. For this pur- partial pressures of the water and oxygen and differ- pose we have built a smaller vacuum chamber in ent catalyst temperatures on Pt. The significant and which we utilize resonantly enhanced multi photon important difference between this reaction and the ionization (REMPI), where the molecules are ion- forward reaction is that the latter is a rapid, irrevers- ized by a multi photon process and then detected as ible exothermic reaction converting H2 and Q2 to a ciirrent between two electrodes. The chamber is water, while the former is a reversible reaction where constructed making a simultaneous comparison be- H2O and O2 landing on the surface decompose to tween REMPI and LIF possible. We have here done OH and H and react again to form H2O and O2 that a comparison of measurements of the rotational desorb from the surface. The experimental data is temperature of NO using the LIF and REMPI tech very well reproduced by the kinetic model calcula- niques (18). REMPI and LIF will laceron be used in tions. Also the apparent desorption energy has been parallel in the UHV system (56). measured for this system and reproduced by the kinetic model. Measurements of the oxidation of hydrogen on C: Laser lonbation Mass Spectrometry Rh and Pd catalysts have shown that Pd behaves as A laser ionization time of flight, TOF, mass- Pt while the measurements on Rh show a more spectrometer for studies of bulk samples, surfaces, complicated behaviour with a strong variation of the gases and volatile liquids (60,61) has been built, Fig. "apparent desorption energy" of OH with gas-mix- 2. The analysis of solid samples is based on sputter- ture. We have by AES analysis found that this may ing with Ar ions, photoionization of the desorbed be due to a difference in surface impurities of boron neutral species followed by time-of-flight mass sepa- when the catalyst is run in oxygen and hydrogen rich ration and detection. The advantages of the method gas-mixtures, respectively. are surface specificity, high sensitivity and multielement capability or high selectivity. By sput- B2. Imaging of radicals desorbed in catalytic tering most atoms are desorbed from the outermost reactions atom layer. Laserionization of the desorbed neutral In practical catalytic processes like carexhaust clean- species ensures a high sensitivity (ppm-range or in"orcavalytic combustions, the reactions take place better). If the ionization is performed as resonant at relatively high pressure causing an interaction multiphoton ionization a specific element or com- between surface and gas phase reactions. Radicals pound can be studied with extreme selectivity and created at a catalyst may initiate gas phase reactions sensitivity, while non-resonant ionization combined close to the catalyst surface and they may be con- with TOF-measurements provides a multielement sumed when they react with reactants or products. spectrum revealing the total sample composition. This might be of great importance when choosing The set-up has been used for analysis of GalnAs the wall materials in an engine or when constructing samples (62), different steel samples (63), gases and catalytic burners in combustion. We have in this volatile liquids (64) and catalysts. For the analysis of project measured the concentration of OH radicals at the steel samples instrumental sensitivity factors for different distances outside the catalyst using a diode various elements have been determined from meas- array (51) and a two-dimensional CCD camera (55) urements on certified reference samples. The con- . We have found that the OH concentration decreases centrations of the most abundant elements in other with increasing distance from the surface, but the samples are then determined using these sensitivity explicit behaviour is strongly dependent on pressure, factors. pumping speed and mass flow in a complex manner.

MATERIALS SCIENCE, 1993 131 MOLECULAR PHYSICS

trig and dtliy Figure 2. Schematic of the experimental set-up. Legend: 1-Primary ion gun. 2-Gas inlet. 3-Solid sample. 4- Excimer laser. 5-Dye laser (only by resonant MPI experi- ments. 6-Excimer or dye laser beam, approaching a prism and a photodiode. 7-Focusing lens. &-€xtraction and accel- eration ion optics. 9-Electro- static lens. 10-Beam of ionized species. 11-Reflector. 12-Detector. 13-Preamplifier. 14-Digital storage oscillo- scope or boxcar integrator. TP-Turbo-molecular pumps.

prism

D: Experimental Studies of Clusters O2 or D2. In the mass spectrometer both reaction Clusters with a countable number of atoms consti- products and unreacted clusters will be detected. tute the smallest pieces of solid matter, and as such Parts of a mass spectrum showing C026 reacting they are important model systems for understanding with O2 at successively higher pressures are dis- the embryonic growth of solid materials. The devel- played in fig. 4. Analysis of these types of spectra opment of new techniques for producing clusters, e. (69,70) has given values of the reactvity or sticking g. the laser vaporization source, has made it possible probabilities for clusters of Fex, CON and CUN, with to do experiments on free clusters of basically all N =10-60. solid elements and many compounds, and this has during the last decade established cluster science as Dual micro channel plate a research area of its own. We have during the last detector two years constructed a new experimental set-up where clusters can be produced of all solid elements Ion Optics and reacted in a low pressure cell, separated from the production region. Reactant gas

01. Production and studies of free metal dusten with laser based methods The set up for production and studies of metal clusters produced by laser vaporization is shown in fig. 3. The system consists of two vacuum chambers, one in which the clusters are produced in a laser vaporization source and seeded in a supersonic He beam. The cluster beam enters the second chamber through a 1 mm diameter skimmer and are ionized with pulsed laserlight, ArF 6.4 eV, and detected in a linear time-of-flightmass spectrometer. The reactiv- Turbo-pump ity of the clusters is probed by measuring the adsorp- Figure 3. The experiment set-up, with the cluster tion/adhesion of different gases when the cluster source, the reaction cell and the time-of-flight beam passes through a reaction cell, containing e.g. mass spectrometer.

132 THE CENTRE FOR MOLECULAR PHYSICS

D2. Production and studies of pure and doped fullerenes The development of the electric arc evaporation method by Krätschmer et al [W. Krätschmer, L.D. Lamb, K. Fostiropoulos and D.R. Huffman, Nature 347 (1990) 354 - 358] for macroscopic production of the football-like carbon cluster Qo also referred to as "Buckminsterfullerene" and other fullerenes has during the last two years created a boom of experi- mental and theoretical research. (See project A2). Fig. 5 shows a schematic overview of the electric arc graphite evaporator (71). When the graphite rods are brought into contact, an electric arc is ignited be- tween them using a commercial welding supply. The chamber is filled with approximately 100 mbar He, supplying the necessary cooling, allowing the graphite evaporated in the arc to condense into large carbon molecules. The soot that collects on the walls of the chamber contains a large number of stable carbon clusters. The dominant species are Qo and C70, but also larger clusters, up to several hundred atoms are found in mass analysis of the soot. By washing the soot in benzene or toluene only the fullerenes are dissolved and from this fullerene solution can get a pure sample by using liquid chromatography. Char- acterization of the soot or the fractions obtained in liquid chromatography have been performed using our cluster beam machine by soft laser desorption of the solid samples into the molecular beam, photoionization with laser light and mass spectrometric detection.

Graphite rod translation

Y//////////////////////////////////A

Figure 4. A sequence of partial mass spectra, centred around C026 • C027. The top panel shows a mass spectrum recorded with no raective gas Each of the following spectra are then recorded at succesively higher pressure. Figure 5. Electric arc graphite evaporator

MATERIALS SCIENCE, 1993 133 MOLECULAR PHYSICS

F: Related projects C70 C60 130 mbar He EL Application of DOAS for studies of combustion gases One of our students Johan Mellqvist is working part time at FVL with Differential Optical Absorption Spectroscopy, DOAS. An experimental set-up has been designed for measurements of differential ab- 260 mbar Ar sorption cross-sections of gases such as NO, NO2 and SO2 at temperatures between 20 and 400<>C (74- 76). The measurements show that the differential ,C70 absorption cross-sections are strongly temperature dependent which has to be taken into account when h^>^v^l4A»W*WW^^J^^VI»^^V^^^ the DOAS technique is used for measurements of Figure 6. Mass spectra of soot from graphite arc flue gases as recently performed in the CFB-com- evaporation in different gase bustion unit at CTH (77).

F2. Infrared laser Stark shift spectroscopy in ammonia E. Calculations for atomic systems The Stark effect in ammonia has been analyzed theoretically (78,79) in cooperation with Svante Höjer at the Dept of Optoelectronics, as a comple- We have for a long time been engaged in theoretical ment to his measurements of the absorption spectra calculations for free atoms and ions in connection of ammonia around 1050 cm-' using lead salt tun- with experimental works performed by other groups able diode and CO2 lasers. The electric field depend- at CTH/GU or groups abroad. Most of the work has ent energy levels have have been evaluated by been performed on the analysis of hyperfine struc- diagonalization of a 6 x 6 energy matrix constructed ture (hfs), and isotope shifts (IS). The hfs of transi- using both electric field independent and field de- tion elements has been analyzed using the effective pendent terms in the molecular Hamiltonian. Results operator formalism and the results obtained are obtained from this project can be used for measure- compared with parameters evaluated with non-rela- ments of electric fields in transformers. tivistic and particularly relativistic self-consistent- field SCF methods as Hartree-Fock-Slater, (HFS), F3. Applications of lasers in medicine, Hartree-Slater, (HS), and Hartree-Fock, (HF). (72) dermatology Usually the breakdown of LS-coupling has been In a diploma work two students Cathrina Hägertz obtained by the analysis of the experimental atomic and Magnus Levinsson, (80) have investigated the fine structure. (Theprocedureforanalysisofhyperfine reflection and transmission of skin form pigs in the structure was presented in a review article fifteen 300 - 800 nm wavelength region using different years ago (I. Lindgren and A. Rosén, "Case Studies skin- and solar lotions. This project is performed in in Atomic Physics", 4, 93 (1974)). These type of cooperation with Prof Magne Alpsten Dept of Ra- investigations have been extended to diation Physics GU and Doc Olle Larkö Dept of multiconfiguration Dirac-Fockcalculations (MCDF) Dermatology Sahlgrenska Hospital GU in which the breakdown of LS coupling is included to some extent in the wavefunctions. Extensive calculations have been done for the alkaline-earth elements to particularly analyze the breakdown of LS-coupling, volume isotope shift and hyperfine structure (73).

134 THE CENTRE FOR MOLECULAR PHYSICS

Publications Smaller project works L.-O Carlsson, J. Hagberg, G. Barrvik, F. Nikolajeff, N. Wendelöw och M. Wiik, "Masspektromctrisk analys Ph.D. Dissertations av gaser och vätskor", CTH April 1990 Sten Ljungström, "Laser diagnostics and kinetics of OH formation in the catalyzed H2 + O2 reaction", PhD P. Andersson, T. Andersson, B Hägglund, T. Larsson, F. Thesis, GU, June 1988, ISBSN 91-7032-352-6 Nilarp, P. Swaren, S. Svensson, "Katalytiska reaktioner och katalysatorytor", CTH April 1992. Tomas Wahnström, "A laser induced fluorescence study of the OH radical desorption in the H2 + O2 reaction on Martin Jägersand, "Identification of peaks in spectra with Pt", PhD. Thesis, CTH, December 1989,1SBSN 91- optimization based methods", CTH June 1991. 7032459-X

Bo Wästberg, "Calculations of electronic properties of Reports and articles metal clusters, fullerenes and molecules adsorbed on 1. B Wästberg Fully numerical solutions of the molecular surfaces", PhD Thesis January 1992, ISBSN 91-7032- Schrodinger equation: The MSXa method for non 639-8 muffin-lin potentials. Submitted licentiate Dissertations 2. B.Wästberg, Calculations of electronic properties of Henrik Fallgren, "A laser ionization mass spectrometer for metal clusters, fullcrenes and molecules adsorbed on the analysis of sputtered neutral species". Fil lic Thesis, surfaces. PhD Thesis January 1992, ISBSN 91-7032- GU, Feb. 1989. 639-8

Erik Fridell, "OH desorption from Pt in the catalytic 3. D. Hcincmann, A. Rosén and B. Fricke, "Spin- formation and decomposition of water". Fil Lic Thesis, polarized Hartree-Fock-Slaicr calculations in atoms GU, June 1990. and diatomic molecules with the finite element method", Chcm. Phys. Lett.166,627 (1990). Mats Andersson, "Laser ionization mass spcciromciry as a method for chemical analysis of solids and surfaces", 4. D. Hcincmann, A. Rosén and B. Fricke, "Solution of Tekn Lie Thesis CTH June 1992. the Hartree-Fock equations for atoms and diatomic molecules with the finite element method", Physica Diploma Work Scripta, 42,692(1990). Mats Andersson, "Experimental and theoretical studies of sputtering processes in connection with laser ionization 5. D. Heincmann and A. Rosén, Basis-independent mass spectrometry", CTH June 1988. potential energy curves for the neutral diatomics of Li, Na and K evaluated by means of Hartree-Fock and Alf-Pctcr Elg, "Construction of a heat-pipe for generation different density functional potentials, Thcorctica of IR radiation using Raman processes", GU Sept Chimica Acta, In press 1989. 6. J. Meyer, W.-D. Sepp, B. Fricke and A. Rosén, Johan Mellqvist, "The Reliability of the DOAS Technique Computation of relalivistic symmetry orbitals for finite for Measurements on Gases at High Temperatures", double groups, Computer Physics Communications 51. CTH Sept 1990. 55 (1989).

Cathrina Hagcrtz and Magnus Levinsson, "Reflektion och 7. V. Pershina, W.-D Sepp, B. Fricke and A. Rosén, transmssion i hud vid bestrålning i våglängdsområdct Relativisuc effects in physics and chemistry of element 300-800 nm",CTHSept 1991. 105.1. Periodicities in properties of group 5 elements. Electronic structure of the pcntachloridcs. J. Chem. Fredrik Gudmundson, "Generation of VUV Light in Rare Phys. 96,8367(1992). Gases by Frequency Tripling: Construction of Appara- tus and Theoretical Survey", CTH, May 92. 8. A. Rosén and T. T. Rantala, Analysis of the reactivity of small cobalt clusters, Z. Physik Pi. 205 (1986).

9. T. Wahnström, A. Rosén and T.T.Ranlala, Analysis of (he electronic properties of small niobium clusters, "Physics and Chemistry of Small Clusters", p 511, Plenum Publ. Corp. 1987. Eds. P. Jena, B. K. Rao and S. N. Khanna.

MATERIALS SCIENCE, 1993 135 MOLEfjLAR PHYSICS

10. T. Wahnström and A. Rosén, Ab intio calculations of 2"i. A. Rosén and B. Wästberg, Elec'ronic structure of the electronic structure and effective magnetic moment spheroidal metal containing carbon shells: study of the

of Nb4, Surf. Sci. 189/190.788 (1987). LaCg) and C«> and their ions within the local density approximation. Proceedings of the ISSPIC 4 Confer- 11. B. Wästberg, A. Rosén and D. E. Ellis, First principles ence, Z. Phys. QiZ, 387 (1989). calculations of the K-edgc X-ray absorption near edge spectra of some transition metal dimcrs, Proceedings of 22. B. Wästberg and A. Rosén, Electronic Structure of Ceo the ISSPIC 4 Conference, Z. Phys. PJ2,377 (1989). and its Alkali Atom Containing Compounds MC«)> M=Li, Na, K, Rb, Cs and K2C«), Physica 12. B Wästberg, A Rosén and D E Ellis, First principles Scripta.44,276(1991). calculations of the K-edgc X-ray absorption spectra for some small iron and nickel clusters, Z. Phys. D13.153 23. A. Rosén and B. Wästberg, Buckminsterfullerene Qo - (1989). a surface with curvature and interesting properties, ECOSS Conference Stockholm Sept 10-14,1991, 13. B. Wästberg and A. Rosén, Calculations of Surface Science 269/270,1121(1992).

photoionization cross sections for Na2-g and K2-8 clusters, Z. Phys. D18,267(1991). 24. A. Rosén, and D. östling, Electronic structure of doped Buckminsterfullercnc, Mater. Res. Soc. Symp. Proc. 14. B. Wästberg and A. Rosén, Calculation of 270,141(1992). photoionization cross sections of small metal clusters, Proceedings of the Sth International Symposium on 25. A. Rosén, Analysis of the electronic structure of C«> Small Particles and Inorganic Clusters, ISSPIC-5, doped with p-clcments, Z. Physik D in press Konstanz Sept 10-14,1990, Eds. E. Recknagel and 0. EchtZ.Phys.D19,71(1991). 26. D. Östling, and A. Rosén, calculations of the electronic structure of doped Buckminstcrfullerene, Proc. ISSPIC 15. B. Wästberg and A. Rosén, Calculation of the VI, Chicago, Sept. 15-22,1992, Z. Physik D photoionization cross sections for small metal clusters. Springer Series in Nuclear and Particle Physics, Proc. 27. D. östling, and A. Rosén, Electronic Properties of the "Cluster Phenomena in Atoms and Nuclei", Turku C«) molecule doped with Potassium, Chem. Phys. Lett, Finland, June 3-7,1991, Eds. M. Brenner, T. Lönnroth, in press F.B. Malik. Springer -Verlag Berlin Heidelberg, 1992. 28. B. Wästberg and A. Rosén, Analysis of the position on 16. S. Larsson, A. Volosov and A. Rosén, Optical spec- the 2p*-derived states for CO adsorbed on the Pl(l 10) trum of the icosahcdral Qo, — follene — 60, Chcm. surface. Surf. Sci. ]31, L7-L16 (1988). Phys. Lett. J3J, 501 (1987). 29. T.T. Rantala and A. Rosén, Electronic damping of 17. M. Braga, A. Rosén and S. Larsson, Electronic adsorbatc motion: CO vibration on Cu (100) surface. transitions in C«) and its ions, Proceedings of the Sth Phys. Pev.fiH, 837 (1986) International Symposium on Small Particles and Inorganic Clusters, ISSPIC-5, Konstan/ Sept 10-14, 30. J. Reif, H. B. Nielsen, O. Semler, E. Matthias, E. 1990, Eds. E. Recknagel and O. Echl, Z. Phys. Westin and A. Rosén, Multiphoton processes at the D19,435(1991). (111) surface of BaF2 crystals.Physics Scripta, 2i, 532 (1987). 18. M. Braga, S. Larsson, A. Rosén and A. Volosov, Electron : transitions in Qo- On the origin of strong 31. E. Matthias, H. B. Nielsen, J. Reif, A. Rosén and E. interstellar absorption at 217 nm. Astron. Astrophys. Westin, Multiphoton-induccd desorption of positive 245,232(1991). ions from bariumfluoridc. Extended paper presented at the 2nd Topical Meeting on Microphysics of Surfaces 19. A. Rosén and B. Wästberg, First principles calculations Beams and Adsorbates. Santa Fe, New Mexico, 16-18 of the ionization potentials and electron affinities of the Feb. 1987. J. of Vacuum Science and Technology, fi5_, spheroidal molecules Q» and LaQo. J. of Am. Chcm. 1415 (1987). Soc.ilfl, 8701 (1988). 32. H.B. Nielsen, J. Reif, E. Matthias, E. Westin and A. 20. A. Rosén and B. Wästberg, Calculations of the ioniza- Rosén, Multiphoton- Induced Desorption from BaF2 tion thresholds and electron affinities of the neutral and (111) in Desorption Induced by Electronic Transitions, negatively charged C60, —follcne— 60, J. Chcm. DIET III, Proceedings of the Third International Phys. 20,2525(1989). Workshop of Desorption Induced Electron Transitions, Springer Scries in Surface Science.

136 THE CENTRE FOR MOLECULAR PHYSICS

33. A. Rosén, E. Wcsiin, E. Matthias, H. B. Nielsen and J. 45. S. Ljungström, B. Kascmo, A. Rosén, T. Wahnström Reif, Molecular cluster calculations for the Analysis of and E.Fridell, An Experimental Study of the Kinetics Laser Induced Emission of Electrons and Ions from the of OH and H2O Formation on Pt in the H2 + O2 (111) Surface of BaF2. Invited paper to the EPS 7 Reaction, Surface Science 216,63 (1989). Conference 'Trends in Physics", Helsinki, Aug. 1987, Proceeding, Physics Scripta 122,184 (1988). 46. T. Wahnström, A Laser Induced Fluorescence Study of OH Radical Desorption in the H2 + O2 reaction on Pi. 34. E. Westin, A. Rosén and E. Matthias, Molecular cluster PhD Thesis, Göteborg Nov 1989. calculations of the electronic structure of the (111) surface of CaF* Fourth International Workshop on 47. T. Wahnström, E. Fridell, S. Ljungström, B Hellsing, Desorption Induced by Electronic Transitions DIET B. Kascmo and A. Rosén, Determination of the

IV, Gloggnitz, Austria, OcL 2-4,1989. Springer activation energy for OH desorption in the H2 + O2 Series in Surface Sciences 19,316(1990). reaction on polycrystalline platinum.. Surface Science, 223, L905 (1989). 35. E Westin, Evaluation of electrostatic potentials for surfaces and solids from an embedding scheme. In 48. T. Wahnström, S. Ljungström, A. Rosén and B. manuscript Kasemo, Laser-induced fluorescence studies of the rotational state populations of OH desorbed in the 36. J. Reif, P. Tepper, E. Matthias, E. Westin and A. oxidation of hydrogen on Pt, Surface Science, 234, Rosén, Use of optical second harmonic generation for 439(1990). surface crystallographic studies on cubic ionic crystals. Applied, Physics, B4fc 131 (1988). 49. E. Fridell, B. Hellsing, B. Kasemo, S. Ljungström, A. Rosén and T. Wahnström, Determination of the 37. E. Westin and A. Rosén, Study of the electronic activation energy for OH desorption in the catalytic H2 structure and second order nonlinear optical + O2 reaction on Pt. Extended abstract. Proceeding of polarizabilitics at surfaces of ionic crystals, ECOSS the 1 lth international Vacuum Congress (IVC-11) and Conference Stockhom, Sept 10-14,1991. Surface 7th International Conference on Solid Surfaces (ICSS- Science, 269/270,577(1992). 7) 25-29 Sept. 1989. Eds. A. Benninghoven and H. P. Bonzel, Vacuum, 41,732 (1990). 38. E. Westin and A. Rosén, Study of linear and nonlinear microscopic polarizabilitites of Cgo, Mater. Res. Soc. 50. E. Fridell, OH dcsorplion from Pt in the catalytic Symp. Proc. 270,221(1992). formation and decomposition of water, Lie Thesis, GU, June 1990. 39. E. Westin and A. Rosén, Evaluation of linear and nonlinear microscopic polarizabilities of Ceo, Int. J. 51. E. Fridell, U. Westblom, M. Aldén and A. Rosén, Mod. Phys. B) Proc. of Adriatico Conference on Spatially resolved laser- induced fluorescence imaging Clusters and Fullerencs, ICTP Italy 23-26 June 1992. of OH produced in the oxidation of hydrogen on Eds. V. Kumar, T. P. Martin & E Tosatti. platinum, J. of Catalysis, 128,92 (1991).

40. E. Westin and A. Rosén, Analysis of absorption 52. E. Fridell, B. Hellsing, B. Kasemo, S. Ljungström, A. spectrum of Ceo and its doped compounds. Proc. Rosén and T. Wahnström, Hydroxyl desorption from ISSPIC VI, Chicago, Sept. 15-22,1992, Z. Physik D platinum in the catalytic formation and decomposition of water, J. Vac. Sci. Tcchnol. A9,2322 (1991). 41. E. Westin and A. Rosén, Evaluation of nonlinear microscopic polarizabilitites of Ceo and its Doped 53. E. Fridell, Kinetics of OH formation on Pi in H2O/O2 Compounds, Proc. ISSPIC VI, Chicago, Sept. 15-22, mixtures at high temperatures, Chcm. Phys. Lett. 188, 1992, Z. Physik D 487 (1992).

42. D. Östling, P. Apell and A. Rosén, Theory of Collec- 54. E. Fridell, M. Andersson, Alf-Peter Elg, S Ljungström, tive Resonances of the Ceo Molecule, Euro. Phys. Lett. B. Kasemo and A. Rosén, Studies of intermediates in In press catalytic reactions, catalysts, and catalytic combustion using laser spectroscopy, mass spectrometry and 43. D. Östling, P. Apell and A. Rosén, Analysis of collec- kinetic modelling, FÖRPEX, 4-5 Nov 1992. tive resonances and electromagnetic properties of the C6o molecule, Proc. ISSPIC VI, Chicago, Sept. 15-22, 55. F. Gudmundsson, E. Fridell, and A. Rosén, Spatially 1992, Z. Physik D Resolved Laser-Induced Fluorescence Imaging of OH Produced in Catalytic Reactions, FÖRPEX, 4-5 Nov 44. A. Rosén, Kolfotbollar - Fullerener - ett nytt material 1992. av kol. Fysikaktuellt, Fysikaktuellt Nr 3-4, September 1991

MATERIALS SCIENCE, 1993 137 MOLECULAR PHYSICS

56. A. P. Elg, S Ljungström, and A. Rosén, A comparison Particles and Inorganic Clusters, ISSPIC-5, Konstanz, of the use of the REMPI and LIF techniques for studies Sept 10-14,1990, Eds. E. Recknagel and O. Echt Z. of molecules in catalytic reactions, FÖRPEX, 4-5 Nov Phys. D19,81, (1991). 1992. 69. }L. Persson, M. Andersson and A. Rosén, Reactivity 57. E. Fridell, B. Kasemo and A. Rosén, A laser induced of small transition metal clusters, Proc. ISSPIC VI, fluorescence study of OH desorption from Pt in H2O + Chicago, Sept. 15-22,1992, Z. Physik D Hj and H2O + H2 mixtures. Langmuir, submitted 70. M. Andersson, J. L. Persson and A. Rosén, Oxidation 58. M. Andersson, J. Persson and A. Rosén, Experimental of small transition metal clusters,, Cancun, Sept. 21- studies of the electronic structure and catalytic proper- 2x, 1992, Nanostructured Materials ties of metal clusters, FÖRPEX, 4-5 Nov 1992. 71. A. Rosén, M. Andersson, F. Gudmundson, J. Persson, 59. A. P. Elg, S Ljungström, and A. Rosén, A comparison E. Wcstin, B. Wästberg, D. Östling, FuIIcrcnes - new of the use of the REMPI and LIF techniques for studies materials made from soot, FÖRPEX, 4-5 Nov 1992. of molecules in catalytic reactions, FÖRPEX, 4-5 Nov 1992. 72. T. Olsson, L. Fraenkel, I. Lindgren, A. Nyberg, L. Robcrtsson and A. Rosén, Laser and radiofrcquency 5 4 60. H. Fallgren, A laser ionization mass spectrometer for spectroscopy of the 4d 5s 5D0> 1,2,3,4 and 4d 5s5p the analysis of sputtered neutral species, Fil lic Thesis, 5P],2,3 states in Mo I: Hypcrfine structure and isotope GU, Feb. 1989. shifts'. Physica Scripta M, 24 (1986).

61. M. Andersson, Experimentella och teoretiska studier av 73. T. Olsson, A. Rosén, B. Frickc and G. Torbohm, sputtringsproecser i samband med lascrjonisations- Analysis of the electronic structure, hyperfinc structure, masspektrometri. Examensarbete, June 1988. and volume isotope shifts in the low lying states of Ba I and Ba II. Physica Scripta 22,730(1988) 62. M. Andersson, H. Fallgren and A. Rosén A time of flight mass spectrometer for the analysis of solids, 74. J. Mellqvist, The Reliability of the DOAS Technique gases and liquids, Proceeding of the Fifth International for Measurements on Gases at High Temperatures, Symposium on Resonance Ionization Spcctroscopy Diploma work and its Applications (RIS-90) Varese Italy, 16-21 September 1990, Eds. J.E.Parks and N. Omcnetto, Inst. 75. H. Axelsson, J. Mcllqvist and V. Vcscly, Utvärdering Phys. Conf. Scr. No 114:459 (1991). av temperatur- och olincaritctscffckicrs inverkan på DOAS- teknikens tillförlitlighet vid rökgasanalys, 1VL, 63. M. Andersson and A. Rosén, Quantitative Analysis of Värmcforsk rapport Nr 409. Steel Samples with Laser lonization Mass Spcctro- metry. "XXVII Colloquim Spectroscopium 76. J. Mcllqvist, H. Axelsson and A. Rosén, The tempera- Internationale", June 10-14,1991, Bergen Norway J. ture dependence of the absorption spectra of NO, NO2 Anal. At. Spcctr. 7,261(1992). and SO2 in the DOAS application "XXVII Colloquim Spectroscopium Internationale", June 10-14,1991, 64. L.-O Carlsson, J. Hagberg, G. Barrvik, F. Nikolajcff, Bergen Norway, Analyst, 117,417 (1992). N. Wendelöw och M. Wiik, Masspektrometrisk analys av gaser och vätskor, Projektarbete CTH, April 1990 77. J. Mcllqvist, H. Axelsson and A. Rosén, The DOAS technique in emission monitoring of flue gases, 65. P. Andersson, T. Andersson, B Hägglund, T. Larsson, F?RPEX,4-5 Nov 1992. F. Nilarp, P. Swarcn, S. Svensson, Projektarbete April 1992. 78. S. Höjer, H. Ahlbcrg and A. Rosén, Inlrarcd Laser Stark Shift Spcctroscopy in Ammonia: Theoretical and 66. F. Gudmundson, Generation of VUV Light in Rare Experimental analysis for Sensing Electric Field Gases by Frequency Tripling: Construction of Appara- Strength, Appl. Phys. B52,200 (1991) tus and Theoretical Survey, Diploma work CTH, May 92. 79. S. Höjer, H. Ahlbcrg and A. Rosén, Measurements of the electric field strength dependent line strength of the 67. H. Fallgrcn and T.P. Martin, Photoabsorplion of Csg ssR(5,3) ammonia line, Report No 90252, Department and CsioO clusters, Chcm. Phys. Lett. 168,233(1990). of Optoelectronics and Electrical Measurements, CTH 1990. 68. H. Fallgren K. M. Brown, and T.P. Martin, Photo- absorption spectra of CSJVO and Csv clusters, Proceed- 80. Cathrina Hägcrlz and Magnus Levinsson, "Reflektion ings of the 5th International Symposium on Small och transmssion i hud vid bestrålning i våglängds- området 300-800 nm", CTH Scpt 1991.

138 THE CENTRE FOR Engineering Chemistry

Research Summary Graduate Students The research activities within the materials science Brian Schoeman civ.ing. area at the department of Engineering Chemistry is Magnus Skoglundh tekn.lic. concentrated on the preparation and characterization Anders Tömcrona civ.ing of different materials in the form of small particles, what we call small particle technology. We consider Technical Staff the small particle technology an approch to achieve Torild Isaksson ing. different objectives. One such objective is new and Kurt Löfgren ing. improved catalysts. Catalysts are invariably built up Mary Mattsson ing. of different types of small particles. Properties of these particles such as size, shape, chemical compo- Secretary: sition etc determine the pore-size, surface area and Elisabeth Hamawi activity of the catalysts. A detailed knowledge of preparation and characterization of systems of small particles is therefore essential if one wants todevelop Major Instrumentation improved catalysts. Most of ourresearch in the small Reactors particle technology area is currently directed to- • FCC-Pilot plant. Feedstock, prepared either by wards development of catalysts, especially catalysts in-house process studies or submitted from for pollution control. Knowledge of small particles external sources, are evaluated for cracking is, however, also essential in other areas such as characteristics (product yields and qualities) in adsorbents, ceramics, inorganic membranes, pig- a continous circulating fluid catalytic cracking ments, fillers in paper and plastics etc. Furthermore, unit built under license from the Atlantic development of new materials in the form of small Richfield Company. Having four interchange- particles can be considered an objective in itself as able reactors, this unit can handle feedstocks exemplified by our research activities on zeolite with Conradson Carbon Numbers up to 4 and synthesis. duplicate the performance of full scale com- mercial FCC units. Address • Microactivity (MAT) test unit for cracking Department of Engineering Chemistry catalysts. Built to meet ASTM standard Chalmers University of Technology D3907-80, this unit has been modified to S-412 96 Göteborg, Sweden improve accuracy by careful control of both Phone+46 31772 2970 temperature and the feed injection systems. Fax+46 31 160062 MAT units are world-wide analytic standard of the petroleum and catalyst industries. • Continous hydroprocessing reactors for cata- Staff lytic treatment and conversion of oils. Two Senior Members units for 30-150 ml of catalyst, pressures of Sven-Ingvar Andersson tekn. dr. maximum 160 bar, and temperatures of 500°C. Börje Gevert tekn. dr. One atmospheric unit for temperatures up to Lars Löwendahl tekn. dr 450°C. Both different oils, model compounds, Jan-Erik Otterstedt professor and catalysts can be studied. Johan Sterte docent

MATERIALS SCIENCE, 1993 139 ENGINEERING CHEMISTRY

• Batch reactor for hydroprocessing studies. • Liquid chromatographs. Two flexible systems Capable of operating at pressures up to 200 bar (Hitachi and Waters) for HPLC and GPC, for and temperatures up to 350°C, this unit is useful detalied analysis of hydrocarbons, lignins, and in studying reaction kinetics and mechanisms other organic compounds. in regard to both feedstocks and catalysts. • Thermal Activity Monitor 2270 from Therme- • Pulse reactor. A microreactor on-line with a tric. This fully automated instrument measures gas chromatograph for rapid screening of heat evolution in the range 0.1-3000pW, catalyst activity. This reactor is also useful for approximately equivalent to differences in chemisorption studies. temperature of 10-8 - 1(H K. • Reactor system for activity testing of automo- • Malvem Zetasizer 2c. Laser scattering instru- tive catalysts and catalysts for combustion of ment for measurement of Z-potential, electro- solvent with on-line analysis of oxygen phoretic mobility, particle size, and diffusion (OM14, Beckman), carbon monoxide coefficient. (UNOR6, Maihak), carbon dioxide (UNOR6, • In addition to these advanced instruments we Maihak), nitrogen oxides (CLD5O2, TECAN) have a number of gas-chromatographs, an and total hydrocarbons (VE5, JUM ENG.) atomic absorption spectrophotometer (Perkin Elmer), a UV-spectrophotometer (Shimadzu) Analytical facilities and instruments for measurement of viscosity, • Digisorb 2600 from Micromeriucs. An auto- surface tension etc. mated instrument for measuring the surface area, pore volume and pore size distribution Materials preparation facilities (range 14-3000 Å) of porous solids. • Vacuum distillation unit for petroleum fractio- • Chemisorb 2800 from Micromeritics. This nation. Capable of working at very low pres- automatic instrument measures chemisorption sures (down to 0.2 Pa) to produce petroleum of such gases as hydrogen, CO, NO on metal cuts with high TBP. and metal oxide catalysts. Chemisorption data • Ultrafiltration unit with tangential flow for can be correlated to catalyst activity. It oper- rapid concentration of e.g. colloidal particles ates in the ranges 25-750°C and 10-5 to 900 for batch size up to 100 litres (Millipore, mm Hg pressure. Pellicon Cassette System.) • Scanning electron microscope equipped with • Ultracentrifuge. Sorvall RC5-b. Maximum x-ray microanalysis including a mapping relative centrifuge force 49 000 g. function (Link QX 200) to study elemental composition (Jeol, JSM-5200). • Tank reactor system. Computer controlled reactor system for large scale preparations of • Elemental analyzers: LECO RO-116, LECO sols and zeolites. SC-132, LECO CHN-600. The CHN-600 measures carbon, hydrogen, and nitrogen. The • Zeolite preparation equipment. Autoclaves and SC-132 measures sulfur content of oil, coal, reactors are available for preparation of types coke, and other non-metallic materials, while A, X, Y, rare earth Y, calcined REY, ultra- the RO-116 measures oxygen content. stable Y, ZSM-5, silicalite, and mordenite in quantites up to 5 kg. • Two Hewlett Packard gas chromatographs. Two Series 5880A including HP 3888A • Spray dryer. Niro Mobil Minor spray dyers Integrators and HP 7671A automatic samplers equipped with a counter/cocurrent two fluid used for analysis of feedstocks and the liquid nozzle for drying of aqueous slurries. and gaseous products from laboratory runs. • Extruder of radial type (Nica) for low and medium pressure preparation of 0.2-5 kg samples.

140 THE CENTRE FOR ENGINEERING CHEMISTRY

Steam and/or heat-treaters. Two units for Fibrillar boehmite and hydrothermally treated deactivation of catalysts with a combination of alumina were found to be more effective wash-coat steam and air. One unit can handle catalyst materials than corpuscular alumina as shown by samples of 10-100 g and the other unit samples lower light-off temperatures for oxidation of xylene. of 2-4 kg at temperatures up to 800°C. We have also studied the effects of the total content at Pd+Pt and the ratio of Pd to Pt on the light- Pulping and bleaching equipment. Autoclaves off temperature for oxidation of cO and different for pulping and bleaching of pulp. Equipment hydrocarbons. The optimal Pd:Pt ratio was found to for gas treatment of wood pulp. be 80:20on a molar basis. This project is financed by In addition to this we have a multi-purpose STU and PERSTORP AB. unit, a freeze-drying unit, a ball-mill, screening References: See publication list No. 35.36 equipment, ovens, vacuum ovens, furnaces etc. A2: Transition Metal Oxide Based Catalysts for Pollution Control In this project we are investigating inorganic mate- Major Fields of Research rials, primarily of perovskite or zeolite typ as caa- lysts for oxidation of hydrocarbons and for reduction A: New catalysts and materials for pollution of nitrogen oxides. Perovskite structures containing control La, Sr, Co, Cu have been tested with and without participants: Jan-Erik Otterstedt, Johan Sterte, doping with Ru. Doping with Ru results in an Lars Löwendahl, Magnus Skoglundh, Anders enhanced activity for NO reduction. Of particular Törncrona interest are La-Sr-Cu perovskites as they show a significant NO reduction activity even in the pres- B: Refining catalysts. ence of relatively large amounts of oxygen. participants: Jan-Erik Otterstedt, Johan Sterte, A preliminary study of Cu-exchanged zeolite Börje Gevert, Ying Zhong-Shu ZSM-5 as a catalyst for NO reduction gave very promising results. A high conversion of NO in the C: Synthesis of zeolites and pillared clays, presence of 10% O2 was obtained. This material participants: Jan-Erik Otterstedt, Johan Sterte, may be of interest for reduction of nitric oxides in Brian Schoeman, Anna-Karin Johansson diesel exhausts. This project isfinanced by NUTEK.

A3: Fibrous Catalysts for Pollution Control Research Projects The objective of this project is to build up a microporous structure on quartz fibers. This material A: New Catalysts and Materials is to be used for cleaning of diesel exhaust gases. We for Pollution Control. have managed to prepare such a material. The mate- rial consists of 2 pm quartz fibers coated with a Al: Noble Metal Catalysts for Pollution Control In this project we have studied the effect of different wash-coat materials in noble metal catalysts for reduction of pollutants in automotive exhaust and in industrial waste and stockgases. The objective was to find wash-coat materials which combine a large surface area with a large pore size and a high availability of the active species on the catalyst surface. Wash-coat materials such as Na-free silica, fibrillar alumina and hydrothermally treated alumina were studied and compared with corpuscular alumina conventionally used in catalytic converters.

MATERIALS SCIENCE, 1993 141 ENGINEERING CHEMISTRY microporous structure of silica particles (see figure above). The silica particles are applied on the fiber surface by electrostatic forces. After a hydrothermal treatment the structure is mechanically stable and has a high specific surface area {~Wrv2 /g). Our intention is now to prepare a filter from this type of fibers with optimal properties for filtering of soot particles in diesel exhaust gases and then to impreg- nate the wash- coat with active metals and test it as a catalyst for oxidation of soot and hydrocarbons in diesel exhaust gases. This project is financed by Volvo Research Foundation.

B: Refining Catalysts SEM photograph of conventional zeolite Y crystals. Bl: New Catalysts and Processes for Upgrading of Coal Tars to Transportation Fuels This project has the objective to develop new cata- lysts for upgrading of coal oils to transportation for fuels primarily by hydroprocessing and catalytic cracking. The project is part of an international IEA project on hydropyrolysisof coal. Within this project we have developed cracking catalysts and hydroprocessing catalysts adapted for the upgrading of coal tars. This catalyst is also very active for hydrodemetallization of heavy petroleum oil frac- tions. This project is financed by NUTEK. References: See publication list No. 28,29

C: Zeolite Synthesis

Cl: Colloidal Zeolites by Small Particle Technology SEM photograph of collodial particles We have developed methods for the preparation of of type zeolite Y. a number of different zeolites, e.g. zeolite Y, zeolite A, ZSM-2, hydroxysodalite and silicate, in the form of monodisperse sols of discrete micro- crystals. These products are unique as they exist as stable collodial suspensions in which the micro crystals have a size of less than 100 nm and in some cases even less than 50 nm. An advantage with the synthe- sis procedure is that the zeolites are crystallized from clear solutions, in contrast to conventional zeolite synthesis in which the zeolites are crystallized from an amorphous gel. This opens unique possibilities to study the zeolite mechanisms by di- rect methods, such asdynamic light scattering, which cannot be used when the zeolite is crystallized from Collodial zeolite hydroxysodalite a gel. We are now looking at different technical particle size <40 nm. applications for micro-crystalline zeolites. This project is financed by TFR

142 THE CENTRE FOR ENGINEERING CHEMISTRY

Abrahamsson, Peter "Improved phosporic acid catalyst on Publications silica for oligomerization of iso-butcne to polygasolinc" 1988 Ph.D. Dissertations "Dclignification and Blcachability of Kraft Pulps Gränsbo, Göran" Water soluble polymers and their Prctrcaicd with Nitrogen Dioxide". 1992-04-09, Per rhcological properties" 1988 Larsson Nilsson, Charlotta " Anaerobic digestion of biomass and "Experimental studies of aqueous surfactant systems by the organic fraction of municipal solid waste" 1989 use of membrane filtration". 1992-06-16, Salch M Mahdi Briihl, Pia " Anaerobic digestion of biomass and the organic fraction of municipal solid waste" 1989 "Oxygen-alkali treatment of kraft pulp ?nd ccllobiitol". 1992-09-09, Bengt Järrchult Jönsson, Rutger "Studies of fillers" 1989

"Influence of the gas phase on pretrcatment of kraft pulp Schocman, Brian "Synthesis of zcolitic microcrystals" with nitrogen oxides". 1992-09-11, Dennis Rasmusson 1989

Licentiate Dissertations Skoglundh, Magnus "Promotion effects of Pt and Pd on "Nya katalysatorer för avmctalliscring av tunga oljor". catalytic oxidation of xylcne" 1989 1988, Kerstin Lindström Andersson, Cecilia "Development and preparation of "Membrane filtration for the recycling of mctalworking Synthetic Collector" 1989 fluids". 1989, Salch M Mahdi Gren, Anette " Development and preparation of Synthetic "Surface chemistry aspects on adsorption from a multi- Collector" 1989 component model mctalworking fluid". 1989, Mats Tunius Mrak. Jonni" A study of various ash components, CaCOys and carbons N2O-catalysing effect." 1989 "Förbehandling av sulfatmassa och sulfallignin med kväveoxider". 1990, Urban öjtcg Elofsson, Ulrika " Different partstrcams influence in respect to the cleaning result in the wastcwatcr treat- "Hydromctallisation of Nickel and vanadyl-ctioporphy- ment plant at Hallsta papcrmill" 1989 rincs". 1991-01-21 Peter Abrahamsson Dcllvc, Anna-Carin " Catalytic Hydrogenation of "Nobel metal catalysts for combustion of volatile organic Anthraquinonc: support structure with high specific compounds". 1992-03-27 Magnus Skoglundh surface area and large average pore size" 1989

Diploma Work Karlsson, Jan " Investigation of the influence of metal Andersson, Pär "Hydroproccssing of directly liquefied poisoning on cracking catalysts containing different biomass" 1988 lypesofzeolitcY"1990

Sandqvist, Stefan " Hydroproccssing of directly liquefied Eriksson, Mikael, "Hydrodcoxygcnation of dimcthylphe- biomass" nols over sulphidcd cobolt molybdenum catalyst: activation energies" 1990 Evaldsson, Lennart" Catalytic oxidation of xylcne. Evaluation of monolith catalyst coated with AI2O3" Eriksson, Peter "Hydrodcoxygcnation of dimcihylphcnols 1988 over sulphidcd cobolt molybdenum catalyst: activation energies" 1990 Wcttcrlin, Karin " The amount of organic material in the waste water from AB Pripps Bryggerier and proposal Höskuldsson, Pall" Manufacture of Zeolite A from for its reduction" 1988 Kaoline clay" 1990

Rubinstein, Li" The amount of organic material in the Hcijnesson, Anette " Retention aid systems in paper" 1990 waste water from AB Pripps Bryggerier and proposal for its reduction" 1988 Strid, Maria " Bleaching of birch kraft pulp with nitrogen dioxide without elemental chlorine" 1990 Svensson, Stefan " Ethylcyanoacclalc. Process evaluation including cost estimate" 1988

MATERIALS SCIENCE, 1993 143 ENGINEERING CHEMISTRY

Greenwood, Peter" The blcachability with chlorine 6. Menon, P.G., "Hydrogen effects in industrial catalysis. dioxide of different oxygen bleached, prctrcatcd or Chapter 7 in Hydrogen Effects in Catalysis-Fundamen- unprctrcatcd kraft pulps" 1991 tals and Practical Applications.P.G.Menon & Z.Paäl (Eds.), Marcel Dekken New York, (1988). Karlberg, Helena " The effect of catalyst pore structure on oxidation products under hydro-processing conditions" 7. Oticrstedt, J-E., Gevcrt, S.B. and Sterte, J., "Catalytic 1991 cracking of heavy oils." ACS Symposium Scries, 375 266 (1988). Öhman, Cecilia " Fat containing waste prevention" 1991 8. Otterstcdt, J-E., Yan-Ming, Zhu. and Sterte, J.,"Cata- Fajcrsson, Måns " Catalytic total oxidation of kctones and lytic Cracking of Heavy Oil over Catalysts Containing aldehydes" 1992 Different Types of Zeolite Y in Active and Inactive Matrices Applied Catalysis, 38,143-155 (1988) Nordqvist, Anna " Reduction of aromatic compounds from polluted water with airstrippingtcchnic" 1992 9. Stertc, J, "Hydrolhcrmal Treatment of Hydroxycation Precursor Solutions". Catalysis Today, 2,219-23» (1988) Pettersson, Stina " Catalytic reduction of NO in automative exhausts over mixed oxides of Pcrovskitc-typc" 1992 10. Stertc,J.Jhulin, H.,Otterstcdt, J-E. and Massoth, F.E. "Characterization of Alumina-Montmorillonite Synncrdahl, Pcr-Olof" Final bleaching of NOx-trcatcd Complexes". Applied Catalysis, 38,119-129 (1988) pulp" 1992 11. Stcrtc, J. and Otterstcdt, J-E. "Catalytic Cracking of Tcgnandcr, Anna " Rccirculation of process water in the Heavy Oil: Use of Alumina-Montmorillonites Both as zinkphosphating process with elcctrodialysis" 1992 Catalysts and as Matrices for Rare Earth Exchange Zeolite Y Molecular Sieve." Applied Catalysis 38, Åhman, Johan "A comparative evaluation of kompopig- 131-142(1988) ment: A new type of pigment" 1992 12. Evaldsson, L.Lowcndahl, L. and Ottcrstcdl, J-E, "Fibrillar Alumina as a Wash-Coat on Monoliths in the Reports and articles Catalytic Oxidation of Xylcnc", Appl. Cat. 55 (1989) 1. Axelsson, I.M., Löwcndahl, L. and Olterstcdt, J-E., 123. "Hydrolhcrmal Stability of Siiica as a support for Platinum in an Oxidation Catalyst". Appl. Cat. ,44,251 13. Golcc, K.,Hill, E.C., Kazcmi, P. and Sköld, R.O." Oil/ (1988). water partition for some hydroxyalkylamincs and antimicrobial efficiency in mctalworking coolants". 2. Elvin, F., Ottcrstcdt, J-E. and Stcrtc, J., "DEMET- Tribology International, 22 (1989) 375-382 proccss for dcmetallization of fluid cracking catalysts". ACS Symposium series, 375,229-237 (1988). 14. Ottcrstcdt, J-E-.Schocman, B. and Stcrtc, J. "Effektiva zcolitcr tar bort ammoniak ifrån kloaker" Kemisk 3. Gcvcrt, S.B., Andersson, A.Järås, S.G. and Tidskrift,! 3,49,(1989) Sandqvist,S., "Hydroproccssing of directly liquefied biomass". Preprints, Am.Chcm.Soc.,Fucl 15. Ottcrstcdt, J-E.,Persson, G and Wannholt, L. 'Teknik Chcm.,33,4913-19(1988) för uLslappsprcvcntion 1: Problcminvcntcring". Kemisk Tidskrifl.14,1989 4. Kjällström, B., Baker, E.G., Beckman, D., Elliott, C.C., Gevcrt,S.B., Hömcll, C, östman, A., Nissalä, M. and 16. Stertc, J. "Hydrothcrmal Stability and Catalytic Soulantausta, Y., 'Technocconomic assessment of Cracking Performance of some pillared Clays". direct biomass liquefaction proccsscs.Fundamcntals of Preprints ,Div of Petrol.Chcm. ACS,34,489(1989). thcrmochcmical biomass conversion". Phoenix, May 2-6,1988 17. Elliott, D.C., Baker.E.G., Östman, A.. Gcvcrt, B.S., Beckman, D., Solantansta.Y. and Hocmcll, C. 5. Mcnon, P.G., "Hydrogen as a tool for characterization "A Technical Economic Analysis of Direct Biomass of catalyst surfaces by chemisorption, gas tilrauon and Liquefaction" Energy from Biomass and Wastes, 13, temperature-programmed techniques". Chapter 4 in 743-67(1990) Hydrogen Effects in Catalysis-Fundamentals and Practical Applications. P.G.Menon & Z.Paäl 18. Elliott, D.C., Baker, E.G., Beckman, D., Solantausla, (Eds.),Marccl Dckkcr: New York, (1988) Y., Tulcnhcimo, V., Gcvcrt, S.B., Hocrncll.C, östman, A. and Kjcllström.B. "Tcchnocconomic Assessment of Direkt Biomass Liquefaction to Transportation fucls",Biomass,22,251 -69 (1990)

144 THE CENTRE FOR ENGINEERING CHEMISTRY

19. Gcvcrt, S.B., Andersson, B.W., Järäs, S.G., Tokarz, 30. Ottcrstedt, J-E., Gcvcrt, B., Stcrtc, J., Articles on M.T. and Sandqvist, S.P., "Hydroprocessing of directly "Catalytic Conversion of Petroleum" in Kemisk liquefied biomass with large pore catalysts". Energy Tidskrift (KT). and Fuels.4,78 (1990) a) "Effektivare raff gräver djupare i oljefatet" KT 1/ 1991,31-38 20. Gevert, S.B., Bruehl, P., Nilsson, P., Linne, M. and b) "Bensin går alltid att göra men det kostar" KT 2/ Nilsson, B, "Digestion of Lucem and the Organic 1991,39-42. Fraction of MSW". Energy from Biomass and Wastcs,13,981-99(1990) 31. Elliott, D.C., Beckman. D., Bridgcwatcr, A.V., Dicbold, J.P., Gevert, S.B. and Solantausta, Y., 21. Gevert, S.B., Abrahamsson, P. and Järås, S., "Developments in direct thcrmochemical liquefaction "Oligomcrization of Isobutcnc with an Improved of biomass: 1983-1990. Energy & Fuels, 1991,5,9.399- Catalyst". ACS Symposium Series, 437 272 (1990) 410.

22. Löwcndahli. and Otterstedt, J-E., "Effect of 32. Menon, P.G. and Vrieland.CE., "Nature of the cataly- Hydrothermal Treatment on Alumina as Support for tically active carbonaceous sites for the dchydrogena- Noble Metal Catalysts". Appl. Cat. 59,89 (1990) tion of cthylbcnzcnc to styrcne: A brief review. Applied Catalysis.77,1-8.(1991) 23. Mcnon, P.G., "Coke on catalysts-Harmful, Harmless, Invisible and beneficial types. Journal of Molecular 33. Mcnon, P.G., Engvall, K. and Holmlid, L, "Compara- Catalysis, 59,207-220 (1990) tive loss of alkali promoter by dcsorpiion from two catalysts for the dchydrogcnalion of cihylbcnzcnc to 24. Mcnon, P.G., Lundin, J., Engwall, K. and Holmlid, L. styrcne". Applied Catalysis, 77,235.241 (1991) "Mechanism of potassium loss by dcsorpiion from an iron oxide catalyst for the styrene process. Catalysis 34. Mcnon, P.G., "Post mortem examination of industrial Utters, 6.85-93 (1990) catalysts". Catalysis Today, 11,161-172 (1991)

25. Otterstedt, J-E., Gevcrt, S.B., Löwendahl, L. and 35. Skoglundh.M., Löwendahl. L. and Otlcrslcdt, J-E. Stcrte, J., Articles on "Pollution Prevention Technol- "Combination of Pt and Pd on Modified Alumina ogy" in Kemisk Tidskrift (Kl). Supports as Oxidation Catalysts for Pollution Control. a)"Ytfcnomcn klarar luftföroreningar" Applied Catalysis, 77 (1991)9. KT1/1990,31^0 b)"Fasseparcring renar vatten och luft" 36. Skoglundh, M., Löwendahl, L., Mcnon, P.G., KT 2/1990,25-35 Stenbom, B.Jacobs, JP., Van Kcsscl. O. and c)"Mikroorganismer bryter ned föroreningar" Brongcrsma, H.H., "Characterization of a Pt-Pd KT 3/1990,73-81 combustion catalyst on an alumina washcoat, with and d)"Hur klarar vi avfallsproblcmet?" KT 4/1990,99-110 without prior hydrothcrmal treatment of the washcoat". c)"Rcn teknik minimcrar utsläpp och avfall" Catalysis Letters, 13 (1992) 27-38 KT 5/1990,39-49 37. Stcrtc, J., "Preparation and Properties of Large/Pore 26. Stcrtc, J, "Preparation and Properties of Largc-Porc La/Al-pillarcd Montmorillonitc". Clays & Clay RE/Al-pillarcd Montmorillonitcs. A Comparison of Minerals, 39 (1991) 167. RE-cations". Preprints Vth International Symposium on "Scientific Basis for the Preparation of Hctcrogcnous 38. Mcnon, P.G., Holmlid, L., Engvall, K. and Åman, C. Catalysts".p.l 13-122 (1990). "A new approach to loss of alkali promoter from industrial catalysts: Importance of the excited stale of 27. Sterte, J., "Preparation and Properties of Pillared the alkali". 10th International Congress on Catalysis, Intcrstratificd Illitc/Montmorillonitcs". Clays and Clay Budapest, July 1992. Paper accepted for oral presenta- Minerals, 38,(1990)609. tion.

28. Haglund, R., Ottcrstedt, J-E., Stcrtc, J., "Upgrading of Hydropyrolysis Coal Tar by Hydroproccssing" Erdöl Erdgas Kohle. 107 Jahrgang, Hcft 5, Mai 1991

29. Otlerstedt, J-E., Yan-Ming, Zhu. and Stcrte. J. "Effects of matrix alumina-silica Ratio on the perfor- mance of heavy oil cracking catalysts containing zeolite Y in matrices of amorphous silica-alumina". Applied Catalysis, 70, (1991) 43-52

MATERIALS SCIENCE, 1993 145 Electronic and opto-electronic materials

Solid State Electronics 148 Semiconductor Physics and Heterostructures. 157 Liquid Crystals 164

MATERIALS SCIENCE, 1993 147 Solid State Electronics

Research summary Address The research at the Department of Solid State Elec- Department of Solid iState Electronics tronics is specialized on silicon and silicon related Chalmers University of Technology materials, devices and circuits. Within these borders S-412 96 Göteborg, Sweden the activities take place in a rather wide interval on an Phone+46 31 772 1860 axis representing the dimension basic-applied re- Fax+46 31 772 3622 search. In recent years, our work has involved the thermodynamic properties of charge carriers in semi- conductors, materials phenomena in the bulk of Staff silicon and at a variety of different interfaces, new Senior members technologies for device preparation, novel devices Engström Olof professor/prefekt tekn. dr. and design of circuits in silicon technology. Jeppson Kjell högskolelektor tekn. dr. We cooperate with a number of the larger Swedish Christensson Sven högskolelektor tekn. dr. companies (ABB, Ericsson, Volvo, SAAB-Scania Bengtsson Stefan forskarass. tekn. dr. Combitech, Bofors) as well as smallerfirms (Ergovent Andersson Gert lab manager tekn. dr. AB, SiTek AB, SEM) and have recently initiated a Andersson Mats l:eforskn. ing. tekn. dr. spin-off company (Samba Sensors AB) for develop- Hedenstiema Nils l:eforskn. ing. tekn. dr. ment of sensors based on original ideas at the depart- ment. Our international connections involve a number Graduate students of universities and research institutes. Karlsson Peter tekn. lic. Thedepartementrepresentsabroadactivity within Xiao Zhaohua tekn. lic. the silicon technology area and is organized in four Jauhiainen Anders tekn. lic. groups as shown below and on the following pages. Sveinbjömsson Einar tekn. lic. Our aims are to keep close contact with the interna- Liss Bo tekn. lic. tional research community, create relevant knowl- Lundgren Per civ. ing. edge for the established companies in Sweden and Ericsson Per civ. ing. even to be a seed for ideas which can be transferred Bergh Mats civ. ing. to novel technical business. Ragnarsson Lars-Åke civ. ing.

Solid State Electronics

Technology / "\ Processes Materials Design Gert Andersson Stefan Bengtsson Mats Andersson Kjell Jeppson \. J ^ J V J v )

\

New enterprises The International research community

148 THE CENTRE FOR SOLID STATE ELECTRONICS

Technical staff Major Reids of Research civ. ing Larsson Rickard A: Silicon technology laboratory civ. ing Vidovic' Nevio Employees: lab manager Gert I Andersson, civ. ing Bergqvist Roy tekn. dr. Rickard Larsson, civ. ing. Roy Andersson Christer ing. Bergqvist, civ. ing. Christer Andersson, ing. Andersson Jan ing. Horst Vormbrock Vormbrock Horst techn. B: Silicon based insulator-semiconductor Secretary structures Werme Annika Participants: professor Olof Engström, tekn. dr. Mats Andersson, tekn. dr. Bo Liss, civ. ing. Per Lundgren, civ. ing. Lars-Åke Ragnarsson, civ. Major Instrumentation ing. Silicon processing equipment Contact: Gert Andersson (phone 772 19 15) C: Semiconductor wafer bonding With the implementation of the strategy mentioned Participants: professor Olof Engström, tekn. above the department has to its disposal the whole dr., Stefan Bengtsson, tekn. dr., Anders chain of equipment from CAD to circuit manufac- Jauhiainen, tekn. lie, Per Ericsson, civ. ing., turing. Equipment for mask generation, step and Mats Bergh, civ. ing. repeat, etc. arc located in the mask laboratory in direct connection to the main process lab. D: Integrated circuit design The Silicon Technology Laboratory facilitates: fur- Participants: högskolelektor Kjell Jeppson, naces for oxidation, diffusion and annealing; a tekn. dr., högskolelektor Sven Christensson, polysilicon LPCVD; an atmospheric pressure CVD tekn. dr., Nils Hedenstierna, tekn. dr., Peter (Vapox); a plasma etcher, evaporation equipment, a Karlsson, tekn. lie. DC/RF magnetron sputter; lithography equipment; optical and IR-microscopy; a surface profiler; anisotropical etch capabilities; wet chemistry in Research Projects clean benches, etc. A: Silicon technology laboratory Electrical measurements etc. The Silicon Technology Laboratory has three main Contact: Mats Andersson (phone 772 18 78) objectives. First it should be able to supply the • Computerized HP and Keithley equipment for technological knowledge to fabricate experimental electrical measurements such as current- structures within the component and micromechnical voltage, capacitance-voltage, noise spectra and sensor research areas. Second the Silicon Technol- deep level transient spectroscopy (DLTS). ogy Laboratory should develop process technology for silicon manufacturing, and finally but not least be • Liquid helium continuous flow optical cryostat a basic resource for silicon process technology at and infrared spectrometer Chalmers and in the region of Göteborg. The project strategy from the beginning was to create a process • Three closed-cycle compressed-He optical line for a metal gate 5 |im CMOS process. With this cryostats strategy the Lab has the main basic set-up for many different research activities. The first working cir- • Park Scientific Instruments air STM/AFM cuits were produced during 1987. Since then the process capabilities in the Silicon Technology Labo- ratory have been extended and refined. Almost all the different research structures that have been investiga.ed in the research groups have been fabricated in the Silicon Technology Labora-

MATERIALS SCIENCE, 1993 149 SOLID STATE ELECTRONICS tory. Furthermore, the laboratory staff is continu- silicon dioxide based insulator silicon structures. ously running development projects related to indus- We devote the work to defects and degradation try and occasionally minor scale production; pres- phenomena caused by electrical and thermal stress ently for Volvo, Bofors, SAAB Combitech AB, of devices. The measurement methods currently in SEM, Ergovent, and Samba Sensors AB. use includecapacitance-voltage (C-V), current-volt- The structures processed in the Silicon Technol- age (1- V), noise measurements. Scanning Tunneling ogy Laboratory for different projects are fabricated Microscopy (STM), Scanning Tunneling in close co-operation between laboratory staff and Spectroscopy, and Atomic Force Microscopy (AFM). the scientists. The detailed project description is The test objects are mainly produced in the silicon found in the description of the relevant group. The technology laboratory at the department. We aim to laboratory is presently involved in processing ot maintain a balance between work in pure and applied research and prototype structures for the following projects in silicon-based technologies. One example projects: of the applied work is the collaboration project with ABB HAFO on the influence of processing condi- • Silicon based insulator-semiconductor tions on the electrical quality of the oxides. Thus, we structures also have access to devices produced in a commer- • Atomic bonded materials (Si-Si, Si-SiC>2, cial environment, but still suitable for our experi- SiO2-SiO2, Si-Diamond, etc.) ments. In a new project, we will expand our knowl- • A novel component for storage and processing edge into the properties of insulators produced using of optical information Remote Plasma Enhanced Chemical Vapor Deposi- • Surface protection of power components tion (RPECVD). Ultra-High Vacuum equipment for (Oxygen doped polysilicon) this purpose will be installed at the department in • Process induced defects in semiconductor November 1993. components • Gettering processes in silicon Annealing and charging of metal-tunnel • Micromechanical structures and sensors in oxide-silicon (MTOS) diodes silicon: In recent years, we have studied the charging and - Pressure sensor for high temperatures annealing properties of ultra-thin (2-3.5 nm) oxide (optical sensing) MTOS devices with polycrystalline silicon and - Pressure sensor for low pressure ranges aluminum gates [ 1 -51. This was made using I-V and (electrical and/or optical sensing) current density-time (J-t) measurements on small - Electric field sensible sensor with devices. Among other findings, we have discovered an optical output signal that only the aluminum gate devices respond signifi- - One-axial accelerometer cantly to post-metallization annealing (PMA) and (piezoresistive sensing) can be charged negatively after electrical stress at - Three-axial accelerometer low voltages, whereas devices fabricated using both (piezoresistive sensing) gate materials can be charged positively during - A monolithic gyroscope in silicon electrical stress. Now, by increasing the device area, with an electrical output signal we can also apply C-V measurements, enabling us to • Development of deposition technology better distinguish between different typesof charges. (Sputtering of various materials) We have demonstrated |6,7| that PMA of aluminum gate metal-oxide-silicon tunnel diodes can be suc- cessfully used to anneal fast interface states even in B: Silicon based Insulator-semiconductor the 2-3.5 nm oxide range. The PMA also removes a structures parallel negative voltage shift. The observed nega- The function of the insulator-semiconductor inter- tivecharging during low-vol tage stress of unannealed face in metal-insulator-semiconductor (MIS) de- samples involves the decrease of the same type of vices is crucial to many applications in modem interface states as in the PMA, but it does not affect electronics. Recognizing this, we focus our attention the parallel negative voltage shift. In contrast, the to the electrical properties of thin oxide, 2-100 nm, positive charging at higher voltages does not affect

150 THE CENTRE FOR SOLID STATE ELECTRONICS the density of fast states, but is shown to be related to Analysis and improvement of a build-upof slow states in the interfacial region. Our dielectrics based on silicon dioxide previously obtained result that the rate of positive This is a collaboration project with ABB HAFO AB charging is not strongly controlled by the flux of and the University of Uppsala. The first undertaking tunneling electrons is confirmed by the C-V meas- is to characterize and to increase the understanding urements. of the oxidation processes that are crucial to ABB HAFO AB at present. One example is the charging properties of the multiply oxidized layers that are used in advanced custom-design circuits. In a second part, we aim to improve the electrical properties of the oxides by introducing a new technique, nitridation of the silicon dioxides, in a laboratory scale. The ultimate goal of the project is to strengthen the competitiveness of ABB HAFO by upgrading the processing technology on the base of increased knowledge. Another important goa' is to increase the competence at the universities in the fields of silicon technology and the physical properties of MIS de- vices.

C: Semiconductor wafer bonding If the bonded structure is annealed at an elevated temperature, the mechanical strength of the bonded inlf two polished silicon surfaces are contacted an adhesive force will develop between them. The Fig. 1AFM gray-scale image of a ~2 nm thick spontaneity of this bonding is strongly correlated to oxide (left part of picture) on silicon (right part of the smoothnessandcleannessof the surfaces, terface the picture). The vertical scale spans from 0 increases, reaching a strength comparable to that of (black) to 70 (white) Å. bulk silicon after annealing at temperatures above approximately 1000° C. Research is performed on We have recently obtained and installed a combined the bonding procedure including the combination of Scanning Tunneling Microscope and Atomic Force different materials and on p-operties, mainly electri- Microscope for operation in an air ambient. These cal, of the formed structures and interfaces. These highly sensitive, high-resolving instruments provide activities are made as a part of the collaborative detailed information about local properties in the project "BELLA", financially supported by The immediate vicinity of the surface. This is expected to Swedish National Board for Industrial and Techni- give a very valuable contribution to the evolving cal Development (NUTEK). picture of the charging properties, which we suspect bonded interface at different positions in the oxide to be influenced to a significant degree by local (x/d=0.44 and x/d=0.80) and in one reference ca- effects. Methods are now being developed to use pacitor. these powerful instruments for characterization and stress of the oxides. As an example, in Fig. 1 we show an AFM image of a ~2 nm thick oxide (left part of Electronic properties of interfaces formed by waff bonding picture) on silicon (right part of the picture) after The electrical properties of the bonded interfaces dipping the oxidized wafer in a hydrofluoric etch. formed between silicon and/or oxidized silicon in all The equipment is also used in a separate project to the possible combinations have been investigated correlate the bonding properties in direct wafer and methods for the characterization have been bonding to various initial surface treatments. developed. It was found that the electrical properties of bonded silicon - silicon junctions are strongly

MATERIALS SCIENCE, 1993 151 SOLID STATE ELECTRONICS dependent on the chemical surface treatment prior to are very sensitive to this illumination. As a result the wafer contacting. Low-resistive silicon - silicon interface state density at the thermally grown silicon junctions require hydrophobic (HF-etched) surfaces. - silicon dioxide increases. An annealing of the A model for the current transport across bonded structure at 425° C in presence of hydrogen again silicon - silicon junctions as well as the capacitance reduces the density of interface states. The increase of these structures has been proposed. A pronounced and decrease of the density of interface states can be charging was found to occur at orclose to the bonded made in several cycles of illumination and anneal- interface formed between two oxidized silicon wa- ing, indicating a role of hydrogen atoms in the fers when electric fields above 7 M V/cm was applied observed phenomena. We are also planning to use across these oxides. The measurements were per- Secondary Ion MassSpectroscopy (SIMS) tocharac- formed on MOS-structures with a bonded interface terize the regions surrounding different bonded in- located within the oxide. At such high electric fields terfaces. This will be made together with SIMS-lab charge carriers are injected from the silicon or the at the Physics Department, Chalmers. metal contact into the conduction band of the silicon dioxide by Fowler-Nordheim tunneling. Figure 1 The formation of sllicon-orKJIamond materials demonstrates the oxide field necessary to maintain a by wafer bonding constant injection current for one reference (stand- The objective of this project is to investigate if ard MOS-structure) and two bonded MOS-capaci- polycrystalline diamond can be used as the buried tors. When charges are trapped in the oxide, the insulator in Silicon-On-Insulator (SOI)-materials electric field picture in the oxides will change and instead of the conventional silicon dioxide. We are therefore the applied bias necessary to maintain a planning to manufacture Silicon-On-Diamond constant current will change. Thus, a large change in (SOD)-materials by means of wafer bonding. The the applied electric field means a large change in the advantage of using diamond instead of silicon diox- trapped oxide charge. ide comes in terms of thermal conductivity. When critical device dimensions are decreased and circuit frequencies are increased self-heating of SOI-de- vices will become an increasing problem. Diamond has a thermal conductivity which is of the order of 1000 times higher than that of silicon dioxide. How- ever, to be useful the diamond films must exhibit a high resistivity, low probability of charge trapping, high breakdown integrity and having interfaces to 7.0 silicon with acceptable properties in terms of charg- 1013 1014 1015 1016 1017 Qjnj (charges/cm2) ing, interface states etc. Currently we are investigat- ing the electrical characteristics of thin diamond Fig. 1 Oxide field during charge injection from the films (thickness: 1 - 3 nm). The diamond films are substrate vs injected charge (current density: 1O5 A/cm2) in two bonded capacitors with the bonded deposited by CVD-methods and the films are avail- interface at different positions in the oxide (x/ able for the Department of Solid State Electronics d=0.44 and x/d=0.80) and in one reference through a collaboration with Diamonex Inc, USA capacitor. and with the Department of Inorganic Chemistry at Uppsala University. Figure 2 demonstrates the con- Currently the activities are directed towards investi- ductance vs voltage characteristics at different tem- gation of silicon dioxide - silicon dioxide interfaces peratures of a structure consisting of an 1.9 urn by means of a photo current vs voltage technique. polycrystalline diamond film on top of an n-type Both bonded materials made in house and commer- silicon wafer. The conductivity shows an ohmic-like cially available materials are investigated. In this behavior at low voltages and a field activated region method charge carriers are injected into the silicon at higher voltages. The large signal resistivity calcu- dioxide by aid of illumination with UV light. During lated at an applied bias of 50 V is of the order of 101 ] the illumination a relatively small bias is applied flcm. across the oxide. It is found that the bonded oxides

152 THE CENTRE FOR SOLID STATE ELECTRONICS

Basic researcho n the fundamentals Publications 1991/1992 of wafer bonding Work is also made to increase the understanding of Ph. D. Dissertations the conditions required for a successful bonding as M.O.Andersson: "Characterization and modeling of well as on a generalization of the bonding technique electrically active point defects in silicon/silicon to other materials than silicon and silicon dioxide. dioxide structures", 1991 These activities are aimed to increase the understandings of the wafer bonding phenomena as S.Bcngtsson: "Preparation and electrical characterization of well as of the requirements for successful bonding of silicon structures formed by wafer bonding", 1991 different materials. Some important parameters in CLAndersson: "Electrical properties of process induced this context are the morphology of the surfaces and defects in silicon junctions", 1992 the cleaning procedures prior to wafer contacting. The question of surface morphology will be ad- Licentiate Dissertations dressed by the use of a surface profilometer (alpha- RKarlsson: "Direct extraction of DC-parameters for MOS stepper) and an Atomic Force Microscope (AFM) transistor models", 1991 available at the Department. The chemical treatment Diploma works of the wafer surfaces prior to wafer contacting is P.Lundgrcn: "Si-SiO2 interface trap annealing in metal- important for the spontaneity of the bonding as well tunnel oxide semiconductor (MTOS) devices", 1991 as for the properties of the formed interfaces. Differ- ent wet chemical treatments aid plasma treatments T.Stcmmc: "En datoriserad mätmetod för bestämning av en of the wafer surfaces will be investigated. The plasma kisclstrukturs resonansegenskaper", 1991 cleaning and preparation procedures can be made in Reports and artides a new ultra-high vacuum (UHV) system for deposi- 1. G.I. Andersson and O. Engström, tion of high quality insulators which will be deliv- Forward bias tunneling at defect clusters in silicon ered in November 1993. This system is a remote emitter junctions plasma enhanced chemical vapor deposition J.Appl.Phys. 69,4418 (1991) (RPECVD) reactor. The primary objective is to produce insulators with an electrical quality equal to 2. A. Ricksand and O. Engström Deep level transient spectroscopy: Increased accuracy or comparable to that obtained in conventional, of interpretation of silicon silicon dioxide interface thermal oxidation, but at a much lower temperature; state data by the assistance of computer simulations -300° C as compared to -1000° C, but it can as well J.Appl.Phys., 70,6915 (1991) be used for the preparation of hydrogen terminated silicon surfaces. 3. A. Ricksand and O. Engström Thermally activated capture of charge carriers into irradiation induced Si/SiO2 interface states J.Appl.Phys., 70,6927 (1991)

4. MO. Andersson, K.R. Farmer and O. Engström Negative charging in ultra-thin mctal-oxidc-silicon tunnel diodes J. Appl. Phys.,71,1846 (1992)

5. S. Bengtsson, G.I. Andersson, MO. Andersson and O. Engström •100 -75 -50 -25 0 25 50 75 100 The bonded uni-polar silicon-silicon junction Gata voltage (V) J.Appl.Phys. 72,124(1992) Fig. 2 The conductance vs gate voltage for an Al- diamond-silicon device. The thickness of the 6. K.R. Farmer, M.O. Andersson and O. Engström polyerystalline diamond film was about 1.9 am. Tunnel electron induced charge generation in very thin The curves corresponds to different temperatures. silicon oxide dielectrics Appl. Phys. Lett., 58,2666 (1991)

MATERIALS SCIENCE, 1993 153 SOLID STATE ELECTRONICS

7. K.R. Farmer, M.O. Andersson and O. Engström 18. Nils Hedcnsticma and Kjell O. Jcppson, Time dependent positive charge generation in very thin Comment on 'A Module Generator for Optimized silicon oxide dielectrics CMOS Buffers' Appl. Phys. LetL, 60,730 (1992) IEEE Transactions on CAD of Integrated Circuits and Systems, CAD-11, No 7,1992 8. S. Bengtsson and O. Engström, Electrical methods for the characterization of bonded 19. Nils Hedenstierna and Kjell O. Jcppson silicon/silicon interfaces The Halo Algorithm - An Algorithm for Hierarchical Jap. J. Applied Physics, 20,356 (1991) Design Rule Checking of VLSI Circuits, IEEE Transactions on CAD of Integrated Circuits and 9. B. Liss, A. Lindgren and O. Engström Systems, CAD-11, No 10,1992 in press Charging properties of SIPOS used as a passivation layer on silicon 20. Kjell O. Jcppson, Sven Christcnsson and Nils Microelectronic Engineering 15,125 (1991) Hedenstiema Formal Definitions of Geometric Design Rules 10. A. Dejenfelt and O.Engström IEEE Transactions on CAD of Integrated Circuits and MOSFET channel mobility degradation as a result of Systems, in press Fowler-Nordheim electron injection Microelectronic Engineering 15,461 (1991) 21. Peter R. Karlsson and Kjell O. Jcppson An Efficient Parameter Extraction Algorithm for MOS 11. E.Ö.Sveinbjömsson and O.Engström Transistor Models Transformation of gold in n-type silicon from a new IEEE Transactions on Electron Devices, ED-39, No 9, deep level to the gold acceptor level 1992, in press MaLRes.Soc.Symp. Proc. 262, (1992) in press 22. AT. Dcjcnfelt and O. Engström, 12. S. Bengtsson, A. Jauhiainen and O.Engström 18) MOSFET degradation following Fowler-Nordheim Oxide degradation of wafer bonded MOS capacitors electron injection following Fowler-Nordheim electron injection Manuscript 1991, submitted to IEEE Trans. Electron. JElectrochem. Soc., 1992, in press Dcv.

13. S.Bengtsson 23. AT. Dcjenfelt, Semiconductor wafer bonding. A review of interfacial Modeling impact ionizau'on in Si and hot electron properties and applications injection into SiOsdo3(2) in a spatially varying electric J£l.MaL, 1992, in press field by the direct integration method Manuscript 1991 14. P.T.Landsberg and O.Engström Semiconductor statistics 24. E.Ö.Sveinbjörnsson and O.Engström Handbook of Semiconductors, Vol.1 (Elscvicr, 1992), A novel hydrogen-gold related deep acceptor in N-typc in press silicon Manuscript, 1992, submitted to Appl.Phys.Lctl. 15. G.I. Andersson, M.O. Andersson and O. Engström Discrete conductance fluctuations in silicon emitter 25. O. Engström, S. Bengtsson, G.I.Andcrsson, junctions due to defect clustering and evidence for M.O.Andersson and AJauhiaincn structural changes by high-energy electron irradiation Electrical characterization of bonding interfaces and annealing Manuscript, 1992, submitted to J.Electrochcm.Soc. J. Appl. Phys., in press 26. O.Engström and H.Richcrt 16. L. Löfdahl, G. Stemme and B.Johansson Fiberoptisk tryckgivarc Reynhold stress measurements using direction sensi- Svensk patentansökan, inlämnad till Patent- och tive double-chip silicon sensors registgrcringsverket Measurement Science and Technology. 2,369 (1991) 27. P.R.Karlsson and K.0 Jcppson 17. G.Stemme Extraction of series resistance indepenent MOS Resonant silicon sensors tranistor parameters J. Micromechanics and Microengineering, 1,113 Manuscript, 1992, subm. to IEEE Elctron. Dev. Lett. (1991) 28. P.R.Karlsson and K.OJeppson A direct extraction algorithm for a submicron MOS transistor model Manuscript, 1992, subm. to ICMTS 93

154 THE CENTRE FOR SOLID STATE ELECTRONICS

29. N.Hcdcnslicnia and K.OJeppson 38. P.Lundgrcn, K.R.Farmcr, M.O.Andcrsson and Comments on the CMOS tapered buffer buffer O.Engström problem Creation and annihilation of charge states in mcial- Manuscript, 1992 oxidc-silicon tunnel diodes Proc. 15th Nordic semiconductor meeting, 30. K.OJeppson Hämecnlinna, Finland, 1992, p.261 Modeling the influence of the transistor gain ratio and the Miller capacitance on the CMOS inverter ramp 39. A Jauhiainen, S.Bengtsson and O.Engström delay Charging phenomena at SiO2-SiO2 interfaces formed Manuscript, 1992 by wafer bonding Proc. 15th Nordic semiconductor meeting, 31. M.O. Andersson, KR. Farmer and O.Engström Hämecnlinna, Finland, 1992, p.265 Electron trapping-induced conductance and noise dynamics in ultra-thin melal-oxide-silicon diodes 40. S.Bengtsson, G.I.Andersson, M.O.Andersson och Proc. International Conference on Insulating Films on O .Engström Semiconductors, Defects in bonded silicon-silicon structures Liverpool, 1991 Proc. 12th General Conf. of the Condcnccd Matter Division, Prag, April, 1992 32. KR. Farmer Random telegraph signals and related phenomena in 41. A Jauhiainen, S .Bengtsson and O.Engström MOS device structures Charge trapping in wafer bonded MOS structures Proc. International Conference on Insulating Films on Manuscript, 1992, to be presented at ESSDERC '92 Semiconductors, Liverpool, 1991 (Invited) 42. Z.Xiao, S.Norrman and O.Engström A fibcroptical voltage sensor prepared by 33. A. Dcjcnfclt and O. Engström nicromachining and thermal bonding MOSFET channel mobility degradation as a result of Manuscript 1992, submitted to IEDM, 1992 Fowlcr-Nordheim electron injection Proc. 21st European Solid Stale Device Conference 43. G. Slcmmc and E. Slemmc (ESSDERC '91), Montreaux, 1991 A capacitivcly excited and detected resonant pressure sensor with temperature compensation 34. B. Liss, A. Lindgren and O. Engström Proc. Eurosensors '91, Rome, 1991 Charging properties of SIPOS used as a passivation layer on silicon 44. G. Stemmc Proc. 21st European Solid Slate Device Conference Resonant silicon sensors (ESSDERC '91), Montreaux, 1991 Furosensors '91, Rome, 1991 (Invited)

35. S. Bengtsson, A. Jauhiainen and O. Engström 45. Kjell O Jeppson Oxide degradation of wafer bonded MOS capacitors An improved timing model for the CMOS inverter following Fowler-Nordheim electron injection Proceedings of the 1991 European Conference on Proc. First International Symposium on Semiconductor Circuit Theory and Design (ECCTD-91), pp 567-576, Wafer Bonding Science, Copenhagen, September 2-6,1991 Phoenix, Arizona, 1991 46. Kjell O. Jeppson, Sven Christcnsson and Nils 36. O. Engström and S. Bengtsson Hedcnsticrna Electrical characterization of bonding interfaces Formal definitions of geometric design rules Proc. First International Symposium on Semiconductor Proceedings of the Norsilc/Norchip Seminar 1991, Wafer Bonding Science, paper 10, Copenhagen, October 1991 Phoenix, Arizona 1991, (Invited) 47. Nils Hedcnslierna and Kjell O Jeppson 37. K.R.Farmcr, M.O.Andcrsson, PLundgren and A parallel hierarchical design rule checker O.Engström Proceedings of the 1992 European Conference on Time-dependent charging in aluminum and Design Automation (EDAC '92), pp 142-146, Brus- polycristalline silicon gate metal-tunnel oxide- silicon sels, March 1992 diodes IEEE Semiconductor Interface Specialists Conference, Lake Buena Vista, Florida, 1991

MATERIALS SCIENCE, 1993 155 SOLID STATE ELECTRONICS

48. Peter R. Karlsson and Kjell O. Jeppson An analytical strategy for fast extraction of MOS transistor DC parameters applied to the SPICE MOS3 and BSIM models Proceedings of the International Conference on Microelectronics Test Chips (ICMTS-92), pp 78-83, San Diego, March 1992

49. Peter R. Karlsson and Kjell O. Jeppson Influence of the series resistance on extracted MOS transistor parameters Proceedings of the 15th Nordic Semiconductor Meeting, pp 175-178, Hämeenlinna, June 1992

156 THE CENTRE FOR Semiconductor Physics and Heterostructures

Research Summary Address The research is foe used on quantum structures based Department of Physics on III-V semiconductor materials with motivation to Chalmers University of Technology developaphysicalunderstandingofquantumeffects S-41296 Göteborg, Sweden in artificially layered materials and demonstration of Phone+46 31 772 3308 new device concepts. The work comprises growth Fax +46 31772 3385 by molecular beam epitaxy and studies of structural, electrical and optical properties of semiconductor quantum structures. One theme is studies of physical Staff effects as a result of charge confinement in artifi- Senior Members: cially layered materials. Other fields are limitations Thorvald Andersson docent/ass prof of the MBE technique such as conditions for growth Gösta Swenson docent/ass prof of high purity material, growth of narrow quantum wells (QW) with arbitrary shape and multiple — Graduate Students: coupled and uncoupled — wells, superlattices and Weiquan Chen fil lic layered growth of lattice mismatched materials. Michael Ekenstedt fil lic Physical characteristics of semiconductors de- Jöran Roslund civ ing pend on their electronic band structure. The direct Pong Songpongs (part time) M Sc band gap and high electron mobility in III-V com- Shumin Wang tekn lic pound materials, as a contrast to silicon, are em- Diploma workers ployed in optical and high frequency devices. In Tapas Ganguli artificially layered structures new phenomena, dif- Technical Staff: ferent from the hulk, are introduced. Quantum struc- Håkan Millquist instr.mak. tures provide an addition.' freedom in tailoring the Lars-Åke Sidenberg ing. material to a predicted characteristic. Jan Thordsson fil kand Lattice mismatched semiconductor layers give a possibility to use the strain to tailor-make the physi- cal properties of importance for electronic and optoelectronic devices. An obvious limitation is the Major Instrumentation critical layer thickness. We have used lattice mis- • Molecular beam epitaxy system, a modified matched InxGal-xAs/GaAs as a model system for Varian MBE 360, for growth of III-V com- studies of such strained heterostructures. pounds with Al, Ga, In, As and Sb. The system The most prominent commercial devices grown is equipped with arsenic and antimony cracker by MBE are quantum well structures for laser diodes furnaces and 2" rotating substrate holder for in CD players and the GaAs/AlGaAs HEMT-tran- In-free and In-mounting. The MBE-system sistors in high frequency system such as mobile also has Auger, RHEED, a mechanical probe telephones, satellite antennas, TV-sets, GPS naviga- for accurate substrate (contact) temperature tion receivers, etc. measureme. ts and a mass spectrometer.

• Molecular beam epitaxy system, Varian gen II modular, for growth of high purity III-V compounds from Al, Ga, In and As. The

MATERIALS SCIENCE, 1993 157 SEMICONDUCTOR PHYSICS AND HETEROSTRUCTURES

system is equipped with 3" rotating substrate Research Projects holder for In-free and In-mounting, separate cryo pump, RHEED, mass spectrometer and a A Lattice Mismatched Layer Structures cleavage chamber. A large number of III-V compound semiconductors can be combined from the 9 binaries. Four of these Optical analysis instrumentation for photo- are lattice matched better than ~ 0.7 %; GaAs/ luminescence (PL) and photo current AlxGai_xAs, In 53Ga.47As/InP, InAs/GaSb and spectroscopy, photoluminescence excitation GaSb/AlxGai.xSb.Onlytherwofirstheterostructures spectroscopy, photoreflectance spectroscopy have a major practical use. If high quality lattice and absorption measurements. mismatched epitaxial layers could be grown the number of heterostructures fordexice purposes would Electrical characterisation equipment for Hall be greatly extended. effect, CV-, IV- and DLTS measurements as In lattice mismatched structures, misfit disloca- well as electrochemical profiling and measure- tions or three dimensional (3D) growth share the ments in magnetic fields. misfit with the strain at a certain critical layer thick- ness (CUT). The presence of dislocations can be detected by electrical and optical measurements Financial Support since they act as scattering centres and decrease both Nutek electron mobility and luminescence efficiency. In NFR transmission electron microscopy individual dislo- TFR cations can be observed. If the misfit is larger than FRN approximately 2 % the growth mode switches at a Knut and Alice Wallenberg Foundation CLT from two dimensional (2D) layer by layer Skandinaviska Enskilda Banken growth to a 3D growth where islands form on the growth surface. These islands cause increased inter- face roughening and deterioration of both electrical Major Reids of Research and optical properties. The project has aimed to obtain a deeper insight into the problems related with A: Lattice Mismatched Layer Structures the CLT in the In Ga j , As/GaAs and Sb-compounds participants: Thorvald Andersson, Michael x x on GaAs. The currentinterestinSb-compounds with Ekenstedt and Shumin Wang, small band gap and high mobility, such as InSb and collaborators: J-Y Jao and G Dunlop its alloys InxGal-xSb and InAsxSbi.x, is a conse- quence of potential applications in light emitting IR- B: MBE Growth and assessment of High Mobil- devices, IR-detectors, high frequency eleccronics ity Material and magnetic Hall devices. participants: Thorvald Andersson, Michael Ekenstedt, Gösta Swensson, Jan Thordsson Al: Critical Layer Thickness and Shumin Wang. The microstructure of lattice mismatched strained layers of InxGa l-\As in GaAs has been studied by C: Arbitrarily Shaped Quantum Wells, TEM. Samples were grown by MBE at which two participants: Thorvald Andersson, Weiquan parameters were varied: the composition, x, and the Chen, Jan Thordsson and Shumin Wang. layer thickness. The thickness was controlled on the monolayer scale such that the strained InxGa 1-xAs D: Strained Quantum Wells layers were a few atomic monolayers. After the participants: Thorvald Andersson, Weiquan preparation of cross section and plan view samples Chen, Michael Ekenstedt, Jöran Roslund, the microstructure was studied in the bright field, Pong, Songpongs and Shumin Wang, dark field and weak beam modes. Layers thinner collaborators: V D Kulakovskii than a certain thickness, the critical layer thickness (CLT), showed homogeneous contrast indicating

158 THE CENTRE FOR SEMICONDUCTOR PHYSICS AND HETEROSTRUCTURES that the InxGal-xAs layers were homogeneously B MBE Growth of High Purity Material strained with flat interfaces. The CLT was defined as The preparation of high quality materials is of great- the thickness for the onset of features in the TEM est importance for material research and device micrographs. For x<0.3 dislocations developed at applications. The purity is usually described in terms the CLT while 3-dimensional growth started before of mobility and sharpness of PL-peaks. dislocation generation for x>0.3. For InAs layers embedded in GaAs only the first monolayer is defect Bl: Bulk GaAs and AlxGal-xAs/GaAs free. Heterostmctures The onset of 3D growth, t3D, has been measured We used As4 to achieve very high electron mobility as a function of both substrate temperature and in both bulk GaAs and selectively doped AlxGal- composition and was found todecrease with increas- xAs/GaAs heterostructures. Special efforts were ing In content and growth temperature. made in baking, outgasing and sample preparations Photoluminescence measurements have been used to minimise the background impurity level. Struc- to investigate interface roughening caused by 3D tures were characterised by Hall-effect measure- growth and to give an estimate of the island size. The ments between lOand 300K and Shubnikovde Haas and photoluminescence measurements at 4.2 K. The mobility in thick InxGai.xAs layers grown lattice best mobility was 2.54x105 cm2/Vs with a free mismatched on GaAs was studied as a function of 14 composition, layer thickness and growth tempera- carrier concentration below lxlO cm-3 for bulk GaAs at 42 K. These values are comparable to the ture. Recent and ongoing investigations concern 2 strain mediation in a double quantum well structure best mobility resultseverreported:2.95xl05cm /Vs for bulk GaAs. For a 2-DEG the mobility was 2x 106 from a strained Ino.36Gao.64As layer through a GaAs 2 barrier. The results show an increasing strain media- cm /Vs at an electron concentration of 2x1011 cm- 2 at 4.2 K. The low background impurity level tion with decreasing barrier thickness. indicated a very clean MBE system suitable for For growth of InxGal-xSb on inexpensive growth of high quality device materials. substrates such as GaAs, the difference in lattice constant, Da/a ~ 7 to 14 % depending on the compo- sition, introduces a large strain in the thin layers. B2: InxGal-xAs/lriyAli^As Heterostructures Dislocation generation and multiplication occur af- Lattice matched structures of InxGal-xAs/InxAlj. ter a few monolayers when the lattice mismatch can xAs (x > 0.5) on InP have demonstrated very good no ionger be accommodated only by biaxial strain. device propeties. The reason is that the high In- The CLT has been investigated for InxGal-xSb content provides large values of both electron mobil- layers grown on GaAs by MBE for the full range of ity and band offset. Structures based on phosphorous composition. Both PL and TEM were used to study arcusually grown by MOCVD (metal organic chemi- the CLT as a function of In-mole fraction. The results cal vapour deposition) since there are pronounced indicate an increasing CLT for increasing In-content difficulties with P in connection with MBE. If In- that is contradictory to results normally found in compounds instead could be grown on GaAs such strained systems and predictions from theory. devices could be integrated with GaAs IC-technol- ogy. The InxGai.xAs/GaAs heterostructure is sup- A2: Interface between Lattice posed to be a good material candidate for high Mismatched Layers. electron mobility transistors. However, because of During growth of lattice mismatched layers defects the lattice mismatch the In composition is limited; are formed at the interface and at the growth front. To typically x <0.3. By introducing InxAlyGal-x.yAs understand the physical conditions of dislocation in the barrier and/or buffer layers, the In composition generation and 3D-growth we used the layer thick- in the 2-DEG channel can be increased to a higher ness, strain and growth temperature as parameters in value. We have used different layered structures to InxGa|.xAs/GaAs growth to detect the transition manipulate the channel in order to improve the from layer-by-layer to 3D growth. conduction in basically lattice mismatched systems. We have grown both conventional InxGai .xAs/GaAs HEMT structures (x=0.15 to 0.25) and structures with x=0.8 and 1 using the InxAlyGal-x.yAs buffer

MATERIALS SCIENCE, 1993 159 SEMICONDUCTOR PHYSICS AND HETEROSTRUCTURES layer. The mobility improved with x. We also tested two-step QW and inverse parabolic QW. These were the effect of a short period In As/GaAs superlattice in grown by MBE and measured by photoluminescence the channel region to further reduce alloy scattering. andphotocurrenttechniques. Large Stark shifts were From Hall measurements, it was found that the found in the experiments, in good agreement with electron mobility increased by 10 % with the inser- our theoretical predictions. tion of this superlattice. Typical mobility values at 77 Kwas 15000 cm2/Vsorhigherwith2-DEG concen- C3: Aifoitrarlly Shaped Quantum Wells trations of ~ 2xl012 cm-2. Arbitrarily shaped semiconductor quantum wells as a contrast to conventional square ones exhibit inter- esting physical phenomena of possible use in de- C Quantum Well Layers vices. Growth of such structures demands a good The MBE process allows atomic layer-by-layer control of alloy compositions within a certain thick- growth with monolayer resolution. Therefore very ness, which is a challenge for MBE. We have thin layers with high uniformity and precise compo- recently succeeded in growing wide AlGaAs/GaAs sition can be grown. Quantum well (QW) structures parabolic quantum wells (PQWs), inverse PQWs are single or multiple layered structures where indi- (IPQW) and narrow triangular quantum wells (TQW) vidual layers are thin enough to introduce quantum by MBE using digital, compositional grading and effects. Thicknesses are typically monolayers to migration enhanced epitaxy techniques. For wide -200 Å. PQWs, we found that a linear ramp of the Al source temperature was a good approximation to fulfil the Cl: Calculation of Confined Levels desired potential shape. The quantum well shape Calculations of the confined electron and hole states was further t »nfirmed by low temperature are very important when employing the quantum photoluminescence showing an equal energy sepa- effects in electronic and optical devices. We have ration between neighbouring interband transitions. established a numerical method to calculate energy Digital, compositional grading and migration en- levels and wave functions in arbitrarily shaped quan- hanced epitaxy techniques were used for growth of tum wells. The model includes the nonparabolicity narrow, < 150Å, triangular QWs and inverse PQWs. effect and a position dependent effective mass and The compositional variation was controlled by in can be used for single as well as coupled QWs. The situ monitoring the Al source temperature during the Schrödinger equation was solved for a seriej of growth. Secondary ion mass spectroscopy was used differently shaped wells to compare their interband to check the composition depth profile and revealed and intersubband transitions under an applied elec- the desired shape with very good quality. tric field. From these calculations, we obtained the Photoluminescence, photocurrent and Hall effect knowledge on how to design structures by control- measurements were employed to characterise opti- ling the confined levels and wavefunctions. cal and transport properties. It was found that struc- tures grown by the digital method had better optical C2: Quantum-Confined Stark Effect and transport properties than ones using the The quantum-confined Stark effect is a shift (Stark compositional grading method. shift) of the exciton absorption edge to lower energy with an electric field applied over a semiconductor quantum well. This effect offers a tuneable optical D Strained Quantum Structures response which can be used for a number of impor- The electronic structure of quantum wells not only tant device applications, such as high-speed optical depends on their shape and size but also on charge modulators and photodetectors. The Schrödinger density and strain. Photolumincscence, in combina- equation was solved for arbitrarily shaped quantum tion H ith hydrostatic pressure and magnetic fields wells so transition energies could be calculated. perpendicular to the layers, has been used to analyse From this the observed Stark effect in a number of physical properties of QWs. StudiesofInxGai_xAs/ differently shaped quantum wells grown by MBE GaAs SQW's by PL revealed the direct-to-indirect could be described. Based on calculations of the transition with pressure. With magnetophoto-lumi- Stark effect we suggested two novel structures; the nescence a new magnetoplasmon-phonon coupling was observed in dense 2-DEGs.

160 THE CENTRE FOR SEMICONDUCTOR PHYSICS AND HETEROSTRUCTURES

Two MBE-systems are used: Vanan MBE-360 Tomas Holmquist, "Quantum Wire Fabrication by Cleaved for Al, Ga, In, As (cracker) and Sb (cracker) and Edge Overgrowth using MBE", 1993. Varian Gen-II Modular for Al, Ga, In and As. The Tapas Ganguli, "A Review of High resolution X-ray Diffraction Studies in Semiconductor Supcrlatticcs", MBE technique includes equipment for sensitive 1993. RHEED-oscillation detection and leliable measure- ment of growth temperatures from -380 °C. Mate- Journal Articles rial growth is mainly AlxGai_xAs/GaAs, and the 1. Photolumincsccnce and Photoconductivity Measure- lattice mismatched InxGai_xAs/GaAs system but ments on Band Edge Offsets in Strained InxGaixAs - also to InSb- and GaSb-compounds as well as In As/ GaAs Quantum Well Hcterostructures Grown by MBE, T. G. Andersson, Z-G. Chen, V. D. Kulakovskii, InGaSb superlattices. Grown materials are charac- A. Uddin and J. T. Vallin, Phys. Rev. B3J (1988-1) terised by electrical and optical methods as well by 4032. TEM, SIMS and XRD. • MBE-systemsVarian MBE-360 and gen-II 2. A Multiple State Memory Cell Based on the Resonant Modular. Tunnelling Diode, J R Söderström and T G Andersson, IEEE Electronic Device Letters EDL9 (1988) 200. • Optical techniques such as photoluminescence. • Hall effect, IV- and CV- techniques. 3. The Geometry of a Gate-Controlled n-n+-n GaAs Wire, • Low temperature magnetoresistivity. P M Rodhc, A Rouhani-Kallch and T G Andersson, • Semiconductor processing equipment. Semiconductor Science and Technology 3. (1988) 823.

4. Structure of Lattice-Strained In,Gai xAs/GaAs Layers studied by Transmission Electron Microscopy, J Y References 1988-1992 Yao, T G Andersson and G L Dunlop, AppI Phys Lett. 52(1988)1420.

Ph.D. Dissertations 5. GaAs/AlGaAs Resonant Tunnelling Diodes: The Ji-Yong Yao, 'Transmission Electron Microscopy of Dependence of the Peak-To-Valley Current Ratio on Strained Layer Structures". 1990. Barrier Thickness and Height, J. Söderström and T. G. Jan Söderström, "Novel III-V Semiconductor Tunnel Andersson, Superlatticcs and Microstructurcs, 5_ (1988) Stmclures Grown by Molecular Beam Epitaxy", 1990. 109.

Licentiate Dissertations 6. InxGai .xAs Quantum Wells and Band Offset, T G Ali Rouhani-Kallch, "Processing and electrical measure- Andersson, SPIE Vol. 243_, Quantum Well and ments of mesa- and split gate wires made of n-t-GaAs Supcrlaiucc Physics II, (1988) 159. andAlGaAs/GaAs2-DEG's", 1989. Malcolm dimming, "Hall Effect Measurements on GaAs 7. Investigation of High Quality GaAs:In Layers Grown and InSb Grown by Molecular Beam Epitaxy, 1991. by Molecular Beam Epitaxy, A Uddin and T G Michael Ekenstedt, "The Influence of Growth Temperature Andersson, J. Appl. Phys. & (1989) 3101. on the Critical Layer Thickness of Suvined In,Gai.

xAs/GaAs Hcicrostruclurcs Grown by Molecular Beam 8. Phoioluminesccnce of Residual Shallow Acceptor in Epitaxy", 1991. In,Gai.xAs (x<0.24) Grown on GaAs, Z-Y Xu, J-Z Weiquan Chen, "Quantum Confined Stark Effect in Xu, T. G. Andersson and Z-G Chen, Solid St. Comm. Different Quantum Well Structures", 1992. 20(1989)505. Shumin Wang, "The Band Edge Offset and the Critical

Layer Thickness in III-V Compound Semiconductor 9. Hot Carrier Photolumincscencc from Strained InxGai. Hctcrostructures", 1992. aAs/GaAs Single Quantum Wells Structure, T G Andersson, Z-G Chen, Z-Y Xu, J-Z Xu and W-K Gc, Diploma Work J.Cryst Growth 25.(1989)215. Michael Ekenstedt," Halleffektmätningar", 1988. Ulf Eriksson, "RHEED-oscillationcr och Mätning av 10. Interfacial Microstructurcs in InxGai ,As/GaAs Substrat-temperatur", 1989. Strained Layer Structures, J. Y. Jao, T. G. Andersson Jan Thordson, "Phololumincsccncc Studies on Ultrathin and G. L. Dunlop, Material Research Symposium Proc. Quantum Wells of AIGaAs/GaAs and GaAs/InGaAs Vol J4S (1989) 303. Grown by Molecular Beam Epitaxy", 1992. Niklas Mros, 'Tunnelling Across Single AlGaAs Barriers", 11. Renormalisalion of the Carrier Dispersion Law in a 1992. Dense Electron-Hole System in an InGaAs Quantum Well, L. V. Butov, V. D. Kulakovskii T. G. Andersson and Z. G. Chen, JETP Lett. 48,(1989) 280.

MATERIALS SCIENCE, 1993 161 SEMICONDUCTOR PHYSICS AND HETEROSTRUCTURES

12. Time-Resolved Photolumincscence from InxGai.xAs/ 23. Growth and Characterisation of High-Current Density GaAs Single Quantum Well, S Qian, S Yuui, Y Li, T High-Speed In As/AlSb Resonant-Tunnelling Diodes, J G Andersson, Z Chen, W Peng and Z Yu, Ch. Phys. R Söderström, E R Brown, C D Parker, L J Mahoney, J Leu. fi(1989) 559. Y Yao, T G Andersson and T C McGill, Appl. Phys. Lett. 51(1991)275. 13. A Weak Beam Imaging Technique for the Characteri- sation of Interfacial Roughness in (InGaAs)/GaAs 24. Characterisation of Interfacial Topography in Lattice Strained Layer Structures, J. Y. Jao, T. G. Andersson Strained InxGai.xAs/CaAs Heterostructures by the and G. L. Dunlop, Material Research Soc. Symp. Proc. Weak Beam Imaging Technique, J Y Yao, T G 152(1989)345. Andersson and G L Dunlop, Phil. Mag. A64 (1991) 173. 14. Picosecond Spcctroscopy of Hot Carrier Distribution in In,Gai.xAs/GaAs Strained Single Quantum Well 25. The Interfacial Morphology of Strained Epitaxial Structures, Z Xu, W Ge, J Xu, B Zheng, Y Li, T G InxGai.xAs/GaAs, J Y Yao, T G Andersson and G L Andersson and Z-G Chen, Chinese Journal of Infrared Dunlop, J. Appl. Phys. 62 (1991) 2224. and Millimeter Waves 8 (1989) 137. 26. Many-body Effects of a Dense 2D Electron-Hole 15. Influence of Thermal Annealing on Deep Levels in System in a Strained InxGai-xAs/GaAs Quantum Well, MBE-Grown High Purity GaAs Thin Films, H-D Xu L V Butov, V D Kulakovskii and T G Andersson, and T G Andersson, Chinese Journal of Semiconduc- Phys Rev. B44 (1991) 1692. tors 11 (1989) 31. 27. Photon-Assisted Resonant Tunnelling through Vari- 16. The Thermalization of Photoexcited Hot Carriers in ably Spaced Supcrlatticc Energy Filters, A Larsson, SI

InxGai.xAs/GaAs Strained Single Quantum Well Borenslain, B Jonsson, I Andersson, J Wcstin and T G Structures, Z Xu, W Ge, J Xu, Y Li, B Zheng, T G Andersson, Appl. Phys. Lett. 5j£ (1991) 1297. Andersson and Z-G Chen, Superlatliccs and Micro- structures 2 (1990) 13. 28. Long Wavelength Infrared Spcctroscopy of an Asym- metrically Structured Ga.6AI 4As/GaAs Supcrlatticc, S 17. Localisation Effects, Energy Relaxation and Electron I Borcnstain, I Grave, A Larsson, D H Rich, B and Hole Dispersion in Selectively Doped n-AlyGa|. Jonsson, I Andersson, J Westin and T G Andersson, yAs/InxGai.xAs/GaAs Quantum Wells, L V Butov, V Phys. Rev. Mi (1991) 9320. D Kulakovskii, T G Andersson and Z-G Chen, Phys. Rev. B42 (1990) 9472. 29. Observation of resonant Tunnelling in InSh/AIIrSb Double-Barrier Structures, J R Söderström, J-Y Yao 18. Photolumincscence of a Dense Quasi-2D Electron- and T G Andersson, Appl. Phys. Lett. 5S (1991) 708. Hole System in a Modulation-Doped Hctcrostructurc with Strained InGaAs QW, LV Butov, VD 30. Temperature Dependent Critical Layer Thickness for Kulakovskii and TG Andersson, Phys. Stat. Solidi, 15J) In 36Ga.64As/GaAs Single Quantum Wells, M J (1990) 165. Ekcnstedl, S M Wang and T G Andcrsscn, Appl. Phys. Lett. 5J£ (1991) 854.

19. Phototransmission Study of Strained-layer InxGa|.xAs/ GaAs Single Quantum Well Structures, S. Yuan, S. 31. Critical Thickness and Microstructurcs of Strained Wang, S. Qian, Y. Li, T. G. Andersson and Z-G Chen, InxGa,.xAs/GaAs QW's Studied by PL and TEM, T G J. Appl. Phys. 6S (1990) 5388. Andersson, V D Kulakovskii, S Wang and J-Y Yao, SPIE Proc. 1261 (1991)?. 20. Thickness Dependent Migration of Au Films, G Pctö, T Lohner, L Pogäny and T G Andersson, Vacuum, 4J. 32. A Mechanical Probe for Accurate Temperature (1990)1128. Measurements in Molecular Beam Epitaxy, M J Ekenstcdt and T G Andersson, J Vac Sc Tcchnol Bj), 21. Magnetic field Increased LO-phonon Raman Scatter- (1991) 1605. ing in Selectively Doped n-AIGaAs/GaAs Quantum Wells, L V Butov, V D Kulakovskii, B N Shepcl and T 33. Effective Carrier Masses in a Neutral Quasi-two- G Andersson, Superlatticcs and Microstructurcs 16 Dimcnsional Electron-Hole Plasma in InGaAs/GaAs (1991)265. Quantum Wells with a Non-Degenerate Valence Band, JETPLctt.52 (1991)39. 22. Critical Layer Thickness in InxGa|.xAs/GaAs Quan- tum Wells Studied by Photolumincsccncc and Trans- 34. Effect of the Nonparabolic Mass on the Electron mission Electron Microscopy, S M Wang, T G Confinement in Arbitrarily Shaped Quantum Wells, Andersson, V D Kulakovskii and J-Y Yao, Wciquan Chen and T G Andersson, Phys Rev. B44 Supcrlatticcs and Microstructurcs 2 (1991) 123. (1991)9068.

162 THE CENTRE FOR SEMICONDUCTOR PHYSICS AND HETEROSTRUCTURES

35. Many-Body Effects in Dense Electron-Hole Plasma in 45. InxGai.xSb/GaSb Quantum Well Structures Grown by InGaAs QW's with Simple and Complex Valence Molecular Beam Epitaxy, M J Ekenstedt, E Olsson, G Band, LV Butov, V D Kulakovskii, T G Andersson, A Treideris, T G Andersson, S M Wang and H Qu, Forchel and D Griitzmacher, Surf. Sc. 262 (1991) 457. Superi. Microstr. Microdevices, 12 (1992) 341.

36. Interface Morphology in Molecular Beam Epitaxy 46. Magnctoluminescence Study of Many-body Effects in

Grown In sGa 5As/GaAs Strained Heterostructures, S a Dense Electron-hole Plasma of Strained InxGaj .xAs/ Wang, T G Andersson and M J Ekcnstedt, Appl. Phys. GaAs Quantum Wells, LV Butov, V D Egorov, V D Lett. 52 (1991) 2156. Kulakovskii and T G Andersson, Phys Rev. B4& (1992-1) 15156. 37. Preparation of a Pt-GaAs Schottky Contact by Ion Plating, G Petö and T G Andersson, Solid-State 47. Temperature Dependent Transition from two Dimen- Electronics M(1991)591. sional to Three Dimensional Growth in Highly Strained (0.36

49. Intcrfacial Microstructure In InxGai.xAs/GaAs 40. Molecular Beam Epitaxy Growth and Characterisation Strained Layer Structures, J Y Yao, T G Andersson of InSb Layers on GaAs Substrates, J Söderström, M and G L Dunlop, MRS Proc. 148 (1989) 303. M dimming, J-Y Yao and T G Andersson, Scmic. Sc. Tcchnol.2(1992)337. 50. A Weak Beam Imaging Technique for the Characteri- sation oh Intcrfacial Roughness in Strained Layer 41. Quantum-Confined Stark Shift for Differently Shaped Structures, J Y Yao, T G Andersson and G L Dunlop, Quantum Wells, W Q Chen and T G Andersson, MRS Proc. 159(1989). Semic. Sc. and Tcchnol. 7 (1992) 828.

51. InxGai.xAs/GaAs Critical Thickness Analysed by PL 42. Intcrsubband Transitions for Differently Shaped and TEM, T G Andersson, V D Kulakovskii, S Wang Quantum Wells Under an Applied Electric Field, W Q and J Y Yao, 20th Int. Conference on Physics of Chen and T G Andersson, Appl. Phys. Lett. öö (1992) Semiconductors, Aug. 6-10,Thcssaloniki, 1990. 1591. 52. Critical Thickness and Microstructurcs of Strained 43. Electron Mobility ant. Si-incorporation in In Gai. As x x InxGai.xAs/GaAs QW's Studied by PL and TEM, T G Layers Grown on GaAs by Molecular beam Epitaxy, Andersson, V D Kulakovskii, S Wang and J-Y Yao, M J Ekcnstcdt, P Songpongs and T G Andersson, SPIE's Int. Conf. of Phys. Concepts of Mat. for Novel Appl. Phys Lett. £1 (1992) 789. Optoelectronic Device Applications, Oct. 28- Nov. 2, Aachen, 1990. 44. Direct Observation of Magneloplasmon-phonon Coupled Modes in the Magnctophotoluminesccnce 53. Quantum Confined Stark Shift for Differently Shaped Spectra of the Two-dimensional Electron Gas in Quantum Wells, W Q Chen and T G Andersson, 6th InxGai-xAs/GaAs Quantum Wells, LV Butov, VI International Conference on Solid Films and Surfaces, Grincv, V D Kulakovskii and T G Andersson, Phys June 29-July 3,1992, Paris, France. Rev. Bi6_(1992-II) 13627.

MATERIALS SCIENCE, 1993 163 Liquid Crystals

Research Summary optic properties, and their exploitation in various The activities of the liquid crystal group cover basic useful devices strongly stimulates further research and applied research on thermotropic liquid crystals. on these materials. The emphasis during the period reported has been on Many chiral smectic substances exhibit a smectic liquid crystals, with particular attention to ferroelectric-paraelectric transition at the tempera- ferroelectric smectics. An extensive installation of ture of the tilted- non-tilted (e.g. C*-A*) transition. experimental equipment for thermal, electrical and In the non-tilted phase, an external electric field will partially induce an orientational order of the molecu- optical investigations has been made. Since the lar dipoles, and because of the chiral structural group internationally is a pioneer in the field of chiral symmetry also induce a molecular tilt, i.e. transform smectic liquid crystals, the development of novel the non-tilted phase into a tilted one. Thiselectroclinic and often unique experimental techniques and meth- effect has been studied both from a fundamental and ods forms an important part of the activity. Equally an applied point, and its occurrence also in chiral fundamental is theoretical progress, especially in the nematics is under investigation. The over-all experi- areas of phase transitions, continuum theory and mental situation in chiral smectic materials is very ferroelectricity, and in several cases basic experi- rich and promising, as was also evidenced by the mental methods and theoretical concepts, now used Second International Ferroelectric Liquid Crystal routinely in many laboratories, have their origin in Conference (FLC 89), held in Göteborg June 26-30 work performed at Chalmers. The detailed physical 1989 and arranged by the Chalmers group. investigations of smectics rely on the possibility to obtain aligned samples of good quality. This moti- vated the installation of a clean-room facility with heavy equipment, e.g. a thin-film evaporator, and Address processing facilities. Department of Physics The definite identification of smectic phases in a Chalmers University of Technology novel liquid crystal substance is a time-consuming S-41296 Göteborg, Sweden but very important work, as is the establishment of Phone+46 31772 3379 phase diagrams and transition characteristics. Meth- Fax+46 31 772 3436 ods used in our laboratory are optical microscopy of textures, miscibility studies and thermal analysis (DSC). Staff Chiral tilted smectic phases are the first examples Senior Members of ferroelectric fluids, and it is of fundamental inter- Sven T. Lagerwall professor est to study the nature of this type of ferroelectricity Bengt Stebler docent and its relation to symmetry and structural proper- Kent Skarp docent ties. Typical experiments in this field are studies of Tomas Carlsson docent the ferroelectric hysteresis, the molecular tilt angle Gunnar Andersson fil.dr. and the helicoidal macro-structure. Collective mo- Ingolf Dahl fii.dr. lecularexcitations, such as soft-mode and Goldstone (atHasselblad Opt.Imaging) mode in the C* -phase, are studied by dielectric Fathi Gouda fiLdr. spectroscopy. This technique also enables one to Lachezar Komitov Ph.D. determine important viscosity and elasticity param- Peder Rodhe Ph.D.(atFLCOptics/CIT) eters. Ferroelectric liquid crystals have unique electro-

164 THE CENTRE FOR LIQUID CRYSTALS

Graduate Students Research Projects Anders Dahlgren fil.lic. A: Physics of ferroelectric liquid crystals Marek Matuszczyk fil.lic. Thomasz Matuszczyk fil.lic. Al: Ferroelectric polarization Marius Buivydas M.Sc. and viscosity David Hermann fil.kand. The most important and distinguishing property of a Per Rudqvist civ.ing. ferroelectric material is the occurrence of spontane- ous polarization or macroscopic dipole moment. Techn.adm. personal This basic parameter is closely linked to the symme- Harriet Hast/Ingrid Riedl secretary try propertiesof the ferroelectric crystal. Ferroelectric Johan Persson liquid crystals (FLC) are no exception from this rule, although the appearance of the polarization has some surprising and distinguishing peculiarities. The po- Major Instrumentation larization vector is related to the smectic layer nor- • Differential Scanning Calorimeter, Perkin mal and the local optical axis direction by a vectorial Elmer DSC-7 cross product. Consequently, in a study of FLC it is • Balzers Evaporator BAK-600 important to specify polarization as well as crystal • Zeiss Photomicroscope directions. This implies the need for techniques to • Leitz Orthoplan polarizing microscope make samples of good alignment quality. • HP 4192 Impedance Analyzer w. computer We have developed two experimental set ups for • Bruker Magnet determination of spontaneous polarization where • Clean room w. processing equipment the ferroelectric contribution to the electrical con- • Malvem Correlator ductivity can be separated and measured. The ex- (for light scattering studies) periments are combined with optical polarization • Edwards evaporator 306A microscopy which enables determination of the nec- • Edwards RF-sputter ESM100 essary crystal properties of the FLC. Also important • Mask- Aligner OAI800 molecular dynamic properties like the rotational viscosity can be determined in these experiments. The strange features with the liquid crystal Financial Support ferroelectricity are a result of symmetry and order. • The Swedish National Board for Technical Thus only line defects are permitted in the 3D Development, NUTEK medium, which prohibits the formation of walls and • Swedish Technical Research Council, TFR thereby of polarized domains. Therefore, the • The Swedish Natural Science Research Göteborg results from 1979-80 that the FLC materi- Council, NFR als can be polarized in thin samples by the action of • The Swedish Work Environment Fund, AMF surfaces - the so-called surface-stabilized ferroelectric • The Bank of Sweden Tercentenary liquid crystals (SSFLC) - was the turning point that Foundation, RJ developed this branch into the most active one in • The Carl Trygger Scientific Research liquid crystals in the last decade. The seminal paper Foundation in Appl. Phys.Letters from 1980 is increasingly referred to (according to The Citation Index this paper alone was referred to 45 times in 1987 and 102 times in 1988). This Chalmers research has also been Major Reids of Research the basis for essentially all FLC applications so far, A: Physics of ferroelectric liquid crystals. with &-, exception of the latest years when the first B: Electro-optics and applications of ferroelectric applications of the second basic breakthrough by our liquid crystals. group, the soft-mode effect (ef. A2) were announced. A second strange feature is that the electrostatic interaction between local dipoles is not responsible for the macroscopic polarization. This should be

MATERIALS SCIENCE, 1993 165 LIQUID CRYSTALS reflected in the order parameter, although no satisfy- and then further developed in a collaboration be- ing proposal for such a parameter had been presented tween the Chalmers and Ljubljana groups. From so far. A considerable part of our activity has there- these Landau models of the smectic A*-C* phase fore been directed to the ferroelectric order and to the transition one can deduce the temperature depend- molecular origins of ferroelectricity, which will be ence of the most important parameters, e.g. the tilt mentioned further below under A3. angle, the spontaneous polarization and the dielec- tric constant. A2: The electro-clinic effect In chiral orthogonal smectic phases (A*, B*, E*), the A4: Dielectric properties application of an electric field along the layers Dielectric studies of liquid crystals provide valuable induces a molecular tilt. This electroclinic effect has information of great interest both from fundamental been studied in the group extensively in later years, and applied aspects. Chiral smectic liquid crystals and it forms an extension of our work in chiral exhibit a rich variety of fundamental dielectric phe- smectics from the tilted ferroelectric phases (C*, I*, nomena, many of them of great application rel- H*, G*) to the non-tilted paraelectric phases (A*, evance and therefore most of our dielectric studies B*, E*), where the electroclinic effect is a soft-mode are focussed on the chiral smectic A (A*) and excitation. The important features of the soft-mode smectic C (C*) phases. Additionally we also have effect can be summarized briefly: the induced mo- carried out some measurement on non-chiral mate- lecular tilt 6 is a linear function of the field E, whereas rials. In dielectric studies one usually measure the the response time is field-independent. Near the real e' and imaginary e" parts of the complex second-order transition to the ferroelectric phase, the dielectric permittivity e*. In our group this study is situation is more complicated, with a field-depend- carried out in the frequency regime 1 Hz - 13 MHz ent response time and non-linear tilt-field character- as a function of temperature. In order to resolve the istic. main tenscrial components of e* (namely E|| and E_L), we carry out the measurements in two different A3: Basic theory for the smectic phases measuring geometries; homeotropic and planar The order parameter concept, the Landau theory of orientations (to measure ey and ej_ respectively). The phase transitions, and the elasticity theory are basic former orientation is achieved by surfactant, and the elements in the theoretical description of the physics later is obtained either by means of a magnetic field of the smectic-A and -C phases. Ourresearch aims at or by shear and small signal ac field. a coherent, systematic description, fulfilling basic symmetry principles, in a form that is comprehensi- ble and applicable to all possible geometries that can be found experimentally. A systematic choice of order parameters together with the corresponding Landau expansion has been presented. The elasticity theory from the Orsay group (1971) was reformu- lated in a new systematic vector formulation in Dahl and Lagerwall (1984), and further discussed in a review article by Lagerwall and Dahl (1984) This elasticity theory was further developed with the inclusion of the effects due to flexoelectric effects and inhomogeneties in the electric field. The elastic- ity theory has also been extended to cover the case of compressible layers. This research project is also covered by the thesis of Dahl (1990). A slightly »•' 10' Kr1 I05 m1 Id" K>" I»" differentlineof theoretical research on chiral smectics Frequency / Hz is the approach, based on the Landau theory of phase transitions, taken first by a Russian group in the 70's, Dielectric relaxation modes in a ferroelectric liquid crystal.

166 THE CENTRE FOR LIQUID CRYSTALS

In the A* phase there is an additional contribution to neous polarization in ferroelectrics. A chopped light ex due to distortion of the tilt angle, the so-called soft beam generates a temperature ripple in the sample. mode. In the ferroelectric C* phase, in addition to the Since the electric polarization is in general tempera- permittivity characteristic of the non-chiral C phase, ture dependent, an electric current pulse response there are two contributions to e_|_. The first one is the can be detected. This method has some advantages soft mode-as in the A* phase- and the second one due over our standard methods, where the substance is to the helix distortion, the so-called Goldstone mode. reoriented by an electric field. In the pyroelectric In collaboration with the Ljubljana group (Yugosla- method, the external electric field is not an integral via), we have studied temperature and bias field part of the measuring process, and effects of the field dependence of the dielectric permittivity and relaxa- can be sorted out. Since the sample is not reoriented tion frequency of the soft mode and Goldstone mode the method is suitable for high viscosity substances, which are the distinctive features of the dielectric like ferroelectric liquid crystalline polymers, which properties of the A* and C* phases. From our are of future interest for us. From the electric field investigation of the soft mode in the A* and C* dependence of the pyroelectric coefficient the ni- phases we have offered a way to determine the A* - electric suspectibility is obtained. Elasticity and vis- C* temperature to a good accuracy. cosity can be calculated from the pyroelectric coef- One of the main aims of this research is to utilize ficient and tilt angle and relaxation time data.We dielectricrelaxationmeasurementstodeterminesome want to include pyroelectric studies in our arsenal of of the important material properties, e.g. viscoelastic experimental techniques. Therefore, we have built a coefficients, tilt angle, and dielectric anisotropy. In setup for basic pyroelectric measurements, to gain the C* phase, when the helical structure is deformed experience in this technique. A diploma work on the and allowed to relax, it does so with a characteristic pyroelectric effect has been completed. relaxation time to the unperturbed state driven by an elastic torque and counteracted by a dissipative A6 Calorimetry and phase identification viscous torque. The appropriate expressions have ofsmecticLC's been derived and we have determined the involved Differential scanning calorimetry (DSC) measure- elastic constant and the rotational viscosity of the ments along with optical and electrical measure- Goldstone mode. Based on dielectric absorption ments are important tools in development and basic measurements of the parallel component of e* in the understanding of the nature of different phase tran- A and C phases of chiral and non-chiral compounds, sitions in liquid crystalline materials. As there are we have determined the tilt angle and its temperature about 20different liquid crystalline phases identified dependence in the C phase. to date in thermotropic systems alone, the situation The major technical significance of dielectric is complex but rich, in particular in areas like com- studies at present is the importance of the dielectric mensurate - incommensurate transitions and the anisotropy (£|| - Ex) for device applications. We have Landau theory of phase transitions. studied the frequency dependence of the dielectric The purpose of differential thermal systems is to anisotropy for different commercially available record the difference between the enthalpy change ferroelectric liquid crystal materials in the frequency which occurs in a sample and an inert reference range 103 -106 Hz. Using these measurements we material. The sample and reference are provided have calculated the dielectric torque and compared it with individual heaters, making it possible to record with the ferroelectric torque. These results enabled the difference in power input to the two system us toconsider the torque balance asafunction of field ovens, giving a "null-balance principle" system. It is and frequency, and thereby identify appropriate convenient to think of the system as divided into two driving conditions for FIX devices. control loops. One loop for average temperature control of sample and reference oven, so that it is A5: Pyroelectrlcity possible to increase or decrease the temperature at a The pyroelectric effect can be used to measure the predetermined rate, which then is recorded. Sec- electric polarization in various polarized materials, ondly, the other loop ensures that if a temperature and the method is suitable for measuring the sponta- difference develops between sample and reference

MATERIALS SCIENCE, 1993 167 LIQUID CRYSTALS due to an exothermic or endothermic reaction in the able property of being bistable. sample (for instance a phase transition), the power The application areas of SSFLC's span from input to the sample is adjusted to maintain constant simple light beam choppers through camera shut- temperature at the sample and reference. The signal ters, printer engines, wide viewing angle computer- proportional to the difference in power input to the and TV-screens to high speed optical processing, sample and to the reference, dH/dt, is then fed into a devices, such as real-time fourier transformers and computer. The recorded data are plotted in the form correlators and optical computer elements for paral- of a thermogram, from which several important lel numerical processing. features of the phase transitions can be evaluated. Suitable driving waveforms are different from the conventional ones and their design is based on the following considerations: B Electrooptlcs and applications • the SSFLC cell can be switched between two of ferroelectric liquid crystals stable states by applying a polar voltage pulse of certain height and length; Bl: Applications of ferroelectric • there exists a sharp switching threshold deter- liquid crystals mined by a critical pulse integral; The polar coupling of ferroelectric liquid crystals' • in order to prevent electrochemical degradation (FLC's) large optical anisotropy to external electric a DC content in driving waveforms should be fields is useful for light-modulating devices with the avoided at the same time as DC pulses have to desirable combination of fast, low-voltage, low- be used in every individual switching opera- power switching properties. This combination of tion.. properties is not found in any other electrooptic A liquid crystal display consists of a pair of glass technologies, ensuring that FLC's will find aplace as plates with a set of transparent electrodes sputtered the light-controlling element in e.g. light-modula- on each of them. Then an additional black mask and tors, computer screens and optical processing de- aligning layers are evaporated, the glasses fitted on vices. The rapid change of their polarization with top of each other with a distance of l-2fjm, where- temperature near the phase transition makes them after they areglued and the cell filled with a also useful as thermoelectric detectors. The large ferroelectric liquid crystal mixture. The electrodes international effort over the past ten years to develop usually form a matrix. Elements of such a matrix (so practical devices exploiting FLC's has required the called pixels) can be switched by scanning one set of development of a detailed understanding of the electrodes (rows) while applying proper data-wave- physics of FLC devices and the techniques used to forms to the second one (columns). Due tobistability fabricate them. of SSFLC devices such scanning can be performed continuously, periodically (frame updating - when B2: Electrooptic addressing desired) or selectively (row or pixel updating). Dur- Currently available liquid crystal devices of the ing a scan, voltage pulses of desired polarity and area nematic type react with a quadratic response to the are sequentially applied to selected pixels. Non- presence of an electric field. When the field vanishes selected pixels should then experience signals well the device returns to an OFF state by means of elastic below threshold (or frequency high enough to let the forces only. This strongly limits the speed and achiev- dielectric torques dominate - so called AC able multiplexing rate. stabilization). Surface stabilized ferroelectric liquid crystals Theoretical and experimental work has been done (SSFLC) possess a linear electro-optic effect which in our group in order to achieve high optical contrast means that they can be actively switched in both and addressing speed suitable for applications and direction, i.e. symmetrically between the ON and fulfill the above mentioned requirements. OFF states. With the same low voltage and low power requirements as conventional liquid crystals several ciders of magnitude faster. In addition, proper boundary conditions give the effect the valu-

168 THE CENTRE FOR LIQUID CRYSTALS

Conference arranged by the 3. Macroscopic Description of Ferroelectric Chiral Smectic C* Liquid Crystals, BZcks, T.Carlsson, group C.Filipic and A.Levstik, Proceedings of the NATO Second International Symposium on Ferroelectric advanced research workshop: Incommensurate Liquid Crystals, Göteborg, Crystals, Liquid Crystals, and Quasi-Crystals, Ed. J.F. Scott and N.A.Clark, NATO ASI Scries B: Physics Sweden, June 89 (200 overseas participants). Vol 166(1988)

4. Ferroelectric Liquid Crystals. Materials Properties and Applications, K.Skarp and M.A.Handschy, Publications Mol.CrysLLiq.Cryst., 165,439 (1988)

Ph.D. Dissertations 5. Thermodynamic Model of Ferroelectric Liquid Crystals and Its Microscopic Basis, B2eks, Christer Alstermark, Liquid Crystals - Molecular Structure T.Carlsson, CFilipic and B.Urbanc, i toceedings of the and Macroscopic Properties; (1989) 1st Int-Symp. on Ferroelectric Liquid Crystals, Ingolf Dahl, On Order, Fcrroclectricity and Elasticity in Ferroelectrics 84,3 (1988) Smectic Liquid Crystals, (1990) Gunnar Andersson, Electro-Optic Effects in Chiral Smectic 6. The Soft-Mode Ferroelectric Effect, CAndersson, Liquid Crystals, (1992) I.Dahl, W.Kuczynski, S.T.Lagerwall, K.Skarp and Falhi Gouda, Dielectric Relaxation Spectroscopy of Chiral B.Steblcr, Proceedings of the 1st Int.Symp. on Smectic Liquid Crystals, (1992) Ferroelectric Liquid Crystals, Fcrroelcctrics 84,285 (1988) Licentiate Dissertations Christer Alstermark, Synthesis of Chiral Smectic Liquid 7. A 1 "x 0.5" FLC Bar-Graph Display with Short-Term Crystalline Esters, (1986) Memory, K.Skarp, M.Matuszczyk, T.Matuszczyk, Tomasz Matuszczyk, Electronic Addressing of B.BijIcnga, Å.Hömell, B.Stcblcr and S.T.LagcrwaII, Ferroelectric Liquid Crystals, (1991) Proceedings of the 1 st IntSymp. on Ferroelectric Anders Dahlgren, Optical Properties and Helicity in Liquid Liquid Crystals, Ferroelectrics 85,313 (1988) Crystals, (1991) Marek Matuszczyk, Development of Fast-Switching Chiral 8 Measurements of Rotational Viscosity in Four Smcctic Electro-Optic Devices Ferroelectric (C*), Liquid Crystals, K.Skarp, KPlaiischler and S.T.Lagerwall, Proceedings of the 1st Diploma Work Int.Symp. on Ferroelectric Liquid Crystals, Annika Lundström, Johan Nilsson, Methods for making Fcrroclcctrics, 84,183 (1988) SSFLC-Cells for Optical Processors, (1986) Håkan Stennert, Dielectric and Electro-Optic Investigations 9. Rotational Viscosities in Ferroelectric Smcctic Liquid of Ferroelectric Liquid Crystals, (1989) Crystals, K.Skarp, Proceedings of the 1 st Int.Symp. on Eric Toussaere, Pyroelectric Effect in Ferroelectric Liquid Ferroelectric Liquid Crystals, Fcrroclectrics, 84,119 Crystals, (1989) (1988) Peter Richnau, The Interface Between a Personal Compu- ter and an LCD, (1989) 10. Parameter Characteristics of a Ferroelectric Liquid Magnus Wijk, Pyroelectric Effect in Polymeric Crystal with Polarization sign Reversal, R.Eidcnschink, Ferroelectric Liquid Crystals, (1991) T.Geelhaar, G.Andcrsson, A.Dahlgrcn.K.Flatischler, Otto Gcrhäuser, A Joint Transform Correlator F.Gouda, S.Tlagcrwall and K.Skarp, Proceedings of Per Rudquist, The Linear Electro-Optic Effect in a Chiral the 1st Int. Symp. on Ferroelectric Liquid Crystals, Ncmatic Liquid Crystal Ferroclectrics, 84,167 (1988) Alain Gauge, Benoit Sabatier, Eric Pierre, Waveform generator 11. Interaction Between FLC:s and Electric Fields: Flcxoclectric Effects and Surfaces, I.Dahl, Proceedings Reports and articles of the 1 st Int. Symp. on Ferroelectric Liquid Crystals, Fcrroelectrics, 84,345 (1988) 1. Dielectric Relaxation and the Determination of the SmA - SmC* Phase Transition Temperature in DOBAMBC, A.Levstik, T.Carlsson, C.Filipic and 12. Different Types of Bistability in Ferroelectric Liquid B.Zeks, Mol. Cryst. Liq.Cryst. 154,259 (1988) Crystals, I.Dahl, Proceedings of the 1st Int. Symp. on Ferroelectric Liquid Crystals, Fcrroclcctrics, 85,495 2. Experimental Driver and Addressing Techniques for (1988) Ferroelectric Liquid Crystal Devices, J.Wahl and T.Matuszczyk, J. Phys. E: Sci. Instr. 21,460 (1988)

MATERIALS SCIENCE, 1993 169 LIQUID CRYSTALS

13. Temperature and Wave Vector Dependence of the 23 Introduction to Ferroelectric Liquid Crystals, ST. Eigenfrequencies of the Goldstonc Mode and the Soft Lagerwall and N.A.Clark in "Ferroelectric Liquid Mode of Ferroelectric SmC* Liquid Crystals, Crystals", ed. G.W.Taylor, Gordon and Breach, New T.Carlsson, B-Zeks, C.RIipic and A.Lcvstik, Proceed- York, 1989 ings of the 1st Int Symp. on Ferroelectric Liquid 24. Experimental and Theoretical Study of the Influence of Crystals, Ferroelectrics, 84,223(1988) a Bias Electric Field on the Dielectric Properties of the Chiral Smectic A* Phase, F.Gouda, G.Andersson, 14. Interaction Between Electric Field and Liquid Crystals S.T.Lagerwall, K.Skarp, B.Stebler, T.Carlsson, BZcks, with Spontaneous Polarization: Derivation of Suitable CFilipic and A.Levstik, Liq.Cryst., 6,219 (1989) Free Energy Expression For a Cell with an Applied Voltage, I.Dahl, Proceedings of the 1st Int.Symp. on 25. Viscoelastic Properties of the Smcctic A* and C* Ferroelectric Liquid Crystals, Ferroelectrics, 84,327 Phases studied by a new Dielectric Method, F.Gouda, (1988) K.Skarp, G.Andersson, H.Kresse and S.T.Lagerwall, JpnJ.Appl.Phys., 28,1987 (1989) 15. Comments on Liquid Crystal Terminology, Nomencla- ture and Conventions, S.T.Lagerwall, Proceedings of 26. Device Physics of the Soft-Mode Electro-Optic Effect, the 1st Inl Symp. on Ferroelectric Liquid Crystals, G .Andersson, I.Dahl, L.Komitov, S.T.Lagerwall, Fcroelectrics, 85,497 (1988) K.Skarp and B.Stcbler, J. Appl.Phys., 66,4983 (1989)

16 Dielectric Properties near the Smcctic C* - Smectic A* 27. Ferroelectric Liquid Crystals: The Development of Phase Transition of some Ferroelectric Liquid Crystal- Devices, S.T.Lagerwall, N.A.Clark, J.Dijon and line Systems with a very large Spontaneous Polariza- J.F.CJerc, Fcrroelectrics 94,3 (1989) tion, CFilipic, T.Carlsson, A.Lcvstik, B.Zcks, R.BIinc, F.Gouda, S.Tlagerwall and K.Skarp, Phys.Rev. A38, 28. Put the TV on the Wall - the Flat Screen is under Way, 5833(1988) B.Stebler, S.Berg, Electronics (Industry & Develop- ment), 1989 17. Ferroelectric Liquid Crystals: the Key to Lowradiating VDUs, B.Olterholm, Kemisk Tidskrift No 10 (1988) 29. Liquid Crystal Devices Using a Linear Electro-Optic (in Swedish) Effect, CAndcrsson, LDahl, L.Komitov, S.T.Lagerwall, K.Skarp and B.Stcblcr, European 18 Thcrmodynamic Model of Ferroelectric Chiral Smcctic Patent application 8900563-i Submitted February 1989 C* Liquid Crystals, T.Carlsson, BZcks, CFilipic, AlevstikandR.Blinc.Mol.Cryst.Liq.Cryst., 163,11 30. Liquid Crystals - Molecular Structure and Macroscopic (1988) Properties, C.AIsiermark, Ph.D. Thesis, Chalmers University of Technology (1989) 19 Stability of the Shear Flow of Ncmatic Liquid Crystals with a Positive Leslie Viscosity a3, C.Högfors and 31. Theory of Ferroelectric Liquid Crystals, B.Zcks, T.Carlsson, Institute of Theoretical Physics, Institute C.Filipic and T.Carlsson, Physica Scripia, T25,362 Report 89-3 (1989) (1989)

20. Precision Electric Bridge and Fast Electro-Optic 32. The Concept of Rotational Viscosities of Smectic C Detector System for Studies of Ferroelectric Polariza- and Chiral Smcctic CLiquid Crystals, T.Carlsson and tion and Optical Switching in Ferroelectric Smectic B.Zeks, Liq.Cryst., 5,359 (1989) Liquid Crystals, G.Andersson and K.Skarp, Göteborg Institute of Physics Reports, GIPR - 273 33. Determination of the SmA - SmC* Phase Transition in DOBAMBC and its Dielectric Relaxation, A.Lcvstik, 21. Behaviour of the Soft Mode in the Smectic A* and C* T.Carlsson, C.Filipic and BZcks, FIZIKA 22, Suppl.2, Phases Studied by Dielectric Measurements, F.Gouda, 181 (1990) G .Andersson, T.Carlsson, S.T.Lagerv all, K.Skarp, B.Stebler, C.Filipic, B.Zeks and A.Levstik, 34. Theoretical Model of (he Frequency and Temperature Mol.Cryst.Liq.Cryst.Leu., 6,151 (1989) Dependence of the Dielectric Constant of Ferroelectric Liquid Crystals Near the Smcctic C* - Smcctic A 22. Dielectric Relaxation of a Mixture of a Ncmatic Liquid Phase Transition, T.Carlsson, B.Zcks, C.Filipic and Crystal and a Non-Liquid Crystalline Compound, A.Levslik, Phys.Rev. A42,877 (1990) H.Kresse, H.Steuin, F.Gouda and G.Andersson, Phys.Stat.Sol. (a) 111, K265 (1989) 35. A Dielectric Method for Determining the Rotational Viscosity in Thick Samples of Ferroelectric Chiral Smeclic C* Liquid Crystals, A.Lcvsuk, Z.Kutnjak, C.Filipic, I.Lcvstik, Z.Bregar, BZcks and T.Carlsson, Phys.Rev. A42,2204 (1990)

170 THE CENTRE FOR LIQUID CRYSTALS

36. Dielectric Anisotropy and Dielectric Torque in 48 Evolution of the Boulder Model for the Molecular Ferroelectric Liquid Crystals and their Importance for Origins of the Polarization in Ferroelectric Liquid Electro-Optic Device Performance, F.Gouda, Crystals, D.M.Walba, H.A.Ra/avi, A.Horiuchi, CAndcrsson, M.Matuszczyk, T.Matuszczyk, K.Skarp K.F.Eidmar., D.Gitcrholm, R.C.Haltiwangcr, and S.TLagerwall, J.Appl.Phys. 67,180 (1990) N.A.Clark, R.Shao, D.S.Parmar, M.D.Wand and R.T.Vohra, Fcrroelectrics 113,21 (1991) 37. On Order, Ferroelectricity, and Elasticity in Smcctic Liquid Crystals, I.Dahl, Ph.D. Thesis, University of 49. Smcctic Layer Switching Using a Field-Induced N*- Göteborg (1990) C* Phase Transition, G.Andersson, K.FIatischler, L.Komitov, S.T.Lagcrwall, K.Skarp and B.Slcblcr, 38 The Order Parameter and the Landau Expansion in the Fcrroclcctrics 113,361 (1991) Chiral Smcctic C Phase, 'I.Dahl and S.T.Lagerwall, Ferroelectrics 113,77(1991) 50 Sign Reversal of the Elcctroclinic Coefficient in the Smcctic B* Phase, L.Komitov, K.FIalischlcr, 39. The Elasticity Theory of the Smcctic C Phase: Discus- G.Andcrsson, S.T.Lagcrwall, B.Stcblcr, B.Oltcrholm, sion about Different Approaches, I.Dahl, Fcrroclccuics T.Olsson and C.Alstcrmark, Fcrroclcctrics i 14,151 113,103(1991) (1991)

40. The Elasticity Theory of the Smcctic C Phase: The 51. Ncmatic Liquid Crystal Device, G.Andcrsson, Case of Compressible Smcctic Layers, I.Dahl, L.Komilov, S.T.Lagcrwall, B.Stcblcr and K.Flatischlcr, Fcrroclcctrics 113,121(1991) Patent Application PCT/SE90/00101

41. Dielectrics Studies of the Soft Mode and Goldsionc 52. Elcctroclinic Light Switch, A.Dahlgrcn, G.Andcrsson, Mode in Ferroelectric Liquid Crystals. F.Gouda, L.Komitov, S.T.Lagerwall and B.Slcblcr, Mol. C'ryst. K.Skarp and S.T.Lagerwall, Fcrroclcctrics 113,165 Liq. Cryst. 207,281 (1991) (1991) 53. Static Splay-Stripes in a Hybrid Aligned Ncmatic 42. Electrically Controlled Optical Attenuators and Layer, A.Sparavigna, L.Komitov, B.Stcblcr and Switches with Ferroelectric Liquid Crystals, A.Slrigazzi, Mol. Cryst. Liq. Cryst. 207,265 (1991) A.Karppincn, S.Lottholz and K.Myllylä, G.Andcrsson, M.Matuszczyk, K.Skarp, I.Dahl and S.T.Lagcrwall, 54. Surface Induced Alignment Transition in a Ncmatic Fcmelectricsl 14,93 0991) Layer with Symmetrical Boundary Conditions, K.Flatischlcr, L.Komitov, S.T.Lagcrwall, B.Stcblcr and 43. Smcctic A* Materials with 11.25 Degrees Induced Tilt A.Strigazzi, Mol .Cryst. Liq. Cryst. 198,119 (1991) Angle for Full Grey Scale Generation, G.Andersson, I.Dahl, L.Komitov, M.Matuszczyk, S.T.Lagcrwall, 1>5 Theoretical Studies of Smcclic C Liquid Crystals K.Skarp, B.Steblcr.D.Coates, M.Chambers and Confined in a Wedge - Stability Considerations and D.M.Walba. Fcrroclcctrics 114,137 (1991) Fredcriks Transitions, T.Carlsson, I.W.Stewart and F.M.Lcslic, Liq.Cryst., 9,661 (1991) 44. Linear Elcctrooptic Effects in the Chiral Nematic Phase, L.Komitov, S.T.Lagerwall, B.Slcbbr, 56. Hybrid Aligned Ncmatics and Second Order Elarr;:i:/, G.Andcrsson and K.FIatischlcr, Fcrroclcctrics 114,167 A.Sparavigna, L.Komitov and A.Strigazzi, Physica (1991) Scripta43.210 (1991)

45. Till Angle Determinations in Chiral and Nonchiral 57. Electronic Addressing of Ferroelectric Liquid Crystals, Smcctic C Phases using Dielectric Absorption T.Matuszczyk, Tckn. lie. Thesis, Chalmers University Spcctroscopy, F.Gouda, K.Skarp, S.T.Lagcrwall, of Technology (1991) C.Eschcr and H.Krcssc, Journal dc Physique 1,1,167 (1991) 58 Optical Properties and Hclicity in Liquid Crystals, A.Dahlgren, Tckn. lie. Thesis, Chalmers University of 46. A Dielectric Method for Determining the Rotational Technology (1991) Viscosity in Ferroelectric Liquid Crystals, A.Levstik, Z.Kutnjak, C.Filipic, I.Lcvstik, B.Zeks and T.Carlsson, 59. Anomalous Current and Elcctrooptic Response in a Fcrroclcctrics'13,207(1991) Polyacrylate Ferroclcctri»; Liquid Crystal with Large Spontaneous Polarization, K.Skarp, G.Andcrsson, 47. Nonlinear Effects in the Dielectric Response of S.T.Lagcrwall, H.Kapit/a, H.Pots and R.Zcntcl, Ferroelectric Liquid Crystals, B.Urbane, B.Zcks and Fcrroclctlrics 122,127(1991) T.Carlsson, Ferroelcctrics 113,219 (1991)

MATERIALS SCIENCE, 1993 171 LIQUID CRYSTALS

60. Influence of Twist Distortion on the Transition Point 73. Dielectric Relaxation Spectroscopy of Chiral Smcctic Between Two Ncmatic Subphascs Nl and N2 of Liquid Crystals, F.Gouda, Ph.D.Thcsis, Chalmers HOBA, G.Barbcro, L.Komilov, M.Petrov and University of Technology (1992) A.Strigazzi, Intl. J.Mod.Phys.BS, 2229 (1991) 61. Behaviour of Biaxial Ncmatics in the Presence of 74. Electro-Optic Effects in Chiral Smcctic Liquid Crys- Electric and Magnetic Fields-Evidence of Bistability, tals, G.Andcrsson, Ph.D.Thcsis, Chalmers University T.Carlsson and F.M.Lcslie, Liq.Cryst., 10,325 (1991) of Technology (1992)

62. Equivalent Formulations of Smectic C Elastic Ener- 75. Determination of the Dielectric Biaxiality in a Chiral gies, I.W.Stcwart, T.Carlsson, F.M.Lcslie and Smectic-C Phase, F.Gouda, W.Kuczynski, M.Nakagawa, J.Cont.Mcch.Thcrmodyn., 3,237 (1991) S.T.Lagerwall, M.Matuszczyk, T.Matuszczyk and K.SHrp,Phys.Rev.A46,951 (1992) 63. Elcctroclinic Effect in Some Side-Chain Polysiloxane Liquid Crystals, KPlatischler, L.Komitov, K.Skarp 76. Fluorescent Liquid Crystal Polymers Exhibiting and P.Kellcr, Mol.Cryst.Liq.Cryst. 209,109 (1991) Ferroelectric and Electroclinic Switching, G.Scherowsky, A.Bccr, L.Komitov and S.T.Lagerwall, 64. Flow Properties of Biaxial Ncmatic Liquid Crystals, Proc. 21st Freiburg Workshop on Liquid Crystals T.Carlsson, F.M.Leslie and J.S.Lavcrty, (1992) Moi.CrystXiq.Cryst. 210,95 (1992) 77. Anufcrroclcclnc Behaviour in a Liquid Crystalline 65. Biaxial Ncmatic Liquid Crystals - Flow Properties and Polymer, K.Skarp, G.Andcrsson, F.Gouda, Evidence of Bistability in the Presence of Electric and S.T.Lagerwall, H.Pots and R.Zcnicl, Polymers for Magnetic Fields, T.Carlsson, F.M.Leslic and Advanced Technologies 3,241 (1992) J.S.Laverty, Mol.Cryst.Liq.Cryst., 212,189 (1992) 78. Fast Elcctroclinic switching in a Ferroelectric LC- 66. Formation of Walls in Cylindrical Smectic C Layers in Polysiloxane H.Poths, G.Andcrsson, K.Skarp and the Presence of a Tilted Magnetic Field, T.Carlsson, R.Zcntcl, Adv. Mater 4,792 (1992) I.W.Stcwart and F.M.Leslic, Liq.Cryst. 11,49( 1992) 79. Surface Transition in a Ncniaic Layer with Reverse 67. An Elastic Energy for the Ferroelectric Chiral Smectic Prctilt, L.Komitov, S.T.Lagcrwall, A.Sparavigna, C Phase, T.Carlsson, I.W.Stcwart and F.M.Leslic, B.Stcblcr and A.Strigazzi, Mol.Cryst.Liq.Cryst. 223, J.Phys.A. 25,2371 (1992) 197(1992)

68. Soft Mode Dielectric Anomaly of the Chiral Smcctic B 80. A Macroscopic Theory for the Row Behaviour of Phase with Sign Reversal Elcctroclinic Response, Smcctic C and Smcctic C* Liquid Crystals, F.Gouda, T.Carlsson, K.Flatischlcr, L.Komitov, T.Carlsson, F.M.Leslic and N.A.Clark, Phys.Rcv. A, S.T.Lagcrwall, K.Skarp and B.Stcbler, Phys.Rcv.A 45, submitted for publication 5362(1992) 81 Continuum Theory for Biaxial Ncmatic Liquid 69. Electrically Induced Mechanical Vibrations of a Crystals, F.M.Leslic, J.S.Lavcrty and T.Carlsson, Surface Stabilized Ferroelectric Liquid Crystal Cell, QuarU.Mech.Appl.Math (in press) N.Ebcr, L.Komitov, S.T.Lagcrwall, M.Matuszczyk, K.Skarp and B.Stcbler, Fcrroclcctrics 129,19 (1992) 82. Broad Band Dielectric Relaxation Spectroscopy of a Chiral Smcctic B - Crystal Phase F.Gouda, K.Skarp, 70. Influence of a Magnetic Field on the Peru* ;Splay- S.T.Lagcrwall, B.S'-.1 Icr, F.Krcmcrand S.U.Vallcricn, Stripcs in Hybrid Aligned Ncmatics, A.Sparavigna, Phys.Rcv.A, accepted for publication L.Komilov and A.Strigazzi, Mol.Cryst.Liq.Cryst. 212, 289(1992) 83. Theoretical Studies of the Influence of Backflow on the Dynamical Behaviour of a Fredericks Transition of a 71. S ign Reversal of the Spontaneous Polarization in the Ferroelectric Smcctic C* Liquid Crystal in the Book- C* Phase of a Side-Chain Polyacrylatc and its shelf Geometry, T.Carlsson, N.A.Clark and Z.Zou, Monomer, G.Schcrowsky, B.Braucr, K.Griincbcrg, Liq.Cryst., submitted for publication U.MUllcr, L.Komitov, S.T.Lagcrwall, K.Skarp and B.Stcblcr, Mol.Cryst.Liq.Cryst. 215,257 (1992) 84. Manifestation of the Biquadratic Coupling in (he Smcctlc C* Phase from the Soft Mode Dielectric 72. Investigations of Soft-Mode and Elcctroclinic Re- Response, F.Gouda, T.Carlsson, G.Andcrsson, sponse in a Ferroelectric Liquid Crystal withDs = S.T.Lagcrwall and B.Slcblcr, Phys.Rcv.A., submitted 5mC/m2, K.Skarp, G.Andcrsson, T.Hirai, for publication A.Yoshizawa, K.Hiraoka, H.Takc/.oc and A.Fukuda, Jpn.J.Appl.Phys. 31,1409(1992)

172 THE CENTRE FOR Superconductors and nanometer structures

Applied Solid State Physics 174 Condensed Matter Theory 196 See also under Materials Physics

MATERIALS SCIENCE, 1993 173 Applied Solid State Physics

Research Summary plates, shallow or deep steps etched into substrates, This is a rather large research group fluctuating nanobridges and so on. The nature of these weak between 25 and 37 persons depending upon the links is not fully understood. The junctions are number of guest researchers, vacations, etc. The utilized in a number of feasibility studies: Supercon- research is focussed onto tunneling, superconductiv- ducting Quantum Interference Devices as sensor of ity and very small structures made in a controlled extremely small changes in magnetic fluxes; flux way. The research encompasses sample preparation, flow oscillators, coupled Josephson oscillators, am- like epitaxially grown films or amorphous alloys, plifiers, and mixers for very high frequencies; hot and their characterization (using structural, electron devices; and digital circuits based on single microstructural, compositional, electrical transport flux quantum transport or flux flow transistors. and tunneling methods) and processing (patterning, Novel three-terminal devices are also invented. plasma etching, oxidation, etc) into structures that Work is also continuing on conventional super- are investigated. Components are developed and conductors at high frequency. investigated. In particular, we specialize in studies of A speciality of the group is single charge tunneling. new quantum effects and investigate theirfeasibility Charges (single electrons or Cooper pairs in a super- in possible detectors or sensors operating at the conductor)can tunnel coherently one byonein ultra- quantum limit. The group operates the national small tunnel junctions. The periodic motion can be nanometer facility that is used by several groups at phase locked to an external microwave signal giving Chalmers and by other groups in Sweden, Europe rise to voltage steps at currents I=nef. Including a and America. The activity contains mainly basic but Josephson coupling, it is possible to obtain Bloch also applied research within both science and tech- oscillations. The transition region between single nology. A large network of world wide cooperation electron and single pair tunneling is of great interest. has been built up. We investigate materials from It is also possible to control the tunneling of single insulators to superconductors, fabricate structures electrons by shifts much less than a single charge down to 20 nm (or even smaller by STM), use quantum of the charge distribution on a small elec- temperatures from 300 K to 0.005 K, and perform trode between two junctions. Our feasibility studies very sensitivemeasurements from sub-Hz (1/f noise) give electrometers with a sensitivity of 0.0001 e/VHz to THz frequencies. and single electron transistors with high power gain. Epitaxial films of high temperature superconduc- 2D arrays and transitions between Josephson and tors are deposited by several methods. The film Coulomb blockade dominated regions are also stud- nucleation and growth is studied by a number of ied. methods, likeelectron microscopy, atomic force and Another topic is the development of new scan- scanning tunneling microscopy, and electrical trans- ning microscope probes and their utilization in study- port. Multilayers, in particular superconducting lay- ing surfaces with atomic resolution. ers separated by insulators are needed for many applications and a large effort is devoted to the epitaxial growth of such layers. The layers have to be Address free from particles, large inclusions or other defects. Department of Physics Crossings of lines, needed in, for example, coupling Chalmers University of Technology transformers, and interconnects, are large problems, S-412 96 Göteborg, Sweden and basic materials research is needed. The films are Phone+46 31 772 3303 processed to Josephson junctions, using bi-crysta! Fax+46 31 16 5176 based grain boundaries, bi-epitaxial growth on tem-

!74 THh CENTRE FOR APPLIED SOLID STATE PHYSICS

Staff Collaborators Senior Members: Vladimir Antonov, Inst of Microel Technology, Tord Claeson professor Chemogolovka, Russia Per Delsing tekn.dr. Yuri Boikov, Ioffe Institute, St Petersburg, Russia David Haviland Ph.D. Jim Boyce, Xerox, Palo Alto, USA Zdravko Ivanov Ph.D. Frank Bridges, UCSC, USA Håkan Olin tekn.dr. Lie Chen, Academy of Sciences, Beijing, China Håkan Olsson tekn.dr. Donats Erts, University of Latvia, Latvia Dag Winkler tekn.dr. Ted Geballe, Standford University, USA Long Term Visiting Scientists: Evgeni Gershenzon, Moscow State Pedagogical Yuri Boikov Ph.D. Inst, Russia Donats Erts Ph.D. Gregory Goltsman, Moscow State Pedagogical Yuichi Harada Ph.D. Inst, Russia Vsevolod Kaplunenko Ph.D. Yuichi Harada, Tokyo Institute of Technology, Sergei Kubatkin Ph.D. Japan Leonid Kuzmin Prof. Sergei Kubatkin, P Kapitza Inst for Physical Victor Petrashov Prof. Problems, Moscow, Russia Evgeni Stepantsov Ph.D. Vsevolod Kaplunenko, Inst of Radio Eng and Alexandre Tzlentchouk: Ph.D. Electronics, Moscow, Russia Erland Wikborg doc. Boris Karasik, Moscow State Pedagogidal Inst, Stefan Zarembinski Ph.D. Russia Leonid Kuzmin, Moscow State University, Russia Graduate Students Gennadi Ovsyannikov, Inst of Radio Eng and Vladimir Antonov M.Sc. Electronics, Moscow, Russia Göran Brorsson civ.ing. Yuri Pashkin, Moscow State University, Russia Martin Danerud tekn.lic. Victor Petrashov, Academy of Sciences, Chen ChiiDong M.Sc. Chernogolovka, Russia Per Davidsson tekn.lic. Andy Poliakov, Moscow Jonas Edstam tekn.lic. Evgeni Stepantsov, Academy of Sciences, Mos- Rafi Gatt M.Sc. cow, Russia Niklas Mros civ.ing. Alexandra Tzlentchouk, Academy of Sciences, Per-Åke Nilsson tekn.lic. Moscow, Russia Yuri Pashkin M.Sc. Shouzheng Wang, Peking University, China Magnus Persson tekn.lic. Stefan Zarembinski. PAN, Warsaw, Poland Joakim Pettersson tekn.lic. Michael Zorin, Moscow State Pedagogical Inst, Jaime Ramos M.Sc. Russia Huai-ren Yi M.Sc. Collaboration within ESPRIT program with Univ. Zhang Yongming tekn.lic. Tubingen, Glasgow, Salerno, DTH, CNRS Technical Staff Grenoble Alexei Bogdanov Ph.D. Collaboration within ESA program with DTH, Ove Eriksson ing. Univ. Twente, NKT, Univ. Copenhagen Zdravko Ivanov Ph.D. Collaboration within NORPAS program with Peter Larsson civ.ing. Ericsson, ABB, NKT, DTH, LiTH. Bengt Nilsson civ.ing. Staffan Pehrson ing. Secretary Major Instrumentation Ann-Marie Frykestig • Nanometer laboratory • 9 deposition units • Cryogenic laboratory, 300 - 0.006 K.

MATERIALS SCIENCE, 1993 175 APPLIED SOLID STATE PHYSICS

Rf, microwave and mm wave measurements Research Projects Sensitive measurements in shielded room STM, AFM, and other scanning probes A: Superconducting Microelectronics

Al: Films of High Tc Superconductors Major Fields of Research The aim of the project is to study the mechanism of A. Superconducting Microelectronics epitaxial growth and properties of high-Tc thin films: participants: G. Brorsson, T. Claeson, M. YBaCuO, BiSrCaCuO and TIBaCaCuO. Different Danerud, Z.G. Ivanov, P. Larsson, P.Å. deposition methods, as co-evaporation, magnetron Nilsson, J. Ramos sputtering and pulsed laser deposition are involved, collaborators: J. Alarco, A. Andersson-Fäldt, C.G. but the main effort is in the pulsed laser deposition. Granqvist, E. Olsson, (Phys. Dept.), G.L. Epitaxial thin films have been grown on a variety of Johansson, (Chem. Dept.), M. Löfgren, (Appl. substrates, including single crystal and amorphous El. Phys.), ö. Rapp, (Royal Inst. of Techn., ones, with state-of-the-art results. Films are charac- Stockholm), V. Kaplunenko, G. Ovsyannikov terized by transport measurements and microstruc- and M. Tarasov (Inst. Radio Eng. and Elect., ture analysis. A natural prolongation of the activity Moscow), E. Wikborg (Ericsson, Stockholm), is to study film growth of high-Tc films on semicon- Yu. Boikov (Ioffe Inst., St. Petersburg), E.A. ductor substrates, Si and GaAs, with buffer layers. Stepantsov, A.Ya. Tzalenchuk (Inst. Cryst., Moscow), S. Dubonos (lost. Microel. Techn., A2: Multilayers of High Tc Superconductors/ Chernogolovka), T. Freltoft (NKT, Denmark), Insulators A. Samoilov (Kapitza Inst., Moscow). Multilayer structures of high-Tc materials are the corner stone in the development of high-Tc super- B. Nanofabricatlon and Nanotechnology conducting integrated circuits. This project aims at participants: Alexei Bogdanov, B. Nilsson,, developing a basic understanding of growth mecha- Andrei Poliakov nisms of multilayer structures based on high-Tc collaborators: This is a national facility which is superconductors, insulators, semiconductors and utilized by a large number of researcher within normal metals. Multilayers YBCO/NdGaOj and and outside the university. YBCO/SrTiO3/PrGaO3 have been grown and stud- ied. 'Hie growth conditions are correlated with mi- C. Mesoscoplc Physics crowave and transport properties of superconduc- participants: P. Delsing, D. Haviland, Y. Harada, tors and their microstructure. This study is required L. Kuzmin, M. Persson, J. Pettersson, Chen for the future development of high-Tc devices: mi- Chiidong crowave passive circuits and integrated digital cir- collaborators: V. Antonov, Y. Pashkine and V. cuits. Petrashov A3: Patterning of Superconductors D. Scanning Tunneling Microscopy The project is connected with development of participants: H. Olin, P. Davidsson nondestructive patterning of high-Tc thin films by T different methods. Photo- and e-beam lithography in collaborators: B.O. Aronsson, I . Engström, J. combination with dry or wet etching are used to Gold, C-G. Granqvist, B. Kasemo, J. Lausmaa, define patterns with dimensions on um- and sub-^m- G. Mbise, G. Niklasson, H. Norden, E. Olsson, scale for device application. Nanobridges are under M. Rodahl, A. Rosén, K. Skarp (Phys. Dept.), development to study current transport in one di- L. G. Johansson (Chem. Dept.), T. Hjertberg mensional high-Tc filaments and Josephson junc- (Polymer Techn.), H. Bertilsson (Polymeric tions. A considerable enhancement of critical cur- Materials), G. Stemme (Computer Eng.), D. rents has been obtained. Erts (Univ. Latvia), M. Stenberg (Inst Histol- ogy), S.E. Kubatkin (Kapitza Inst., Moscow).

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A4: Josephson Junctions Based on High vs temperature on the input: P=kAfG(T+TDSB). Temperature Superconductors Later measurements ha"e displayed lower noise It is difficult to fabricate tunnel junctions using high than predicted by the Heisenberg uncertaintety rela- Tc superconductors. Part of the reason for this is the tion, T 70 K) superconducting (HTS) materials, is today maybe the most interesting kind of weak A6: SQUIDs based on High Tc superconductors links that can be -tudied in this field. It has the i>est World record low noise levels of YBCO SQUIDs current-voltage (I-V) characteristic (almost identi- fabricated on (Y)ZrO bicrystal substrates. Se= 10- cal to the traditional resisiively shunted low Tc 29 J/Hz at 77 K which compares well with LTc junctions), the tunneling takes place in the a-b plane SQUID sensitivities at 4 K, see figure below. H.K. for c-axis oriented films, the weak link formation is Olsson et al. Appl Phys. Lett. 61, 861 (1992). within 5 Å, and the junction characteristics are - 1O26 •••!•••;••'[•••! reproducibly dependent on the misorientation of the O i o Chalmers HTc SQUID 27 O grains. Other structures that have been examined at =• io U • Commercial LTc SQUID'S Chalmers include diffusion type microbridges, step 4 K 77 K 8 : 28 : edge junctions, and bi-epitaxial grain boundary junc- 1 0 0 o I 1<°-0 ][ c tions. In the diffusion type microbridge, a thin strip T I °o0 of aluminum isdiffused into the natural grain bounda- ä>10 ,-29 0 %a> -ft- ries in a narrow region of a YBCO film. This method ö • : is fairly reproducible, but relies on the film growth w jo•30 ... i 20 40 60 80 100 and actual film morphology. In the second case, a «_*.... .1 .Temperatur , . e |K| step is formed in the substrate, and a YBCO layer is grown on top of this structure. The step induces grain boundaries, which form Josephson weak links. Prom- Noise sources: Identified two different 1/f noise ising results have also been obtained for bi-epitaxial contributions to the noise: film and junction voltage grain boundary junctions recently. noise. Close to Tc, a peak in the noise power was observed due to small pinning energies for magnetic A5: Parametric amplifiers and tunnel junctions vortices in the superconductor. At lower tempera- based on Low-Tc superconductors tures, the noise was found to increase due to large World-record low noise temperatures of Josephson currents being forced through the junction electron parametric amplifiers operated very close to the first traps. Minimum noise at 85 K, see figure below. non-linear bifurcation 1/1 and l/2).TosB=3+-4Kat H.K. Olsson et al. IEEE TRans Magn 1993, to be 9 GHz. The Figure shows the amplifieroutput noise published.

MATERIALS SCIENCE, 1993 177 APPLIED SOLID STATE PHYSICS

10" magnetic wave and power is generated. The FFO is i Electrojn Vbrtex ; .trapping pawing similar to a traveling wave tube in its operation. The FFOcan deliver appreciable power, but the linewidth has been an open question. We were able to deter- > 10' mine the composite linewidth of twoFFOs to 2.1 MHz in the band 280-330 GHz. The coupled power to a 10 Q microstripline was about 0.5 (J.W, which is more than enough to pump an SIS mixer in this band. 10"' 70 75 80 85 Furthermore, we demonstrated that the output power TEMPERATURE [K] could be tuned with very little frequency shift by simply varying the current biasing of the FFO on its resonant step. This is of utmost importance for the practical use of integrated superconducting local A7: Coupled high frequency cscillators oscillators. Similar circuits are investigated in the and High Tc mixers high-T program, and recently, evidence was seen The first demonstration of heterodyne mixer using c for the same fluxon motion. HTc materials. The Figure shows the mixing prod- uct vs bias voltage of the HTc junction and in the A9: 1 THz spectral analysis using High-Tc inset the point contact mixer sitting in a waveguide. superconductors Signal frequency = 70 GHz and IF ouput frequency The figure shows an example of a spectrum obtained = 50 MHz. Note V=hf/q since lql=2e also for HTc. with a HTc integrated Josephson junction and H.K. Olsson et al., J. Appl. Phys. 62,2113, (1987). microstrip resonator. A broad band coverage is achieved by simply measuring the IV-curve of the junction (f=2eV/h) and detecting the resonances. Note the operating frequency of this novel spectrum analyzer: 0-200 GHz. One can imagine these de- vices being used to investigate dielectric materials, gases, conductors, etc. A FIRST with HTc supercon- ductors! The frequency range has now been ex- .1 « • tended to 1000 GHz. J. Edstam et al., Appl. Phys. Lett. 62,896, (1993). 0.6 200 400 600 800 VOLTAGE

A8: Flux Flow Oscillators A flux flow oscillator consists of a long narrow Josephson junction. Since the junctio.t is several Josephson penetration depths long, it can have sev- eral magnetic flux quanta trapped in the barrier region. These fluxons follow soliton solutions (the perturbed sine-Gordon equation) and can move along the junction. If a current is applied through the junction in the presence of a magnetic field, fluxons will nucleate atone end of the junction and be moved by the Lorentz force. If the fluxon velocity ap- proaches the wave velocity for electromagnetic wave propagation through the junction, energy will be 50 100 150 200 transferred from the fluxon motion to the electro- f|GH/.|

178 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

AlO: Rapid Single Flux Quantum Devices and three terminal device has recently appeared that uses Circuits the motion of magnetic vortices in a superconduct- The project aims to develop a new family of Rapid ing film. High speed (>90 GHz) and compatibility Single Flux Quantum Circuits (RSFQ) based on with slower semiconducting devices make them high-Tc superconductors. The idea tode velop digital extremely interesting for applications. The theory devices where the logic unit is presented by a single field around these vortex phenomena has virtually flux quanta of magnetic field resulted in a large exploded in size the last few years and several family of low Tc integrated circuits. Recently, elaborate models to explain the behavior are dis- Conductus (USA) and our laboratory have proven cussed. For instance, a freezing into a vortex glass experimentally that RSFQ circuits can be based on state much like the spin glass model seem to describe high-Tc superconductors. For the further develop- several features well. Ourexperiments reproduce the ment of high-Tc RSFQ, electronic Josephson junc- critical dynamics predicted for a vortex glass phase tions, suitable for integrated circuits and multilayer transition. structures, will be developed.The project includes H.K. Olsson et al., Phys. Rev. Lett. 66,2661 (1991) intensive simulations of RSFQ integrated circuits and H.K. Olsson and R.H. Koch, Phys. Rev. Lett., and fabrication of integrated circuit. 68,2406, (1992).

All: Digital Elements Based on Flux Row In A13: Low Noise Quasl-Particle (SIS) Mixers High Tc Superconductors Integrated SIS (superconductor-insulator-supercon- Vortex flow ductor) mixers is a collaboration with Yale Univer- region sity on developing SIS mixers with both integrated fixed broadband tuning and with electronically on- chip tuning using the non-linear quasiparticle reac- tance of a tuning SIS array. The first direct measure- menv and observation of the quantum conductance and susceptance for a large voltage bias interval in Control current both the low and high signal limits was obtained. A superconducting detector electronically tuned by an Transistor action integrated array of SIS junctions using the nonlinear A very promising vortex transistor has come out of quantum susceptance was also demonstrated. the work with high-Tc films (Martenset. al., Sandia). Due to the lower pinnhig and smeared onset of High A14: Hot Electron Devices Tc superconductivity it is possible to bias a thin film Hot electron bolometers, mixers, fast switches and strip in a stable way (non-heating). By placing a modulators are applications that might emerge from control current lead close to the strip, vortices are ultra thin and narrow high-Tc films. This program is induced in the film and are accelerated via the conducted together with the Moscow Pedagogical Lorentz force. A transistor action is obtained. University and Department of Microwave Technol- ogy. The purpose of this study is to combine studies A12: The vortex glass (H>Hcl) and coherence of non-equilibrium states in high-Tc materials and to effects (H=0) provide a new generation of advanced detectors for This is a hot scientific field.The behavior of HTc "difficult" bands in e.g. the infrared. Switching times superconductors in magnetic fields differs from that of ~ 10 ps or modulation frequencies of the order of encountered in LTc superconductors. This fact has 30 GHz or more are predicted for radiation ranging important implications for large scale applications, from microwave to infrared. The physical phenom- thin film applications and the theory build-up around ena is based on electron heating effects. Incoming High-Tc superconductivity. Most large scale appli- radiation is interacting with the electron system, cations include a superconducting coil which gener- which is relaxed by electron-electron and electron- ates a large self-field in which the superconductor is phonon scattering. The hot phonons are then relaxed operated e.g. levitating trains, electric motors, en- by other phonon or electron collisions or they diffuse ergy storage etc. In electronics, a promising novel away from the interaction region into the substrate or

MATERIALS SCIENCE, 1993 179 APPLIED SOLID STATE PHYSICS film banks. Non-equilibrium electron heating can be and varying oxygen distances (tentatively coupled to accomplished by sufficient removal of hot non- different valence charge distributions) in doped su- equilibrium phonons from the interaction region, if perconductors based on BaBiOj. the electron-electron scattering time is much shorter than theelectron-phonon time. Theelectron-phonon time should be short for fast responses. This situation B. Nanofabrlcatlon and Nanotechnology will allow for non-equilibrium electron heating, where the electron gas will be at an elevated effective Bl: Development of Technology for Nanometer temperature compared to the lattice temperature. Fabrication Potential applications for the hot electron effects in Development of positive and negative resist tech- high-Tc are bolometers, microwave through infrared nologies, proximity corrections, lift-off and etching mixers, fast switches or demodulators for techniques. CAD design implementation with inte- optoelectronics, etc. By studying the upper cut-off grated electron exposure simulation tools. Experi- frequency of the beating signal in a mixer experi- mental methods to verify simulations for different ment, the electron phonon time can be obtained. We material combinations. Selective etching using NiCr have obtained an increased sensitivity by using a masks on Si and GaAs substrates has been studied. new modulation technique and both this technique Good selectivity could be achieved using a chlorine and pulsed laser (20 ps lasers, X=0.85 \an) measure- based chemically assisted reactive ion beam etch ments are in accordance, showing that the supercon- process. ducting hot electron sensor has a response time shorter than 30 ps. B2: Examples of Projects Utilizing the Nanometer Laboratory A15: Three-Terminal Devices The nanometer fabrication facility is used by several The project is directed towards development of groups at Chalmers, Linköping, Uppsala and Stock- three-terminal Josephson devices with a holm as well as some groups in Copenhagen, Hel- semiconducting channel controlled by electric field. sinki, and Sofia. Here, we report on activities by CTH The devices are based on low-Tc superconductors groups in the form of research projects. with GaAs channel or high-Tc superconductors. In the latter case we have shown that semiconducting Development of an ultra high speed GaAs high electron mobility transistor(HEMT) technology. channel can be created by using YBCO 45° grain So far, MESFETs and different HEMTs have been boundaries on ZrO2 bi-crystals, or doped bi-crystal fabricated successfully. The produced components junctions. Another line in the project will be the are far better than commercial ones and comparable development of artificial semiconducting channels with the best ones reported in litterature with similar by using semiconductors as PrBaCuO, BaZxOs or gatelengths. Current activities concentrate on de- doped YBaCuO. The underlying phenomena in both creasing the gatelength down to approximately 0.1 cases are not well understood and the effort will be Hm by using electron beam lithography. The pro- mainly to study the physical processes. Develop- jected and measured fmax is above 300 GHz. Inte- ment of a device model and study of microwave and grated millimeter wave circuits like monolithic am- noise properties will be performed. plifiers and receivers for low-noise applications are A16: Local Structure by XAFS being developed and have been tested successfully X-ray Absorption Fine Structure (XAFS) up to 1 OOGHz. The project is supervised by H Zirath, spectroscopy can be used to study the local environ- dept of Applied Electron Physics and utilizes the ment around absorbing atoms. Collaborating with nanometer lab. researchers at Xerox, Stanford, UCSC, and many Comer reflector lasers. sample suppliers, we have investigated high Tc superconductors. The problems have included the Microfabrication of opto-electronic and electronic effect of substitutions, like Fe, Co, Zn, and Ni in components on a single chip is a growing field of YBCO (where we see local distortions, chain func- research. It is desirable to place driver circuits and lasers for external communication on the same chip. tion, clustering etc), the effect of oxygen depletion,

180 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

The 8 micrometer diameter Chalmers Emblem is A gate structu.e on top of a GaAs/AIGaAs made of Au-Pd lines on bulk silicon using electron heterostructure for observation of a single elec- beam lithography. The smallest linewidth is about tron tunnel effects and 0-1 dimensional transport 50 nm. phenomena. The 2DEG under the gates is de- pleted when a voltage is applied defining two dots connected by point contacts.

The conventional method of forming the laser mirror Multilevel phase holograms. by cleaving the GaAs crystal can only be employed It is possible to fabricate computer generated holo- for one mirror and only if the laser is placed at the grams that will have a high utilization of the light.e.g. edge of the chip. The other mirror has to be formed for display purposes or power laser machining. by etching. If the laser only needs to emit radiation Holograms with almost continous control (63 levels) through the cleaved mirror, the other plane mirror of the surface topography have been realized by may be replaced by an etched comer reflector with electron beam lithography. This level of control is total internal reflection, which also gives a better unique among the groups working with this kind of mode formation in the laser cavity than two plane diffraction optics. Hologram diffraction efficiencies mirrors. To reach highest possible quality of the as high as 84% of the theoretically predicted 89% facets, the mask is defined by electron beam lithog- efficiency were measured by a group at Applied raphy and the facets are dry etched using an ion Electron Physics. This the highest reported value to beam. A new type of surface emission laser has date. recently been developed, using a combination of two - M. Ekberg, M. Larsson, S. Hård, Appl.El.Phys., in etched corner reflectors and a special surface grat- cooperation with B. Nilsson, nm-lab. ing, made by e beam lithography. The emission profile of such a device is better than what you get Single traps and quantum transport from a conventional edge-type laser. Since the radia- in nanometer size MOSFETs. tion isemitted vertically, the design can be utilized in The purpose of the project is to study single electron integrated arrays very easily, and may be interfaced traps and quantum transport in nanometer size sili- to other systems. The threshold current density of con MOSFETs. Together with electron beam lithog- this laser is equal to or better than for a conventional raphy, a special dry etching technique is developed edge-type laser. for the fabrication of the small MOSFETs. So far, - Mats Hagberg and Torgil Kjellberg, Dept. of etched MOS structures in the 80 nm range has been Electrical Measurements and Optoelectronics. fabricated. Traps and "telegraph noise" have been studied in diodes fabricated with sub-micron dimen- sions. The project is pursued by the dept of Solid State Electronics (Engström, Andersson, Xiao) with aid from and using the nanometer laboratory.

MATERIALS SCIENCE, 1993 181 APPLIED SOLID STATE PHYSICS

Artificial micro- and nanostructures for phenomena are also of general scientific interest biomaterials research and applications. since they are an example of macroscopic quantum In order to further understand the interaction be- phenomena, which presents a new experimental tween living tissue and foreign material on the realm for testing the predictions of standard quantum cellular level, micro- and nanofabrication techniques mechanics. Our group is engaged is several experi- can be used to produce test surfaces having control- ments which are of both applied and general scien- led surface topographies and compositions. It is tific interest: possible to systematically modify the interaction • Two dimensional arrays of tunnel junctions surfaces, one property at the time. Free particles in have been studied in both the normal and suspension can be produced with similar methods, superconducting state. We have recently with well controlled size, shape and composition, for investigated the role of the Josephson coupling interaction with living cells. energy and its effect the threshold voltage and -The Biomaterials Consortium with Julie Gold and activation energy for transport in insulating Bengt Nilsson as participants. arrays.

• One dimensional arrays of tunnel junctions C. Mesoscoplc Physics have shown the existence of SET oscillations. Simulations and experiments on coupled one Cl: Single Charge Tunneling In Metallic and dimensional arrays have been carried out to Superconducting Structures look for synchronisation of tunneling in each The tunnelling of an electron from one electrode to array. another through a large potential b?. rier occurs in packets of charge having a unit value of e. If the • Superconducting multi-junction experiments in capacitance of the tunnel junction is small enough, loop geometries have shown the combined the energy required to charge the junction capaci- effect of phase and charge quantization in the tance with a single electron, EQ= e2/2C, can become circuit. These devices obtain modulation of the quite substantial. This charging energy can act to I-V curve with both magnetic flux and gate inhibit tunneling of the electron. This is the essence voltage. of the Coulomb blockade. The charging energy can • Current biased circuits are achieved by insert- also give rise to a strong correlation of tunneling ing high resistance leads (ca. 30kQ/um) in the events in multi-tunnel junction circuits where the leads, very close to the jnnel junctions. Such tunnel junctions are close to one another. Further- experiments allowed the observation of Bloch more, by changing the charge distribution in multi- oscillations and SET oscillations in a single tunnel junction circuits by means of external gate tunnel junction. electrodes, the coulomb blockade can be modulated resulting in a single electron transistor effect. C2: Single Charge Tunneling In superconducting tunnel junctions, the tunne- In Semiconducting Structures ling occurs via paired electrons (Cooper pairs), Small conducting islands can be confined by an having charge 2e. Several pairs exist in a phase electrostatic potential in a two-dimensional elec- coherent state, and the strength of the phase coherent tron-gas (2DEG), which is an epitaxially grown tunnelling of Cooper pairs is given by the Josephson heterostructure. The islands are contacted by quan- coupling energy EJ. The phase and charge are quan- tum point contacts, with an adjustable tunneling tum mechanically conjugate variables in the macro- probability for the electrons. It is in this way different scopic, phenomenological description of the super- from the metallic system with oxide tunnel barriers. conducting junction. The Coulomb blockade in the The transport through a quantum dot is affected by superconducting junction with EJ ~EQ, manifests the energy level spectrum of the dot, magnetic fluxes itself in a radically different way than that of the penetrating the dot, and the charging effects. Charg- normal tunnel junction. ing effects in semiconductors is a field of great Coulomb blockade phenomena are of substantial interest. Current steps have been demonstrated in a interest forpotential applications inelectronics. These turnstile. Single electron transistors have been made.

182 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

Cotunneling effects and the energy level spectra We will need to integrate small field effect transis- have been studied. tors directly below or beside the SET output to We have observed magneto-conductance oscil- minimize stray capacitance from leads. lations of a dot at low magnetic fields, with a period corresponding to the Aharonov-Bohm period of a rinj. These oscillations were not expected at low D. Scanning Probe Microscopy fields, only at high fields where the current is trans- Scanning probe microscopy (SPM) is a growing ported in edge channels. They coexist with the family of high resolution techniques employing the charging effects. Thus it is possible to investigate the same principle as in the scanning tunneling micro- depopulation of the Landau levels of the dot by scope (STM), but with the tunneling tip replaced by single electrons. another local probe. One common type of probe microscope is the atomic force microscope (AFM) C3: Mesoscopic transport phenomena where repulsive forces are measured using a tech- in wires and rings nique similar to an ordinary record player. With the We have measured the magneto resistance and the AFM non-conducting samples are possible to image current voltage characteristics on a large number of with a resolution down to the atomic scale. mesoscopic size rings and wires. In many of these samples we placed superconducting electrodes on A new extended laboratory for scanning probe top of the current leads, or alternatively on "stubs" microscopy has been set up during 1992. The labo- perpendicular to the current leads. These supercon- ratory is a joint effort between the Materials Science Centre, five physics groups (Claeson, Kasemo, ducting electrodes act as "mirrors" where electrons Nordén.Granqvist, and Rosén), twochemical groups are Andreev reflected. (Hjertberg and Bertilsson), and the educational de- Aharonov Bohm effect: In rings without super- partment. The SPM-lab consists of two commei rial conducting mirrors we observe h/2e oscillations of STM/AFM (for use in air, liquid, and electrolyte) the magneto resistance. The amplitude of these and a number of home-built probe microscopes. Aharonov-Bohm oscillations are up to 400 times larger when superconducting "mirrors" are present Dl. Development of Scanning Probe compared to a ring without mirrors. Microscopes For samples with "mirrors" we also observe h/4e Air-liquid STM/SPM. An STM for use in air and oscillations which are due to Phase coupling be- liquid has been developed. The microscope is spe- tween electrons and the superconducting conden- cially designed to allow other probes to be inserted. sate. As an electron is Andreev reflected at the SN SICM. A probe microscope suitable for biologi- boundary it acquires the phase of the superconduc- cal samples is the scanning ion conductance micro- tor. This results in the h/4e oscillation of the magneto scope (SICM). Using glass pipettes as the probe we resistance. have reached a resolution of about 0.S (am on a leaf Conductance fluctuations of the resistance is sample. The resolution in the SICM is limited by the observed for both rings and wires with "mirrors". As size of the pipette aperture. Standard pipettes be- the superconductivity is suppressed by a magnetic come increasingly fragile when the diameter of the field, the change in resistance can be both positive or aperture is made smaller. To increase the resolution negative. we have started a development of a new kind of The response of a ring to an electric field supplied pipette with aperture openings down to 5 nm. by a gate (an attempt to observe the electrostatic A- Low-temperature. To study tunneling phenom- B effect) showed that screening in a ID system is ena, superconductors and mesoscopic physics at low much less effective, than in a 3D system. temperatures STMs suitable for operation at helium C4: Integrating metaHbased single electronics temperatures has been build. The STMs are suitable with semiconductors for operation down to 1.3 K and 50 mK. The aim is to impedance-match SET transistors with the environment, hereby increasing the maximum output frequency by several orders of magnitude.

MATERIALS SCIENCE, 1993 183 APPLIED SOLID STATE PHYSICS

D2. SPM Studtes of High Tc Superconductors; mesoscopic object. The mesoscopic sample is a Film Growth, SET point contact made using the STM-tip at 1.2 K iust A number of important questions related to the before the measurement. We detect abrupt changes micTostructure of YBCO high Tc films have been in the mesoscopic signal both as a function of the tip investigated. One is the unknown nature of the position and tip-sample voltage. They could be defects responsible for flux pinning. Another ques- interpreted as due to spatial shifts or changes in the tion concerns the nucleation and growth mecha- activity of scattering centers in the sample. nisms of the films. Our STM measurements showed that changes in surface morphologies occurred when the substrate temperature during deposition was varied. These variations couL be related to a de- crease in critical current and increase in surface resistance with increasing temperature. An extensive study has been performed using a combination of AFM and TEM on the early stages of growth of YBCO thin films. Important micro- structural characteristics, which are strongly corre- lated to properties such as the critical current density and the transition temperature, are established at these early stages of growth. We have also studied Tl2Ba2CaCu2O8 high Tc Scanning tunneling microscope image films. Using the STM we observed a high density of of graphite atoms. nm-sized particles on the surface. Tunneling spectroscopicmeasurementon these samples showed large coulomb blockades. In contrast to previous experiments that have been performed at a tempera- ture below IK, these measurements were made at room temperature.

D3. Other STM/AFM Studies In Air Biomaterials. Titanium oxide is a successful biomaterial. However, the mechanism for the biocompatibility is not known. One influencing fac- tor can be the topography at the nanometer scale. To investigate the topography at this scale, we per- formed STM/AFM experiments on different sam- ples. The results are used for in vivo or cell studies to get correlation between surface roughness and bio- compatibility. Other studies include AFM measurements of surface morphology of CaF2 films as a function of film thickness, deposition angle, rate, and pressure for understanding of the dynamics and morphology of growing rough surfaces.

D4. Metoscopic and Superconductor Studies Using Low-Temperature STM A new method has been introduced to study electron High-temperature superconductors (YBCO). Scanning Tunneling Microscope image showing transport in mesoscopic samples. The electric field the layered structure of this material. from an STM-tip is used to locally influence a Also, note the screw dislocation.

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5. Study oT in situ Laser Deposited YBCO Thin Films Publications G. Brorsson, J.A. Alarco, Z.G. Ivanov, H. Olin, P-Å. Nilsson, and T. Claeson, J. of the Less-Common Ph.D. Dissertations Meials, 164&165,383-390,1990. and Licentiate Dfssertlons P. Delsing, "Single Electron Tunneling in Ultrasmall 6. In-situ dc Sputtered High Tc Y-Ba-Cu-O Films Tunnel Junctions", 90, Thesis. S. Zarcmbinski, J. Ramos, Z. Ivanov, and T. Claeson. M. Danerud, "Thin Films and Optical Detectors Made of J. of the Less-Common Metals, 164&165,329-335, 1990. G. Brorsson, "Laser Deposited Thin Films of the High Temperature Superconductors YBaCuO and 7. Ac-Impedance at the Superconducting Vortex Glass BiSrCaCuO",June91. Transition. PÅ Nilsson, "Thin Films of YBa^O? deposited by CO- HK. Olsson, R.H. Koch, W. Eidelloth, and R. evaporation, Josephson Junctions, and dc-SQUIDs, Robertazzi. APS Cincinaui, March 1991, and EPS June 91. Exter, April 1991 and invited at 5M3I Intermag Y. Zhang, "Theoretical and Experimental Studies of the conference, Pittsburg, June 1991, invited Swedish HTc Flux-Flow Type Josephson Oscillator", October 91. annual meeting, May 1991. P. Davidsson, "Symmetric Scanning Tunneling Micro- scopes for Ultra High Vacuum and Very Low Tem- 8. Observation of Critical Scaling Behavior in the ac peratures", April 92. Impedance of the Onset of Superconductivity in a J. F.dsiam, "Lumped Arrays of Josephson Junction Oscilla- Large Magnetic Field tors", March 92. H.K. Olsson, R.H. Koch, W. Eidclloth, and R. P. Davidsson, "Symmetric Scanning Tunneling Micro- Robertazzi. Phys. Rev. Letters 66,2661 (1991). scopes for Ultra High Vacuum and Very Low Tem- peratures", April 92. 9. Growth and Properties of NdGaO3/YBCO J. Edstam, "Lumped Arrays of Josephson Junction Oscilla- Multilayer Structures tors", March 92. Yu. Boikov, G. Brorsson, T. Claeson, and Z.G. Ivanov, H. Olin, "Scanning Probe Microscopy: Design and Appli- E-MRS, Int. Conf. Adv. Mat.: High Tc Superconductor cations", 93, Thesis. Thin Films, ed. by . Correra, Elsevier Science Publ., 1992, p. 721-726. Rim Fabrication and Properties 1. Elemental Profiling Through Superconducting 10. YBCO Thin Films on Yttria Stabilized Zirconia - BiSrCaCu Oxide Layers Deposited by Laser Growth and Properties Ablation on Different Substrate Materials. J.A. Alarco, G. Brorsson, t. Clacson, Z.G. Ivanov, and E.U. Engström, Z. Ivanov and A. Loading, Proc. Conf. M. Lövgren, E-MRS, Int. Conf. Adv. Mat.: High Tc on Analytical Chemistry - EUROANALYSIS VII, Superconductor Thin Films, ed. by L. Correra, Elsevier Vienna. Austria, 1990. Science Publ., 1992, p. 647-652.

2. Superconducting (Bi,Pb)-Ca-Sr-Cu-0 Thin Films 11. Very Thin YBaCuO Films Made by Coevaporation Prepared in Situ by Laser Ablation. M. Danerud, P.Å. Nilsson, and J. Alarco, E-MRS, Int. Z. Ivanov and G. Brcrsson, Appl Phys Lett. 5j5_, 2123 Conf. Adv. Mat.: High Tc Superconductor Thin Films, (1989). ed. by L. Correra, Elscvicr Science Publ., 1992, pp 421-426. 3. High Quality YBCO Thin Films • Laser Deposition, Co-Evaporation, and Device Fabrication 12. Epitaxial Growth and Properties of YBazCuaO-V J.A. Alarco, G. Brorsson, T. Claeson, M. Danerud, U. NdGaOj/YBa2Cu3O7.d Trilayer Structures Engström, Z.G. Ivanov, P-Å. Nilsson, H. Olin, and D. Yu.Boikov, G.Brorsson, T. Claeson, and Z.G.Ivanov, Winkler, Physica Scripta 44, 35-101 (1991). Appl. Phys. Lett. 59,2606 (1991).

4. In situ YBCO Thin Films Made by Laser Deposi- 13. YBCO thin films on Yttria-stabilized Zirconia and tion LaAIO3: growth and properties G. Brorsson, Z. Ivanov, and P-Å. Nilsson, Science and J.A. AJarco, G. Brorsson, T. Clacson, Z.G. Ivanov, M. Technology of Thin Film Superconductors 2, edited by Lofgren, and P.Å. Nilsson, Physica C, 185-189,2017- R.D. McConnel and R. Noufi, Denver, Colorado, 1990, 2018(1991). pp 169-175. 14. Scanning Tunneling Microscopy of Laser Deposited YBCO Thin Films H. Olin, G.Brorsson, P.Davidsson, Z.G.Ivanov, P.Å.Nilsson, and T.Clacson, Ultramicroscopy 42-44, 734 (1992).

MATERIALS SCIENCE, 1993 185 APPLIED SOLID STATE PHYSICS

25. Properties of Artificial Grain Boundary Weak 15. Laser-deposited PrGaO» films on SrTiOj substrates Links Grown on Y-ZrO2 Bkrystab.

and in 15.15. YBa2Cu3O7/n-Ga(VYBa2Cii3O7Tri Z.G. Ivanov, P.Å. Nilsson, D.Winkler, J.A. Alarco, G. layers, Brorsson, T. Claeson, E.A. Stepantsov, and A.Y. G. Brorsson, P.Å. Nilsson, E. Olsson, SZ. Wang, and Tzaknchuk, Supercond. Sci. Technol. 4,439-441 T. Claeson. AppL Phys. Lett 61, (1992). (1991).

16. Growth and Properties of a Multilayer System 26. Grain boundaries in YBaCuO thin films - a semi-

Based on Y^Ci^O, and Amorphous Y-ZrO2 conductor? Yu. Boikov, Z. G. Ivanov, J. A. Alarco, G. Brorsson, Z.G. Ivanov, T. Clacson, R.I. Shekhler, D. Winkler, and T. Claeson, J. Appl. Phys. 22(1), 199-202 (1992). E.A. Stepantsov, and A.Y. Tzalcnchuk, in Proceedings of the Joint Nordic Spring Meeting '92, edited by P.-A. 17. Effects of substrate temperature on the mkrostruc- Lindgård (Risö-R-628(EN)), Risö National Laboratory, ture oT YBa^CujOj-j films grown on (001) Y-ZrOj Roskilde, Denmark, 7-10 May, 1992. substrates, Appl. Phys Lett, 61 723-725(1992). 27. Properties of YBCO junctions and SQUIDs on YSZ bkrystals 18. Epitaxial growth and properties of Yi P.-Å. Nilsson, Z.G. Ivanov, D. Winkler, H.K. Olsson, Pb(ZrousTio.4)03-Y,Ba2Cu30, and Amorphous Y- G. Brorsson, T. Claeson, E.A. Stcpantsov, and A.Y. Tzalenchuk, Physica, vol. C 185-189, pp. 2597-2598, Yu. Boikov, S.K. Esayan, Z.G. Ivanov, G. Brorsson, T. 1991. Claeson, J. Lee, and A. Safari, Appl. Phys. Lett., 6L 528(1992). 28. Metal-Doped Artificial Grain Boundary Weak Links in YBCO Films 19. Superconducting properties of electrochemically E.A. Stepantsov, A.Ya.Tzalcnchuk, Z.G. Ivanov, and Li+ intercalated YBaCuO thin films T.CIacson, ZI in Materials and Crystallographic Z.G. Ivanov, A.M. Andersson and CG. Granqvist, J. of Aspects of High-Tc Superconductivity, edited by E. Alloys and compounds, J9J,343-346 (1993) Kaldis, Erice, Italy, 1993, May 17-29,.

20. YBaCuO/NdGaO/YBaCuO Tri-layers by Mopified 29. Sub-micron Size, High Current Density Nb/PbBi OfT-Axis Sputtering, Window Tunnel Junctions SZ. Wang, E. Olsson, J.A. Alarco, 7.G. Ivanov, D. J. Edstam and H.K. Olsson, SQUID'91, subm. Winkler, V. Langer, and P. Beraslegui, subm. to J. AppLPhys. 30. Narrow YBCO Microbridges in Lltrathin Laser Deposited Films M. Dancrud, M.E.Gershenson, Z. Ivanov, D.Winklcr, Processing and Junctions and T.Claeson, Physics C, 185-189,1939 (1991). 21. Microbridges in High-Tc Superconductors: High 31. Microstructure of an YBa CujO7.5 artificial gra'" IcRn Products 2 Z.G. Ivanov, G. Brorsson, and T. Claeson, J. of the boundary weak links grown on a 0- 45° (001) tilt Y- Less-Common Metals, 164&165,1529-1535,1990. ZrO2 bicrystals J. A. Alarco, E. Olsson, Z. G. Ivanov, P. Å. Nilsson, D. Winkler, E. A. Stepantsov, and A. Ya. Tzalcnchuk, 22. High Resolution Patterning of High-Tc Supercon- ducting Thin Films Frontiers of Electron Microscopy in Materials Science, Z. Ivanov, P-Å. Nilsson, E-K. Andersson, and T. Oakland, California, April 21-24,1992. to be pub- Claeson, Supercond. Sci. Technol. 4,112,1090. lished,.

32. YBaCuO Josephson weak links based on shallow 23. High Tc Superconducting Diffusion Type Weak Links ion beam etched steps in MgO substrates Z O. Ivanov and T. Claeson, Physics B, 165&166 II, J. Ramos, Z. G. Ivanov, E. Olsson, and T. Clacson, 69-70,1990. Proc. BIHTS'92, World Sci, Singapore, to be pub- lished. 24. Fabrication and Properties of NTS Diffusion Type Weak Links 33. Properties of ion beam stimulated bi-epitaxial Z.G. Ivanov, G. Brorsson, and T. Clacson, IEEE Trans. Josephson junctions Magnetics Mag-21,3324 (1991). J.H. Ramos, Z.G. Ivanov, E. Olsson, and T.CIacson, IEEE Trans.Magn., to be publ.

186 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

34. Crossovers and Vias in YBaCuO/PrGaO3/YBaCuO 45. Observation or a peak in the real part of the rf- Trilayer Structures conductivity, Re|s(T)|, of YBaCuO Nilsson, P. Å., Brorsson, G., Olsson, E., Ivanov, Z. G., H.K. Olsson and R.H. Koch. Physica C 185-189,1847 & Claeson, T. (1992). IEEE Trans. Magn., subm. (1991).

35. Weak Links and dc-SQUIDs on Artificial Non- 46. Comment on "Observation of Conductivity Coher- Symmetric Grain Boundaries in YBa2CujO7^ ence Peak _." by Holzcer et. al. PRL 67,152(1991) Z.G.lvanov, PÅ.NiIsson, D.Winkler, J.A.Alarco, H.K. Olsson and R.H. Koch. Phys. Rev. Lett., 68, T.Clacson, E.A.Stepantsov, and A.Ya.T/alenchuk, 2406,(1992). Appl. Phys.Lett. 59,3030-3032 (1991). 47. A quasiparticle-tuned superconducting mixer 36. Sub-micron sized, high-current density Nb/PbBi N.G. Ugras, A.H. Worsham, D. Winklcr, and D.E. window tunnel junctions Probcr, Appl. Phys. L ett., vol. pp. to be published J. Edstam and H.K. Olsson, Superconducting Devices 1993. and Their Applications, eds. H. Koch and H. Liibbig, Springer Verlag, Berlin 1992, pp 224-227. 48. A 75-110 GHz SIS mixer with integrated tuning and couped gain D. Winklcr, A.H. Worsham, N.G. Ugras, D.E. Prober, High frequency effects N.R. Erickson, and P.F. Goldsmith, In Nonlinear 37. Design of a Lumped array of Josephson Junction Superconductive Electronics and Josephson Devices, Oscillators (Plenum Press, New York, 1991), G. Costabile, S. J. Edstam and H.K. Olsson. IEEE Trans. Magn., Pagano, N. F. Pcuersen and M. Russo, Ed., 1991, pp. MAG-29, (1993), to be published. 73-79.

38. Direct detection of high frequency resonances in 49. Self-Induced Resonances in YBCO Bicrystal Grain bkrystal Josephson junctions Boundary Josephson Junctions J. Edstam, P.Å. Nilsson r id H.K. Olsson Applied D. Winklcr, Y.M. Zhang, P.A. Nilsson, E.A. Superconductivity Conference, Chicago, Ai g 1992. Stcpantsov, and T. Claeson, in XX International Conference on Low Temperature Physics, cd'tfrt by Eugene, Oregon, USA, 1993, August 4-11. 39. 100 GHz Oscillations on Monolithic HTC Chip J. Edstam, P-Å. Nilsson, E. A. Stcpantsov, and H.K. Olsson. Appl. Phys. Leu., 62,896,1993. 50. Detection of mm and submm wave radiation from soliton and flux-flow modes in a long Josephson junction 40. On-chip Diagnostic of HTC Superconductors at mm-Wave Frequencies Y.M. Zhang, D. Winklcr, and T. Claeson, IEEE Trans. J. Edstam, P.-Å. Nilsson, E. A. Stcpantsov, and H. K. Appl. Supercond, to be published 1993. Olsson. J. Alloys and Compounds, 1993. To be published. 51. Linewidth measurements of Josephson flux-flow oscillators in the band 280-330 GHz 41. Broad band microwave spectroscopy of cooled Y.M. Zhang, D. Winkler, and T. Claeson,, Appl. Phys. monolithic circuits Lett., vol. pp. accepted for publication. H. K. Olsson and J. Edstam. INTERMAG 93, Stock- holm Sweden, April 13-16 1993. 52. Linewidth measurements of flux-flow Josephson oscillators using a CAD designed integrated sub- 42. London penetration depth of YBCO for the fre- mm wave receiver quency range 80-700 GHz Y.M. Zhang, D. Winklcr, and T. Claeson, in Fourth J. Edstam and H.K. Olsson. XX International Confer- Inicrnalif ,al Symposium on Space Terahertz Technol- ence on Low Temperature Physi. s, Eugene OR, Aug ogy, edxd by UCLA, Los Angeles, USA, March 30 - 4-11 1993. April 1,1993 1993, submitted.

43. Integrated microstrip resonator structures using 53. Josephson parametric amplifiers: low noise at 9 GHz high-Tc materials J. Edstam and H.K. Olsson, XX International Confer- H.K. Olsson and T. Claeson, Advances in supercon- ence on I ow Temperature Physics, Eugene OR, Aug ductivity, cis Kitazawa and Ishiguro, Springer-Verlag 4-11 1993. Tokyo, 1989, pp 93-97.

44. Scaling behavior at the vortex glass transition 54. Dielectric Constant of Evaporated SiO at Frequen- H.K. Olsson, R.H. Koch, W. Eidelloth, and R. cies Between 13 and 103GHz. Robcriazzi. Physica C 185-189,1815 (1991). H.K.Olsson, IEEE Trans. Magn., 25 (1989) 1115.

MATERIALS SCIENCr. 1993 187 APPLIED SOLID STATE PHYSICS

55. Low Noise Josephson Parametric Amplification and 65. High Tc Superconducting IR Detectors Oscillations at 9GHz. from Y-Ba-Cu-O Thin Films H.K.Olsson and T.CIacson, J.Appl.Phys.64 M. Lindgren, H. Ahlberg, A. Larsson, S.T. Eng, and (1988)5234. M. Danerud, In Superconductivity Applications for Infrared and Microwave Devices (Hcinen, ed.), SPIE 56. Numerical Calculation or the Height of Velocity- Proc. 1292,1990, to be published. Matching Step of Flux-Flow Type Josephson Oscillator 66. Observation of Critical Scaling Behavior in the ac Y.M. Zhang and P.W. Wu, J. Appl. Phys. 68,9,1990. Impedance of the Onset of Superconductivity in a Large Magnetic Field 57. Effect of Losses on the Output Voltage of a Flux- H.K. Olsson, R.H. Koch, W. Eidelloth, and R. Flow Type Josephson Oscillator Robenazzi. Phys. Rev. Letters 66,2661 (1991). Yongming Zhang. Nonlinear Superconductive Elec- tronic and Josephson Devices, Eds. N.F. Pedersen, M. 67. Ac-impedance at the superconducting Russo, A. Davidson, G. Costabile and S. Pagino, vortex glass transition. Plenum, NY 1991, p. 145. H.K. Olsson, R.H. Koch, W. Eidelloth, and R. Robenazzi., J. Appl. Phys. 70,6194 (1991). 58. Effect of Losses on Output Voltage of Flux-Flow Type Josephson Oscillator. 68. Mm-wave radiation in high-Tc two-dimensional Yongming Zhang and Tord Claeson, presented at LT- Josephson arrays, 19,1990. G.A. Ovsyannikov, Z.G. Ivanov, J. Mygind, NP. Pedersen, and T. Claeson, to be publ. 59. Hyper-Vortices in Granular Superconducting Thin Films G.A. Ovsyannikov, Z.G. Ivanov, G. Brorsson, and T. SQUIDs and Three Terminal Devices Claeson, Physica B, 165&166 II, 1609-1610,1990. 69. Vortex transistor devices for logic elements Y. Zhang, G. Brorsson, M. Danerud, J. Edstam, P. 60. Hyper-vortices in high Tc superconducting bridges Larsson, P-Å Nilsson, E. Wikborg, and H. K. Olsson. G.A. Ovsyannikov, Z. Ivanov, G. Brorsson and T. XX International Conference on Low Temperature Clacson, Proc. Int. Conf. Transport Prop, of Supercon- Physics, Eugene OR, Aug 4-11 1993. ductors, May 1990. 70. Design of Multi-Loop Input Circuits for High 61. The Quantum Tunneling Currents in a Supercon- Temperature Superconducting Quantum Interfer- ducting Junction ence Magnetometers, A.H. Worsham, N.G. Ugras, D. Winklcr, D.E. Prober, S. Zarembinski and T. Claeson, J. Appl. Phys., to be N.R. Erickson, and PP. Goldsmith, Phys. Rev. Letters. subm. 67,3034(1991).

71. YBCO dc-SQUIDs on Y-ZrO2 Bkrystals 62. A Full-Band Waveguide SIS Receiver with Inte- Z.G. Ivanov, P.Å Nilsson, D. Winkler, G. Brorsson, T. grated Tuning for 75-110 GHz Claeson, E.A. Stephantsov, and A.Y. Tzalenchuk, D. Winkler, N.G. Ugras, A.H. Worsham, DP,. Prober, SQUID'91, to be publ. N.R. Erickson, and P.F. Goldsmith, IEE E Trans. Magn. MAG-27,2634 (1991). 72. Low 1/f noise in YBaCuO SQUIDs on bicrystal (Y)Zr02 substrates 63. Picosecond detection of infrared radiation with H.K.Olsson, R.H. Koch, Z.Ivanov, P-Å Nilsson, E.A. YBa2Cu3O7.fi thin nims Stepanlsov, and A.Ya. Tzalcnchuk, Appl.Phys.Leu. 61, M. Danerud, MZorin, MLindgren, V.Trifonov, 861-863(1992). E.M.G. B.Karasik, G.N.GoI'Lsman, and D.Winkler., submitted to the proceedings of International Confer- 73. Superconducting Transport Properties of Ohmk ence on IR and MM-Waves, 1993, Sussex, England. Contacts Z G Ivanov, phys.stat.sol.(a) Hi, 439 (1989). 64. ' he Superconductor Insulator Superconductor 4ixer Receiver - A Review 74. Design or" Multi-Loop Input Circuits for High R. Blundell and D. Winkler, in Non-linear Supercon- Temperature Superconducting Quantum Interfer- ductive Electronics and Josephson Devices, Ed. by ence Magnetometers N.F. Pcdcrson, M Russo, A. Davidson, G. Costabile, S. Zarembinski and T. Clacson, J. Appl. Phys., Sept and S. Pagano, Plenum, London, 1991, p. 55. 1992.

188 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

75. Low l/f noise in YBaCuO SQUIDson bicrystal 84. Occupation of Distorted Cu(l) sites by Co and Fein (Y)ZrO2 substrates HJCObson, R.H. Koch. Z.Ivanov, P-Å Nilsson, E.A. F. Bridges, J.B. Boyce. T. Claeson. T.H. Geballe. and Stcpanlsov, and A.Ya.Tzalcnchuk. Appl. Physlxu. 61, JJvl. Tarascon, MaLRes.Soc.Proc. 143,163 (1989). 861 (1992). 85. X-Ray AbsorptMi Study of Superconducting 76. Field Effect Transistor Based on Metal-Insulator, Artificial Gran Boundary Josephson Junction T. Cbeson, J.B. Boyce, F. Bridges, T.H. Geballe, J.M. Z.G. Ivanov, T. Claescn, E.A. Stepantsov, AYa. Remeika, and A.W. Sleight. Physica C162-164,544 Tzaknchuk, and R.I. Shekhier, IEEE Trans.Magn., to (1989). bcpuW. 86. Substitution on the Cu Sites in YiBajCus 77. Field effect devices based on metal-insulator Evidence for Distorted Chain Sites for Co-and Fe- YBaCuO films, Substituted Material Yu. Boikov, G. Brorsson, Z.G. Ivanov, and T. Claeson, F. Bridges, J.B. Boyce, T. Claeson, and J.M. Tarascon, IEEE Trans.Magn., lo be publ. PhyskaC162-164,969 (1989).

78. dc-SQUIDs with low noise and large Devalues on 87. Second Neighbor Shells Around Cu in Oxygen- Bicrystal (Y)ZrQz substrates Deficient and Transition-Metal-Doped HX. Olsson, R.H. Koch, PÅ. Nilsson, and E.A. Stephantsov. IEEE Trans. Magn., MAG-29,1993, lo J.B. Boyce, F. Bridges, T. Claeson, T.H. Geballe, be published. PhysicaB 158,453 (1989).

79. Present status and future of dr-SQUIDs nude from 88. X-ray absorption of BaBiOj and superconducting high-Tc supercondctors BaBio.25Pbo.75Q, H.K. Oisson, R.H. Koch, B.Oh, R. Robertazzi, R.B. J.B. Boyce, F.G. Bridges, T. Claeson, T.H. Geballe, Laibowitz, A. Gupta, and W.Y. Lee. Invited, ASM and J.M. Remeika, Phys. Rev. B 41,6303,1990. materials research conference, San Fransisco 24-28 Aug 1990, and "Science and Technology of Thin Film 89. Local structure about Ni atoms in Ni-substituted Superconductors 2", Eds. R.D. McDonnel and R. Noufi, Plenum, Press, New York, p. 563,1990. F. Bridges, J.B. Boyce, T. Claeson, T.H. Geballe, and J.M. Tarascon, Phys. Rev. B 42 2137.1990.

XAFS 90. XAFS Determines Mini-Clusters ofNi-0 in Ni 80. Temperature Dependence of the Local Structure of Doped YBa2Cu3O7.fi

Y1Ba2Cu3O7^ with Varying Oxygen Content: An J.B. Boyce, F. Bridges, T. Claeson, T.H. Geballe, and X-Ray Absorption Study J.M. Tarascon, Supercond. Sci. Techno!. 4,343 (1990). J.B.Boycc, F.Bridges.T.Claeson, and M.Nygren, Phys.Rev.B, 39,6555 (1989). 91. Local Structure of Ni in YBa^Cu wNi.aujbO?.* J.B. Boyce, F. Bridges, T. Claeson, T.H. Geballe, and 81. Distorted Chain Sites for Co-and Fe-Substituted J.M. Tarascon, Physica B 165&166,1697 (1990).

F.Bridges, J.B.Boyce, T.Clacson, T.H.Geballe, and 92. Local Structure and Distorsions in Pure and Doped J.M.Tarascon, Phys.Rev.B39,11603 (1989). YBa2CujO7.6: X-Ray Absorption Studies J.B. Boyce, F. Bridges, and T. Claeson, in Supercon- 82. Second Neighbor Shells Around Cu in Oxygen- ductivity and Applications (ed. by H.S. K wok et al), Deficient and Transition-Metal-Doped Plenum Press, N.Y. 1990, p 303.

Y,Ba2CujO7.8 J.B. Boyce, F. Bridges, T. Claeson, and T.H. GebaJle, 93. Local Structure of BaBi,Pbi.,O3 Determined by X- PhysicaB 158,453,1989. ray Absorption Spectroscopy T. Claeson, J.B. Boyce, F. Bridges, T.H. Geballe, G.G. 83. Local Structure and Vibrations of YBaCuO with Li, and A.W. Sleight, Phys.Rcv.B44,6961 (1991). Differing Oxygen Content and Impurities on the Copper Site J.B.Boyce, F.Bridges, T.Claeson, R.S.Howland, T.H.Geballe, M.Nygrcn, and J.M.Tarascon, Proc.EXAFS V.

MATERIALS SCIENCE, 1993 189 APPLIED SOLID STATE PHYSICS

Disordered Alloys 102. Two Fundamental Results from Low-Tempera- and Bult High T Superconductors ture Experiments with One-Dimensional Arrays c of Ultrasmall Tunnel Junctions. 94. Critical magnetic field of disordered Zr-Cu alloys; T. Clacson, P. Dclsing, L.S. Kuzmin, K.K. Likharcv, Density of states awl spin-orbit scattering time Proc. 3rd InL Symp. Foundations of Quantum A. Nordström, ö. Rapp and Z. Y. Liu, Phys. Rev. B. Mechanics. Tokyo. 1989, p.255. 41,6708,1990. 103. Single Electron Charging Effects in Arrays of 95. TheMicrostnictureofaBi-Ca-Sr-Cu-OHighTc Ultra-Small Tunnel Junctions Superconductor Produced by Rapid Solidification L.S. Kuzmin, P. Delsing. T. Clacson, and K.K. Ping Liu, M. Knutson, Liu Zhi Yi, E. Olsson and G.L. Likharcv. Proc. 1989 InL Superconductivity Electron- Dunlop, Supcrcond. Sci. Technol. 1(1989)254. ics Conf.. Tokyo, 1989, p. 549. 96. Study of the Effert of the Substitution of O by F.S, and Cl on the Superconductivity of YiBa^C 11307.7 104. Single Electron Tunneling in Ultrasmall Junctions Liu Zhi Yi. M. Persson, and S. Eriksson. Z. Physik B T. Claeson, P. Delsing, L. Kuzmin. and K.K. 74(1989)423. Likharev, Proc. 5th Petra School of Physics, Septem- ber 1989. 97. Superconducting and Electronic Properties of the 105. 1-D Array implementation of the Resistivdy Metallic Glass System LarsSi^M, (M=Cr, Mn, Coupled Single Electron Tunneling Transistor Fe,Co,Ni,Cu,B,ALGaJn) P. Dclsing, T. Claeson, K.K. Likharcv, and L.S. Liu Zhi Yi, J.Kanski, ZJtiys.B. 22,495-499 (1989). Kuzmin. IEEE Trans. Magn. 27,2581 (1)91). 98. Negative magnetoresistance in an YBa2Cu3O7.fi 106. Observation of Single Electron thin film Tunneling Oscillations W. Holm, M. Andersson, Ö. Rapp, Z.G. Ivanov, and U. Engström, to be published, Physica B. P. Delsing, K.K. Likharev, L.S. Kuzmin. and T. Claeson. Phys. Rev. B 42,7439,1990.

107. Single Electron Tunneling Oscillations Single Charge Tunneling in One-Dimensional Arrays 99. Single Electron Charging Effects in One-Dimen- of Ultrasmall Tunnel unctions sional Arrays of Uttrasmall Tunnel Junctions P. Dclsing, T. Clacson, K.K. Likharcv, and L.S. L. S. Kuzmin, P. Delsing, T. Claeson and K. K. Kuzmin. Physica B 165&166,929,1990. Likharev, Phys. Rev. Lett. 62,2539 (1989). 108. Time-Correlated Single Electron Tunneling 100. Effect of High-Frequency Electrodynamic Envi- P. Delsing, T. Clacson, K.K. Likharcv, and L.S. ronment on the Single Electron Tunneling in Kuzmin. Proceedings of the 8lh European Physical Utrasmall Junctions Society Conference (EPS-8), p. 667,1990. P. Delsing, K. K. Likharev, L. S. Kuzmin and T. Claeson, Phys. Rev. Lett. 63,1180 (1989). 109. Correlated Single Electron Tunneling in Ultrasmall Tunnel Junctions 101. Time-Correlated Single-Electron Tunneling in T. Clacson, P. Dclsing, D. Haviland, L. Kuzmin, and One-Dimensional Arrays of Ultrasmall Tunnel K.K. Likharev. To he published in Non-linear Junctions Superconductive Electronics and Josephson Devices, P. Delsing, K. K. Likharev, L. S. Kuzmin and T. Ed. by N.F. Pedcrson, M. Russo, A. Davidson, G. Claeson, Phys. Rev. Lett. 63,1861 (1989). Coslabilc, and S. Pagano, Plenum. London, 1990.

Field effect transistor based on metal-insulator- 110. Correlated Tunnel Events >n Arrays artifkial grain boundary Josephson junction, of Ultrasmall Junctions Z.G. Ivanov, T. Claeson, E.A. Slepantsov, A.Y. T. Clacson and P. Delsing, to be published in Pro- Tzalcnchuk, and R.I. Shckhicr, in 1992 Applied ceedings of NATO Science Forum '90: Highlights of Superconductivity Conference, edited by D. C. the Eighties and Future Prospects in Condensed Larbalcsticr Chicago, USA, submitted to IEEE Matter Physics, Plenum, New York, 1991. Transactions on Superconductivity August 24-28, 1992. 111. Experimental Study of Submicron Josephson Tunnel Junctions with High-Ohmic Bias resistors L.S. Kuzmin, D.B. Haviland, Yu.V. Nazarov, P. Dclsing, and T. Claeson, LT-1? Satellite Conf: Macroscopic Quantum Phenomena 1990, Brighton.

190 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

112. Cooper-Pair Tunneling in Ultrasmall Junctions 121. Experimental Evidence for the Coulomb Blockade Affected by Strong Quantum Fluctuations of Cooper Pair TunneKng and Bloch Osculations L.S. Kuzmin. YILV. Nazarov. D.B Haviland, P. in Single Josephson Junctions. D.Haviland. Delsing, and T. Claeson, Phys. Rev. Letters, in prim. L.S.Kuzmin, P.Deking. K.K.Likharev. and T.CIaeson. Z Phys. B 85,339 (1991) Observations of the Noch Oscillations in an UHrasnuB Josephson Junction 122. Experimental Investigation of Two-Dimrnsional L.S. Kuzmin and D.B. Haviland, Phys. Rev. Letters, Arrays of Ultrasmall Josephson junctions. Chen subm. Chiidong. P.Dclsing, D.B.Haviland, and T.Clacson. Hclv. Phys. Acta, 65.406 (1992) 114. Observations of the Bloch Oscillations Hi Ultrasmall Josephson Junctions 123. Single Charge Tunnrting-Time Correlation of L.S. Kuzmin and D.B. Haviland, Proc. Tunnel Events. T.CIaeson. P.Dclsing. D.Haviland, Nanostructures and Mesoscopic Systems, to be publ. L.S.Kuzmin, K.K.Likharev, and Yu.V.Nazarov. In: Supercon. Sci. Tnech, p.393 IOP (1991) 115. Observation of the Coulomb Blockade of Cooper Pair TuMeting in Single Josephson Junctions 124. Single Electron Turnsole and Pump Devices Using D.B. Haviland, L.S. Kuzmin, P. Delsing, and T. Long Arrays of SmaH Junctions. P.Dclsing and Clacson, Europhysks Letters, 16,103 (1991). T.Clacson. Physica Scripla Vol. T42,177 (1992).

116. One-Dimensional Arrays 125. Experimental Investigation of Two-Dimensional of Small Tunnel Junctions Arrays of Ultrasmall Josephson junctions. P. Delsing, in Single Charge Tunneling (ed. by H. C.D.Chen, P.Dclsing, D.B.Haviland, and T.CIaeson. Grabcrt and M. Devorei, Plenum Press, N.Y.), p. Physica Scripta Vol. T42,182 (1992). 249,1992. 126. From Josephson to Single Charge Tunneling. 117. New Results on SET-Oscillations in CD.Chcn, T.Clacson, P.Delsing, Y.Harada, One-Dimensional Arrays of Tunnel Junctions D.Haviland, L.S.Kuzmin, and Yu.Pashkin. Proc. Int. P. Delsing, D. Haviland, T. Claeson, K.K. Likharcv, Conf. on Macroscopic Quantum Phenomena p.55 and Korotkov, in Single Electron Tunneling and (1993). Mesoscopic Devices, cd. by H. Koch and H. Liibbig, p. 97 (Springer, Berlin 1992). 127. Single Charge Electronics Based on Ultrasmall Tunnel junctions - Comparison with Josephson 118. Single Electron Tunneling Oscillations in One- Electronics. T.CIaeson, P.Dclsing, D.Haviland, Dimensional Arrays of Ultrasmall Tunnel Junc- L.S.Kuzmin, and Yu.Pashkin. Esprit Conf. Brussels tions. P.Dclsing, T.CIacson JC.K.Likharcv, and 1992. L.S.Kuzmin. Proc. 19lh Int. Conf. Low Temp. Physics (LT-19), Physica B 165&166,929 (1990). 128. Thermal Activation and Injection of Charge Solitons In Two-dimensional Arryas of Small 119. Coulomb Blockade and Incoherent Tunneling of Josephson Junctions. P.Dclsing, C.D.Chen, Cooper-pairs in Ultrasmall Junctions Affected by D.B.Haviland, Y.Harada, and T.Clacson. Submitted Strong Quantum Fluctuations. L.S.Kuzmin, to: The 20ui ImXonf. on Low Temp. Physics, LT-20, Yu.V.Nazarov, D.Haviland, P.Dclsing, and (1993). T.Clacson. Phys. Rev. Lett. 67,1161 (1991) In: "Single Electron Tunneling and Mesoscopic De- 129. A New Temperature Sensor in Low-temperature vices" , ed. by H.Koch and H.Liibbig, p.97 (Springer, Composite Bolometers for Detection of Nuclear Berlin 1992) Particles. F Delsing, C.D.Chen, T.CIaeson, P.Davidsson, B Jonson, M.Lindroos, S.Norrman, 120. Comparison of the Transition to the Insulating G.Nyman, and S.Qutaishat. Submitted to: The 20th State in Two-Dimensional and One-Dimensional Int.Conf. on Low Temp. Physics, LT-20, (1993). Arrays of Ultrasmall Tunnel Junctions. P.Dclsing, Chen Chiidong, D.B.Haviland, and T.Clacson. In: 130. Vortex Mobility in Two-dimensional Arrays of Single Electron Tunneling and Mesoscopic Devices, Small Josephson Junctions. C.D.Chen, P.Dclsing, cd. by H.Koch and H.LUbbig, p.137 (Springer, Berlin D.B.Haviland, Y.Harada, and T.Clacson. Submitted 1992) to: The 20th IntConf. on Low Temp. Physics, LT-20, (1993).

MATERIALS SCIENCE, 1993 191 APPLIED SOLID STATE PHYSICS

131. MagnelkFhn and Gate Voltage Dependence of 140. IVoxiniity-coniDensaltdkinofonDS directly thr Current m a Superconducting Loop of UKra- written by etectron-beat lithography sauH TMMC! Junctions. Y.Harada, D.B.Haviland, M. Ekberg. M. Larsson and S. Hård.. SPIE Proceed- CD.Chen, RDdsing, and T.Claeson. Submitted lo: ings of Holographies Inicmationa] 92, Vol.1732. The ?0ih IntConf. on Low Temp. Physics, LT-20, 1992. (1993). 141. TOverkuagav högeffektiva fashongram, 132. 2e Periodic Modulation of tke I-Vcurveofa Knoformer Current Biased Superconducting Transistor. M. Ekberg, M.Larsson and S. Hard,". YiLPasNun, D.B.Haviland, L.S JCuzmin, C.D.Chen. Raduvetensteptig konferens, RVK 90,1990. PDelsing, and T.Claeson. Submitted to: The 20th IntCcnf. on Low Temp. Physics. LT-20, (1993). 142. High efficiency computer generated diffractive optical elements F. Nikolajcff, M. Ekberg, M. Larsson and S. Härd,, Mesoscopic Transport Phenomena, Radiovetenskaplig konferens. RVK 93,1993. Scanning Probe Microscopy 143. Fabrication of ultra high quality vertical struc- 133. Electron Transport ål Mesoscopic Conductors tures in Ga As with Superconducting Contacts Mats Hagberg,, SPIE Micro'92, Vol.1672,1992. V. Petrashov, V. Antonov and M. Persson, Phys. ScripiaT42(1992). 144. GaAs/AIGaAs corner reflector laser for mono- lithic integration 134. Electron phase memory effects in normal nwtal Mats Hagberg,, European Conference on Optical rings with superconducting mirrors Communications, September, 1992. V. Petrashov, V. Antonov, P. Dclsing, and T. Claeson, Phys.Rev.Lcti, 70,347 (1993). 145. Mkroengineered Material Surfaces for Studying Cellular Responses to Controlled Surface Rough- 135. Nonlinear Phase Memory Effects in Mesoscopic ness and Composition Rings With Superconducting "Mirrors". J.M. Gold,, BIOINTERACTIONS, 1993. VXPetrashov, V.N Antonov, RDelsing, and T.Claeson. Submitted to: The 20th IntXTonf. on Low Temp. Physics, LT-20, (1993). 146. Two Methods of Experimental Evaluation of Long-range Proximity Function Components in E- beam Lithography 136. Electric field effects and screening in mesoscopic AL.Bogdanov and A. Polyakov,, The 37th Sympo- Bismuth wires sium on Electron, Ion and Photon Beams, 1993. V.T. Petrashov and V.M. Anionov and B. Nilsson, J. Phys.: Condens. Matter, No.3,9705-9711,1991. 147. Quantum Interference Effects in Percolated Metal Networks 137. A Resistive HEMT-mixer with Very Low LO- M.E.Gcrshcnson, P.M. Echtcmach, H.M. Bo/lcr, Power Requirements and Low Intermodulatio A.L. Bogdanov, B.Nilsson,, International Conference Zirath H., Rorsman N.,, 21st EuMC, 1469 -1474, on Low Temperature Physics, 1993. 1991

138. Nd:YAG Laser Machining with Multilevel Resist Kinoforms Microelectronics and Other Studies Mats Ekberg, Michael Larsson, Aldo Bolie and Based on Nanometer Fabrication Sverker Hard,", SPIE Proceedings of current develop- 148. Site-specific adhesion of S. epidermidis in Ti-AI-V ment in optical design and optical engineering, metal systems Vol.1527,1991 Gabriel, B. L, Gold, J., Gristina, A. G., Kascmo, B., Lausmaa, J., Mroczck, C, Myrvik, Q. N., & Nilsson, 139. Proximity-compensated kinoforms directly B., in Surfaces in Biomaterials Symposium, written by electron-beam lithography Minneapolis, USA, 1992) 126-130. M. Ekberg, M. Larsson and S. Hård,, SPIE Proceed- ings of Workshop on Digital Holography, Vol. 1718, 149. Scanning Tunneling Microscopy of Laser Depos-

1992 ited TI2Ba2CaCu2Oji Thin Films Erts, D., Ivanov, Z. G., Johansson, L. G., Olin, H., & Clacson, T., to be submitted, 1993.

192 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

ISO. STM studies of Single Electro* Tunneling Effects 160. A Balanced Millimeter Wave Doubter Based on » ThB^CaCöiOg Th« Films at 300 K Pseudomorphic HEMT's Ens, D., Ivanov. Z. G., Johansson. L. G., Oiin. H., & Angclov I., Zirath H., Rorsman N.. Granqvist H.. Claeson, T., to be submitted. 1993. accepted for IEEE-MTT-S. 1992.

151. Mriti Phase Hotoeji i Manufactured by 161. Fabrication of uttrahigh quality vertical facets in Electron Beaai Lithography GaAs using pattern corrected electron beam Mais Ekberg. Michael Larsson and Sverker Härd, lithography Optics Letters. Vol.15. No. 10, 568-569. May, 1990. M. Hagberg, B. Jonsson, and A. Larsson, J. Vac. Sci. Technol. B, Vol.10, No.5,2243-2250, Sep/Oct, 1992. 152. Nd:YAG Laser Machining whh Multilevel Resist Kinofbnas 162. Single-ended output GaAs/AIGaAs single quan- Mais Ekberg. Michael Larsson, AMo Bolie and tum well laser with a dry-etched corner reflector Sverker Hard., Applied Optics, Vol. 30, No. 25. M. Hagberg, A. Larsson, and S. T. Eng.,, Appl. Phys, 3604-3606, September, 1991. Lett. Vol.56, No.20,1934-1936, May, 1990.

153. Multilevel gratia*, array 163. Investigation on the Spectral Characteristics of tared by el DFB-Lasers with Different Grating Configuration Mats Ekberg, Michael Larsson, Sverker Hård, Jari made by Electron Beam Lithography Timmen, Mohammad R. Taghizadeh, Jan T. Kjellberg, S Nilsson, T. Klinga, B. Broberg and R. WcsterhoJm, Antti Vasara. Optics Communications, Schatz,, Journal of Lightwave Technology, volume Vol.88, No.l,37-41,March, 1992. II, August, 1993.

154. Proximity-Compensated Blazed Transmission 164. Model Based on Trap-assisted Tunneling for Two- Grating Manufacture with Direct- Writing level Current Fluctuation in Submicrometer Electron-Beam Lithography Metal-Silkondioxide-Silicon Diode M. Ekberg, F. Nikotajeff, M. Larsson and S. Härd, M. O. Andersson and Z. Xiao and S. Norrman and O. Accepted for publication in Applied Optics, 1993. Engström,, Physical Review B, Vol.41, No.14,9836 - 9842, May, 1990. 155. Successive-Development Optimization of Resist Kinofbrms Manufactured with Direct Write 165. Phase relaxation in One-dimesional Metal Films Electron-Beam Lithography P.M. Echtcmach, M.E. Gcrshenson, H.M. Bozlcr, M. Ekberg, F. Nikolajcff, M. Larsson and S. Härd, A.L. Bogdanov, B.Nilsson, Nyquist, Phys Rev Accepted for publication in Applied Optics, 1993. Letters B, submitted.

156. A New Method for Determination of the Peak- 166. Quantum Interference Effects in One-dimensional velocity in Epitaxial Semiconductor Sructures by Gold Films DC-measurements on Mkrobridges P.M. Echtemach, M.E. Gcrshcnson, H.M. Bo/.lcr, Strupinski W., Zirath H., Grönquist H., Rorsman N., A.L. Bogdanov, B.Nilsson, Physics Review B, Appl. Phys Letters, Vol.59,3151-3153,1991. submitted.

157. A New Empirical Nonlinear Model for HEMT 167. Fine Undercut Control in Bilayer PMMA- and MESFET Devices P(MMA-MAA) resist system for E- beam Lithog- Angclov I., Zirath H., Rorsman N., submitted to raphy with Submicron Resolution MTT. Alcxci L. Bogdanov, Eva Karin Andersson, SPIE Electron-Beam, X-Ray, and Ion-Beam 158. A Millimeterwave SubharmonUally Pumped Submicrometer Lithographies for Manufacturing, Resistive Mixer Based on Heterostructure Field Vol.1465,1991, p 324-329. Effect Transistor Technology Zirath H., Angclov I., Rorsman N., IEEE-MTT-S, 168. Selective Chemically Assisted Ion Beam F.tchinr, of 1992. Si, Polysilicon and SiO2 Using Ni-Cr Mask and CI2 159. A New Empirical Nonlinear Model Z. Xiao and B. Nilsson and P. Svedberg, Journal of for HEMT-devices Electrochemical Society, Vol.137, No.5,1579-1581, Angclov I., Zirath H., Rorsman N., accepted for May, 1990 IEEE-MTT-S, 1992.

MATERIALS SCIENCE, 1993 193 APPLIED SOLID STATE PHYSICS

149. Good Selectivity Betweea a Ni-Cr mask and and 177. Tim rlfcas of YBazCujOr Deposited by Co- GaAs and AIGaAs by Chemical Assisted Urn Evaporatioa, Josephson Junction, and DC- Beam Etching with CB Gas SQL'IDs Z. Xiao and B. Nilsson, G ", Journal of Per-Åke Nilsson, Lic. Thesis, Dcpt Physics. Electrochemical Society, Vol.138.No.lO. 3092-3095, Chalmers Univ. Tcchn.. Gothenburg, 1991. October, 1991. 178. Scanning Probe Microscopy, Design and Applications Reviews H. Olin. (1993) Ph. D. Thesis, Chalmers Umv. of 170. H^ Temperature Superconductor Assessment Tech. Study for Spaceborn Sensor Applications G. Brorsson, T. Clacson, M. Danenid, J. Edstam, Z. 179. Theoretical and Experimental Studies Ivanov. PÅ Nilsson U. Helmcrsson, S. Rudncr, S. of the Flux-Flow Type Josephson Oscwator Dahl-Poerscn, T. Freltofl, J. Hyktoft, P. Vase. MX Yongming Zhang, lie. Thesis, Dcpt. Physics, Chalmers Univ. Tcchn., Gothenburg. 1991. Lcvinscn, J.B. Hansen, C.S. Jacobscn. and N.F. Pcdcrsen, ESTEC 8007/88/NL/PB(SC). 180. Lumped Arrays of Josephson Junction OsctBators 171. Superconducting Detectors Tor mm and Jonas Edaam, Lie. Thesis, Dcpt. Physics, Chalmers Sub-mm Waves Univ. Tcchn., Gothenburg, 1992. D. Winklcr, Z. Ivanov, and T. Clacson, in Supercon- ducting Technology: Ten Case Studies (cd. by K. 181. Symmetric Scanning Tunneling Microscopes for Fossheim) World Scientific, Singapore, p. 51 -86 Ultra High Vacuum and Very Low Temperatures (1591). Per Davidsson, Lie. Thesis, Dcpt. Physics, Chalmers Univ. Tcchn., Gothenburg, 1992. 172. Single Electronics K K Likharcv and T Clacson, Scientific American, June 1992, p 80-85. Scanning Probe Microscopy 182. Design of a Scanning Probe Microscope 173. A Pilot Study for High Temperature Supercon- Olin, H., Mcas. Sci. Tech., 1992, submitted. ducting Gravity Gradiometers C.S. Jacobscn, A. Kuhle, J. Mygind, N.F. Pcderscn, 183. Scanning Tunneling Microscopy of Laser Depos- J.B. Hanscn, T. Frcltoft, Y. Shen, P. Vase, T. ited YBCO Thin Films Clacson, Z. Ivanov, P.Å. Nilsson, J. Flokstra, H. Olin, H., Brorsson, G., Davidsson, P., Ivanov, Z. G., Hilgenkamp, and E. Annandillo, ESA/ESTEC Nilsson, P. Å., & Clacson, T., Ultramicroscopy, 42- Workshop on Space Applications or High Tempera- 44,1992,734-737. ture Superconductors, ESTEC, Höland, April 27-28, 1993 184. Design and Operation of a Low Temperature Scanning Tunneling Microscope Suitable for Operation below IK Theses Davidsson, P., Olin, H., Persson, M., & Pchrson, S., 174. Single Electron Tunneling in Ultrasmall Tunnel Uliramicroscopy, 42-44,1992,1470-1475. Junctions Per Dclsing, Ph. D. Thesis, Dcpt. Physics, Chalmers 185. Movement of Scattering Centers in a Point Univ. Tcchn., Gothenburg, 1990. Contact Induced by a Scanning Tunneling Microscope Kubatkin, S. E., & Olin, H., to be publ. 175. Thin Films and Optical Detectors made of

Martin Danerud, Lie. Thesis, Dcpt. Physics, 186. Scanning Tunneling Microscopy of Oxidized Chalmers Univ. Tcchn., Gothenburg, 1991. Titanium Surfaces in Air Olin, H., Aronsson, B. O., Kascmo, B., Lausmaa, J., & Rodahl, INI, Ultramicroscopy, 4244,1992,567- 176. Laser Deposited Thin Films of the High Tempera- 571. ture Superconductors YBaCuO and BiSrCaCuO Göran Brorsson, Lic. Thesis, Dcpt. Physics, Chalmers Univ. Techn., Gothenburg, 1991. 187. Microfabricated nanopipettes Olin, H., Stenberg, M., Stcmmc, G., & Olsson, E, Mcas. Sci. Tech., 1992, submitted.

194 THE CENTRE FOR APPLIED SOLID STATE PHYSICS

IM. Sto*pecaVadlMsiNorS.CFtilcrButis»Ti-AI-V awtal systems Gabriel, B. L., GoU, J., Gristina, A. G., Kascmo, B.. Lausmaa. J.. Hancr. C. & Myrvik. Q. N.. submitted, 1992.

189. Movenwat of Scattering Centers in a Po«t Cotact Indnccd by a Scaaaiag TaaataTag Micro- scopc Kubadun, S. E., Ota», R, Davidsson. P., Danilov. A. V., &. Cfaeson, T., Physka B. submitted. 1993.

type DsapcrcoadactorsasiBg the very low teMseratarc fancKag Mcroscope Davidsson, P., & din, H., Physka B, submitted, 1993.

191. Atomic farce microscopy and tnwsmissioB electron Microscopy of early stages of growth of YBa^wjO^ thin fans on (001) Y-ZrO* Substrates Alan», J. A.. Brorsson, G., Olin, H.. Olsson, E., &. Clacson, T, SCANDEM 93,1993.

192. Early stages of growth of YBazCu3O74hign.Tc thin finns on (001) Y-ZKh Alarco, J. A., Brorsson, G., Olin, H., Olsson, E., & Claeson, T., to be submit- ted, 1993.

MATERIALS SCIENCE, 1993 195 Condensed Matter Theory

Research Summary Address The research of the group involves three major Department of Theoretical Physics and Mechanics directions with many interconnections: (i) Super- Chalmers University of Technology conductors and high-temperature superconductiv- S-412 % Göteborg, Sweden ity, (ii) atoms, molecules and solids in strong radia- Phone+46 317721000 tion fields, and (iii) electronic structure and excita- Fax 446 31772 3204 tion spectra of clusters and solids. Over the last two years focus has been on problems involving super- conductors or clusters, or both. During this period Staff two major projects have been started: One project is Senior Members: to calculate the electron dynamics of small clusters Göran Wendin docent and molecules for interpretation of photoabsoiption Bo Wästberg tekn.dr. and photoelectron emission spectra. This gives in- Sergey Rashkeev Ph.D. formation about single-electron and collective be- haviour and about geometric and vibrational struc- Graduate Students: ture. Another project is to address some central Magnus Hurd civ.ing. issues in the field of high-temperature superconduc- Jarek Luberek civ.ing. tivity, HTSC. One such issue involves calculation of optical properties and Raman spectra to test theoreti- Secretary: cal models for the normal and superconducting Jane Johansson properties of HTSC. Another issue concerns various manifestations of the Josephson effect in weak links and grain boundary junctions in thin films of high- temperature superconductors. Major Instrumentation » Sun work stations The work on superconductivity is partly done • Macintosh personal computers within the framework of the Consortium on Super- conducting Materials, and in collaborations with scientists from Russia and Ukraine, while the cluster work is done in collaboration with American and Major Reids of Research Croatian scientists. A: Superconductors and High-Temperature At the moment we are involved in some rather hot Superconductivity topics. One topic involves the dynamics of the participants: Göran Wendin, Magnus Hurd, Josephson current in a weak link tunnel junction Sergey Rashkeev, Alex Bratkovsky, irradiated by intense electromagnetic radiation. This collaborators: Zeljko Crljen, Robert Shekhter, kind of work might one day lead to the develpment Vitaly Shumeiko of a superconducting transistor with an optical gate. Another hot topic involves many-electron dynamics B: Atoms, Molecules and Solids in Strong Radia- in Qo and Ba-Qn: Our recent results show both tion Fields collective effects and multiple-scattering interfer- participants: Göran Wendin ence effects in Ba-Qn, La-Qo and related systems, collaborators: Peter Johansson, Lars Jönsson, and the method has a great potential for further Vitaly Shumeiko development and as a testing ground for many- electron theory.

196 THE CENTRE FOR CONDENSED MATTER THEORY

C: Electronic Structure and Excitation Spectra of A2: Transport Properties Superconductors In Ousters and Solids External Fields participants: Göran Wendin, Jarek Luberek, The first project started as a Swedish-Soviet collabo- Bo Wästberg, Alex Bratkovsky ration [5] and soon developed into a variety of collaborators: Zeljko Crljen, Zachary H. projects, involving tunneling [10,11], and effects of Levine irradiation with light [10,12,13,18,23,25]. Of par- ticular interest is our present work on the time- dependence of the Josephson current in a weak link tunnel junction irradiated by intense electromag- Research Projects netic radiation [25]. We intend to develop this work A: Superconductors and High- into an important collaboration with experimentalists Temperature Superconductivity and to investigate various possibilities to influence superconducting electronics with electromagnetic Al: Optical Properties of High-Temperature radiation. This may find applications in sensors and Superconductors optoelectronic components. This project began with an analysis of spectroscopic resultsforHTSC[l]and continued with calculations of photoabsorption spectra and optical conductivity B: Atoms, Molecules and Solids in for YBaiCuiOj within a model which describes Strong Radiation Fields well the electron dynamics of the atomic cores, but Fora long time we have been heavily involved in the not of the vaience electrons [2,3,14]. This is one field of interaction of atoms and quantum-well struc- reason why the cluster work was started, to describe tures with intense laser radiation. This work recently molecular effects in photoionization arising within resulted in two dissertations and a number of re- e.g. the CuO and BaO units [9,24,26]. At present we search papers [6-8,15], and is now influencing our are focussing on the low-frequency (0-1 eV) spec- present work in many ways, in applications to super- trum of HTSC, studying optical conductivity and conductors [13,18] and superconducting mesoscopic electronic Raman scattering within the framework structures like weak links and junctions [25]. of Eliashberg theory and beyond, including effects of stro-g inelastic scattering bandstructurc [19]. We are also working in general analysis and survey of the field [20].

6000 BaC (N=232+5t>) 5000 n

4000

3000 Figure 1 The calculated photo- 2000 absorption cross section for a jellium shell with N=232 1000 (Ceo) (dashed line) and for a Ba atom (Z=56) embedded in a jellium shell with N=232 (BaCeo) (solid line) using the TDLDA method. At -1000 -tttft t tt t ttt the bottom of the figure, the 3s2f2d2pll2s Ik 5pij li Ih5slglfldlpls thresholds for photo- -2000 emission from the variuos occupied shells of a Ba and 10 15 20 25 30 35 40 C6o have been marked with photon energy (eV) arrows.

MATERIALS SCIENCE, 1993 197 CONDENSED MATTER THEORY

C: Electronic Structure and Excitation DipkMnaWortt Spectra of Clusters and Solids Thomas Mattsson, "Resonant inverse photoemission via plasmons", July 1990 This project includes a variety of problems within Computational Physics, (i) One-center cluster mod- Reports and articles els, calculating the electronic dynamics within the 1. "Spectroscopic views of high-Tc superconductors"., G. time-dependent local-density approximation Wendin, in "Physics of Low-Dimensional Systems",

(TDLDA) for CuOx, BaOx [9,24], (ii) electronic Ed. S. Lundqvist Physica Scripta 122,1989,31 excitations in heavy many-electron atoms embed- ded in electron gas, describing metals and impurites 2. "Calculation of photoionization cross sections of high- Tc superconductors", G. Wendin and Z. Crljen, in metals [21], (iii) spherical cluster models, in Phvsica C 162-164.1989,1327 particular for Qo and Ba, La-Qo within TDLDA [22], and (iv) electronic structure and excitations in 3. "Optical conductivity and photoemission spectra for magnetic alloys and disordered systems (supercell models of high-Tc superconductors", G. Wendin and Z. cluster calculations) [17]. Crljen, in Electronic Properties of High-Tc Supercon- ductors and Related Compounds, edited by H. Kuzmany, M. Mchring and J. Fink, Springer Scries in Solid State Sciences, vol 99 (Springer Verlag, Berlin, Publications 1990), 147-151 Ph.D. Dissertations 4. "Theoretical investigation of low-energy electron- Lais Jönsson, "Diagrammatic many-body theory for atoms impact excitation and ionzation of rare-earth and in high-intensity laser fields", September 18 1990 actinidc solids". H.R. Moscr, and G. Wendin, Phys. Rev. B 44,1991,6044 Peter Johansson, "Theory of inelastic tunneling - applica- tions to double barrier structures and scanning 5. "Transport of local pairs in the electric Field and tunneling microscopes", June 61991 frequency dependence of the oxide conductivity.", R.I. Shekhter, G. Wendin and O. Kulik, Phys. Rev. B 44, Licentiate Dissertations 1991,10215 Ola Nyqvist, "Screening effects in layered compounds: Applications to semiconductor interfaces and high-Tc", 6. "Diagrammatic many-body theory for atoms in high- June 101991 intensity laser fields. Part I"., L. Jönsson and G. Wendin, J. Opt. Soc. Am. B 2,1992,627

40 i 1 7\~T 1 1 i i 35 _ a) // \ BaC60 i VA \ 53 + C60 Figure 2 30 c Photoabsorption cross C 60 section cross sections of I 1i v/ \\ 25 - \V •4d-f(BaCJ- Ba and BaC6o showing the 4d 4d-f giant dipole resonance. 20 - The cross sections were ! calculated using the TDLDA 15 - - method for a Ba atom and for Ba in a jellium shell 10 - K (ISN288). The BaC6o cross * j section is compared to the 5 - cross section of the N=232 jellium shell model for C6o. n i i i i— -t 4 "-t the Ba atom + the N=232 80 90 100 110 120 130 140 150 16 jellium shell cross section and thge 4d-f cross section

photon energy (eV) of BaC6o-

198 THE CENTRE FOR CONDENSED MATTER THEORY

7. "Diagrammatic many-body theory for atoms in high- 17. "Supercell spin-polarized and full-potential LMTO intensity laser fields. Part II". L. Jönsson, J. Opt. Soc. calculations of the electronic structure of the glassy Am. B 2,1992,646 metal Ni2B", A.M. Bratkovsky, SJM. Rashkeev, A.V. Smirnov and G. Wendin, 8th Int. conf. on Liquid and 8. 'Tunneling through a double-barrier structure irradi- Amorphous Metals, Vienna, 1992. Full paper submit- ated by infrared radiation", P. Johansson and G. ted to Phys. Rev. B. Wendin, Phys. Rev. B 46., 1992,1451 18. "Effects of ne^ative-U correlation on superconducting 9. "Calculation of electronic excitation and ionization and optical properties of two-band superconductors"., processes in high-Tc superconductors "., Z. Crljen, G. V. Shumeiko, L. Jönsson, R. Shekhter and G.Wendin, Wendin and Z.H. Levine, in Electronic Properties of submitted to Phys. Rev. B. High-Tc, Superconductors and Related Compounds, edited by H. Kuzmany, M. Mehring and J. Fink, 19. "Electronic Raman continuum for YBa^ujOz^: Springer Series in Solid State Sciences, (Springer Effects of inelastic scattering and interband transi- Verlag, Berlin, 1992), in press tions"., S.N. Rashkeev and G. Wendin, submitted to Phys. Rev. Lett 10. "Investigation of tunneling, linear and non-linear optical properties of negativc-U local pair models for 20. "Different views of optical conductivity of high-Tc high-Tc superconductors"., Z. Crljen, M. Hurd, L. superconductors". G. Wendin, invited paper, to be Jönsson, R.I. Shekhter, V. Shumeiko and G. Wendin, submitted to Mod Phys. Leu B in Electronic Properties of High-Tc Superconductors and Related Compounds, edited by H. Kuzmany, M. 21. "Calculation of photoionization cross sections of Ba, Mehring and J. Fink, Springer Series in Solid State, La and Th atoms embedded in electron gas: Effects of Sciences, (Springer Verlag, Berlin, 1992), in press. hybridization on giant dipolc rcsonances".G. Wendin och J. Luberek, to be submitted to Phys. Rev. Leu. 11. "Single-electron tunneling into randomly distributed double-electron slates: linear voltage and temperature 22. "Many-electron effects in models of Qo and BaXa- dependences of the conductance"., M. Hurd, R.I. C(5o: Collective response and molecular effects in Shekhter and G. Wendin: Phys. Rev. B 46., 1992,8527. optical conductivity and photoionization.", G. Wendin and B. Wästberg, to be submitted to Phys. Rev. Leu. 12. "Optical spectroscopy of localized states in metallic oxides"., R.I. Shekhter, Z. Crljen and G. Wendin, 23. "Anisotropy of infrared optical absorption in layered PhysicaScr.Ti2,1992,76. superconductors'W. Shumeiko and G. Wendin, to be submitted to Phys. Rev. B 13. "Infrared threshold absorption in strongly correlated two-band super-conductors"., V. Shumeiko, L. 24. "Collective response and molecular effects in Jönsson, R. Shekhtcrand G. Wendin, Physica Scr. photoionization of a BaQ2 cluster. A one-center T42,1992,83. TDLDA calculation"., Z. Crljen, J. Luberek, G. Wendin and Z. H. Levine, to be submitted to Phys.Rcv. 14. "Calculation of optical conductivity and electron energy loss spectra for YBa2Cu3O7 in the 10-160 eV 25. "Optical nutation of Josephson current in a tunnel range"., G. Wendin and Z. Crljen, Z. Phys. B, in press contact"., V. Shumeiko, G. Wendin and E. Bratus', to be submitted to Phys. Rev. Lett. 15. "Exact diagrammatic solution of a three-level system in a high-intensity laser field"., L. Jönsson, J. Phys. B 26. "Calculation of electronic excitation spectra of copper 21,1992,5085 oxide clusters". Yu-juin Wang, G. Wendin, M.D. Newton and J.W. Davenport, to be submitted to Phys. 16. "Oxygen diffusion and dynamical disorder in high-Tc, Rev. B. superconductors: low frequency noise in superconduct- ing tunnel junctions"., R.I. Shekhter, A.M. Zagoskin and G. Wendin, Z. Phys. B, in press

MATERIALS SCIENCE, 1993 199 Ceramics

Swedish Ceramic Institute, SCI 202 See also under Microscopy and Microanafysis

MATERIALS SCIENCE, 1993 201 Swedish Ceramic Institute, SCI

Research Summary separate projects are funded from industry and gov- The Swedish Ceramic Institute (SCI) is a co-operative ernment sources in different proportions but 50 % research institute within the group of Industrial from industry and 50 % public funding are common. Research Institutes of Sweden (IRIS). SCI provides The remaining more development-oriented work support to manufacturers of ceramics by carryingout at SCI is composed of different services to the applied research within the area of ceramic process- industry, from small analysing tasks to other typi- ing techniques such as powder preparation, shape cally short- term projects, altogether about 20 % of forming and sintering. It also provides support to the entire R & D. These activities are funded by the users of ceramics by evaluation of properties of industry. materials, selection of materials, manufacturing of Processing is the key issue in producing ceramic prototypes and failure analysis. The number of in- componentsatreasonable prices. SCI has four groups dustrial members in SCI is around 25. working on Powder pressing & Injection moulding, About 50 % of the R & D at SCI is long-term Slip casting, Sintering and Evaluation of properties research performed within the framework program respectively. All the main materials systems within for engineering ceramics and traditional ceramics. the structural ceramics area are represented within The program consists of a number of individual SCI such as alumina, silicon carbide, silicon nitride, projects that often are linked together, they have a zirconia, mullite, composites with these matrices duration time of 3 years and are jointly planned and and fibers such as silicon carbide, carbon, alumina steered by SCI and the program committees, one for and silicon carbide whiskers. each area, representing the member companies of SCI has an extensive co-operation with many SCI. Connected to each individual project within the materials-oriented groups and departments at program isaproject committee which meets twice or Chalmers University of Technology such as the three times every year. In addition to the steering Electron Microscopy group - Physics, Engineering function these committees also have a very impor- Metals, Polymeric Materials, Chemical Technology, tant role to transfer technology from SCI to the Polymer Technology, Inorganic Chemistry, Physi- industry. Most of the projects within the framework cal Chemistry, Building Materials. program have a general aim and are of interest to a majority of the members and, hence, the results are Address available to all member companies of SCI. How- Swedish Ceramic Institute, SCI ever, in certain areas there are only a few companies Box 5403 interested in a specific project and then this project is S-402 29 Göteborg, Sweden financed and is open only for some of the member Phone+ 46 31772 0500 companies. The framework programs are funded 60 Fax + 4631 1853 80 % from industry and 40 % from the Swedish Na- tional Board for Industrial and Technical Develop- ment (Nutek). Staff As a complement to the framework program SCI R. Carlsson professor, VD also carries out separate projects for individual com- E. Carlström tekn.dr. panies or a consortium of companies. The total S. Karlsson civ.ing. extent of such separate projects is about 30 % of the E. Liden civ.ing. entire R & D at SCI. Most of these projects are also R. Pompe docent of a long-term nature and are steered in the same way K. Rundgren ni.dr. as the projects within the framework program. The

202 THE CENTRE FOR SWEDISH CERAMIC INSTITUTE, SCI

Graduate Students: Instrumentation for machining: J. Brandt civ.ing. • Profila, Surface grinder L. Kahlman civ.ing. • Different cutting machines and sample prepa- A. Kristoffersson civ.ing. ration equipment K. Lindqvist civ.ing. 0. Lyckfeldt civ.ing. Instrumentation for manufacturing B. Nyberg civ.ing. of ceramics: • Centorr, Graphite furnace, 2100°C Technical Staff: • Pfeiffer, Graphite furnace, 2200°C C. Bemm ing. • Ruhstrat, Graphite furnace, 2500°C L. Eklund ing. • Different fast furnaces for maximum 1700°C E. Freiholtz lab.assistant • Different furnaces for maximum 1500-1700°C H. Leandersson ing. • Loomis, Cold isostatic press R. Salomonsson lab.assistant • Brabender, Z-blade mixer M. Sjöstedt ing. • Peltsman, Low pressure injection moulding machine Secretaries: • Troester, Roller mill/Calander U-B. Jigholm • Tape casting machine for continuous casting of M. Jansson thin layers in organic media or water • Netzsch, Pressure slip casting machine • Biichi, Mini spray dryer Major Instrumentation • Biichi, Thermal evaporator Instrumentation tor analysis • Leybold, Freeze dryer of chemical composition etc: • Cole-Parmer, Ultrasonic homogeniser • Jeol, JSM-5300 Scanning Electron Microscope • Feutron, Climate chamber (with Tracer X-ray analyser) • Different mills, sieves and presses • Jeol, JXA-8600 Electron microprobe X-ray analyser Instrumentation for process analysis: • Kontron, IBAS Image analysing system • Contraves, Viscometer • Leco, Carbon analyser • Rheometer for constant stress analysis • Masstorr, Mass spectrometer • Repab, Zeta potential meter • Philips, X-Ray diffractometer • Micromeritics, Particel size analyser • Micromeritics, Specific surface area analyser Instrumentation for mechanical testing: • Micromeritics, Mercury porosimeter • Cerama, Hydraulic tensile testing machine • SG, Equipment for analysis of the dewaxing • Åbo Akademi, Fibre tensile testing machine of polymers • Zwick, Universal mechanical testing machine • Mettler, Thermobalance and Differential • Controls, Compressive testing machine Thermal Analyser, 1600°C • SCI, Stepped temperature stress rupture testing • Harrop, Thermobalance, 1600°C machine • Harrop, Differential Thermal Analyser, • Briiel & Kjaer, Modulus of elasticity tester 1600°C • Zwick, Microhardness tester • Harrop, Dilatometer, 1600°C • Zwick, Gypsum hardness tester • Zwick, Impact testing machine • Tonindustrie, Impact testing machine for porcelain plates • SCI, Friction and wear testing machine • SCI, Glaze wear testing machine

MATERIALS SCIENCE, 1993 203 SWEDISH CERAMIC INSTITUTE, SCI

Major Reids of Research Research Projects A: Processing of Engineering Ceramics A: Processing of Engineering Ceramics participants: J. Brandt, E. Carlström, S. A1: Freeze Granulation of Ceramic Powders Karlsson, A. Kristoffersson, E. Liden, K. A2: Forming of Metal and Cemented Carbide Lindqvist, O. Lyckfeldt, B. Nyberg, R. Powders Pcmpe, K. Rundgren A3: The Development of a Low Cost Route for collaborators: Powder Technology Center Making Tough Ceramics Göteborg, Engineering Metals, Polymeric A4: Fabrication of Si3N4 and Si2N2O-ZrO2 Materials, Physics and other departments at Composites by NPS Technique and Fabri- Chalmers University of Technology, the cation of Liquid Phase Sintered SiC Ceram- Center for Ceramic Research, Rutgers Uni- ics versity, NJ A5: Development of Slips for Pressure Slip Casting and Filament Winding B: Wear Resistant Materials participants: E. Carlström, L. Kahlman, S. B: Wear Resistant Materials Karlsson, E. Liden, R. Pompe, K. Rundgren B1: Wear Resistant Materials collaborators: Physics Dept. - Chalmers C: Thermal Insulation Materials C: Thermal Insulation Materials Cl: Thermal Insulation Materials participants: E. Liden, O. Lyckfeldt collaborators: Physics Dept. - Chalmers D: Ceramic Membranes Dl: Ceramic Membranes D: Ceramic Membranes participants: E. Liden, O. Lyckfeldt E: Processing of Traditional Ceramics collaborators: Physics Dept. - Chalmers E1: High Strength Traditional Porcelain E2: Refractories for Melt and Warm-Holding E: Processing of Traditional Ceramics Furnaces for Aluminium and Aluminium participants: S. Karlsson, A. Kristoffersson, Alloys R. Pompe, K. Rundgren F: Inorganic Binders F: Inorganic Binders Fl: Inorganic Binders participants: S. Karlsson 6: Technology Transfer and Standardisation G: Technology Transfer and Standardisation G1: Technology Information on Engineering participants: E. Carlström, L. Kahlman, R. Ceramics Pompe G2: Powder Technology 90 Acivities (PT90) collaborators: Powder Technology Center G3: Pre-standard/Standardisation Activities Göteborg - Chalmers

N.B. In all research fields above obviously the Al Freeze Granulation of Ceramic Powders member companies cf SCI and other companies that In order to press ceramic bodies for sintering the are partners in co-operation are important collabora- powder has to be granulated. The standard methods tors but they are not specified separately. for granulation of ceramic powders consist of spray drying and mechanical granulation. A method for freeze granulation of powders has been developed at the Swedish Ceramic Institute. A powder slurry is sprayed into liquid nitrogen. The frozen droplets are removed from the liquid nitrogen and freeze dried. The advantages with the freeze granulation are that no migration takes place during freezing or drying

204 THE CENTRE FOR SWEDISH CERAMIC INSTITUTE, SCI

(sublimation). This eliminates problems with binder material. The Swedish Ceramic Institute has devel- migration and inhomogenei ties caused by migration oped a computer controlled method for removalo f of sintering additives that takes place when standard organic temporary binder. The component is placed granulation techniques, such as spray drying, are on a balance in a furnace and the weightloss rate used. Another advantage is that the density of the during heating is computed. The weightloss rate is granules can be controlled. Low density granules used as a measurement to control the heating and in break down easily during pressing. Large pores this way control the binder removal. The method is caused by remnants of granules, not readily crushed, being used to minimize the removal time while can be eliminated in the green body. During spray- maintaining a high quality of the produced compo- drying the granule density iscontrolled by the stabil- nents. Injection molding of metals such as stainless ity of the slip. The density can only be reduced by steel is also investigated within the project. destabilizing the sup which has a number of disad- Alternative methods to injection molding, such vantages. In spray-freezing the granule density can as gel casting, pressure casting and freeze forming, be directly controlled by controlling the powder are based on liquid forming media instead of poly- content of the slip. mers and waxes. The liquid based methods have The compaction behaviour of freeze dried gran- lower mold costs, little need for binder removal and ules will be studied and compared with spray-dried some of them use less expensive equipment than granules from a collaborative pressing project at the injection molding. These methods are still at the Center for Ceramic Research at Rutgers University. developing stage. Within this project such methods The granule density - pressure relations necessary are tried out on metal and cemented carbide pow- for a complete break down of the granules will be ders. studied. The influence of the granulation method on the density gradients in the pressed green body will A3 The Development of a New Low Cost Route also be characterized. The homogeneity of the pressed for Making Tough Ceramics green bodies will be studied using image analysis in Ceramic components with a fracture toughness and order to quantify and describe the amount and scale a reliability suitable for aircraft applications have so ofinhomogeneities. far only been manufactured from long fiber compos- ites. An alternative method based on a laminate A2 Forming of Metal and Cemented structure, analogous with a marine shell, has been Carbide Powders invented by B. Clegg at the University of Cam- Forming ceramic powders to complex shapes by bridge. Expensive ceramic fibers and slow and ex- injection molding and slip casting are well estab- pensive infiltration methods (chemical vapour infil- lished techniques. Some more; recent methods that tration) can be avoided using this method. The have been developed for the forming of ceramic method is being developed into a production method powders are gel casting, pressure casting and freeze within a BRITE/EURAM project. Tapes are devel- forming ("Quick Set"). More recently these methods oped and manufactured (Tioxide) and methods for have been applied tocemented carbides and metallic laminating arid forming the tapes to components are materials. The injection molding of cemented car- developed (Ceramique et Composites). These com- bides is developed in this project together with ponents will be tested as cornbustor linings for Polymeric Materials and Engineering Metals at aerospace applications (Deutsche Aerospace, MTU Chalmers University of Technology. AB Sandvik and Volvo Flygmotor). The strengthening mecha- Formsprutning isbuilding a pilot plant facility for the nisms, the microstructure and the mechanics of the forming of cemented carbide components by injec- interface layers will be studied (Cambridge Univer- tion molding and is another partner in this collabora- sity). tive project. In powderinjection molding the powder The current material is based on silicon carbide is mixed with a polymer/wax binder and is then laminated with carbon layers. A crack that develops molded at high pressure in an injection molding in the brittle silicon carbide will be dispersed and machine. The polymeric binder then has to be re- stop at the weak carbon layer. In order to make the moved prior to sintering. This is a time consuming material even tougher and more resistant to oxida- step where defects can easily be introduced into the tion, new interface layers will be developed. These

MATERIALS SCIENCE, 1993 205 SWEDISH CERAMIC INSTITUTE. SCI interface layers require tougher and stronger silicon A5 Development of Slips for Pressure Slip carbide layers. The layers will be developed at the Casting and Filament Winding Swedish Ceramic Institute using a liquid phase The most interesting forming techniques for ceram- sintered silicon carbide with high toughness. SCI ics are based on colloidal processing techniques, will also improve the laminate by forming thinner where the powders are dispersed in a liquid (usually tapes using both tape casting and calendering. The water). To develop the colloidal processing tech- casting and calendering methods will be improved niques, as for example pressure slip casting, it is using colloid chemistry tocontrol the rheology of the important to have a knowledge of the rheological ceramic systems. properties ofthe slip used. The rheology is critical for the results obtained at the forming stage and deter- A4 Fabrication of SI3N4 and SI2N2OZ1Q2 mines the final propertiesof the ceramic component. Composites by NPS Technique SCI has carried out a project concerning pressure slip and Fabrication of UquM Phase casting of S13N4 gas turbine rotors. Spin test discs Sintered S»C Ceramics have been produced using a pressure slip casting This is a cooperative project on structural ceramics machine (Netzsch). In this project knowledge has between The Centerfor Ceramic Research at Rutgers been built up in the area of pressure slip casting of University, NJ, US A and Swedish Ceramic Institute. high performance ceramics and the results obtained The aim of the project is to improve the mechanical in the project have shown that this processing tech- properties, especiallythe fracture toughness, ofSi3N4, nique has a great potential in the production of larger Si2N2O and SiC based ceramics. The materials are ceramic components with complex geometries. In processed using colloidal methods, densified by the case of pressure slip casting it might be desirable pressureless sintering and the resulting mechanical to use slips which are partially flocculated toenhance and microstructural properties are evaluated and the casting rate. In this case it is important to be able correlated to the process used. In the sub-project to study and control the floe structures/sizes in the concerning S13N4 and Si2N2O the objective is to slip and relate this to the particle packing/green explore the potential of the NPS (Nitriding Pressure- microstructure as well as the casting properties. less Sintering) technique forpreparation of dispersoid Production of long fibre composites by filament composites. The NPS technique features high green winding is another example of a forming technique density (low linear shrinkage), fine (down to nano- where the rheological behaviour of the ceramic slip size) particle size and fine/narrow pore size S13N4 is very critical for the results obtained. In this project matrix which is important for optimal densification the slips for both pressure slip casting and filament of a composite system. Two types of systems are winding are developed. being investigated: (a) a system with morphologically different Bl Wear Resistant Materials econd phase constituents such as SiC whisk- Ceramic materials can replace metals in applications ers and platelets, where it is of interest to have reduced weight, low (b)a paniculate composite system with Z1O2 coefficient of friction, chemical stability, high hard- (PSZ) particles. ness and high temperature resistance. Despite disad- vantages smh as brittleness and in some cases ex- In the sub-project concerning LPS-SiC the aim is to pensive raw materials or forming processes ceram- explore the potential of the LPS (Liquid Phase ics have a future as wear parts. The literature on wear Sintering) technique for the preparation of silicon is extensive but the majority of the publications carbide ceramics for wear applications. The aim is concentrate on wear testing using "standard" meth- also to evaluate high temperature creep (STSR) and ods. Very little information is given about the impor- oxidation resistance for LPS-SiC (and NPS-Si3N4, - tance of the relation between microstructure and S12N2O) ceramics for applications at a temperature wear properties in specific applications. of 1200°C or higher. Within the project wear applications such as valve trains, nozzles, seal rings, textile thread guides etc are studied. It has been found that an R' factor of crack initiation by thermal shock is a good indicator

206 THE CENTRE FOR SWEDISH CERAMIC INSTITUTE, SCI of the resistance to abrasive wear. The R' factor out the risk of cracking of the ceramic component. increases with increased thermal conductivity. The Instead of producing ceramic port liners, the coat- material development of these materials has there- ings of port liners is developed in this project. This fore aimed at increasing this specific property to- coating/interface layer should take up the compres- gether with further improvements of the fracture sion stresses from the shrinkage of the cast iron and strength. In applications such as valve trains the hence make the whole insert-casting process more chemical environment and lubrication are of impor- reliable. In order to understand the whole insert- tance together with stress analysis in the compo- casting process, stress analyses are necessary. The nents. This system is very specific and it is not easy project is carried out in close cooperation with the to understand the mechanisms involved. automotive industries, AB Volvo and Saab Scania The main objectives within the project are AB. The casting experiments are made by these companies. - general knowledge of ceramics in wear applications Dl. Ceramic Membranes - fabrication of prototype wear components Polymeric membianes have been used for separa- - application oriented wear testing tion methods (such as ultrafiftration, reverse osmo- - iterative development of materials selection. sis, gas separation) for a long time in the processing industry. The use of ceramic membranes represents Cl Thermal Insulation Materials a new technique that has generated much interest. There is a great interest in the automotive industry to Among the advantages of ceramic membranes can use ceramic materials with low thermal conductivity be mentioned their good mechanical and high tem- for insulation of engine parts where considerable perature properties and their resistance to chemicals. heat losses are to be expected. An example is the Ceramic membranes can have a catalytic function development of ceramic port liners. The properties besides their selective function. The development of of ceramic port liners must be properly adjusted to sol-gel technology has greatly enhanced the per- allow for insert-casting into the cylinder head (alu- formance capabilities and lowered the cost of mem- minium or cast iron), where they serve as thermal branes. Membranes in general are used in many insulation. This means that except for a low thermal different applications and industries as for example conductivity (<2 W/mK) the ceramic material must in Food and Beverages, Biotechnology/Pharmaceu- have very good thermal shock properties to resist the tical, Gas separation, Environmental control, thermal shock of the metal casting (cast iron in this Petrochemical, Metal refining and Electronics. In project). Furthermore, the ceramic material must this project ceramic membranes are studied and resist the shrinkage stresses exerted by the contract- knowledge is built up in the area of ceramic mem- ing metal during casting and the thermal stresses branes and the most interesting applications for these generated by thermal cycling in service life. Among types of membranes are identified. Ceramic mem- the most studied materials for this application is branes are developed in the project by the use of sol- aluminium-titanate (AI2T1O5) which has a low ther- gel technology. mal conductivity, low thermal expansion and low Young's modulus and hence very good thermal shock properties. SCI has studied the development El High Strength Tradttloral Porcelain of Al-titanate but also other thermal insulation mate- Traditional porcelains have bending strengths around rials such as porous cordierite and the socalled NZP- SO to ISO MPa and a fracture toughness below 1 2 materials (sodium-zirconium-phosphate ceramics). MPam'/ . A traditional triaxial porcelain with a Although it is possible to adjust the thermal proper- composition including china clay, quartz and feld- ties of the ceramic material to obtain better thermal spar is used as a model system. This project aims at shock properties, the results from earlier projects in increasing the bending strength and the fracture this area have shown that there are difficulties in toughness so as to widen the application field of the achieving good reliability at the insert-casting stage. material. One of the objectives of the project is to get Therefore, it is important to develop a system that is a better understanding of which microstructural fea- "safe" so that insert-casting can be performed with- tures enhance the mechanical strength. Reduction of defects such as agglomerates, porosity and cracks

MATERIALS SCIENCE, 1993 207 SWEDISH CERAMIC INSTITUTE. SCI surrounding large quartz particles has proven to be The project involves evaluation of suitable test successful in increasing the strength. Toughening of methods and knowledge how to modify inorganic the material through internal stresses (particle rein- binders in order to improve the high temperature forcement) achieved through thermal expansion resistance. Bending tests (4-point) using low loading mismatch between glassy phase and thequartz grains speeds and bending creep tests have been used is investigated. The processing methods include together with more traditional compressive test meth- freeze granulation of the powders and cold isostatic ods in the evaluation. The creep resistance of sodium pressing of the test bars. The materials are character- and ammonia stabilized silica sols isquite similar but ised by 4-point bending and fractography, fracture dramatic improvements in load bearing capacity are toughness (CVNB-method), thermai expansion, reached when small amounts of alumina are present phase composition and microstructure. (for example canonic silica sol). Mullite forming silica sols and alumina sols also show improved resistance. Besides good mechanical properties at E2 Refractories for Melt and WamtHoMmg high temperatures it is important as well that a binder Furnaces for Aluminum and Aluminum Aloys gives enough green strength. In industrial applica- Aluminum as pure metal or as an alloy with elements tions the binders must be able to work well in a such as silicon, iron, magnesium, zinc, nickel, silver temperature range from mom temperature up to a and lithium is today used in many important indus- temperature limit set by each application. trial applications, e.g. in the automotive and the Inorganic binders are not only used for high aircraft industry. In this project industrially used Al- temperature applications. Some binders have large alloys are studied in melted state in contact with potentials as !ow temperature binders or construc- different refractories in melt furnaces of various tion materials as well. Cold (Chemically) Bonded kinds. Corrosion tests in laboratory scale are used in Cement (CBC) is a class of materials which harden order to simulate the conditions in industrial fur- at low temperatures. Within the CBC group compo- naces such as thermal stresses, atmosphere and slag sitions based on modified cements and aluminum properties etc. A selection of interesting Al-alloys phosphates are found. The materials are postulated (Al-Mg, Al-Zn-Mg etc) and refractories (commercial to have a future as construction materials working at and new ones produced at SCI) are studied. Parallel low and moderate temperatures. Chemical reactions with the laboratory tests, these combinations of during setting are studied. refractories and Al-alloys are tested in real produc- tion furnaces. The project is mainly focused on Gl Technology Information companies melting Al and Al-alloys for the produc- on Engineering Ceramics tion of castings or materials for plastic machining. An important feature in the spreading ofinformation Producers of refractories are also members of this about the potential of new materials is to bridge the project as are manufacturers of furnaces for the Al- gap between the material society and the engineering industry. designers in the industry. In order to bridge this gap SCI has a program directed toward users, especially Fl Inorganic Binders (Adhesive*) in the mechanical industry and the process industry. Inorganic binders such as colloidal silica sol, During the initial stage new users can get free ethylsilicate, alumina sol, various phosphates, re- consultancy to discuss the possible use of ceramics fractory cements and others are used in numerous in new products. To inspire and to teach the engi- applications working at elevated temperatures. Se- neering designers how to use ceramics, information lected applications such as ceramic shell moulds, and design guides are drawn up. Design courses for refractory linings and refractory fibre preforms for people active in the industry are arranged in coopera- thermal insulation or as reinforcements in metal tion with the industry, other institutes and the univer- matrix composites (MMC) use one or several types sities. These activities also give SCI good contacts of inorganic binders. High strength and creep resist- with the users of ceramics and opportunities to learn ance at elevated temperatures are important proper- about their needs, which might serve as a guide for ties. future development of engineering ceramics.

208 THE CENTRE FOR SWEDISH CERAMIC INSTITUTE, SCI

G2 Powder technology 90 (PT 90) activities questionnaire has been sent out to more than 100 SCI has beer participating actively in the planning companies and evaluated. It has been clearly indi- and implementing phase of the new action area cated that prototyping, testing and evaluation of new POWDER TECHNOLOGY 90 (Pulverteknik 90) product concepts and long-term development con- which is directed at product-oriented R & D within tracts are particularly attractive for user companies. both the ceramic and the P/M area. The institute is a A project proposal for establishment of such a member of the Powder Technological Center in pilot scale facility has been prepared and is expected Gothenburg (PTC-G) at Chalmers with the secre- to reach the implementation phase during the fiscal tarial responsibility in its working committee. PTC- year 1992/93. G is one of the four centers established at the univer- sity sites in Stockholm, Gothenburg, Luleå and G3 Pre-standard/standanlsatk>n activities Linköping. The Center has been given a special A broad market introduction of structural ceramic R&D competence profile in the field of processing components calls for standardised test methods cov- technology for large scale fabrication of nearly or ering the whole processing route (rom raw materials fully dense components with near net shape (NNS). to finished products. Because of the novel and still This profile fits closely with the R&D objectives of strongly generic nature of this field, a considerable SCI. pre-standardisation research effort is required in The institute makes its contribution both in the order to identify the factors which are significant for ceramic and the P/M field. Together with other the standard test methods under development. SCI is departments at PTC-G and companies, new P/M involved in both types of activities: shaping techniques based on MIM (Metal Injection (a) pre-standardisation work within IEA (Interna- Moulding) and other wet shaping methods are suc- tional Energy Agency) including major com- cessfully being developed. As a result of a pre-study panies and organisations in the US, Germany concerned with product and production develop- and Japan, ment of structural ceramics and advanced refracto- ries a number of commercially viable product con- (b) standardisation of test methods within MNC cepts have been proposed and corresponding projects TC 301 and CEN technical committee TC 184 are being formulated in collaboration with the indus- which works on a special mandate from the try. A major project for development of ceramic EG/EFTA countries. matrix composites (CMC) for combustion chamber in aircraft engines is under preparation. In the framework of the IEA collaboration the insti- tute is involved in method development for powder A NUTEK study aimed at a new action area characterization and mechanical testing. The re- entitled "Product and production technology for sponsibilities also include data evaluation for the technically advanced ceramics for industrially quali- final reports and technical leadership within specific fied applications" has been carried out at SCI. The powder analysis areas. SCI is responsible for techni- purpose is to create a complementary action area to cal coordination of the IEA work in Sweden. PT 90 supporting the producers of technically ad- Within the standardisation field the institute is vanced ceramic components. As a result, a consor- active via the membership in MNC (TK 301 tium has been formed at PTC-G with Höganäs Eldfast AB and Ifö Ceramics AB as core companies Keramer). A program involving a total of 52 stand- involved which will propose projects in the product ard methods in five different working fields is under areas of significant market potential. treatment with the goal toestablish European stand- ards by 1992. SCI has a member representing Swe- Efficient technology transfer has been identified den in the CEN/TC184 international technical com- as one of the key aspects of the technological devel- mittee and in the working group concerned with opment of small and medium sized enterprises. A powder standards. study has been carried out together with The Institute The work within IEA and CEN/TC 184 has been for Production Engineering (IVF) to develop facili- coordinated by the working group for engine and ties at the PTC in Gothenburg and Luleå into i high temperature ceramics established by NUTEK. ceramic pilot scale workshop. A comprehensive

MATERIALS SCIENCE, 1993 209 SWEDISH CERAMIC INSTITUTE, SCI

5. Carlström E, Sjöstedt M, Mattsson B and Hermansson Publications L: "Binder Removal from Injection Moulded Ceramic Turbocharger Rotors", Science of Ceramics 14, ed by Ph.D. Dissertations Derek Taylor, p. 199-204 (1988) E. Carlström, "Defect Minimisation in Silicon Carbide, Silicon Nitride and Alumina Ceramics", Jan'90 6. Lundberg R, Pompe R, Carlsson R: "HIPed Carbon R. Lundberg, "Fibre Reinforced Ceramic Composites", Fiber Reinforced Silicon Nitride Composites", Ceram. Sept'89 Eng. Sci. Proc., 9 (7-8), 901-906 (1988) M. Persson, "Slip Casting and Pressing of Ceramics based on Colloidal Processing Techniques", Dec'89 7. Lundberg R, Nyberg B, Williandcr K, Persson M, Carlsson R: "Glass Encapsulated HIPing of SiC Diploma Work Whisker Reinforced Ceramic Composites", Proc. First B. Carlsson, "The Mechanisms Behind Textile Wear of Int. Conf. HIP, Luleå, cd. by Garvare T, Centck Publ. Ceramic Thread Guides", Oct'92 323-327 (1988) J. Forshamn, "Aluminium Phosphate Bonded Ceramic Coalings on Metal", Feb'93 8. Carlsson R, Adlerborn J, Dahlberg R, Lindberg J, A. Kristoffersson, "Fast Drying Binder System for Ceramic Mellgard I och Regestad G: "Kerampansar", förstudie Shell Moulds", May'92 inom STU:s insatsområde "Konstruktionskeramer", 16 0. Lyckfeldt, "Stabilisation and Slip Casting of Silicon and sidor (1988) Silicon Nitride in Organic Media", Sept'9O N. Modig. "Preparation and Evaluation of Sintered Silicon 9. Lundberg R: "Fiberförslärkla kcramcr", Jcmkontorcts Nitride and Gas Pressure Sintered Silicon Nitride", Forskning D627,8061/87 (1988) Feb'93 G. Sjögren, "Effect of Carbon and Iron Impurities During 10. Ekberg I-L, Lundberg R, Warren R and Carlsson R: Nilridation and Sintering of Silicon Nitride", May'89 "Indentation Testing of SiC-Whiskcr Reinforced AI2O3 G. Skoglund, "Development of a Reaction-bonded Composites", Brittle Matrix Compositcs-II, Elscvicr Alumina and Mullite Matrix for Ceramic Long Fibre Publ. (1988) Composites", Nov'92 A. Rubenowitz, "Ceramic Wear Coatings on Bioimplants 11. Bostedt E: "Mctallalkoxidcr - en litteraturstudie", of Titanium Based on Sol- gel Technique", April'90 KeramRapport 89-1(1989) A. Törnkrona, "Inorganic Binders for High Temperatures", Dec'91 12. Bostedt E och Persson M: "Yimodificring av A. Warren, "Development of Oxide Long Fibre Compos- kcramiska material", KcramRapport 89-2 (1989) ites by Slurry Infiltration and Reaction Bonding", April'93 13. Brandt J och Persson M: "Utvärdering av moderna tryckgjutningsmetoder för formning av Engineering Ceramics konstruktionskeramer - en förstudie", Kcram-Rapport 1. Tjcmlund A K, Pompe R, Holmström M, och Carlsson 89-3 (1989) R: "Sintering and Phase Studies m the System Si3N4-ZrO2-Al2O3", Advances in Ceramics, Vol. 24B, 14. Sjögren G: "Föroreningars form och roll vid Science and Technology of Zirconia III, 101S-1021 framställning av Si3N4-bascradc kon- (1988) struktionskeramer", KcramRapport 89-4 (1989)

2. Rundgren K, Elfving P, Pompe R, Lagerlöf P och 15. Lindqvist K, Carlström E, Persson M and Carlsson R: Larsson B: Comparative Study of Sol-Gel Prepared "Organic Silanes and Titanales as Processing Additives Mullite and Mullite-ZKh Composites with and without for Injection Moulding of Ceramics", J. Am. Ccram. Y2O3" Advances in Ceramics, Vol 24, Science and Soc. 72 [1199-103 (1989) Technology of Zirconia III, 1043-1052 (1988) 16. Carlström E, Persson M, Bostedt E, Kristoffersson A 3. Carlström E: "Reserapport från forskarvistclse i Japan and Carlsson R: "Slip Casting and Sintering of Silicon vid GIRI Nagoya 23 sept - 23 okt 87", SILIKAT- Carbide", Ceramic Transactions Vol 2, Silicon Carbide RAPPORT 884 (1988) '87, Am Ceram Soc. Columbus, 175-1,5, (1989)

4. Carlsson R: "Finns någon kunskap om kcramiska 17. Carlsson R: "The Shaping of Engineering Ceramics", material", IVA-rapport 338: Nya material i Materials & Design, 10 (1), 10-14 (1989) produktionen: Företagens strategi för införande av ny teknik, p. 113-120(1988) 18. Carlsson R: "Kcramcr som pansarmatcrial", Militär Teknisk Tidskrift, 58 (1), 19-25 (1989)

210 THE CENTRE FOR SWEDISH CERAMIC INSTITUTE, SCI

19. Lundberg R and Goursat P: "Silicon Carbo-Nitride 32. Carlström E: "Defect Minimisation in Silicon Carbide, Ceramic Matrix Composites by Polymer Pyrolysis", Silicon Nitride and Alumina Ceramics", Ph. D. Thesis, Proc. Inl Conf. ECCM-3, Bordeaux, 93-98 (1989) Chalmers tekniska högskola, Göteborg (1989)

20. Nyberg B, Carlström E, Persson M and Carlsson R: 33. Kahlman L: "Metoder och uTustning för bearbetning "Uniform Distribution of a Pressing Aid", Proc. 2nd och mekanisk testning av konstruktionskeramer", Int. Conf. Ceramic Powder Processing Science, 573- KeramRapport 89-6 (1989) 580(1989) 34. Falk L K L, Hermansson T, Rundgren K: "Microstruc- 21. Lindqvist K, Carlström E and Carlsson R: "Low ture of Hot-Pressed Si3N4-ZrO2 (Y2O3) Composites", Pressure Injection Molding of Alumina", Proc. 2nd Int J. Mäter. Sci. Letters, 1032-1034 (1989) Conf. Ceramic Powder Processing Science, 589-597 (1989) 35. Swan A H, Olsson E, Linde K M and Lundberg R: "The influence of Microstnicture on the Mechanical 22. Bostedt E, Persson M and Carlsson R: "Colloidal Properties of SiC Whisker Reinforced Si3N4", Proc. Processing Through Surface Modification", Euro- 5th SSMS Conf. New Materials & Processes. Copen- Ceramics Vol 1: Processing of Ceramics, pp. 1.140- hagen (1989) 1.144(1989) 36. Persson M: "Adsorption and Stabilization of Alumina 23. Holmström M, Charticr T, Besson J-L and Boch P: in Water by High Molecular Weight Polyacrylic Acid", "Influence of Z1O2 on the Preparation and Properties of in M. Perssons's Ph.D. Thesis "Slip Casting and Tape-Cast, Laminated, ZrC^-Mullite Composites", Pressing of Ceramics based on Colloidal Processing Euro-Ceramics, Vol 1: Processing of Ceramics, pp. Techniques", Chalmers tekniska högskola, Göteborg 1.299-1303(1989) (1989)

24. Falk L K L and Holmström M: "Microstructural 37. Karlsson S: "Forskarvistelse vid GIRI Osaka, Japan Development During Processing of a SisNVZrC^ hösten 1989. Reserapport", KcramRappon90-l (1990) Material", Euro-Ceramics, Vol 1: Processing of Ceramics, pp. 1.373-1.377(1989) 38. Rubcnowitz A, Bostedt E och Persson M: "Keramiska nötningsskikt pä bioimplantat av titan med hjälp av sol- 25. Brown 1W M, Pompe R and Carlsson R: "Preparation gel teknik", KeramRapport 90-2 (1990) of Sialons by the NPS Technique", Euro-Ceramics Vol 1: Processing of Ceramics, pp. 1.484-1.488(1989) 39. Kahlman L: "Konstruktionskeramer i världen 1990. Dagsläge och prognos", KeramRapport 90-3 (1990) 26. Rundgren K, Pompe R, Carlsson R, Kishi K and Umcbayashi S: "On the Reaction Mechanism and 40. Linde K, Karlsson S: "Oförstörande provning - Mechanical Properties of Nitrided Pressurclcss utvärdering av några metoder för karakterisering av Sintered (NPS) Siafy-ZrCty+Y^) Composite A^Oj-fibcrförformar samt Si3N4 i grönt och sintrat Ceramics", Euro-Ceramics Vol 1: Processing of tillstånd", KeramRapport 9(M (1990) Ceramics, pp. 1.489-1.493 (1989)

41. Ekberg I-L: "Högtemperaiuregcnskaper hos Si3N4: 27. Linde K M, Persson M, Pompe R, Karlsson S and Litteraturreferat", KeramRapport 90-6 (1990) Carlsson R: "Iterative Strength Development of Slip 42. LyckfeldtO, Persson M och Liden E: "Dispergering Cast SJ3N4", Euro-Ceramics, Vol 3: Engineering och slamgjutning av kisel och kiselnitrid i organiska Ceramics, pp. 3.126-3.130, (1989) system", KeramRapport 90-7 (1990)

28. Carlsson R, Garvare T, Karlsson L och Warren R: 43. Lindqvist K och Carlström C: "Extrudering av keramer "Fogning Keram-Metall", förstudie inom STU:s - en litteraturstudie", KcramRappon 90-8 (1990) insatsområde "Konstruktionskeramer", 9 sidor (1989) 44. Lundberg R, Pompe R, Carlsson R and Goursat P: 29. Carlström E: "Konstruktionskeramcr", "Fibre Reinforced Silicon Nitride Composites", kurskompendium, 44 sidor (1989) Composites Science and Technology, 37,165-176 (1990) 30. Lundberg R: "Fibre Reinforced Ceramic Composites", Ph. D. Thesis, Chalmers tekniska högskola, Göteborg 45. Manguin-Frilsch A, Dubus M, Abouaf M, Du Mouza (1989) J, Carlström E, Sjöstedt M, Mustcl W: "Optimization of binder removal in injection molding of technical 31. Persson M: "Slip Casting and Pressing of Ceramics ceramics", Euram final report, 1990 based on Colloidal Processing Techniques", Ph. D. Thesis, Chalmers tekniska högskola, Göteborg (1989)

MATERIALS SCIENCE, 1993 211 SWEDISH CERAMIC INSTITUTE, SCI

46. Pompc R: "Prospects for Non-Oxide Paniculate 56. Lyckfeldt O, Bostedt E, Persson M, Carlsson R and Composites at High Temperatures, Proc. 1 lth Rist» Int. Bergström L: "Stabilization and Slip Casting of Silicon Symp. on Metallurgy and Materials Science: Structural and Silicon Nitride in a Non-Aqueous Media", Proc. Ceramics - Processing, Microstructure and Properties, 7th CIMTEC, "Ceramics Today - Tomorrow's Ceram- Ris0 Nat Lai)., Roskilde, 97 -110 (1990) ics", 1073-1082 (1991)

47. Bergström L and Lyckfeldt O: "Adsorption Behaviour 57. Malghan S G, Dragoo A L, Hsu S M, Hausner H and and Dispersion of S13N4 Powders in Non-Aqueous Pompe R: "Physical and Chemical Characterization of Media", Proc. 1 lth Ris0 Int. Symp. on Metallurgy and Ceramic Powders in an International Interlaboralory Materials Science: Structural Ceramics - Processing, Comparison Programme", Proc. 7th CIMTEC, "Ce- Microstructure and Properties, Ris0 Nat Lab., Ros- rarnxs Today -Tomorrow's Ceramics" 3249-3259 kilde, 193-198(1990) (1991)

48. Karlsson S and Iwasa M: "Wear Behaviour of Silicon 58. Liden E, Persson M, Carlström E and Carlsson R: Nitride Based Ceramics", Proc. 1 lth Rise Int. Symp. "Electrostatic Adsorption of a Colloidal Sintering on Metallurgy and Materials Science: Structural Agent on Silicon Nitride Panicles", J. Am. Ceram. Ceramics - Processing, Microstructure and Properties, Soc., 74 [6] 1335-1339(1991) Rise Nat Lab., Roskilde, 365 - 370 (1990) 59. Lindqvist O, Sjöberg J, Hull S and Pompe R: "Struc- 49. Resetar T M, Schaefer G E, McCauley J W, Dragoo A tural Changes in O'-Sialons, Si2.xAl,N2.xO|+x, L, Hsu S M, Johnsson D R, Hausner H and Pompe R: 004

54. O'Mcara C, Pömpe R and Rundgren K: "The Mic- 65. Eriksson P och Kahlman L: "Elektriskt ledande Si3N4- rostructure of Si2N207ZrO2 Composite Ceramics", TiN-komposiier", KeramRappon 91-2 (1991) Proc. 7th CIMTEC, "Advanced Structural Inorganic Composites" 179-187(1991) 66. Lyckfeldt O, Liden E: "Värmcisolerandc kcramiska material. Litteraturrapport", KcramRapport 91-3 55. Bergström L, Emstsson M, Gruvin B, Brage R, Nyberg (1991) B and Carlström E: "The Effect of Wet and Dry Milling on the Surface Properties of Silicon Nitride 67. Karlsson H och Karlsson S: "Fogning av kcram/tnclall Powders", Proc. 7th CIMTEC, "Ceramics Today - - genom limning", (IVF-skrift91833), KeramRappon Tomorrow's Ceramics", 1005-1014 (1991) 91-4(1991)

212 THE CENTRE FOR SWEDISH CERAMIC INSTITUTE, SCI

68. Falk L K L and Rundgren K: "Microstructurc and 79. Carlström E: "Konstruktionskcramer", SKS Short-Tom Oxidation of Hot-Pressed S13N4/ kurskompendium "Keramiska material", 51 sidor ZIO2(+Y2QJ) Ceramics", J. Am. Ceram. Soc. 75 [1] (1992) 28-35 (1992) 80. Kahlman L: "Konstruera rätt med keramer", 69. Pettersson ABA, Bytnan-Fagerholm H and kurskompendium "Konstruera rätt med ke.-amer", Rosenholm J B: "Surface Acid-Base and Electrokinetic Kristianstad, 20 sidor (1992) Properties of Si^, Z1O2, AI2O3, Y2Q3 and T1O2 Powders", Proc. 4th Int. Symp. on Ceramic Materials 81. Karlsson S: "Fogning av keramer", kurskompendium & Components for Engines, Elsevier, 260-268 (1992) "Konstruera rätt med keramcr", Kristianstad, 30 sidor (1992) 70. Sjöberg J and Pompe R: "Structural Details of Sialons - Their Influence on Phase Stability", Proc. 4th Int 82. Rundgren K, Brandt J, Pompe R and Carlsson R: Symp. on Ceramic Materials & Components for "Low-Cost Nitrided Pressurcless Sintered (NPS) Engines, Elsevier, 269-276 (1992) S12N2O-Z1O2 Composites", Proc. European Ceramic Society Second Conference, Augsburg 1991 (to be 71. Cheng Y, O'Meara C, Slasor S. Pompe R and published) Thompson D P: "Some Features and Limitations of Zirconia Toughened Nitrogen Ceramics", Proc. 4th Int. 83. Lyckfeldt O, Pompe R, Liden E and Carlsson R: Symp. on Ceramic Materials & Components for "Fabrication of Nitrided Pressurcless Sintered (NPS) Engines, Elsevier, 657-664 (1992) Silicon Nitride by Slip Casting", Proc. European Ceramic Society Second Conference, Augsburg 1991 72. Lundberg R, Scenholm T, Pcjryd L and Kahlman L: (to be published) "The Influence of Static Loads on the Oxidation Behaviour of Fibre Reinforced SiC/SiC Composites", 84. Liden E, Carlsson R, Persson M and Bergström L: Proc. 4th Int Symp. on Ceramic Materials & Compo- "Surface Modification of Ceramic Powders", Proc. nents for Engines, Elsevier. 691-698 (1992) European Ceramic Society Second Conference, Augsburg 1991 (to be published) 73. Brandt J, Rundgren K, Pompe R, Lundberg R and Pejryd L: "Development of Silicon Nitride Based 85. Byman-Fagerholm H, Liden E, Carlsson R and Matrices" Proc. 4th Int Symp. on Ceramic Materials & Rosenholm J-B: "Slip Casting and Pressurcless Components for Engines, Elsevier, 765-772 (1992) Sintering of Si3N4-Zr02 Composites", Proc. European Ceramic Society Second Conference, Augsburg 1991 74. Malghan S G, Hsu S M, Dragoo A L, Hausner H and (to be published) Pompe R: "Analysis of Physical Properties of Ceramic Powders in an International Intcrlaboratory Compari- 86. Nyberg B, Carlström E and Carlsson R: "Granulation son Program", Proc. 4th Int. Symp. on Ceramic of Ceramic Powders for Pressing by Spray-Freezing", Materials & Components for Engines, Elsevicr, 920- Proc. European Ceramic Society Second Conference, 935 (1992) Augsburg 1991 (to be published)

75. Brandt J, Kahlman L, Pompe R and Lindblad K-E: 87. Kishi K, Umcbayashi S, Rundgren K and Elfving P: "Manufacturing of Ceramic Valve Discs and Their Use "Room Temperature Strength of B-Sialon (z=2) in a Rotor Cam Engine", Proc. 4th Int. Symp. on Fabricated from ct-Si3N4, AIN and Aluminum-iso- Ceramic Materials & Components for Engines, propoxide Solution", J. Mater. Sci. Let. (to be publish- Elsevier, 1093-1100(1992) ed) (1992)

76. Brandt J, Rundgren K, Pompe R, Swan H, O'Mcara C, Lundberg R and Pejryd L: "SiC Continuous Fibcr- Traditional Ceramics Rcinforced S13N4 by Infiltration and Reaction Bond- 1. Carlsson R: "Mechanisms of Deterioration in Ceramics ing", Ceram. Eng. Sci. Proc. 13 [9-10]part2of2,622- and Glass", Durability of Building Materials 5,421-27 631 (1992) (1988)

77. Kahlman L: "Konstruera rätt med keramcr", 2. Fanto M, Pompc R, Sandrén Å och Carlsson R: kurskompendium "Konstruera rätt med keramcr", "Eldfasta keramiska massor för induktionsugnar inom Trollhättan, 20 sidor (1992) gjuteriindustrin", SIL1KAT-RAPPORT 88-1 (1988)

78. Karlsson S: "Limning av keramcr", kurskompendium 3. Karlsson S: "Alkalisilikatcr som "Konstruera rätt med kcramcr", Trollhättan 11 sidor högtcmpcraiurbindemcdcl - Litteraturstudie", (1992) SILIKAT-RAPPORT 88-2 (1988)

MATERIALS SCIENCE, 1993 213 SWEDISH CERAMIC INSTITUTE, SCI

4. KarlssonS och Lundberg R: "Långtidsegenskaper hos 18. Karlsson S: "Keramiska fiberförformar för keramiska fibrer för ugnsisolering", SILIKAT- aluminiumkompositer, tillverkning och RAPPORT 88-5 (1988) karakterisering", KeramRapport 90-5 (1990) 5. Karlsson S.Lundberg Rand Carlsson R: Tensile Strength of Ceramic Thermal Insulation Fibres". 19. Linde K: "Glasyrers slitageegenskaper -1", Science of Ceramics 14, ed by Taylor D, Canterbury KeramRapport 90-9 (1990) 1987 p. 633-637 20. Linde K: "Glasyrers slitageegenskaper - II", 6. Karlsson Sand Carlsson R: "Adhesive Force of Slip KeramRapport 90-10 (1990) Cast Body to Plaster Mould Surface", ibid p. 157-162 21. Linde K: "Keramer och OFP", NDT forum 1,5 (1990) 7. Holmström M, Persson M and Carlsson R: "Viscosity and Flow Behaviour of Glaze Melts", ibid p. 359-364 22. Carlsson R: "Brewing av keramiska material - teori", SKS kurskompendium "Bränning i keramisk industri", 8. Nildasson U: "Framställning med pulverteknik och 15 sidor (1991) dispergeringsförsök av högtemperaturesupraledaren

YiBa2CujO7.x", SILIKAT-RAPPORT 88-7 (1988) 23. Ekberg IL, Persson M och Carlsson R: "Strength Improvements of a Traditional Feldspar Porcelain by 9. Nordänger S och Carlström E: "Framställning av Defect Minimization", Proc. Silicer 90, Fort-

supraledaren YiBa2Cu3<>7.x med pulverteknik", schrittsberichte der DKG, 7 [1], 247-254 (1992) SILIKAT-RAPPORT 88-9 (1988) 24. Tömcrona A, Karlsson S och Persson M: "Oorganiska 10. Karlsson S: "Lösliga alkalisilikater som bindemedel för bindemedel för höga temperaturer", KeramRapport 92- oorganiska material. Hållfasthet och fuktupptagning", 1(1992) SILIKAT-RAPPORT 88-10 (1988) 25. Persson M, Törncrona A and Karlsson S: "Evaluation 11. Blomström P och Carlström E: "Studie av of Silica Sols as Ceramic Shell Binders at High sintringsförioppet hos YiBa^ujOy., keramer Temperatures", kurskompendium (1992) framställda med sol-gel teknik", SILIKAT- RAPPORT 88-12(1988) 26. Carlsson R: "Tillverkning av keramiska material - en introduktion", SKS kurskompendium "Keramiska 12. Pompe R, Carlsson R and Sandrén Å: "On the Reac- Material", 14 sidor (1992) tions Involving Refractories for Aluminum Casting", Proc. UNITECR '89, Vol 1,906-911 (1989) 27. Carlsson R: "Bränning av keramiska material - teori", SKS kurskompendium "Keramiska material", 21 sidor 13. Karlsson S and Carlsson R: "Pore Structure in Plaster (1992) Moulds", Euro-Ceramics, Vol 2: Properties of Ceram- ics, pp. 2.533-2.537, ed by de With G, Terpstra R A and 28. Karlsson S, Linde K och Karlsson R: "On the Influence MetselaarR(1989) of Glaze Properties on Glaze Damage", Proc. European Ceramic Society Second Conference, Augsburg 1991 14. Karlsson S, Carlsson R and Ahmad B: "Colour (to be published) (1992) Development in Unglazed Floor Tiles", Euro-Ceram- ics, Vol 2: Properties of Ceramics, pp. 2.538-2.542, ed 29. Shirazi A R, Eklund L and Lindqvist O: "Direct by de With G, Terpstra RA and Metselaar R (1989) Quantitative Analysis of Mineral Matter and Different Pyritic Sulphurs in Coal by Electron Probe Micro 15. Linde K M, Karlsson S and Carlsson R: "Wear Analyser (EPMA) and Automatic Ii.iage Analysis Properties of Ceramic Whiteware Glazes", Euro- (AIA)" (to be published) (1992) Ceramics, Vol 3: Engineering Ceramics, pp. 3.559- 3.563, ed by de With G, Terpstra RA and Metselaar R (1989)

16. Karlsson S: Torskarvistelse vid GIRI Osaka, Japan hösten 1989. Reserapport". KeramRapport90-l (1990)

17. Linde K och Karlsson S: "Oförstörande provnin? • utvärdering av några metoder för karakterisering av Al2O3-fiberförformar samt S13N4 i grönt och sintrat Ullstånd", KeramRapport 904 (1990)

214 THE CENTRE FOR Metals

Engineering Metals 216 Microscopy and Microanalysis 228 Mechanics - Swedish National Testing and Research Institute, SP 240

MATERIALS SCIENCE, 1993 215 Engineering Metals

Research summary materials when subjected to controlled fatigue crack The research activities in the Department of Engi- growth, cyclic deformation and low cycle fatigue. neering Metals are concentrated in the following The research on high temperature materials con- areas: materials for high temperature applications, cerns in addition to intermetallics also ceramics and powder metallurgy; corrosion and surface treat- fibre reinforced ceramics. Particular interest is taken ment; mechanical properties of metals and ceramics; in studying deformation and fracture under static joining technology. load at 20-1500°C. The research on ceramics is further extended to studies of brazed metal/ceramic In the research on high temperature materials, joints. The aim is to develop reactive brazes for high special interest is taken in the development of inter- temperature applications, e.g. nickel alloy/silicon metallics; silicides and aluminides. The aim is to nitride joints. Another area where joining problems improve the room temperature ductility and still are investigated is adhesive bonding of metals for preserve good high temperature properties. The structural applications. The primary objective for intermetallic materials studied are syntesized by this activity is to improve the bonding beween the means of powder metallurgical (PM) methods. A polymer adhesive and the oxide on the metal surface modern PM technique - Metal Injection Moulding - by pre-treatment. Focus is placed on aluminium is treated in another project The objective of the alloys. project is to gain understanding about binder/pow- der interactions. The use of surface sensitive tech- niques (ESCA, AES) for studying surface product formation related to powder fabrication and consoli- Address dation comprises a major part of the current PM Department of Engineering Metals research. One example is in the development of new Chalmers University of Technology PM produced martensitic stainless steel for steam S-412 96 Göteborg,!Sweden turbine applications. Another example is a project Phone+46 31 772 1263 aiming at development of methods for surface clean- Fax+46 31 772 1262 ing of high alloy powder. Studies of the influence of pore and precipitate characteristics on dynamic properties of PM stainless steel have recently been initiated. Staff Senior members The corrosion research has so far been focused on Olefjord Ingemar professor/prefekt fundamental studies of thedissolution and passivation Karlsson Birger professor of stainless steel. One current subject is the passivation Li Changhai docent of austenitic stainless steel in hydrochloric acid up Nyborg Lars docent to 70°C. Another project deals with thin intermetallic Mattson Håkan tekn.dr. films formed by means of sputtering technique. The Wasén Jonas tekn.dr. depositedfilmsarecharacterised (ESCA, AES.EDX, etc) and their electrochemical properties are studied. Graduate students Extensive work dealing with the mechanical prop- Börjesson Susanne fil.kand. erties of high performance materials is carried out. Hansson Thomas tekn.lic. The prime interest is dynamic properties of materi- Holmquist Magnus civ.ing. als. Materials concerned are duplex stainless steel Holmström Maria civ.ing. and aluminium-base composites. The stainless steel Levin Magnus tekn.lic. studied has various phase (austeni te/ferrite) content. Lindstedt Ulf civ.ing. The aim is to clarify the fracture behaviour of the Norell Mats civ.ing.

216 THE CENTRE FOR ENGINEERING METALS

Nylund Anders tekn.lic. SEM (Scanning Electron Microscopy), JEOL Nyström Magnus tekn.lic. 733, microprobe, quantitative X-ray micro- Svensson Patrik berging. analysis. Secondary contact: Changhai Li Tunberg Thomas tekn.lic. (phone 772 1246). Wegrelius Lena tekn.lic. Hardness testing equipment and optical micro- Warren Anna civ.ing. scopes with microhardness measuring facility. Technical staff Secondary contact: Peter Sotkovszki (phone Bragée Jan civ.ing. 777 1255) Fritze Göran ing. Impact/tensile testing machines. Secondary Heiskanen Pertti ing. contact: Jonas Wasén (phone 772 1245) Jelvestam Urban ing. Kjellgren Ulla Servohydraulic testing machines, Instron 8032/ Olefjord Yvonne fil. kand. 8502, maximum load 100 kN. Secondary Sotkovszki Peter Dr. ing. contact: Jonas Wasén. Secretary Dedicated testing machine for creep and Maxe Maria tensile testing of brittle materials up to 1600°C. Norden Marita Secondary contact: Jonas Wasén. Bend testing machine for measuring fracture toughness of brittle materials up to 135O°C. Major instrumentation Secondary contact: Jonas Wasén. Prime contact: Professor Ingemar Olefjord (phone 772 1241) Laboratory vacuum sintering furnace for tempe- ESCA (Electron Spectroscopy for Chemical ratures up to 1600°C. Equipped with diffusion Analysis), PHI 5500, small spot 50 \m lateral pump for high vacuum performance. Second- resolution. Secondary contact: Anders Nylund ary contact: Lars Nyborg (phone 7721257) (phone 772 1261/772 1259). Dedicated vacuum furnace for wetting experi- SIMS (Secondary Ion Mass Spectrometry), ments up to 1200°C. Equipped with diffusion PHI 3700, static, masses 0-250 amu. pump for high vacuum performance. Secondary Secondary contact: Håkan Mattson (phone 772 contact: Maria Holmström (phone 772 1258) 1243/7721259). Laboratory atomization unit (Rotating Electrode AES (Auger Electron Spectroscopy), PHI 660, Process) for inert fabrication of metal powder. Auger microprobe, 0.1 Mm analytical and 0.03 Secondary contact: Lars Nyborg (phone 772 pm imaging (SEM) resolutions. Equipped with 1257). Link Systems AN 10000 for quantitative X-ray Laboratory annealing furnace for process microanalysis. Secondary contact: Lars simul^on in hydrogen/nitrogen atmosphere Nyborg (phone 772 1257/772 1259). up to 850°C. Secondary contact: Urban Sputtering equipment for preparation of thin Jelvestam (phoe 772 1256). alloy layer on substrate. Equipped with double ion guns and targets. Secondary contact: Urban Jelvestam (phone 772 1256). Microscopy and materials testing. Prime contact: Professor Birger Karlsson (phone 772 1242).

MATERIALS SCIENCE, 1993 217 ENGINEERING METALS

Major Reids of Research Research Projects

A: Corrosion and Surface Technology Al: Adhesive Bonrfng of AlumWum Alloys Participants: professor Ingemar Olefjord, tekn. Adhesive bonding offers the possibility of construct- dr. Håkan Mattson, tekn. lic. Anders Nylund, ing light structures with beneficial mechanical prop- tekn. lic. Lena Wegrelius, civ.ing. Susanne erties (e.g. good fatigue resistance). The surface Börjesson, civ.ing. Magnus Holmquist, ing. condition is of primary significance for the bond Urban Jelvestam. performance. The adhesive polymer links to the Co-workers: Professor C Qayton, Stony Brook oxide formed on the adherend. This oxide is formed University, N.Y. Directeur de Recherches, Dr. during the pretreatment of the metal and its thickness P. Marcus, CNRS, Ecole Nationale Superieure and morphology are dependent on the chemical de Chemie de Paris. Professor M. Lakatos- composition of the alloy. Varsanyi, Eötvös University, Budapest. Aluminium is especially well suited for adhesive bonding. In this project various such alloys are B: Mechanical Properties studied. The project aims at clarifying the influence Participants: professor Birger Karlsson, tekn. of surface pretreatment on the joint durability. The dr. Jonas Wasén, tekn. lie. Magnus Levin, joints are exposed in a humid atmosphere at elevated tekn. lie. Magnus Nyström. temperature and tested mechanically at regular inter- vals. The exposures in progress have lasted more C: Powder Metallurgy than 6 years. The surface state is studied by surface Participants: professor Ingemar Olefjord, sensitive techniques (small spot ESCA, Auger elec- professor Birger Karlsson, docent Lars Nyborg, tron spectroscopy, SIMS). The relationship between docent Changhai Li, tekn. lic. Anders Nylund, joint durability, alloy composition and pretreatment teka lic Thomas Tunberg, civ.ing. Mats Norell, is being evaluated. civ.ing. Ulf Lindstedt. Project leader Tekn.dr. Håkan Mattsson Co-workers: docent B. Uhrenius, Swedish Institute for Metals Research, riving. T. Rost- A2: HydroxMe/Oxkle Formation vall, AB Sandvik Formsprutning, civ. ing. U. on Pure Aluminium Engström, Höganäs AB, tekn. dr. A. Salwén, Oxidation of Al in dry and humid atmosphere has ABB Powdermet been studied by means of ESCA, Auger electron spectroscopy, EDX and Nuclear Reaction Analysis D: Intermetalllcs and (NRA). NRA was used for determining the total Structural Ceramics amount of oxygen bound in the oxide. The thick- nesses of the oxides formed on pure Al (99.998%) Participants: professor Ingemar Olefjord, C professor Birger Karlsson, professor Richard during exposure for 5h at 25 C and 250O°C are 15Å Warren (Luleå University of Technology), and 21.5Å, respectively. Using these data, the at- docent Changhai Li, docent Lars Nyborg, tekn. tenuation length of the electrons (photo and Auger dr. Jonas Wasén, tekn. lic. Thomas Hansson, electrons) was determined. It was found that, using civ.ing. Maria Holmström, civ.ing. Patrik AlKct X-ray source, the attenuation length of the Svensson A12p and Al2s electrons emitted from oxide and Co-workers: docent B. Uhrenius, Swedish metal are 18^ and 20Å, respectively. Quantitative Institute for Metals Research, tekn. lic. L. surface analysis of thin films can be performed using Léstrade, Itec AB, docent T. Thorvaldsson, AB the data obtained. Sandvik Steel During exposure to humid atmosphere (RH=80%) the oxide grows uniformly on pure Al (99 998%). The oxide becomes 22Å during exposure for one week. Exposure for longer times does not change the oxide thickness. On technically pure Al containing low amounts of Fe and Si, localized corrosion takes place around the intermetallic precipitates present on

218 THE CENTRE FOR ENGINEERING METALS the surface. Combined Auger and EDX analyses sition and thickness of the film are almost independ- show that the Fe- and Si-aluminides present on the ent on the composition of the alloy and that anodic surface act as cathode areas. ESCA-studies of pure segregation occurs as a result of active dissolution Al-hydroxide has shown that the surface hydroxide during passivation of stainless steel. The resulting is not stable under UHV condition, and it almost surface composition of the steel is radically different immediately decomposes to oxide and water. The from the bulk composition. Conditions seem to layer decomposed is 7Å thick. favour formation of surface phases of intermetallic Interpretation of ESCA spectra recorded during compounds, which appear to control the kinetics of the initial stages of hydration indicates that a time active dissolution and the composition of the passive dependent space charge is set up in the oxide due to film. We propose that the more complex stainless decomposition of water molecules adsorbed on the steel passivation may be due to the formation of a surface oxide. A theoretical model explaining this duplex kinetic barrier consisting of an outer oxide behaviour by diffusion of AP+- and O2--ions is based passive film and an inner intermetallic surface under development. phase with a higher lattice binding energy than the Project leader Professor Ingemar Olefjord. alloy. Student: tekn. lie. Anders Nylund The resistance against local corrosion attack is considerably increased for high Ni- and Mo-alloyed A3: Influence of Anodcally Segregated stainless steel. Surface analysis shows that Ni is not Elements on Passivity on Alloys present in the passive film. Not even Mo is markedly Surface analyses of stainless steels performed after enriched in the film at potentials where high Mo- exposure to acid solutions have shown that the containing alloys show high performance. These alloying elements Ni and Mo are enriched in the alloying elements are enriched on the surface of the outer surface layers of the metal phase under the metal phase. Polarization diagrams show that the passive film. Our hypothesis is that this enrichment dissolution rate in the active range is much lower for is due to the formation of an intermetallic thin film on the high Ni-Mo alloyed steels compared to that of the the surface and that the corrosion properties are, to low alloyed steels, while the current in the passive some extent, controlled by this layer. range is almost the same. This behaviour can be The aim of this project is to produce synthetic understood from the fact that the active dissolution is intermetallic layers of the same composition as those controlled by the surface metal composition, while formed on stainless steels and then study their the passive current is controlled by the passive film, electrochemical and corrosion behaviour. We have the properties of which are about the same for the built an UHV-sputtering equipment for deposition alloy categories. The increased pitting corrosion of metals and alloys on substrates. The thin films resistance of high Mo- and Ni-alloyed steels is formed can be moved from the sputtering chamber suggested to be due to lower dissolution rate of an to the instruments, ESCA, Auger, SIMS, EDX and initiated pit and thereby a more probable transforma- SEM (Auger) without exposure to air. After charac- tion to the passive state. terisation of the film, the sample can be moved to an Project leader: Professor Ingemar Olefjord. electrochemical cell attached to the system. The Student: tekn. lie. Lena Wegrelius. analysis has shown that intermetallic bonds are formed between Ni and Mo during sputtering depo- A5: Oxide Overlayers sition. Ni and Mo act as electron donor and acceptor The department participates in a consortium dealing in accordance with Engel-Brewer theory. with "Oxide overlayers". All together nine depart- Project leader: Professor Ingemar Olefjord. ments at five universities in Sweden are involved in Student: fil. kand. Susanne Börjesson. the project. The project is organised in four sub- projects. The aim of our sub-project is to develop A4: Pitting of Stainless Steel oxide catalysts for NOX-reduction with low concen- Earlier theories dealing with pitting of stainless trations of catalysis-promoting metallic elements steels have been built on the assumption that the such as Pt, Pd and Ru. composition of the so called passive film controls the properties. Our research has shown that the compo-

MATERIALS SCIENCE, 1993 219 ENGINEERING METALS

Oxides containing La, Sr, Cu and Ru have shown Experimentally produced duplex ferritic/aus- activity comparable with a commercial Pt/Rh auto- tenitic, so called tie-line alloys with ferrite contents motive catalyst The department studies surface ranging from 0 to 100% have been studied. In products formed during catalytic reactions and gives addition a commercial duplex stainless grade has surface analysis support to the other participants in been studied. The fatigue crack growth properties the project. It has been shown that reduction of the were investigated in samples as received and in cold catalyst in hydrogen gives a reduction of the Cu/La rolled conditions. The results indicate that the fatigue ratio due to the agglomeration of the reduced Cu- crack growth threshold is highest in the ferritic species. To be able to obtain a catalyst with high specimens, while austenite Has the lowest threshold efficiency it is necessary to find a way to spread the level, with duplex alloys ranging in between. Cu-compound over the entire surface. Prestraining leads to a pronounced drop in fatigue Project leader Professor Ingemar Olefjord. threshold for all variants, while the crack closure Student: civ.ing. Magnus Holmquist essentially is left unaffected. The results are ration- alised in terms of quantitative fractography data Bl: Fracture Mechanisms in Metal Matrix from fatigue crack surfaces. Composites - Toughness and Fatigue The study on the commercial duplex grade SAF Behavior 2205 (50% austenite, 50% ferrite) revealed a pro- Fatigue properties of alumina and silicon carbide nounced anisotropy in the tensile behaviour, yet in reinforced aluminium AA6061 have been investi- opposite directions for uniaxial tension and impact gated with the matrix alloy being studied as a com- loading situations. The individual deformation be- plement. The studies have concerned crack growth haviour of the two phases in the duplex grade has characteristics of long fatigue cracks, strain control- been studied, as has the influence of hardening due led fatigue, and initiation and growth of short cracks. to decomposition. Both composites have fatigue crack growth thresh- Project leader Professor Birger Karlsson. olds 60% higher than that of the matrix alloy. These Student: tekn. lie. Magnus Nyström. findings are quantified in terms of larger angular crack deviations, less crack tip opening (smaller Cl: Powder Meta'lurgical Turbine Materials elastic moduli) and crack branching. The low frac- Martensitic stainless steel produced by powder ture toughness of the actual composites corresponds metallurgical (PM) technique is currently used in to lower crack growth resistance at high stress inten- steam turbine parts. In order to raise the working sity ranges. temperature and thus improve the energy efficiency, In strain controlled fatigue, the composites have new modifications of PM martensitic steel are being shorter fatigue life than has the matrix alloy at large developed (ABB Stal and ABB Powdermet). plastic strain amplitudes. At small amplitudes, the The mechanical properties of PM material de- reverse is true. Studies of crack nucleation and pend significantly on the reaction products present growth indicate that growth of individual non-inter- on prior particle boundaries (PPBs) in the compacted acting small cracks determines fatigue life of both material. In this project, ESCA and AES are used for composites. Nucleation of cracks always occurs at studying the reaction products formed on powder outer surfaces depending on localised strain concen- surfaces and interfaces during powder fabrication tration as rationalised by FEM modelling. (atomization), consolidation (hot isostatic pressing) Project leader: Professor Birger Karlsson. and high temperature use (creep testing). The objec- Student: tekn. lie. Magnus Levin. tive of the studies is to correlate the properties of the material with the surface and interfacial reactions B2: Fatigue Crack Growth which take place during the processing and use of the of Duplex Stainless Steels material. This project consists of two parts: one study on the Recent findings and developments of the project fatigue crack growth properties of duplex stainless are: analysis and modelling of surface reaction phe- steels, and one study on the mechanical properties in nomena in atomization related to particle size; devel- general of a duplex stainless steel. opment of an improved method for AES depth

220 THE CENTRE FOR ENGINEERING METALS profiling on powder and other irregular samples; The reaction products can be limited by controlling observation of correlation between light element current powder fabrication and consolidation proce- segregation (P, S) and cavities/rnicrocracks in crept dures. However, further improvement in material material. performance and development of new high quality Project leader Docent Lars Nyborg. alloys require even higher surface cleanliness of Student: civ.ing. Mats Norell. powder than thai obtainable today. The aim of this project is to study and develop C2: Metal Irfection Moulding From Metal and improved methods for surface cleaning of high alloy Hardmetal Powder metal powder. Especially, studies concerning The objective of this project within the program degassing, powder handling and surface oxide re- "Powder Technology 90" is to develop competence moval are carried out. Atomized powder is charac- and technique for injection moulding of metal and terized using ESCA and AES both before and after hardmetal parts. The project is carried out in close various heat treatments in vacuum or reducing gas. cooperation with the Swedish Ceramic Institute and Mass spectrometry will also be used in order to the Department of Polymer Materials. Initially, establish reaction schemes during the thermal treat- Anval AB, Höganäs AB and Götene Plast AB have ment of powder. The materials studied are consoli- participated in the project. From 1993 the researchi s dated (hot isostatic pressing) and the effect of PPB extended to injection moulding of hard metals, and reaction products on the mechanical properties are Sandvik AB will be the prime industrial participant. evaluated. The project is carried out in cooperation Our part in the project is to optimize the sintering with Swedish PM industry within the program process, to perform mechanical testing of sintered "Powder Technology 90". products and to analyse fracture surfaces of the Project leaden Docent Lars Nyborg. sintered products using AES. Student: tekn. lie. Thomas Tunberg. A feasibility study has proved that the partici- pants in the project possess knowledge and tech- C4: Influence of Pores and Precipitates niques to produce injection moulded components of on the Mechanical Properties of stainless steel. The processing route used was: mix- Powder Metallurgical Steels ing stainless steel powder with a wax-based binder, The present project concerns the influence of pore moulding; debinding in nitrogen at 500°C; sintering geometry and precipitates on the mechanical pro- in vacuum up to 125O°C. Both gas- and water- perties of powder metallurgical steels. Ferritic and atomized austenitic stainless steel powder were used austenitic, gas atomized powders compacted to vari- as raw material. In the former case, good results are ous densities are studied. The reaction products on obtained: porosities in thin sections, 3 mm, and thick pore surfaces and prior particle boundaries (PPBs) in sections, 6 mm, were 6% and 12%, respectively. The consolidated material are analysed (TEM/STEM/ mechanical properties obtained are comparable to AES). The mechanical properties are characterised those of conventionally produced stainless steel. and related to the pore geometry, grain structure, and Water-atomized powders give higher porosity, 15% PPB-precipitates. In the investigation on mechanical and 24% in the thin and thick sections, and the properties, emphasis is placed on cyclic deforma- mechanical properties obtained are therefore poor. tion, low cycle fatigue and fatigue crack growth. Project leader: Professor Ingemar Olefjord. A key role is placed on quantitative fractography. Student: civ.ing. Anna Warren. Thus, the mechancial behaviour and the fracture processes in particular will be related to the C3: Surface Cleaning of High Alloy Steel Powder microanalytical results. By this means, information The mechanical properties of high alloyed steel is gained on how processing of powder and consoli- powder depend to a significant extent on the reaction dation affect the resulting mechanical behaviour. products on prior particle boundaries (PPBs) in the Project leader: Professor Birger Karlsson. consolidated material. These reaction products arise Student: civ.ing. Ulf Lindstedt from the surface reactions which take place during atomization, powder handling and consolidation.

MATERIALS SCIENCE, 1993 221 ENGINEERING METALS

01: Development of Iran AiuminMes The investigated silicides are prepared by using the for High Temperatures melt-spinning process. X-ray diffraction, SEM/ Iron aluminidcs based on Fe3Al and FeAl arc con- EPM A, TEM/EPMA and SAM are used for micro- sidered as candidates for structural applications at structural and interfacial characterization. elevated temperatures (up to 650°C) because of Project leader. Docent Changhai Li excellent oxidation and sulphidation resistance, good strength comparable with available heat resistant D3: Deformations and Fracture of Structural stainless steel and relatively low density and cost. Ceramics under Tensile Uad Between However, further extensive research is required to 20andl500°C achieve an optimum combination of room and el- The objective of this project is a fundamental study evated temperature properties. The prime objective of deformation and fracture mechanisms in struc- of this project is to establish such optima by applying tural ceramics both at ambient and high tempera- principles of alloy design. The project includes the tures. The project is carried out by participants from following investigations: three differentinstitutes(AdvancedCeramicGroup) - Effect of alloying additions (eg. O, B, Mo, Ti, Si) providingauniquecombinationofexpertise: process- on mechanical properties of F^Al-base material ing at the Swedish Ceramic Institue; microstructural The aim is to improve our understanding of analysis at the Department of Physics; mechanical alloying principles of Fe3Al-alloys. The mate- testing at the Department of Engineering Metals. rials studied are prepared by powder metallur- Three significant features of the project are: gical techniques such as hot isostatic pressing. - Deformation and fracture mechanisms are - Industrially produced alloys with various carried out under precisely controlled tensile compositions are fabricated by using vacuum loading. hot extrusion. - The deformation and fracture mechanisms are The materials studied are characterized with optical studied using advanced microanalytical techni- microscopy, SEM/EPMA, TEM/EPMA and SAM. ques including analytical transmission electron The mechanical properties at room and elevated microscopy. temperatures are tested. - The materials studied, chosen to represent Project leader. Docent Changhai Li. various types of ceramic microstructures, are Student: berg.ing. Patrik Svensson all produced in Sweden, one of them being prepared in the laboratory of the participants of 02: SIHclde* as Potential Structural Materials the Advanced Ceramic Group. This ensures for High Temperature Applications that the materials and their preparation are well Silicides are very attractive intermetallic materials characterized. for use at high temperature because of their usually Project leader. Tekn.dr. Jonas Wasén. high melting temperatures and excellent resistance Student: tekn. lie. Thomas Hansson tohigh temperature corrosion. However, their tough- ness andductility at ambient temperature are low. To D4: Metal/Ceramic Brazing for High overcome this problem, the following three ap- Temperature Applications proaches are investigated. The achievement of good bonding between ceram- - In-situ composite concept to create a uniform ics and metals by metallic brazing requires a good dispersion of fine particles in the intermetallic understanding of the physico-chemical processes matrix. involved, such as wetting and possible chemical - Modification of crystal structure by alloying reactions between the braze alloy and the surface to design based on electron theory. The idea is to be brazed; this is the subject of the research. obtain high lattice symmetry and thereby The wetting of silicon nitride with pure metals as improve toughness and ductility. well as selected alloys has been studied. The study - Partially disturbed bonding between silicon also included the superalloy Incoloy 909 as sub- and metal atoms. strate. As little as 2 wt% Ti was found to be active in promoting the wetting of silicon nitride and Incoloy 909 by an Ag-28wt%Cu eutectic alloy.

222 THE CENTRE FOR ENGINEERING METALS

The studies of wetting with the active Ag- Magnus Nyström. "Fatigue crack growth of duplex stain- 35wt%Cu-1.75wt%Ti have been extended to other less steels", March 1992. ceramics and Ni-base alloys. Relationships between Thomas Tunberg, "Surface reactions during atomization wettability and the observed interf acial reactions are and sintering of austcniuc stainless steel". May 1992. examined. It is concluded that the wettability is not determined directly by the degree of reactivity but Diploma works rather by the wettability of the reaction layer formed Björn Flink: "Spray deposition of stainless steel for nuclear between braze and substrate. piant applications", 1989. The wetting on ceramics by Ni-based brazes was Kaj Eriksson, Thomas Tunberg: "Squeeze casting of generally poor. Some of the ceramic substrates re- aluminium oxide composite", 1989. acted strongly with Ni. However, Si3N4 and AI2QJ did not react and might therefore be used with this David deVal: "Spot welding of steel sheet with Y AG type of braze after further development to improve laser", 1989. wetting. Jonas Adolfsson, Cecilia Askling: "Crack propagation in Project leader Professor Richard Warren, docent super waspaloy - effect of frequency and exposure time in Lars Nyborg. Student: civ.ing. Maria Holmström hydrogen", 1989.

Cecilia Norrby: 'Technical evaluation of alternatives to Publications hcxavalentchromatizing", 1989. Jörgen Johansson: "Non-destructive testing of metal and Ph.D. Dissertations ceramic matrix composites", 1989. Jonas Wasén: "Fatigue crack growth and fracture in steels", January 1989. Jonas Wigforss, Henrik Ahlrén: "Industrial laser cutting of aluminium polymer fibre composites", 1989. Hakan Mattsson: "Oxidation of titanium in aqueous solutions", January 1990. Lars Hammar "Erosive corrosion of plain carbon and low alloy steel", 1989. Lennart Ljungberg: "Joining of ceramics to metals by brazing", June 1992. Stefan Larsson: "The use of XPS and Auger to analyse the carbon content of steel", 1989. Sven Bengtsson: "Short alumina fibre reinforced alu- minium alloy composites", June 1992. Ulla Boman: "Optimization of autoclave hardening cycle for fabrication of carbon fibre/epoxy composites", 1989. Licentiate Dissertations Mats Delin: "Thermally sprayed layers with WC-Co for Ulla Rilby: "Surface treatment for joining of aluminium high erosion resistance", 1990. alloys", February 1989. Henrik Dahlquist: "Induction hardcnability of various Lars Bjomkvist: "Passivation of chromium", May 1989. microstructures", 1990. Anders Nylund: "Surface analysis of rapidly solidified Åsa Svensson: "Influence of pores and microstructure on aluminium powders", June 1989. fatigue fracture in aluminium alloys SS 4251 and SS 4253", 1990. Sven Bengtsson: "Short alumina fibre reinforced alu- minium alloy composites", September 1990. Katarina Boustrdt: "Galling mechanisms - a basic study", 1990. Magnus Ixvin: "Fatigue crack growth properties of a SiC/ aluminium composite material", September 1990. Leo Tiid: "Effect of blasting process and oxide formation on adhesion of thermally sprayed layers", 1990. Thomas Hansson, "Fracture of whisker reinforced and paniculate ceramic composites", September 1991. Camilla Orrhult: "Case hardening of bearings - relations between material properties and imposed stresses", 1991. Lena Wcgrclius, "Surface analysis of stainless steels", March 1992.

MATERIALS SCIENCE, 1993 223 ENGINEERING METALS

Paula Eriksson: "Electrically conducting Si3N4-TiN- 3. The true grain size distribution of a WC-Co alloy, composites", 1991. J. Wasén and R. Warren, To be published in Mater. Sci. &Techn. 1989. Peter Mellander: "Mechanical properties of high tempera- ture brazed nickel brazes", 1991. 4. Experimental characterization and geometrical model- ling of fatigue fracture surfaces, B. Karlsson and J. Christina Eriksson: "Deformation och fracture initiation in Wasén, 7th Int. Conf. Fracture, 'Advances in Fracture fibre reinforcedaluminium" , 1991. Research*, eds. K. Salarna, K. Ravi-Chandar, D.M.R. Taplin, and P. Rama Rao, (Pergamon Press, Oxford, Jonas Nilsson: 'Tensile fracture behaviour of AI2O3 fibre 1989) pp. 3383-3390. reinforced Al-Cu-alloys", 1992. 5. Fracture of whisker reinforced ceramics, R. Warren Jan Isidorsson: 'Titanium aluminides - an overview", 1992. and V. Sarin, Chapter in "Application of Fracture Mechanics to Composite Materials", ed. K. Friedrich, Jerker Fredholm: "High temperature aluminides - new (Elsevier, 1989), pp. 571-614. materials for aircraft and space engines", 1992. 6. Oxide morphology on phosphoric acid anodized Mikael Soderholm: "Long time durability of cnoxy bonded aluminium alloys, U. Rilby, G. Wetter and I. Olefjord, aluminium joints", 1992. to be published in J. of Adhesive Science and Tech- nology, 1989. Ingrid Mathillas: "Thermal fatigue and thermal chock of SiC/S!r: composites", 1992. 7. G. ii'iiion of powder surfaces during the atomizau'on of nizh-alloyed steel, L. Nyborg, Metal Powder Report, Anders Pettersson, Hans Lyckc: 'Tubearing - increased ^,1989^.32-34. formability and endurance by carbonitriding a low carbon steel", 1992. 8. Surface analysis of adhesive-bonded Zn-coatcd steel, G. Wetter and I. Olcfjord, Proc. 5th SSMS, New Karin Schöön: "Stress analysis of a dircctionally solidified Materials and Processes, eds. I. Hansson and H. turbine blade", 1992. Lilholt, (Danish Society for Materials, Copenhagen, 1989) pp. 729-736. Staffan Gråsjö: "The use of pre-coatcd/pre-lacquered sheet in car industry - properties during pressing, welding and 9. Microstructural studies of 5-alumina fibre reinforced painting", 1992. aluminium and Al alloys, S. Bengtsson, C-H. Li and R. Warren, Proc. ICCM7, eds. Wu Yunshu ctal., Nina Hclmrich, Helena Johansson: "Determination of (Pcrgamon 1989) 2, pp. 607-612. temperature profile in brake pads", 1992. 10. Intcrfacial microstructurc and fracture analysis of Olof Hcrvicu: "Controlled cooling as an alternative to Al2O3-fibrc/Al composites, C-H. Li, S. Bengtsson, R. isothermal annealing for two case hardening steels", 1992. Warren, G. Dunlop and I. Olcfjord, Proc. 5th SSMS, eds. I. Hansson and H. Lillholt, (Danish Society for Magnus Holmquist: "Carbon/carbon composites for use at Materials, Copenhagen, 1989) pp. 397404. high temperatures", 1992. 11. High temperature fracture at SiC whisker reinforced Roland Karlsson, Ulf Lindstedt: "Feasibility study concern- alumina, L.X. Han, T. Hansson, S. Surcsh and R. ing powder metallurgical processing of bearing balls", Warren, Proc. 5th SSMS, eds. I. Hansson and H. 1992. Lillholt, (Danish Society for Materials, Copenhagen, 1989) pp. 287-294. Lisa Nilsson, "Wetting of ZtOi by a Ag-Cu-Ti braze", 1992 12. Surface reactions during the hot isostatic pressing of 12%Cr steel, L. Nyborg, Proc. 5th SSMS, New Reports and articles Materials and Processes, eds. I. Hansson and H. 1. Wetting of silicon nitride with selected metals and Lilholt, (Danish Society for Materials, Copenhagen, alloys, L. Ljungberg, R. Warren, Ccram. Eng. Sci. 1989) pp. 485492. Proc., 10,1989, pp. 1655-1666. 13. Reactions between SiC>2-bindcr and matrix in 8-AI2O3/ 2. Surface analysis of ultrasonically gas atomized Al-Mg composites, C-H. Li, L. Nyborg, S. Bengtsson, aluminium and aluminium powders, I. Olcfjord and A. R. Warren and I. Olefjord, Proc. Conf. IPCM, Ed. Nylund, Int. J. Rapid Solidification,!, 1989, p. 271. Jones, (Bultcrworths, 1989) pp. 253-257.

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14. lnicrcomparison of surface analysis of thin aluminium 28. A novel method for identifying phases formed in oxide films, I. Olefjord, HJ. Maihicu and P. Marcus, brazed and soldered joints, L. Ljungberg, R. Warren Surf. Interface Anal., J5_, 1990. andC-H.Li,J.MaLSci. Letters, 2,1990, pp. 1316-1318.

15. Microstnicture and properties of squeeze cast alumina 29. Influence of cold deformation on the near-threshold fibre reinforced aluminium composites, R. Warren, fatigue crack growth in fine-grainedDP-slccls , J. COST 504 Report. Wasén and B. Karlsson, Proc. 4th Intern. Conf. Fatigue and Fatigue Thresholds, Fatigue '90, ed. H. Kitagawa 16. Titanium exposed in water-saturated bentonite clay: and T. Tanaka, (Engineering and Materials Advisory exposures ranging up to six years H. Mattsson, SKB Services, Warley, 1990) pp. 1437-1443. Technical Report, 1989. 30. The relation between fracture surface geometry and 17. Electrochemistry of chromium in acidic chloride crack closure in fatigue, J. Wascn and B. Karlsson, solution, L. Bjönkvist and I. Olefjord Corrosion Proc. 4th Intern. Conf. Fatigue and Fatigue Thresholds, Science, 22,1991, p. 231. Fatigue '90, Ed. H. Kitagawa and T. Tanaka, (Engi- neering and Materials Advisory Services, Warley, 18. Surface analysis of passive state, I. Olefjord and L. 1990) pp. 1289-1294. Wcgrelius, 6th Int Symp. on Passivity, Sapporo, Japan, 1989, in Corrosion Science, 21,1990, p. 89. 31. Surface analysis of water-atomized austcnitic stainless steel powder, L. Nyborg, T. Tunberg, P.X. Wang and I. 19. Theoretical calculation of the inverse logarithmic oxide Olefjord, Proc. World Conf. Powder Metal!. PM90, growth law on titanium, H. Mattsson, to be published (The Instituc of Metals, London, 1990), 2, pp. 199-203. in Corrosion Science 1990. 32. Reaction products on metal powder surfaces and 20. Properties and metallurgical aspects of tungsten-wire interfaces, L. Nyborg, M. Norell, T. Tunberg and I. reinforced metals, R. Warren, Chapter XVIII in "The Olefjord, Proc. Colloq. Controlling the Properties of metallurgy of doped/non-sag tungsten", ed. E. Pink and PM Parts through their Microstructurc, (.French L. Barta, (Elsevier, Barking, England, 1989). Metallurgical Soc., Paris, 1990), pp. 25.1-25.6.

21. Metal matrix composites for structural applications, R. 33. Geometrical quantification of fracture surfaces and its Warren, Chapter in Advanced Materials Technology significance in fatigue studies, B. Karlsson and J. Wasén, International 1990. Proc. 4th Intern. Conf. Fatigue and Fatigue Thresholds, Fatigue '90, cd. H. Kitagawa and T. Tanaka, (Engi- 22. Fibre reinforced aluminium and supcralloy-bascd neering and Materials Advisory Services, Warley, composites, R. Warren, Chapter in Advanced Materials 1990), pp. 279-284. Technology International 1990. 34. Fatigue crack growth in a microduplex stainless steel, 23. Analysis of oxide formed on Ti during exposure in J. Wasén, B. Karlsson and M. Nyström, Proc. 4th Intern. bentonite clay; I. The oxide growth H. Mattsson and I. Conf. Fatigue and Fatigue Thresholds, Fatigue '90, cd. Olefjord, Werkstoffe und Korrosion, 4J., 1990, p. 383. H. Kitagawa and T. Tanaka, (Engineering and Materi- als Advisory Services, Warley, 1990) pp. 1167-1172. 24. Analysis of oxide formed on Ti during exposure in bentonite clay; II. The structure of the oxide, H. 35. The fatigue crack growth characteristics and ils relation Mattsson, C.H. Li and I. Olefjord, Wcrkstoffc und to the quantitative fractographic appearance in a Korrosion, 4i, 1990, p. 478. paniculate AI 6061/SiC composite material, M. Levin, B. Karlsson and J. Wasén, TMS Publication "Funda- 25. ESCA calibration studies of titanium oxides and mental relationships between microstructurc and titanium hydride, H. Mattsson and I. Olefjord, to be mechanical properties of metal matrix composites", published in Surf. Interface Anal. (TMS, Warrcndalc, Pennsylvania, 1990) pp. 421439.

26. Surface characterisation of PM martensilic steel, L. 36. Influence of prcstrain and ageing on the ncar-ihrcshold Nyborg, M. Norell and I. Olefjord Proc. World Conf. crack growth in fine-grained dual-phase steels, J. Wasén Powder Metall. PM90, (The Institute of Mclals, and B. Karlsson, Intern. J. Fatigue,U, 1989, pp. 395405. London, 1990), 2, pp. 364-369. 37. Design requirements - Materials properties: A basis for 27. lntcrfacial interactions in fibre reinforced Al- and Mg- materials selection, U. BcngLson, B. Karlsson and D. alloys, R. Warren and C-H. Li Proc. ICCI-III, cd. Parsmo, Proc. 2nd Intcm. Symp. Materials Property Ishida, (Elsevicr, Barking, England, 1990), pp. 583-599. Data, Orlando, Nov. 1989, (ASTM STP 1106,1991), pp 230-251.

MATERIALS SCIENCE, 1993 225 ENGINEERING METALS

38. Surface composition of stainless steel during active 49. Influence of surface oxide character on the strength and dissolution and passivation, I. Olefjord and C. Clayton, stability of steel-epoxy joints, G. Wetter, L. Kozma and Iron and Steel Inst Japan Int., 31,1991, p. 134. I. Olefjord, to be published in Scand. J. of Metallurgy.

39. Microstruclurc and fracture behaviour of SiCw rein- 50. XPS - Qualitative and quantitative aspects, I. Olefjord, forced alumina, T. Hansson, R. Warren and J. Wasén, Invited lecture. Proc. The Application of Surface 1 lth Risö Symposium Met. Mads. Sci., (Risö National Analysis Methods to Environmental/Material Interac- Lab.,1990), pp. 327-332. tions, eds.D.R. Baer, C.R. Clayton and G.D. Davis, (".' he Electrochemical Soc. Corrosion Div., Pennington, 40. Surface characterization of a rapidly solidified NJ., 1991), p. 2. A^Mn^sCr powder before and after hot extrusion, Nylund and I. Olefjord, Proc. 7th Int. Conf. on Rapid 51. The influence of prcstraining and 475°C annealing on Quenching of Materials, Stockholm 1990, in Mat. Sci. the mechanical properties of a duplex stainless steel and Eng., Alii,1991, pp. 1139-1145. (SAF 2205), M. Nyström, B. Karlsson and J. Wasén, Proc. Stainless Steels '91, ed. K. Yokota, (The Iron Steel

41. Degassing of USGA-atomized Al5Mn6Cr powder after and Steel Institute of Japan, Tokyo, 1991), pp. 738-745. exposure to a humid atmosphere, A Nylund and I. Olefjord, Proc. 7th Int. Conf. on Rapid Quenching of 52. A catalogue of stcreological characteristics of selected Materials, Stockholm 1990, in Mat. Sci. and Eng., solid bodies, vol. 1, Polyhedrons, J. Wasén and R. A134.1991 .DP. 1225-1228. Warren, (Chalmers University of Technology, 1991).

42. Anisotropy effect in the fracture behaviour of a uniaxial 53. Surface analysis of four dental implant systems, I. hot pressed SiC whisker reinforced ceramic composite, Olcfjord and S. Hansson to be published in Int. J. of T. Hansson, R. Warren and J. Wasén, Proc. ECF-8, Oral and Maxillofacial Implants. (EMAS, Warley, UK, 1990), pp. 560-564. 54. In-depth analysis of passive films on Fc-Cr alloy by 43. Fractographic aspects on fatigue crack growth in potential-modulated UV-visible reflection spectroscopy, porous sintered steels, B. Karlsson, J. Wasén and I. N. Hara, I. Olefjord and K. Sugimoto, Proc. Int. Conf. Bcrtilsson, Proc. 8th Europ. Conf. Fracture, ed. D. on Stainless Steels, 1991,Chiba, ISU. Firrao, (Engineering and Materials Advisory Services, Warley, 1990) pp. 421-426. 55. Wetting and interactions between selected ceramics and Ni-base braze alloys, M. Holmström, L Ljungberg, 44. Fatigue crack growth properties of SAF 2205, J. Wasén, A. Warren and R. Warren, Proc. 4th Int. Symp. Ceramic B. Karlsson and M. Nyström, Proc. Mechanical Proper- Materialsand Components for Engines, cd. R. Carlsson, ties of Stainless Steels, eds. H. Nordberg and K. (Elscvicr, Essex, England, 1991). Fernhcden,(Jemkontoret, Stockholm, 1990) pp. 122-135. 56. Principles of preparation of ceramic composites, R. 45. Paniculate ceramic matrix composites, R. Warren and Warren and R. Lundberg, Chap. 3 in 'Structural Ceramic V. Sarin, Chap. 6 in 'Introduction to Structural Ceramic Composites', ed. R. Warren, (Blackic, Glasgow, 1991). Composites', ed. R. Warren, (Blackie, Glasgow, 1991). 57. Fundamental aspects of the properties of ceramic matrix 46. The influence of SiC particle distribution and »restrai- composites, R. Warren, Chap. 4 in 'Svuclural Ceramic ning on fatigue crack growth rates in an aluminium AA Composites', ed. R. Warren, (Blackie, Glasgow, 1991). 6061/SiC composite material, M. Levin and B. Karlsson, Materials Science and Technology, 2,1991, 58. Overview, Chap. 1 in 'Structural Ceramic Composites', pp. 596-607. R. Warren, Ed. R. Warren, (Blackie & Son, Glasgow, 1991). 47. The mechanical properties of a duplex stainless steel M. Nyström, B. Karlsson and J. Wasdn, Proc. Mechani- 59. Hardness friction and fracture behaviour of AI2O3- cal Properties of Stainless Steels, eds. H. Nordberg and SiCw up to 1500cC, C.A. Brookes, P. Green, T. K. Fcrnheden,0emkontoret, Stockholm, 1990) pp. 70-87. Hansson and R. Warren, J. Hard Materials, 1(3), 1991, pp. 183-199. 48. Surface product formation during water atomisation and sintering of austenitic stainless steel powder, L. 60. Fracture toughness anisotropy and toughening mecha- Nyborg, T. Tunberg and P.X. Wang, Metal Powder nisms of a hot-pressed alumina reinforced with SiC- Report, Nov. issue. 1990, pp. 751 -754. whiskers, T. Hansson, R. Warren and J. Wasén, to be published in J. Amcr. Ccram. Soc.

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61. Thickness determination of surface oxides on metal 72. Enhanced vacuum sintering of water-atomized powder by AES depth profiling, M. Norell, L. Nyborg, austenitic stainless steel powder by carbon addition, T. Tunberg and I. Olefjord, Surf. Interface Anal., 12, Proc. of 1992 World Conf. on Powder Metall. "Ad- 1992, pp. 71-76. vances in Powder Metallurgy and Paniculate Materi- als", (MPIF, Princeton, NJ., 1992) pp. 383-395. 62. Surface studies of powder metallurgical stainless steel, L. Nyborg, M. Norell and I. Olefjord, Surf. Interface 73. Fracture strength testing of fibres with variable Anal., J2,1992, pp. 607-614. diameter and length - 5-alumina fibres, A.S. Kim, S. Bengtsson and R. Warren, to be published. 63. Fatigue crack growth of duplex stainless steels, M. Nyström, B. Karlsson and J. Wasén, Proc. Duplex 74. Tensile behaviour of squeeze cast and forged short Stainless Steels '91, Les Editions de Physique, (Les alumina fibre reinforced AA 6061, S. Bengtsson and R. Ulis Cedex, France, 992) pp. 795-802. Warren, to be published.

64. Iron aluminides - intcrmetallic materials for high- 75. Reactions during atomization of martensitic steel, M. temperature use, C-H. Li, R. Warren and I. Olefjord, Norell, L. Nyborg and I. Olefjord, Proc. of 1992 World Report 651/91, Dep of Engineering Metals, 1991. Conf. Powder Metall. "Advances in Powder Metallurgy and Paniculate Materials", (MPIF, Princeton, NJ., 65. Low cycle fatigue of discontinuously reinforced metal 1992) pp. 41-54. matrix composites, M. Levin and B. Karlsson, Proc. 5th European Conf. on Composite Materials, eds. A.R. 76. Forming of components starting from metal powder, I. Bunsell, JJ\ Jamct, and A. Massiah, (Bordeaux, April Olefjord, NUTEK-report, project 91-00527,1992. 1992) pp. 561-569. 78. Oxidation of Aluminium in dry and humid atmosphere 66. Surface reactions during production of PM austenitic studied by ESCA and SEM, A. Nylund and I. Olefjord, stainless steel, L. Nyborg, T. Tunberg, I. Olefjord, C.X. to be published in Surf. Interface Anal. Liu, P.X. Wang, Swedish-Chinese symposium, Oct., 1992, Sanya, China. 79. ESCA analysis of AI2O3 formed on Al under space charging conditions, I. Olefjord and A. Nylund, to be 67. Wetting and chemical interactions of selected ceramics published in Surf. Interface Anal. and superalfoys with a Ag-Cu-Ti active braze alloy, L. Ljungberg, K. Warren and L. Pejryd, to be published. 80. Silicides as potential structural materials for high temperature applications, C.H. Li, R. Warren, I. 68. High temperature fracture of a SiC whisker reinforced Olefjord and L. LÉstrade, Report 680/92, Dep. of alumina in air and vacuum, T. Hansson, A.H. Swan Engineering Metals. and R. Warren, to be published. 81. Fatigue behaviour of a Saffil reinforced aluminium alloy 69. Determination of attenuation lengths of photoelcc trons (AA6061), M. Levin and B. Karlsson, Composites in Al and Al oxide by angledependcnt X-ray photo- January 1993. electron spectroscopy, P. Marcus, C. Hinnen and I. Olefjord to be published in Surf. Interface Anal. 82. Crack initiation and growth during low cycle fatigue of discontinuously reinforced metal matrix composites, 70. Electrochemical and surface analysis of stainless steels M. Levin and B. Karlsson, 1992, Submitted to Intern. exposed to hydrochloric acid, L. Wcgrelius, to be J .Fatigue. published.

71. Microstructure of Ag-Cu-Ti brazed joints between S13N4 and a nickel alloy, L. Ljungberg, L. Pejryd and R. Warren, to be published.

MATERIALS SCIENCE, 1993 227 Microscopy and Microanalysis

Research Summary Staff Research in the Division is concerned with develop- Senior Members ing and improving understanding of the fine scale Anders Thölén professor microstructure of technologically important materi- Hans Norden t.f. professor als. Of importance here is understanding how micro- Hans-Olof Andrén docent structure, down to atomic scale, can be manipulated Lena Falk docent by variation of process variables such as composi- Colette O'Meara tekn. dr. tion, solidification rate, sintering schedules, deposi- Eva Olsson tekn. dr. tion conditions and heat treatment. Of equal impor- Krystyna Stiller tekn. dr. tance is the role which microstructure plays in deter- Graduate Students mining materials properties. José Alarco (B. Se.) The main research tools that have been used are Håkan Björklund (civ.ing.) analytical electron microscopy and atom-probe field Cai Guangjun (M. Se.) ion microscopy. Use has also been made of SIMS Mats Halvarsson (civ. ing.) and Scanning Auger Spectroscopy. Scientists and Maria Knutson-Wedel (civ.ing.) research students within the Division have collabo- Anders Kvist (civ.ing.) rated with many industries and other research groups, Zonghe Lai (M. Se.) both within and outside Chalmers, in order to obtain Per Lindahl (civ. ing.) a complete picture of relationships between process- Ros-Marie Lundh (civ. ing.) ing conditions, microstructure and properties. Lars Lundin (civ. ing.) Types of materials which have been investigated Lars Mattsson (civ.ing.) include: cemented carbides, CVD coatings, high Bengt Olsson (civ. ing.) speed steels, stainless steels, low alloy weld metals, Hu Qiuhong (M. Se.) cast aluminium alloys, rapidly solidified aluminium Bertil Stenbom (fil. kand.) alloys, copper alloys, cast iron cylinder liners, Mattias Thuvander (civ ing) zircalJoy, silicon nitride, zirconia toughened ceram- Boel Wadman (tekn. lic.) ics, metal matrix composites, ceramic composites, zinc oxide varistors, GaAs hetero-structures and Technical Staff high-Tc superconductors. In all cases the emphasis Eduard Guttenberg has been upon a fundamental understanding of micro- Eva-Britt Sjoqvist structure, its manipulation and its importance in Secretary determining the properties of materials Marita Ahlkvist

Address Major Instrumentation Department of Physics • Anew200kVTEM/STEMwithaFEG(field Chalmers University of Technology emission gun)will be installed during 1994 S-41296 Göteborg, Sweden • 200kVTEM/STEM/EDX: JTOL2000FX Phone+46 31 772 3206 • lOOkVTEM: two Philips EM 300 Fax+46 31 165176 • 100 kV STEM/EDX/EELS: VG HB501 (This instrument belongs to Volvo but the Division has full use of it.) • SEM/EDX: CAMSCAN S4-80DV

228 THE CENTRE FOR MICROSCOPY AND MICROANALYSIS

• X-ray diffractometer (H Kreutzer), ESAB AB, Göteborg (L-E Svensson, • Atom-probe field ion microscope (A-PFIM) L Karlsson), Institute of Theoretical and Experi- • Imaging atom-probe field ion microscope (A mental Physics, Moscow (A Suvorov), Max-Planck second A-P FIM is under construction.) Institut fur Metallforschung, Stuttgart (H Fisch- • Specimen preparation: meister, S Karagöz), AB Sandvik Coromant, Stock- diamond cutting machines holm (C Chatfield, U Rolander), AB Sandvik Steel, spark cutting machine Sandviken (T Andersson, A-L Lundström), Seco grinding, polishing facilities TooisAB,Fagersta(HJonsson,TMainert),Studsvik electro-chemical polishing lab AB, Nyköping (K Norring), Vattenfall Bränsle, 3 ion beam thinning machines Stockholm (H Pettersson). • Fully equipped photo-processing lab Contact persons for microstructural investigations: Hans Norden, Research Projects Metals: Hans-Olof Andrén and Krystyna Stiller, Ceramics: Lena Falk and Colette O'Meara, A: Electron Microscopy Studies Electric materials: Eva Olsson. of Materials

Al: SI3N4 Based Ceramic Materials Major Fields of Research Formed by HIP Work carried out within this project has demon- A: Electron Microscopy Studies of Materials strated that it is possible todesign the microstructure Participants: José Alarco, Håkan Björklund, Lena of a Si3N4 ceramic material to a given combination Falk,CaiGuangjun, Mats Halvarsson, MariaKnutson- of properties. The materials have been formed by Wedel, Lai Zonghe, Ros-Marie Lundh, Lars Lundin, glass encapsulation followed by hot isostatio press- Lars Mattsson, Hans Noidén, Eva Olsson, Bertil ing (HIP) at Sandvik Hard Materials. Particular Stenbom, Krystyna Stiller attention is paid to the effect of different types of Collaborators: Avesta AB, Avesta; Elektrolux Mo- metal oxide sintering additives, as well as to how tor AB; Swedish Ceramic Institute, Göteborg; De- amount and type of oxide sintering aid control grain partment of Applied Physics, CTH; Department of morphology and intergranular microstructure of the Engineering Metals, CTH; Departmentof Inorganic SJ3N4 ceramic. The results from analytical electron Chemistry, University of Stockholm; Heraeus microscopy (SEM/TEM/STEM/EDX) and x-ray Asalmaz Katalysator Gmbh, Swedish Institute for diffractometry are related to mechanical properties, Metals Research, Stockholm; Norsk Hydro, i.e. fracture toughness, room temperature and high Porsgrunn, Norge; Sandvik Hard Materials, Stock- temperature strength and hardness. holm; AB Sandvik Steel, Sandviken; Statens References: 5,7,9,11,12,15,17,18,21,23 Teknologiska Institut, Oslo, Norge; SECO Tools AB, Fagersta, AB Volvo, Göteborg; Volvo TU, A2: Microstructure and Oxidation Behaviour of Göteborg; Volvo Flygmotor, Trollhättan; SI3N4/Z1O2, Composite Ceramic Materials S12N4/71O2 composite ceramic materials have a B: Atom Probe Field lon Micioscopy high potential for improved mechanical properties, of Materials e.g. toughness and strength, at both high and low Participants: Hans-Olof Andrén, Cai Guangjun, Hu temperatures, as compared to conventional "single Qiuhong, Anders Kvist, Lai Zonghe, Per Lindahl, phase" SJ3N4 materials. The fine scale microstruc- Lars Lundin, Hans Norden, Krystyna Stiller, Boel tures of Si3N4/ZrO2 ceramics formed by different Wadman processes are characterized in detail by a combina- Collaborators: ABB Atom, Västerås (P Rudling), tion of analytical electron microscopy (SEM/TEM/ ABB Powdermet, Surahammar (A Salwén), ABB STEM/EDX) and x-ray diffractometry. Particular STAL, Finspång (S Fällman), Avesta AB, Avesta attention is given to the effect of other, simultaneous, (M Liljas), Dalhousie University, Halifax, Canada oxide additions upon the internal structure of the

MATERIALS SCIENCE, 1993 229 MICROSCOPY AND MICROANALYSIS

ZrC>2 grains and the intergranular microstructure. A6: Microstructural Development Following The microstructures of the different composites in Heat Treatment of ZiOS^tyO Composites the as-sintered state as well as after various oxidation and Y-SUU-ZrO* Glasses treatments are correlated to fabrication process and A considerable improvement in the mechanical prop- mechanical and chemical properties. erties of silicon based nitrogen ceramics can be References: 2,3,4,8,10,14,24,25 achieved through the addition of small quantities of stabilised Z1O2 particles to the ceramic matrix A3: Whisker Reinforced SI3N4 (dispersion toughening). This work examines the and AI2O3 Ceramics microstructure of as sintered ZrO2-Si2N2O com- Whisker reinforced ceramics may offer improved posites and Y-Si-Al-Zr-O-N glasses and their heat toughness and strength. The aim of this work is to treated (N2 and air) products. The aim of the project develop an improved understanding of the deve- is to identify heat treatment conditions for ZrC«2- Si2N2O composites which avoid the formation of lopment of the fine scale microstructures of Si3N4 and AI2P3 ceramics reinforced by different types of certain deleterious Zr-oxynitride phases and to exa- SiC whiskers. Particular attention is given to matrix mine the effect of Z1O2 additions on the crystallisa- morphology and matrix/whisker interface and these tion behaviour and products of Y-Si-Al-Zr-O-N features are related to variables in the formation glasses. process. Quantitative microscopy is used to charac- References: 30 terize the effect of different additives upon matrix grain size and shape, and the different microstruc- A7: Structural Deactlvation Phenomena tures are related to the mechanical properties of the In Heterogeneous Catalysis ceramics. Sintering of the noble metal particles is one of the major cause for decreased efficiency of supported References: 16,19,20,26 exhaust catalysts. The influence of temperature, A4: Liquid Phase Sintered SIC Ceramics time and atmosphere have been investigated by Addition of metal oxides e.g. AI2O3 and/or Y2O3 TEM and CO-TDS for a Pt/Alumina catalyst. The makes it possible to densify SiC by liquid phase initial sintering rate was found to be rapid in oxidative sintering. This project is concerned with phase reac- atmospheres (O2, NO) compared to in inert or redu- tions during densification, and the relationship be- cing ones (Ar, H2, CO). Different combinations of tween fine scale microstructure and physical proper- noble metals (Pt, Rh) and supports (Alumina, Ceria) ties. The SiC ceramics are formed by pressureless will also be investigated. sintering or hot isostatic pressing. References: 31-34

A5: Mlcrostructural Investigation of Corrosion/ A8 Relations Between Processing Parameters, Oxidation of Engineering Ceramics Micro Structure and Performance Si3N4 and SiC ceramics are the most promising for CVD Coated Cemented Carbides candidate ceramic materials for application in high Multi layer coatings (5-10 alumina layers) consist- temperature chemically severe environments such ing of sub layers of pure (X-AI2O3 and K-AI2O3 as heat engines, process equipment and cutting tool- respectively, have been deposited in a hot wall CVD set-ups. However, to date very little is known about reactor. To nucleate and grow a desired alumina mechanisms, kinetics or effects of chemical attack polymorph in each layer, thin modification layers in ceramic materials. The aim of this work is to were used between the alumina layers. quantify (by XRD, SEM/TEM/STEM/EDX) the In this project the interfacial structure of the effect of well controlled corrosion experiments on modification and the alumina layers are being stu- the microstructure and thereby the mechanical pro- died. Features of the microstructure such as defects, perties of S13N4 and SiC based materials. Special pores at interfaces and orientation relationships are attention is being given to identifying the mecha- being characterised. The materials are examined nism^) of importance during corrosive attack of usingacombinationof XRD, SEM,TEM andEDX, these ceramics. although the major part of the analysis is carried out References: 27-29 by TEM of cross section specimens. References: 106-108

230 THE CENTRE FOR MICROSCOPY AND MICROANALYSIS

A9: Microscopic Wear and Deformation ducting thin films are separated by layers that are Mechanisms in Fretting either metallic, semiconducting, or insulating. The An all metal fretting rig of new design has been properties of the thin layers are significantly influ- completed and mounted in an oil-free environment enced by the interfaces and the behaviour thus differs in a vacuum chamber, where the ambient atmos- from that of bulk materials. The multilayers there- phere can be varied. Ni is being used as a model fore provide the possibility to control and modify the material and microscopic techniques including trans- physical characteristics. The microstructure is the mission electron microscopy (TEM) arc used to key to the understanding these structures. The micro- characterize the damage. structures are studied as a function of fabrication A preparation technique has been developed for parameters. The data provide a source of knowledge TEM specimen where a plated layer is used to forfuture need to control and to make new structures protect the original fretting surface and also retain with predetermined properties. the fretting debris. Using this method cross section References: 36-62 specimens can be prepared, which allow characte- rization of the subsurface structure from all four damage regions. B: Atom Probe Field Ion Microscopy - A: a central contact region, where sticking is of Materials dominant - B: a transition region Bl: Microstructure of Creep Resistant - C: a slip region 12XrChromfum Steels - D: an outer region, where most of the debris is A new class of creep resistant chromium steels, collected made by powder metallurgical methods, is at present Dislocation movement produces a nearly equiaxed oeing developed for use at 600"C. The materials cell structure in the central part of Region A, whereas studied have been given different additions of the the cell structure becomes more elongated towards strong carbide formers (Mo, W, V, and Nb). The the edge. The length to width ratio of the cells dominating mechanism of creep resistance in these increase in Region B and their orientation change. alloys is probably due to a fine precipitation of MC- The initiation of fatigue cracks was observed here. type carbides. We are studying the microstructure of A very fine scaled, elongated cell structure develops two alloys with different composition using atom in Region C probe analysis and transmission electron microscopy, in particular the composition of very small preci- AID: Election Microscopy Studies pitates. of High Temperature Superconductors References: 73,75,76 The electron microscopy of the high temperature superconductors is mainly concerned with epitaxial B2: Microstructure of Weld Metal thin films. The aim of the research is to characterise in Chromium Steels the fine scale microstructure and to relate it to the The microstructure of weld metal of chromium- superconducting behaviour. Grain boundaries play molybdenum steels (5, 9 and 12% Cr) is being an important role in determining the properties and studied both as welded and after post-weld heat special attention is therefore paid to both grain treatment at 750*C, using electron microscopy and boundaries and other types of interfaces. The grain atom probe analysis. The toughness of 12% Cr weld boundaries may act as weak links limiting the critical metal may be rather poor because of precipitation of current density where the detailed behaviour of the large carbides at phase boundaries. Attempts to individual boundary dependson thefine scale micro- modify the composition of the weld metal did not structure. Each basic study of a specific pheno- diminish precipita.ion; however introduction of an menon and each application requires a well defined intercooling treatment to restrict the amount of re- boundary structure that can be fabricated repro- tained austenite and its subsequent eutectoid de- ducibly. In some studies it is necessary to avoid the composition was found to improve toughness con- formation of boundaries. In addition,most structures siderably. requires multilayer structures where the supercon- References: 88-92

MATERIALS SCIENCE, 1993 231 MICROSCOPY AND MICROANALYSIS

B3: High Speed Steels behaviour of the materials. Our work on the microstructure of high speed steels References: 98-101 has continued with studies of overtempering at 600*C in collaboration with Max-Plarick-Jnstitute B6: Mechanisms of Zircaloy Corrosion in Steam fur Metallforschung in Stuttgart. The purpose was to In Zircaloy (Zr-Sn-alloys with small additions of Fe, simulate the behaviour of high speed steel tools Cr, and sometimes Ni) intermetallic precipitates during service. For about 100 minutes the as tem- form during manufacture, which leads to a depletion pered hardness remained high, although small M2C of alloying elements in the matrix between preci- precipitates coarsened during this time. This re- pitates. Using atom probe analysis we have meas- markable hot hardness of high speed steels was ured the extent of this depletion in materials with found to be due to a second wave of precipitation of different corrosion resistancei n 400*C steam. It was extremely small (1.5 nm) MC particles on dislo- found that depletion occurs extremely fast due to an cations, acting as very efficient obstacles against unusually high diff usivity and a low solubility of Fe, plastic deformation. Cr and Ni in Zircaloy. Thin foils of cross sections of Our previous work on the microstructure of high the metal-oxide interface are at present being studied speed steels has been published, and a review of all in the transmission electron microscope, in order to our results on the detailed microstructure of high understand the oxide growth mechanisms. speed steels has been made. References: 84-87 References: 71-74,77 B7: Phase Composition in Cemented Carbides B4: Duplex Stainless Steels The microstructcre of one series of commercial The austenite phase in nitrogen containing duplex cermets of the geneiu! formula (Ti, W, Ta) (C, N)- stainless steels was analysed with atom probe. The Ni-Co and two series of model cermet alloys are large hardening effect of nitrogen additions was being studied in detail using atom probe, transmis- found to be due to nitrogen-molybdenum cluster sion and scanning electron microscopy and X-ray formation in the austenite. Weld metal of duplex diffraction. The first series of model alloys has the stainless steels was heat treated in the temperature composition TiC - (0,10 and 20) vol.% TiN -10% interval 700-950'C, and the kinetics of the resulting Mo2C-(5andlO)%Ni-(10and5)%Coandisused precipitation of intermetallic phases (s, R and c) was to study the effect of a mixed binder phase. With the studied. It was found that the risk of embrittlement second series we will study the occurrence of heavy during normal welding conditions was small. A carbo-nitrides; these alloys have the composition silicon containing duplex stainless steel having high TiC - 20 vol.% TiN - 15% Ni - (10, 20 and 30)% strength, good ductility and high corrosion resis- M02C or WC. All cermet materials have carbo- tance was found to contain small nickel-titanium nitride grains with a core-rim structure, and the silicides in the ferritic phase. composition and compositional variation of these References: 68-70 and the binder phase reflect processes that take place during sintering (diffusion, dissolution, precipita- B5: Microstructure and Corrosion of Grain tion). The distribution of C and N is of particular Boundaries In Nickelbased Superalloys interest. The composition of grain boundaries in several References: 78-82 variants of two Ni-based superalloys, Alloy 600 and Alloy 690, has been measured using atom probe B8: Ordering and Segregation analysis and secondary ion mass spectrometry. in Hfgh-Tc Superconductors Segregation of C and B was found both after manu- The oxygen content of YBa2Cu3(>7_x superconduc- facture and after exposure to high purity water at tors determines the superconducting properties. For 365'C. Depletion of chromium was also observed 0

232 THE CENTRE FOR MICROSCOPY AND MICROANALYSIS erably, as the coherence length is only 0.3-1.5 nm. cally lower the recrystallization temperature of W, The boundaries will also be studied with atom probe. and it is believed that this effect is related to an As a first step, materials with controlled oxygen enhanced diffusivity of Ni and Pd in the grain content and a low porosity (as required for atom boundaries of polycrystalline W. probe analysis) are being prepared in collaboration References: 104,105 with Department of Inorganic Chemistry at Chalmers University. At the same time conditions are being B12: Instruments and Methods, Surface Science optimised for quantitative analyses of HTC super- Our atom probe instrument is being continuously conductors in the atom probe. improved. A new high voltage pulser has been References: 102,103 constructed, methods for correction of pile-up effect in the ion detector has been developed and installed, B9: Mlcroanafysls of Metal Contacts on GaAs and the energy dependence of the ion detector has Rectifying (Schottky) contacts of Au and Ag onto beed determined and compensated for. In a paper all GaAs, as well as ohmic contacts of AuGe on GaAs known factors affecting the accuracy of quantitative are being studied in atomic detail with atom probe. atom probeanalysis were treated. The effect of a high On an oxidised surface, Au and Ag form islands of electric field on the chemisorption of hydrogen was pure metal, whereas on an atomically clean surface studied, with the aim of finding operating conditions (prepared by field evaporation), Au forms an inter- to minimise hydrogen adsorption during atom probe mixed layer while Ag makes a sharp interface against analysis. The formation of molecular ions during GaAs. In the case of AuGe contacts on an oxidised field evaporation is being studied in collaboration surface, gold islandscovered by aGe rich oxide layer with theoretical physicists at Dalhousie University was formed. After heat treatment at 450"C a thin in Halifax, Canada. (6 nm) diffusion zone of high Ge concentration (3 References: 63-67 at%) into GaAs was observed. Ga was found to diffuse out through the gold layer and form an oxide film together with Ge. References: 93-97 Publications

BIO: Radiation Damage Ph.D. Dissertations Earlier work on heavy ion irradiation of W has been Jan Skogsmo, "Microstructurc of C VD Coaled Cemented Carbides", May 26 1989 published. In collaboration with the Institute of Theoretical and Experimental Physics in Moscow Göran Wahlberg, "The Role of Nitrogen in Duplex Stain- radiation enhanced solid solution and diffusion in less Steels", June 9 1989 Ta-2%U is being studied. References: 83 Jiyong Yao, "Transmission Electron Micrscopy of InxGal- xAs/GaAs Strained-Layer Structures", June 5 1990

Bll: Grain Boundary Structure Liu-Ying Wei, "Development of Microstruciurc in Cast and Segregation In W Magnesium Alloys", June 6 1990 The terms grain boundary diffusion and pipe diffu- sion, respectively, are frequently used to describe Ulf Rolander, "Atom-Probe Microanalysis of Cermets", enhanced diffusion effects but very little is known April 5 1991 about the mechanisms behind these phenomena at a 1 Håkan Swan," Microstructurc and Properties of Ceramic more fundamental leve . The object of this project is Matrix Composites", April 28 1992 therefore to study grain boundary segregation and diffusion on an atomic level and in particular to investigate the correlation between these effects and Licentiate Dissertations the related grain boundary structure. Thomas Hermansson, "Supcrplastic Deformation of Pure W doped with small amounts of Ni or Pd is Zirconia",May31 1989 used as a model material. It is well known that the Bocl Wadman, "Matrix composition in Zircaloy", Decem- presence of small amounts of these elements drasti- ber 15 1989

MATERIALS SCIENCE, 1993 233 MICROSCOPY AND MICROANALYS1S

Bertil Josefsson, "Microscopy and Microanalysis of 4. "Microstructural development during processing of an Bainitic Weld Metal", December 11989 Si3N4/ZrO2 material'', L.K.L. Falk and M. Holmström, in Euroccramics, edited by G. de With, R.A. Terpstra Maria Knutson-Wedel, "The Microstructure of Hot andR.Metselaar(Elsevier, 1989) pp. 1.373-1.377. Isostatically Pressed S13N4 Ceramics", May 14 1991 5. "Microstructures of S13N4 ceramics formed by HIP", José Alarco, "Interfacial Microstructure of YBaqCu-jOi^ E.M. Knutson, L.K.L. Falk and T. Ekström, in Euro- High Tc Superconductors", January 18 1993 ceramics, edited by G. de With, R.A. Terpstra and R. Metselaar(Elsevier, 1989) pp. 1.416-1.420.

Diploma Work 6. "Atom Probe Analysis of Zircaloy Needles", B. Jan Andersson, "Metoder för bestämning av tjocklek och Wadman, H.-O. Andrén and L.K.L. Falk, J. Physique struktur hos manganfosfatskikt", 1989 50(1989)C8-3O3-3O8.

Pontus Jonsson, "Mikrostrukturen hos ZrOj-förstärkt 7. "Pressureless Sintered Si3N4-ZrO2 Composites with kiselnitrid framställd genom HIP", 1989 AI2O3 and Y2O3 Additions", T. Ekström, L.K.L. Falk and E.M. Knutson-Wedel, J. Mater. Sci. Letters 9 Mikael Kall, "Inverkan av metanol på tribosystemet (1990)823. kolvring-cylinderfoder", 1989 8. "Microstructure and Oxidation Behaviour of S13N4/ Jörgen Wulfsberg, "Mikrostrukturen hos martensitiska 12% Z1O2 Ceramics", L.K.L. Falk, in proceedings of the kromstål', 1989 11 th International Ris0 Conference "Structural Ceram- ics - Processing, Microstructure and Properties", edited Per Lindahl,"Atomsondsanalys av bindefasen i TIC.TiN/ by J J. Bentzen, J.B. Bilde-Sorensen, N. Christian, A. Co", 1989 Horsewell and B. Ralph, (Ris0 National La'joratory, Roskilde, Denmark, 1990) pp. 277-282. Per-Åke Eliasson, "Inverkan av värmebehandling och kiselhalt pä mikrostrukturen hos Zircaloy-4", 1990 9. "Microstructure and Properties of S13N4 Ceramics Formed by HIP using Different Oxide Additives", Lars Lundin, "Undersökning med atomsond och elektron- E.M. Knutson-Wedel, L.K.L. Falk and T.Ekström, in mikroskop av ett nyu martensitiskt 12%-kromstål", 1990 proceedings of the 11 th International Ris0 Conference "Structural Ceramics - Processing, Microstructure and Mats Halvarsson, "Fretting of Nickel", 1990 Properties", edited by J J. Bentzen, J.B. Bilde- Sorensen, N. Christian, A. Horscwcll and B. Ralph, Anne Bokedal och Herman Heijmans,"Gränszoncn mellan (Ris0 National Laboratory, Roskilde, Denmark, 1990) göt av dentallegeringar och solida metallelement", 1991 pp. 377-382.

Magnus Persson, Titanbunden keramik", 1992 10. "Development of Microstructure in an Si3 Composite Ceramic Material", in "Advanced Structural Lars Bengtsson, "Utskiljning av intermetalliska fasa i ett Inorganic Composites", L.K1. Falk, edited by P. duplext rostfritt svetsgods", 1992 Vincenzini (Elsevier, Amsterdam, the Netherlands, 1991) pp. 169-178. Gunnar Barrvik, "A Device for Cyclic Fatigue of Ceramic Materials Inside a Scanning Electron Microscope", 1992 11. "Si3N4 Ceramics Formed by HIP using additions of ZrO2", E.M. Knutson-Wedel, L.K.L. Falk and T. Ekström, in "Ceramics Today - Tomorrow's Ceram- Reports and articles ics", edited by P. Vincenzini (Elsevier, Amsterdam, The Netherlands, 1991) pp. 1347-1356. 1. "The microstructure of a Bi-Ca-Sr-Cu-0 high Tc superconductor produced by rapid solidification", Ing 12. "Si3N4-ZrO2 Composites with Small AI2O3 and Y2O3 Liu, M. Knutson, Zhi-yi Liu, E. Olsson and G.L. Additions - Prepared by HD»", T. Ekström, L.K.L. Falk Dunlop, Super cond ScTechnol. 1 (1989) 254-259. and E.M. Knutson-Wedel, J. Mater. Sci. 26 (1991) 4331. 2. "The microstructure of S13N4 and Z1O2 based ceramic 13. "Elemental concentration profiles in an oxidised S13N4 materials and the effect of oxidation", Lena KL. Falk, material", L.K.L. Falk and E.U. Engström, J. Am. STU final report nr 86-3348, March 1989. Ceram. Soc. 74[9] (1991) 2286-2292.

3. "Microstructures of hot-pressed Si3N4/Zr02(+Y2O3) composites", L.K.L. Falk, T. Hermansson and K. Rundgren, J. Mater. Sci. Utters 8 (1989) 1032-1034.

234 THE CENTRE FOR MICROSCOPY AND MICROANALYSIS

14. "Microstructure and short term oxidation of hot- 23. "Zirconia Doped Silicon Nitride Ceramics", T. pressed Si3N4/ZrO2 (+Y2O3) ceramics", L.K.L. Falk Ekström, L.K.L. Falk and E.M. Knutson-Wcdel. in and K. Rundgren, J. Am. Ceram. Soc. 75[1] (1992) "Ceramics, adding the value: AUSTCERAM 92", 28-35. edited by M J. Bannister (CSIRO Publications, Melbourne, 1992) pp. 510-516.

15. "Si3N4 Ceramics formed by HIP using Different Oxide Additions - Relation between Microstructure and 24. "Microstructural Development of Si3N4 Ceramics ftnperties", E.M. Knutson-Wedel, L.K.L. Falk, H. Formed with Additions of ZrC^", L.K.L. Falk, to be Björklund and T. Ekström, J. Mater. Sci. 26 (1991) published in Materials Forum. 5575-5584 25. "Intergranular Microstructure and Oxidation Behaviour 16. "Microstructure and Mechanical Properties of Hot of Si3N4 Ceramics Formed with Y2O3, AI2O3 and Isostatically Pressed Whisker Reinforced Si3N4 Z1O2", L.K.L. Falk, E.U. Engström and K. Rundgren, Ceramics", L.K.L. Falk, H. Björklund, J.E. Adlerbom to be published in the proceedings of the MRS sympo- and H.T. Larker, in "Proceedings of the 4th Interna- sium "Silicon Nitride Ceramics - Scientific and tional Symposium on Ceramic Materials & Compo- Technological Advances", Boston, November 30 - nents for Engines", edited by R. Carlsson, T. Johansson December 4,1992. and L. Kahlman (Elsevier, London, 1992) pp. 699-706. 26. "Grain Morphology and Intcrgranular Structure of 17. "Effect of Intergranular Microstructure on Properties of S13N4 Based Ceramics Formed by HIP", H. Björklund, SijN4 Based Composite Ceramic Materials", E.M. L.K.L. Falk, J. Wasén, J.E. Adlcrbom and H.T. Larker, Knutson-Wedel, L.K.L. Falk and T. Ekström, in to be published in the proceedings of the MRS sympo- "Proceedings of the 4th International Symposium on sium "Silicon Nitride Ceramics - Scientific and Ceramic Materials & Components for Engines", edited Technological Advances", Boston, November 30 - by R. Carlsson, T. Johansson and L. Kahlman December 4,1992. (Elsevier, London, 1992) pp. 244-251. 27. "The rate controlling processes in the oxidation of 18. "Microstructure and Mechanical Properties of S13N4 HIPcd Si3N4 with and without sintering aids", J. Chen, Based Ceramics", E.M. Knutson-Wedcl, L.K.L. Falk J. Sjöberg, C. O'Meara and L. Pcjryd, J. Eur. Ceram. and T. Ekström, to be published in the proceedings of Soc., 7,319-327, (1991). the European Ceramic Society Second Conference,

Augsburg, Germany, September 11-14,1991. 28. "Corrosion behaviour of HIPed Si3N4 and a SiC/SiC Composite in Simulated Combustion Environments", 19. "Microstructure and Mechanical Properties of Un- J. Chen, J. Sjöberg, C. O'Meara and L. Pejryd, Proc. of Doped and Low-Doped Whisker Reinforced S13N4 the 4th Int. Symposium on Ceramic Materials and Ceramics Formed by HIP', L.KL. Falk, H. Björklund, Components for Engines, Gothcnburgh 1991, in press. J.E. Adlerborn and H.T. Larker, to be published in the proceedings of the European Ceramic Society Second 29. "The changes in the oxide scale formed on coroding Conference, Augsburg, Germany, September 11-14, non-oxide ceramics", J. Chen, J. Sjöberg, C. O'Meara 1991. and L. Pejryd, Proc. of the 2nd European Ceramic Society Conference (ECerS'91), Augsburg 1991, in 20. "Development of Microstructure in Hot Isostatically press. Pressed AI2Q3 - SiC Whisker Composites", H. Björklund, LKL. Falk, L. Björk and H.T. Larker, to 30 "The effect of Yttria Additions on the Composition of be published in the proceedings of the European Sialons prepared by Pressurclcss Sintering", J. Sjöberg, Ceramic Society Second Conference, Augsburg, C. O'Meara and R. Pompe, accepted for publication in Germany, September 11-14,1991. J. Eur. Ceram. Soc.

21. "Characterization of SijN4 Ceramics Formed with 31. "Thermal Deactivation of a Three-Way Catalyst: Different Oxide Additives", E.M. Knutson-Wcdel, Changes of Structural and Performance Properties", B. L.K.L. Falk and T. Ekström, J. Hard Materials 3 [3-4] Stenbom, G. Smedler, P.H. Nilsson, S. Lundgren, and (1992)435^45. G. Wirmark, SAE Technical Paper Series 900273,1990.

22. "Hislological and Chemo-Morphological Studies of 32. "Structural Deactivation of a Three-Way Catalyst", B. Deciduous Enamel in Amelogenesis Imperfecta", B. Stenbom, P. Lööf, and H. Norden, Micron and Micro- Bäckman, T. Lundgren, E.U. Engström, L.KL. Falk, scopica Acta22,1991, pp. 177-178. J.M. Chabala, R. Levi-Setti and J.G. Norén, accepted for publication in Scand. J. Dent. Res.

MATERIALS SCIENCE, 1993 235 MICROSCOPY AND MICROANALYSIS

33. "Sintering of P1/AI2O3 Catalyst in Oj, CO, NO and 44. "YBCO thin films on yttria stabilised zirconia and CO+NO atmospheres", B. Stenbom, P. Lööf, and H. LaAK>3: growth and properties", J.A. Alarco, G. Norden, Micron and Microscopica Acta 23,1992, pp. Brorsson, T. Claeson, Z.G. Ivanov, M. Lofgrcn and 221-222. P.Å. Nilsson, Physica C 185-189, (1991) 2017-2018.

34. "Characterization ofaPt-Pd combustion catalyst on an 45. "Properties of artificial grain boundary weak links alumina washcoat, with and without prior hydrothcrmal grown on Y-Z1O2 bicrystals", Z.G. Ivanov, P.Å. treatment of the washcoat", M. Skoglundh, L.O. Nilsson, D. Winklcr, I.A. Alarco, G. Brorsson, T. Löwcndahl, P.G. Menon, B. Stenbom, JP. Jacobs, O. Claeson, E.A. Stepantsov and A. Ya. Trrfenchuk, van Kcssel, and H.H. Brongcrsma, Catalysis Letter 13, Supcrcond. Sci. Technol. 4, (1991)439-441. 1992, pp. 27-38. 46 "Weak links and dc-SQUIDs on artificial nonsymmetric 35. "Development of interfacial microstnjcturc during grain boundaries in YBa2Cu3O7d", Z.G. Ivanov, P.Å. cooling of a ZnO varistor material", E. Olsson, R. Nilsson, D. Winkler, J.A. Alarco, T. Claeson, E.A. Österlund and CL. Dunlop, J. Appl. Phys. 66 (1989) Stepantsov and A.Ya. Tzalenchuk, Appl. Phys. Leu. 59 5072. (23), (1991) 3030-3032.

36. "Intcrfacial Microstructurc in YBa2Cu3O7^ High Tc 47. "Very thin YBaCuO films made by coevaporation", M. Superconductors", J.A. Alarco and G.L. Dunlop, Danerud, P.Å. Nilsson and J.A. Alarco, E-MRS, Colloque dc Physique, supplement au n° 1, tome 51, Strasbourg, France, May 1991. (I990)Cl-959-964. 48. "YBaCuO thin films on Yttria-stabilised-Zirconia: 37 "Study of in situ laser deposited YBCO thin films", G. growth and properties", J.A. Alarco, G. Brorsson, T. Brorsson, J.A. Alarco, Z.G. Ivanov, H. Olin, P.Å. Gaeson, Z.G. Ivanov, M. Löfgrcn and P.Å. Nilsson, E- Nilsson and T. Claeson, J. Less-Common Metals 164 MRS, Strasbourg, France, May 1991. & 165,(1990)383-390. 49. "Properties of Artificial Grain Boundary Weak Links 38. "The interfacial microstructurc of SiC-whisker rein- Grown on Y-Z1O2 Bicrystals", Z.G. Ivanov, P.Å. forced Si3N4", A.H. Swan, E. Olsson, R. Lundberg and Nilsson, D. Winkler, J.A. Alarco, G. Brorsson, T. G.L. DunlopJ. Phys. 51 (199O)C1-1O43. Clacson, E.A. Stcpansov and A.Ya. Tzalenchuk, presented at the Third International Superconducting 39. "Transport critical currents and microstructurc of Electronic Conference (ISEC 91), Glasgow, Scotland, yttrium barium cuprate", D.A. Smith, D.R. Clarke, June 25-27,1991. M.F. Chisholm, P.E. Balson and E. Olsson, Proceed- ings of the Xllth Congress for Electron Microscopy, 50. "Observation of a vortex glass phase in polycystalline San Fransisco Press, Inc., 32,1990. YBa2Cu3O7.d in a magnetic field", T.K. Worthington, E. Olsson, CS. Nichols, T.M. Shaw and D.R. Clarke, 40. "Hctcrocpitaxial growth of strained multilayer super- Phys. Rev. B 43 (1991) 10538. conducting thin films of Ndi.^Ceo.^CuOx/ YBa2Cu3C>7.d", A. Gupta, R. Gross, E. Olsson, A. 51. "Crack formation in epitaxial [110] thin films of Scgmiiller, G. Koren and C.C. Tsuci, Phys. Rev. Leu. YBa2Cu3O7.d and PrBajCuiOj^ on [110] SrTiOa 64(1990)3191. substrates", E. Olsson, A. Gupta, M.D. Thoulcss, A. Segmuller and D.R. Clarke, Appl. Phys. Lett. 58 41. "High critical current densities in strained multilayer (1991) 1682. thin films of NdiMCeonCiKVYB^C^Ov./, R. Gross, A. Gupta, E. Olsson, A. Segmiillcr, G. Koren 52 "Elcctropolishing of polycryslallinc and C.C. Tsuei, Appl. Phys. Lett 57 (1990) 203. meet the need for sharp needle geometry", Q.-H. Hu and J.A. Alarco, Surf. Sci. 266, (1992) 538-544. 42. "High Quality YBCO Thin Films - Laser Deposition, Co-Evaporation, and Device Fabrication", J.A. Alarco, 53. "Effects of substrate temperature on the microstructurc G. Brorsson, T. Clacson, M. Danerud, U. Engström, of YBa2Cu3O7-d films grown on (001) Y-Z1O2 Z.G. Ivanov, P.Å. Nilsson, H. Olin and D. Winkler, substrates", J.A. Alarco, G. Brorsson, Z.G. Ivanov, Phys. Scrip. 44, (1991) 95-101. P.Å. Nilsson, E. Olsson and M. Löfgren, Appl. Phys. Lett. 61 (6), (1992) 723-725. 43. "Effects of Composition and Processing on the Micro- structure and Properties of 1-2-3 Superconductors", 54 "Growth and properties of a multilayer system based J.A. Alarco, E. Olsson, H. Norden, H. Medelius and on YBajCuj&jj and amorphous Y-ZrOf1, Yu. Boikov, DJ. Rowcliffc, Micron and Microscopica Acla 22 (1/ Z.G. Ivanov, E. Olsson, J.A. Alarco, G. Brorsson and 2), (1991) 105-106. T. Clacson, J. Appl. Phys. 72 (1), (1992) 199-202.

236 THE CENTRE FOR MICROSCOPY AND MICROANALYSIS

55. "Artificial grain boundary Josephson junctions - 66. "Field dependence of hydrogen adsorption", H-0 properties and applications", Z.G. Ivanov, J.A. Alaico, Andrén and U Rolander, Surf. Sci. 266.1992 pp. 76-80. T. Claeson, RÅ. Nilsson, E. Olsson, HK. Olsson, EA Stcpantsov, A. Ya. Tzalenchuk and D. Winkkr, Beijing 67. "On the performance of a microchannel plate detector International Conference on High Tc Superconductivity used for atom-probe analysis". L Lundin and U (BHTSC92). May 25-29.1992 Beijing. China. Rolander, Appl. Surf. Sci., in press

56. "Cracking of brittle films on elastic substrates", M.D. 68. "Interaction between nitrogen and substiuitional Thoulcss, E. Olsson and A. Gupta, Acta metall. Mater. elements in the austenttic phase of duplex austeniuc- 40(1992)1287. ferritic stainless steels", G Wahlberg, U Rolander and H-0 Andrén, in "High nitrogen steels, HNS 88", Book 57. "Laser deposited PrGaO3 films on SrTK>j substrates 453, (The Institute of Metals, London, 1989) pp. 163- and in YBa2Cu3O7/PrGaO3/YBa2Cu3O7 trilayers", G. 168 Brorsson, P.Å. Nilsson, E. Oisson, SZ. Wang, T. Clacson, and M. Lofgrcn Appl. Phys. Lett. 61 (1992) 69. The kinetics of intermciallic phase formation in 486. duplex stainless weld metals and their influence on mechanical properties", L Karlsson, S Pak, L 58. "YBaCuO Josephson weak links based on shallow ion Bengtsson and U Rolander, in "Appl. Stainless Steel beam etched steps in MgO Superconductivity'', J. 92", in print Ramos, Z.G. Iva..ov, E. Olsson, and T. Claeson, (BHTSC92), May 25-29,1992 Beijing, China. 70. "Precipitation hardening of a new duplex stainless steel", M Liljas, P Stenvall, J Pleva and K Stiller, in 59. "Crossovers and vias in YBazCi^Or/PrGaOs/ "Appl. Stainless Steel '92", in print YBa2Cu3O7 trilayers", P.Å. Nilsson, G. Brorsson, E. Olsson, Z.G. Ivanov, and T. Claeson, 1992, Applied 71. "The role of alloy composition in the precipitation superconductivity conference, Chicago, USA. behaviour of high speed steels", Wang Rong, H-O Andrén, H Wiscll and G L Dunlop, Acta Metall. Mater.

60. "Imcrfacial interactions between high Tc YBIQCUJ(>J.X 40,1992 pp. 1727-1738 thin films and substrates", E. Olsson and S.L. Shinde, a chapter in Interfaces in Superconducting Systems, 72. "Precipitation of secondary carbides during tempering edited by S.L. Shinde and D. Rudman, Springer of high speed steels", H-0 Andrén, in "Proc. 1st Int Verlag, New York, 1992. Conf.High Speed Steels" edited by G Hack! and B Hribemik, (Montanuniversitat Lcoben, Lcobcn, 1990) 61. "Microstructure of an artificial grain boundary weak pp. 392-399 link in an YBat^CujOj^ thin film grown on a (100X110), [001] tilt Y-Z1O2 bicrystal", J. Alarco, E. 73. "Carbide precipitation in chromium steels", H-0 Olsson, Z.G. Ivanov, P.Å. Nilsson, D. Winklcr, E.A. Andrén, S Karagöz, Cai Guangjun, L Lundin and H Stepanlsov, and A. Ya Tzalenchuk, accepted for Fischmeister, Surf. Sci. 246,1991 pp. 246-251 publication in Ultramiscroscopy. (N 9001191/ 9100293). 74. "Microstructural changes during overtempering of high speed steels", S Karagöz, H F Fischmeister, H-O 62. "YBa^uaO^dGaOj/YBa^Or trilayers by Andrén and Cai Guang-jun, Metall. Trans. 23A, 1992 modified off-axis sputtering", SZ. Wang, E. Olsson, pp.1631-1640 JA Alarco, Z.G. Ivanov, D. Winklcr, V. Langer, and P. Bcrastegui, submitted to J. Appl. Phys. (N 9001191/ 75. "A TEM investigation of a new creep resistant 12% 9100293). chromium steel", L Lundin and H-O Andrén, Micron and Microscopica Acla 22,1991 pp.159-160 63. "Statistical correction for pile-up in the atom-probe detector system", U Rolander and HO Andrén, J Phys 76. "Atom probe investigation of a creep resistant 12% (Orsay) 50,1989, pp. C8-529-534. chromium steel", L Lundin and H-O Andrén, Surf. Sci. 266,1992 pp. 397-401 64. "Design of an atom-probe high voltage pulser", U Rolandcr and H-0 Andrén, Surf. Sci. 241,1991 pp. 77. "Secondary hardening in high speed steels", S Karagöz 390-395. and H-O Andrén, Z Metallkunde 83,1992 pp. 386-392

65. "Quantitative atom-probe microanalysis", U Rolander and H-O Andrén, submitted to Microscopy Microana- lysis Microstructurcs.

MATERIALS SCIENCE, 1993 237 MICROSCOPY AND MICROANALYSIS

78. "Atom-probe analysis applied to TiC-Ni based 90 "Microstructure investigation of 12% Cr steel weld cemented carbides", U Rolander and HO Andrén, in metal", Cai G-J and H-O Andrén, Micron and Micro- "Proc. 12th Int Plansee Seminar, edited by H Bildstein scopica Acta 22,1991 pp. 127-128 and H M Ortner (Meiallwerk Plansee GmbH, Reutte/ Tirol, 1989) Vol. 2 pp. 379-388 91. "Microstructure and mechanical properties of 12% Cr weld metal", Cai Guangjun, H-O Andrén and L-E 79. "Evaluation of atom-probe spectra from titanium Svensson, in "Proc. 3rd International Conference on carbonitride", U Rolander and HO Andrén, J Phys Trends in Welding Research" (ASM, Metals Park, (Orsay) 50,1990 pp. C8-371-376 OH) accepted for publication

80. "Atom-probe analysis of a commercial cermet", P 92. "Analytical TEM investigation of precipitation in a 5% Lindahl, U Rolander and H-0 Andrén, Surf. Sci. 246, Cr weld metal during tempering", Cai Guangjun, H-O 1991 pp. 319-322 Andrén and L-E Svensson, in manuscript

81. "Atom-probe microanalysis of TiC-TiN-Mo2C-Ni/Co 93. "Gold-germanium contacts on gallium arsenide", A cermets", U Rolander, C Chatfield and H-O Andrén, Kvist, Hu Q and H-O Andrén, J. Phys (Orsay) 50,1990 submitted to Acta Metall. Maler. pp.C8^65-470

82. "High resolution microanalysis of cermets", P Lindahl, 94. "Atom probe analysis of the silver/gallium arsenide U Rolander and H-O Andrén, J. Hard Mater. 3,1992 contact", Hu Qiuhong, A Kvist and H-O Andrén, Surf. pp. 59-267 Sci. 246,1991 pp. 195-200

83. "Combined field ion microscopy and transmission 95. "Atom probe analysis of Au/GaAs and Ag/GaAs electron microscopy of heavy ion damage in tungsten", interfaces", Hu Quihong, A Kvist and H-O Andrén, K SUUer, Rad. Eff. Defects Sol. 115,1990 pp. 205-215 in"Microscopy of Semiconducting Materials", edited by A G Cullis and N J Long (Institute of Physics, 84. "Direct measurement of matrix composition in Bristol, 1991) InsL Phys. Conf. Scr. Nr. 117, pp. 91-% Zircaloy-4", B Wadman and H-O Andrén, in "8th Int. Symp. Zirconium Nucl. Ind.", (ASTM STP1023, 96 "TEM and atom probe analysis of melal/GaAs inter- Philadelphia, 1989) pp. 423-434 face", Q-H Hu, A Kvist and H-O Andrén, Micron and Microscopica Acta 22,1991 pp. 143-144 85. "Atom probe analysis of thin oxide layers on Zircaloy needles", B Wadman, H-O Andrén and L K L Falk, J 97. "High resolution microanalysis of AuGc contact on n- Phys (Orsay) 50,1989 pp. C8-303-308 GaAs", A Kvist, Hu Qiuhong and H-O Andrén, submitted for publication 86. "Microstructural influence on uniform corrosion of Zircaloy nuclear fuel claddings", B Wadman, H-O 98. "Grain boundary chemistry in nickel base Alloy 600", Andrén, A-L Lundström, P Rudling and H Pettersson, K SUIler, J. Phys (Orsay) 50,1989 pp. C8-329-334 accepted for publication in J Nucl. Mater. 99. "InvesUgaUons of grain boundary microchemistry in 87. "Microanalysis of the matrix and the oxide-metal nickel base superalloys", K Stiller. Surf. Sci. 246,1991 interface of uniformly corroded Zircaloy", B Wadman pp. 225-230 and H-O Andrén, in "Zirconium in the Nuclear Industry: Ninth Int Symposium", edited by C M 100. "Intergranular precipitation in Ni-Cr-Fe alloys", K Eucken and A M Garde (ASTM STP 1132, Philadel- SUller, Surf. Sci. 266,1992 pp. 402-408 phia, 1991) pp. 461-475. 101. "Grain boundary microstructure, chemistry and 88. "Microstnicture and themodynanmic behaviour of a IGSCC in Alloy 600 and Alloy 690", K Norring, K chromium molybdenum submerged arc weld metal in SUller, J-0 Nilsson, in"5th Int. Symp. Environmental the as welded state", B Josefsson and H-O Andrén, Degradation of Materials in Nuclear Power Systems", in'Recent Trends in Welding Science and Technology", (Amer. Nucl. Soc., La Grange Park, 1992) pp. 482-487 edited by S A David and J M Vilek (ASM Interna- tional, Metals Park, OH, USA, 1990) pp. 243-247 102. "Electropolishing of polycrystalline to meet the need for sharp needle geometry", Hu 89. "An APFIM study of the bainitic transformation in Qiuhong and J A Alarco, Surf. Sci. 266,1992 pp. 538- 2.25Cr-lMo weld metal", B Josefsson and H-O 544 Andrén, Mater. Sci. Technol. 7,1991 pp. 849-851

238 THE CENTRE FOR MICROSCOPY AND M1CROANALYSIS

103. "Towards quantitative analysis of YI^C^O^ high-Tc superconductor by AP-FIM", Hu Qiuhong, K Sutler and H-0 Andrén, Appl. Surf. Set., in print

104. "The enhanced concentration of Ni at structural disloctions in a grain boundary in W" Lai Zonghe and H Norden, J. Phys. (Orsay), 49,1988, C6-341-345

105. "Nickel activated recrystallization of doped tungsten wire", Lai Zonghe and H Norden, InsL Phys. Conf. Ser. No. 93,1988, Vol. 2 p. 479-480

106. "Characterization of a-Al2O3 and K-AI2O3 and ot- ic Multioxide Coatings on Cemented Carbides", S, Vuironen and J. Skogsmo, Thin Solid Films, 193/194, 1990,536-546

107. "Space Group Determination and Structure Model for K-AI2Q3 by Convergent -Beam Electron Diffraction (CBED)", Ping Liu and Jan Skogsmo, Acta CrysL, B47,1991,425-433

108. "The formation of ri-Phase in Cemented Carbides During Chemical Vapour Deposition", J. Skogsmo and H. Norden, Refr. Met. & Hard Mater.,11,1992, 49-61

MATERIALS SCIENCE, 1993 239 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE Mechanics

Research Summary Within the laboratory also research in transporta- The determination of expected life or residual life in tion safety, product safety, quality assurance tech- a material or product is essential for the total reliabi- niques and dynamic systems is performed. These lity and economy. The research activities of the sectors are not reported below. Mechanical Laboratory of SP are focused on the development and verification of methods for pre- dicting service life out of performed mechanical Address tests, including improvements of the validity of such Gibraltargatan 35 tests. Mail: Box 240 36 Prediction of residual service life is essential for S-400 22 Göteborg, Sweden maintenance considerations and for several applica- Phone+46 31 2008 70 tions where a prolonged use has become important. Fax 446 31 161295 This also includes diagnostic methods to be used in service as well as strength in aggressive environ- ments. Research Staff In particular, fatigue testing under spectrum load- Gunnar Bergström M.Sc, ing or under the influence of an aggressive environ- Head of Gothenburg branch ment is a crucial part of the performance and life Lars O.Ekerfors Dr.Eng.Sc. assessment of a structure. RMagnus Holmgren M.Sc. Jonas Karlsson M.Sc. The research activities includes a.o. the Gunnar Kjell M.Sc. following: Eva Larsson B.Sc. • development of mathematical methods for the Per Lidström Dr.Eng.Sc. Head of Solid creation of spectra and for the evaluation of Mechanics Group fatigue data, Ulf Olofsson M.Sc. • development of mathematical models for life Thomas Svensson M.Sc. prediction, Håkan O.Torstensson Dr.Eng.Sc., Mgr., Dept.of Material & Mech. • treating low cycle fatigue in certain applica- tions theoretically and experimentally, • studying models for crack propagation and Major Instrumentation implementing them into test methods, • Servohydraulic testing machines • evaluating different methods for the determina- • Crash test facility tion of residual stresses, • Uniaxial and biaxial servohydraulic vibration test rigs • determining mechanical properties under • Various equipment for materials and technolo- environmental influence. gical tests Tribology is a related field of interest, since friction • Equipment for drop and impact testing and wear also have immediate importance for the • Scanning electron microscope performance, reliability and economy of a compo- • Electrodynamic fatigue testing machines nent. The research in this field concerns boundary • Climatic chambers layer lubrication, friction induced vibrations, and • Friction and wear testing equipment sliding contact under high pressure.

240 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - MECHANICS

Financial Support Research Projects Ministry of Industry A: Methodsfor servic e life prediction Nordtest Nordic Industry Fund Al: Fatigue at varying amplifies Swedish Rescue Serices Board Fatigue in material is the result of a large number of NUTEK repeated loadings. The phenomenon has been thor- Foundation for Heating Technology Research oughly investigated for loads with constant ampli- tudes, both theoretically and experimentally. When the magnitudes of the loads vary, there is a problem Major Fields of Research of transferring knowledge and test results from the constant amplitude case. Furthermore new fatigue A: Methods for service life prediction mechanisms appear under spectrum loading. These Participants: Th. Svensson, P. Lidström, M.Holm- problems are treated in this project: gren, E.Larsson, U.Olofsson, G.Bergström, 1. Developments of methods for life prediction at J.Karlsson, G.Kjell variable amplitudes. These methods are based on a Collaborators: Dept of Mathematical Statistics at new simple fatigue mo^e!, discovered at Chalmers Chalmers University of Technology/Univ. of University of Technology, utilizing level crossings Göteborg, Dept. of Construction Technology, rather than cycle count. The aim is to find methods ChalmersUniv.,of Technology, Det norske Veritas, simple enough to be readily applicable, but which Oslo, ABB Corporate Research, Västerås are possible to refine by incorpoprating e.g. know- B: Tribology ledge from fracture mechanics. Participants: L.Ekerfors, U.Olofsson 2. Developmentof methods to generate stochastic Collaborators: FFV Materials Technology, AlfaLaval processes for fatigue testing. In order to test different fatigue models and to study the fatigue phenomenon in detail, load sequences of a particular characterare required. It seems that the theory for stochastic processes is a useful tool to create load sequences with the desired properties.

100

80

60

40

20

stres s 0

-20

-40

Random -60 process, irregularity -80 factor = 0.5 50 100 150 200 250 time (s) MATERIALS SCIENCE, 1993 241 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - MECHANICS

3. Verification by testing of theoretical models strength, durability, environmental resistance and for fatigue at variable amplitudes. Since fatigue fire behaviour. The suitability for hazardous materi- testing is time-consuming and costly it isdesirable to als transportation will then be evaluated. reduce the number of tests and still have statistically valid results One part of the project is therefore A4: Environmentally assisted fatigue focused on the adaption of statistical methods for the The corrosion fatigue properties of four types of analysis of test results. stainless steel have been investigated. Two different environments were used: ambient temperature air A2: Crack propagation models and da/dN and 3% sodium chloride at +80°C. For the materials measurements tested no corrosion contribution to the lowering of The project aims at refining the da/dN techniques for the fatigue limit could be identified. Surface defects constant amplitude and spectrum loads. Models for from the processing and the increased temperature crack propagation have been studied. An error anal- were the significant causes. ysis of the craCK length as a function of the compli- ance has been performed and software has been A5: CFCJree Insulation for culverts developed to integrate Paris'equation. Implementa- The project investigates the material properties of tion of the techniques in corrosive environments and CFC-free insulation. The axial shear strength has determination of threshold values are being planned. been determined by a recently developed method and the creep properties are being examined. Results A3: Fatigue in vehicles obtained show that existing fears for the insufficient 1. Nonpressurized tanks for tank vehicles have thermomechanicalpropertiesof these materialshave occasionally been damaged in long distance trans- been exaggerated. It will however be necessary to port, because the fatigue risk by, say, repeated im- distinguish pressure induced deformation of the pact stresses has not been accounted for in the design closed cells from the temperature dependent creep rules. deformation. Measurements have been made on a tank vehicle in traffic. The results are being analyzed with two methods: maximax response spectrum for singular dynamic overloads, and fatigue damage response spectrum for repeated stresses. 2. Fatigue testing of railcar bogies has been performed with new methods. Load cycles with a prescribed level crossing distribution and irregular- ity factor have been generated and iterated via a feedback loop until cracks were detected. The project has involved software development to optimize both the data storage format and the calculation algo- rithms. ftnfular displacement P) 3. A round robin exercize with 12 European Coefficient of friction versus angular displacement. participants aimed at optimizing methods for data reduction and analysis for measured transport vibra- tions. The SP approach is founded on fatigue damage response spectrum analysis, which gives a basis for developing fatigue test methods. 4. Glass-fibre reinforced plastics have attracted new interest as a material for transport tanks for corrosives, due to its good compatibility, impact- absorbing ability and strength. The project aims at investigating the material properties with regard to

242 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - MECHANICS

B:Tribok>gy

Bl: Friction at high contact pressures B2: Friction Induced vibrations A method has been developed for the determination Studies on the nature of interaction between sliding of the friction coefficient at high contact pressures surfaces have been made and recently applied to the (up to 300 MPa) and very low velocities, of the order problem of friction-induced noise. It was concluded of nm/s. A servohydraulic torsion-tension testing that the friction induces vibrations between nut and machine was adapted for the measurements. screw in a screw-nut transmission, which in succes- The method was used for analyzing steel on sion excite transverse vibrations in the screw. concrete, and to evaluate the performance of lubri- cants in steel against steel movement.

Lubricant no 1 Lubricant no 2

Lubricant no 3 Lubricant no 4

Response surfaces for moo.

MATERIALS SCIENCE, 1993 243 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - MECHANICS

References Andersson, Th., M.Holmgren and UJohansson, Glass fibre reinforced plastics as a material in tanks for the transport of dangerous goods, SP1992 (in Swedish)

Bergström, G., Comprcssive creep of polystyrene cellular plastics, SP 1989

Ekerfors, L. and U.Olofsson, Friction-induced noise in screw-nut transmissions, WEAR, aug 1991.

Holmgren, M. and E.Larsson, Corrosion fatigue in duplex stainless steel, SP 1992 (in Swedish)

Jarfclt, U., G.Bergström and J.Karlsson, Load-bering capability of CFC-rrce culvert insulation at service temperature, VärmcForsk, 1992 (in Swedish)

Lidström, P., Crack propagation and da/dN testing, SP 1992 (in Swedish)

Olofsson, U. and M.Holmgren, Utilizing a servohydraulic torsion-tension machine to measure the friction between steel and concrete at low sliding speeds, SP 1992 (in Swedish)

Olofsson, U., Friction characteristics of a ferritic-austenitic stainless steel during lubricated reciprocating motion, SP1992

Olofsson, U., Stresses in tank vehicles, SP 1991 (in Swedish)

Olofsson, U. and Th.Svensson, Shock response spectra and fatigue damage response spectra for a tank vehicle, SP 1991

Richards, D., Round-Robin Exercize on Transportation Stresses,

Svensson, Th. and M.Holmgren: Numerical and Experi- mental Verification of a New Model for Fatigue Life, SP 1992, to be published in Fatigue and Fracture.

244 THE CENTRE FOR Building materials

Building materials 246 Building technology - Swedish National Testing and Research Institute, SP 257

MATERIALS SCIENCE, 1993 245 Building Materials

Research Summary Staff The division of Building Materials works mainly CAMIAV MflinhAit with cement and wooden based building materials L-O. Nilsson professor and surface coatings on such materials. One major R. Tepfers docent part is a material science approach to flow properties L. Bemtsson tekn.lic. for liquid, gas and ion transport in porous materials. Xu Aimin tekn. dr. Another major part is research on durability and Graduate Students service life, i.e. the behaviour of materials in long- E. Atlassi civ.ing. time use in various environments. The expected S. Hjort civ.ing service-lives are from some decades to more than K. Norling civ.ing. 100 years. J. Möller civ.ing. Cement based materials age continuously. The A. Radocea tekn.lic. time development of the structure, mainly the MRodhe civ.ing. micropore structure, is studied from mixing to com- K. Thalenius civ.ing. pleted haideninganditsrelationshipto the properties TangL B.Sc. and behaviour regarding reaction and flow proper- H. Wengholt civ.ing. ties is a key issue. The work on durability and service-lifeisconcen- Technical Staff trated on parameters decisive for moisture condi- B. Dellming civ.ing. tions in general, emissions from surface coatings on J. Aavik civ.ing. concrete floors, steel reinforcement corrosion in F.Calko ing. concrete structures androot decay in exterior wooden T. Hammarberg ing. structures. Those parameters are the microclimate at B.Hedberg ing. the surfacesof the materials, thedeterioration mecha- A. Johnsson tekn. nisms and the reaction and flow processes involved. I. Limani ing. This knowledge is combined into models for pre- Secretary dicting the service life as a function of design, A. Palmdin compositions of the materials and the environment. Librarian I. Gustafson Address Department of Building Materials Chalmers University of Technology Major Instrumentation S-412 96 Göteborg, Sweden • Thermobalance (TGA): LECO MAC-500,1991 Phone+46 31 7722299 (for 19 samples simultaneously) Fax +46 31 189705 • X-ray diffractometer (XRD): Siemens D5000, 1992. Contact: B Dellming

246 THE CENTRE FOR BUILDING MATERIALS

Major Reids of Research Pore water pressure 4 A: Structure of Cement-Based Materials Forces acting on the structure: participants: E. Atlassi, L-0 Nilsson, A. Gravitation Capillary forces Radocea, Xu Aimin. P1 collaborators: Swedish Cement & Concrete Research Institute, Stockholm ?2 B: Durability of Concrete participants: L. Bemtsson, J. Möller, L-0 Nilsson, Tang Luping, Xu Aimin. Atmospheric collaborators: Cementa AB, Swedish Testing pressure Institute, Borås, LMDC, INSA-UPS, Toulouse

C: Moisture in Building Materials P1 = initial pore pressure participants: B. Hedberg, S. Hjort, L-0 Nilsson, P2 = hydrostatic pressure K. Norling, M. Rodhe, K. Thalenius. t1 = total time of bleeding t2 = time when water menisci collaborators: Royal Institute of Technology, develop at the top surface Stockholm

Changes in pore water pressure Research Projects in fresh cement paste.

A: Structure of Cement-Based Materials

Al: A Study on the Mechanism of Plastic The total relative deformation of a sample can be Shrinkage of Cement-Based Materials estimated by measuring the development of the pore Fresh concrete undergoes a volumetric contraction water pressure and the rate of evaporation. during the very few hours after placing. This contrac- tion is caused by the sedimentation of cement parti- A2: Plastic Shrinkage Clacking of Concrete cles and aggregates (bleeding) and by the develop- The factors which control the development of the ment of capillary forces due to water menisci be- cracks have widely been discussed over the last four tween the outermost particles of the concrete mass decades, but no generally accepted theory that de- (plastic shrinkage). scribes the mechanism of cracking can be found in In order to study the mechanism of bleeding and the literature. plastic shrinkagcatestmethodfor continuous meas- The aim of the project is firstly to study the uring of pore water pressure in fresh and young influence of parameters such as type of cement, cement paste was developed at our division. The water-cementratio, superplasticizer and rate of evapo- method of testing is based on the idea that water, ration on the geometry of the outermost pores of the cement grains and aggregates are incompressible concrete mass and on the modulus of plastic shrink- and that any force acting on the solid particles must age. Secondly, a model to describe the development give rise to a change in the pore water pressure, see of the cracks and a method for estimating the risk of figure. cracking will be developed. The aim of the project was to describe the devel- Normal concrete with water-cement ratios in the opment of capillary pressure in fresh cement paste range of 0.6-0.8, as well as high performance con- and todevelopamodelthatdescribes the mechanism crete are the objects of investigation. of plastic shrinkage. It was shown that the capillary The project will be carried out in collaboration pressure is a function of the geometry of the spaces withNCCVäst,PlatzerByggABandFärdigBetong, between the outermost solid particles, the rate of the work consisting of both field and laboratory evaporation and the volume change of the sample. studies.

MATERIALS SCIENCE, 1993 247 BUILDING MATERIALS

B: Durability of Concrete to the progress of cement hydration and the develop- ment of the pore structure in the concrete during Bl: Carbonatkxi In Concrete hydration and carbonation is an essential part of the As a structural material, concrete has two main program. With laboratory studies on the degree of functions. The concrete supports thv internal and carbonation we try to answer the question: How external loading on the construction and acts as a much of the cement will or can carbonate? Different protective cover for the reinforcement. The durabil- environmental conditions, cement types and con- ity of the concrete is important for both these func- crete mixes are tested. Project completion is esti- tions, and durability aspects are receiving increased mated in 1995. attention by researchers as well as other parties of the construction industry. The deterioration process in B2: Influence of Alkali on Carbonation concrete structures is generally caused by a number of mechanisms, one of which is carbonation. of Concrete Regarding steel reinforcing-bar corrosion in con- Carbonation of concrete may in general be de- crete, the neutralization induced by carbonation has fined as the combination of ongoing chemical reac- arised much concern. It has been shown that car- tions of carbon-dioxide (CO2) with hydrated and bonation of cement/concrete is a multi-factor de- unhydrated cement paste on one hand, and the pendent phenomenon, which, despite intense re- transport of gases, ions and water within the pore search, still remains to be fully explained. Among system on theother hand. The CC^in the atmosphere the many factors, the effect of alkali on carbonation mainly derives from natural growth of vegetation is of special importance. processes and from industrial processes that use In the presence of CO2, alkali salts, such as K2O fossil fuels. In densely populated urban areas ex- and Na2O in concrete, react to form alkali-carbon- haust from cars contributes with the greatest part of ates which are highly soluble. The alkali-carbonates the CO2 in the local atmosphere. readily react with the cement hydration products. Carbonation affects some important properties of This reaction causes dissociation of cement hydrates the paste, but best known, and probably the most and re-produces alkali salts which will react with important effect is probably the change in alkalinity CO2 again. In this way, alkali behaves as a catalyst or decreased pH level in the pore system. The to the cement carbonation. This mechanism has been decrease in pH level (from 13.5 to 8.5) depassivates known to lead to the fatal deterioration of high the concrete steel reinforcement, resulting in corro- alumina cement products, but largely ignored for the sion. The consequence of reinforcement corrosion is carbonation of other types of concrete. the spalling of the concrete cover, often leading to Alkali salt is present as a component in cement or irreversible deterioration or mechanical failure of mineral admixtures (such as fly ash). It can also be the construction. introduced as an activator for the mineral admixtures The aim of the project is to study and map the such as slag and fly ash, or due to the contact between carbonation process as a combined system, rather concrete and alkali baring media. Thus concretes than looking, either on the chemistry alone or the inevitably contain some amount of alkali which may transport processes alone. A more complete descrip- be one factor enhancing the carbonation process. tion of the complex mechanism of the combined The objectives of this project are: transport and chemical binding of carbon-dioxide in 1. The mechanism of concrete carbonation in the concrete is of great value in order to evaluate and presence of alkalies. The research will be focussed predict the service live of a reinforced concrete on the effect of different types of alkali salts and their structure. The fundamental tools, used in the re- contents, e.g., alkali oxide, alkali sulphate, etc., on search program are mathematical modelling and carbonation reaction. computer simulation of destructive as well as non- destructive processes in the concrete, both during 2. Carbonation rate of different concretes, i.e., con- early hydration and during deterioration. cretes made of different cements and/or with addi- tion of mineral admixtures, influenced by alkali. The Collection and evaluation of information on car- concretes studied will be subjected to both labora- bonation, available from the literature, especially tory accelerated carbonation and natural carbona- with respect to gas transport coefficients, the relation tion environments. Special interest will be placed on

248 THE CENTRE FOR BUILDING MATERIALS the carbonation of the alumina-baring hydration Concretes with the same mix designs are also products. This, in addition to practical interests, may subjected to field exposures at the Träslövsläge elucidate the mechanism for the usually higher rate harbor in a parallel project for comparison. of carbonation in concretes incorporating Class F fly ash (note that aluminate phase in this type of fly ash B4: Properties of Aged Reinforced Concrete is one of the main pozzolanic active components). Mostly testing is carried out on young concrete and thus the testing results of aged concrete are not B3: Chloride Transport In Maritime available. It makes it difficult to predict the service Concrete Structures life of concrete structures. Environmental factors Chloride transport in concrete plays an important which include wetting and drying, temperaturevari - role in the durability of a reinforced concrete struc- ation, freezing and thawing, carbonation, chlorides, ture, especially when the structure is exposed in sulphur and nitrogen oxides etc, will influence the maritime environment. The transport is, however, a concrete properties to a great extent, specifically its rather complicated process which involves diffu- structure, capillarity and the hydration products of sion, capillary suction and, sometimes, electro- the cement paste. phoresis, accompanied by chemical and physical In this project 6 years old weathered steel rein- binding. It is of great value to study the combined forced concrete specimens should be analyzed using mechanism of chloride transport in concrete in order phycical and chemical methods. Eight types of con- to evaluate and predict the service life of a reinforced crete compositions including structural lightweight concrete structure. aggregate concretes will be tested. Four types of The aim of Sub-project 1 is to identify some of the surface treatments has been given to each of these most important parameters of the environment, af- concretes. Rehabilitation of weathered concrete sur- fecting the rate of chloride transport into concrete. faces with different methods and their subsequent Environmental parameters studied in Sub-project 1 influence on the important properties are to be evalu- include a) the chemical composition of "seawater", ated. Realkalisation of carbonated concrete and chlo- b) climatic changes such as the frequency of wet-dry ride extraction both by electrochemical methods are cycles in the "splash zone", temperature and relative also to be studied in laboratory conditions. Indica- humidity. The features of the "splash zone" is of tion has been found that these methods might have primary concern, since some mechanisms of trans- deleterious effect on the concrete structure. port (e.g. capillary suction, deposition of chloride due to wet-dry cycles, temperature effects, etc.) other than pure diffusion may be of relative impor- C: Moisture In Building Materials tance. Cl: Moisture in Painted Exterior Wood Panelling Houses should be designed and constructed in such a way as to prevent future damage by moisture and rot. Asa step towards reaching this goal, researchers at Chalmers University of Technology (CTH) and

* the Royal Institute of Technology (KTH) are plan- ning to conduct a joint research project in respect of moisture in painted exterior wood panelling. The r study has two aims. The first is the development of i testing and evaluation methods to make it possible to * predict, for different paint systems, the moisture o \ balance in painted exterior wood panelling, hereby 0,00 N avoiding future damage caused by rot. The second is 0 10 » 10 to provide balanced recommendations regardingth e Otpft HtM ttå Mfftft, Ml design and coating of panelling made of different types of wood, with a view to reducing the mainte- Chloride penetration profiles after half a year's nance of exterior wood panelling in the future. immersion in different solutions.

MATERIALS SCIENCE, 1993 249 BUILDING MATERIALS

Balance

Water-spray

Test-panel

Top board seen from the reverse side

Measuring point for moisture ratio

Schematic drawing of a test setup for monitoring moisture conditions in coated panels. The moisture ratio in the wood and the weight of the panel are measured.

250 THE CENTRE FOR BUILDING MATERIALS

The project will involve basic research, where The concrete must dry out to an average moisture primarily the mechanisms governing moistening content corresponding to a critical level of relative and drying up will be studied in order to develop a humidity (RH) in the material, before a vinyl floor- relevant evaluation method for determining the ing is laid. The RH should not exceed 85-90% for moisture balance in painted wood constructions, as most vinyl floorings used in Sweden today. The well as more applied research, which will result in process of drying is very slow in concrete. Conse- guidelines for the choice of coating, materials and quently, in thick slabs placed on top of an underlying building techniques. The study will focus on coating impermeable material, such as a steel form work or with water-borne paint systems. Besides pine, the cellular plastic insulation, the moisture transport is panelling material studied will include different reduced to one direction and the drying time be- types of wood-based hard-board panels. The part of comes unreasonably long. For such structures it is the study focusing on building techniques will deal favourable to use a self-drying concrete. with joints, nail holes and overlapping surfaces. Self-drying concrete has a low water-to-cement The CTH-side of the project will be led by Stefan ratio and a higher cement content than ordinary Hjort, MSc, Building Materials, and the KTH-side concrete. A large amount of the mixing water is by Birgitta Hässler, PhD, Building Engineering. bound chemically to cement and the amount of Stefan Hjort will be responsible for the theoretical excess moisture left todry out is small. This concrete calculations, laboratory measurements and meas- dries out, even under sealed conditions, to an RH urements carried out at CTH's test-house on the below the critical RH in about one month's time. Swedish west coast. Birgitta Hässler will be respon- At the building site, however, the concrete may be sible for the build-up of knowledge in terms of exposed to very unfavourable drying conditions, materials and paints, for the verification of theories such as additional water, high RH in surrounding air on moisture balance through computer tomography and low curing temperature. It is therefore necessary as well as for electron microscopy with regard to the to examine other properties than internal drying. penetration of penetrating oil and paint into the wood These include the permeability of water and other materials. The study will be evaluated and reported liquids, shrinkage due to high cement content, the in co-operation between the two divisions. process of hydration at low temperatures and low RHs as well as workability. References S. Hjort (I989) "Rot Problems in External Wood Panels", References: Publ P-89-4, Div. of Building materials, Chalmers K. Norling-Mjörnell,"ScIfdcsiccation in Concrete", University of Technology (In Swedish). International Conference on Chcm. of Cement, India, S. Hjort (1991) "How to keep coated wood structures 1992. H. Wengholt-Johnsson, K. Norling-Mjörncll, sufficiently dry to avoid damage caused by rot", IRG "Fuktmätningar i betongbjälklag med kvarsittandc document 2376. form, Stenkullen", 1992, (in Swedish). S. Hjort (1992) "Moisture transport in wood panel - a K. Norling-Mjömell, "Ullorkning av platsgjutna T- question of coating and building techniques, Publ P bjälklag, fullskaleförsök och datorsimulering" (in 92:8, Div. of Building materials, Chalmers University Swedish), 1992. of Technology (In Swedish).

C2: SeffOrying Concrete ordinary concrete A high moisture content in concrete is one reason for damage to vinyl floorings. In the last few years many damages to vinyl floorings on concrete slabs have 85 Self-drying concrete occurred in Sweden, which can partly be explained 80- -The gain in time — by poor adhesiveness, blisters and bubbles caused by admit an earlier sponification of glue and expansion of the vinyl. t- start to lay flooring Also, the emission of chemical components in- appr. 6 month creases when vinyl floorings are exposed to alkaline Relative humidity versus time for moisture. ordinary and self-drying concrete.

MATERIALS SCIENCE, 1993 251 BUILDING MATERIALS

Publications E-90:l 107. Maria Palsclius, Egenskaper hos bruk med kalk

E-89:2 E-92:4 102. Pettersson Mikael, Samuelsson Kristina, Metod för 116. Jasmine Gustafsson, Hclana Patrikson, Fungerar våra fuktdimensioncring av uteluftsvcntilcrade kryprum krypgrunder - en studie av fuktförhållandcn och mögelförekomst i utclufls-ventilerade krypgrunder E-89:3 103. Jansson Elisabeth, Kilenstam Ttwrcsc, Spikning av Reports and artides träfasader 1. Stefan Hjort, Jämförande fuklkvotsbcstämning oå stavlimmad bänkskiva av rödbok Uppdragsgivare: E-89:4 Junkers, Kaj Knstoffcrscn (Göteborg, Mars 1988) 104. Norling Kristina, Nilsson Andrea, Trähuspanclcr - förr och nu 2. Juhan Aavik, Satish Chandra, Mats Rodhc, Testing of pumice stone concrete block from Ethiopia and E-89:5 puzzolanic test of pumice from Nicaragua (Assignment 105. Fritzell Esbjörn, Mankönen Timo, Tryckutmallning av from CBC Engineering, Kungälv, March 1988) höghållfast betong 3. Mats Rodhc, Puz/olanic test on pumice from Ethiopia E-89:6 (Assignment from CBC Engineering, Kungälv, March 106. Witzell Pär, Forsberg Lennart, Fuklvandring i fasader 1988) med puts på mincralullsisolcring (Ej publicerad)

252 THE CENTRE FOR BUILDING MATERIALS

4. Mats Rodhe, Puzzolanic test on pumice from Nicaragua 18. Leif Bemtsson, Polymermc ifierad cementbetong (Assignment from CBC Engineering, Kungälv, March (Föredrag vid VTTs Bromaicrialdagar i Linköping 12- 1988) 13 April 1989)

5. Satish Chandra, Concrete-Polymer composites 19. Stefan Hjort, Felaktiga färger kan göra hus sjuka (RILEM TC-105 CP C, Göteborg, April 1988) (Artikel i Träinformation Nr. 7 Juni 1989)

6. Saiish Chandra, Xu Aimin, A discussion on the paper 20. Durability of concrete aspects of admixtures and "Assessment of simple methods of determining the free industrial by-products (2nd International seminar, chloride ion concrete of cement paste" (Infört i Cement CTH, 26-27 Juni 1989)(BFR Document, D9:1989) & Concrete Research, Vol 18, Nr. 4 1988) 21. Satish Chandra, Influence of pollution on mortar and 7. Satish Chandra, Sate of the art in Scandinavian refrac- concrete (BFR Rappport nr. 830910-4) Göteborg 1990 tory technology (Bidrag till Annual Meeting Abstracts of the American Ceramic Society, Cincinnati, Ohio, 22. Ralejs Tepfers, Conference of young scientists in May 1988) Irkutsk (Reserapport 1990-05-10—15)

8. Satish Chandra, Xu Aimin, Influence of polymer 23. Stefan Hjort, Lars-Olof Nilsson, Rot problems and addition on the rate of carbonation of portland cement moisture balance in painted external wood (Contribution paste (Infört i The International Journal of Cement to "Building Physics in the Nordic Countries" Composites and Lightweight Concrete, Vol 10, Nr. I Trondheim, Norge Augusti 1990) 1988) 24. Leif Bemtsson, Satish Chandra, Tomas Kutti, Principles 9. Stefan Hjort, Lars-Olof Nilsson. En studie av klimat- and Factors Influencing High Strength Concrete påverkningar av målad träpanel drabbad av röLskador Production (Artikel införd i "Concrete International", (Nordtcst-symposium, 1-2 Juni 1988) Nr. 12, December 1990)

10. Satish Chandra, Hydrochloric acid attack on cement 25. Xu Amin, Satish Chandra, A Discussion of the Paper mortar - An analytical study (Infört i Cement and "Ice in Cement Paste as Analyzed in the Low-Tempe- Concrete Research, Vol 18, Nr. 2 1988) rature Scanning Electron Microscope" (Infört i Cement and Concrete Research, Vol 20,1990) 11. Roman Malinowski, Betongens förhistoria (Artikel i Nordisk betong, Oktober 1988) 26. Tang Luping, Interrelations Between Water, Gas and Ion Penetrations of Concrete (Bidrag till "Nordic 12. Satish Chandra, Influence of pollution on mortar and Concrete Research" i Trondheim, 15-18 Augusti 1990) concrete deterioration (2nd NCB International seminar, Indien Januari 1988) 27. Elisabeth Atlassi, High Strength Concrete - the Influence of mix Proportions on some Mechanical and 13. Lars-Olof Nilsson, Nya skador vid platta på mark Physical Properties (Bidrag till "Concrete for the Artikel i Tidskriften Byggforskning Nineties", Lcura, Australien 1990)

14. Leif Bemtsson, Satish Chandra, Ultrahöghållfast 28. Satish Chandra, September - Oktober 1990, Report betong. Tillverkningsprinciper (Göteborg, November from Travel to Japan and China (November 1990) 1988Xska ingå i BFR:s Rapport serie, R8:1989) 29. Xu Aimin, Satish Chandra, Juhan Aavik, Polymer in 15. Stefan Hjort, Färger för trä utomhus. Förberedande Concrete Proceedings of the 6th International Congress information inför studie besök hos JOTUNA A/S, (Tongji University, Shanghai, China, September 24-27 Sandefjord, Norge, 2 December 1988, (Göteborg, 1990) November 1988) 30. Stefan Hjort, Juhan Aavik, Kristina Norling, Fukt- 16. Lars-Olo' Nilsson, Fukt och mögelproblem vid betong- undersökning av trähus oå Eriksbergs varvsområde golv på mark - av brist på materialkunskaper (Uppdragsgivar: Jacobsson & Widmark, Uddevalla (Göteborg, December 1988) 1990-11-19)

17. Saiish Chandra, Per Flodin, Interaction of polymer 31. Saiish Chandra, Report from International Symposium with calcium hydroxide and tri calcium silicate on Concrete Polymer Composites (Bochum-Germany, March 12-14,1991)

MATERIALS SCIENCE, 1993 253 BUILDING MATERIALS

32. Stefan Hjon, How to keep coated wood structures 45. Shondeep L. Särkar, Satish Chandra, Interdependence sufficiently dry to avoid damage caused by rot (Paper of Microstructure on the Strength of Structural Light- prepared for the 22nd annual conference, 20-24 May, weight -aggregate Concrete (Införs i "Cement & Kyoto, Japan) Concrete Compostes")

33. Leif Bcrntsson, Satish Chandra, Läuballast med hög 46. Tomas Kutti, Leif Bcrntsson, Satish Chandra, Shrink- hållfasthet (BFR-anslag 890408-9 frän Statens råd för age of Cements with high Content of Blast-Furnace byggnadsforskning till Färdig betong AB, Göteborg) Slag (Bidrag till "Fourth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Neutral 34. Trng Luping, Lars-Olof Nilsson, Rapid Determination Pozzolans in Concrete", Istanbul, 10 -13 May 1992) of the Chloride Diffusivity in Concrete by Applying an Electric Field (Bidrag till American Concrete Institute, 47. Satish Chandra, Travell report to CANMET/ACI Boston, MA, March 17-21 1991) Conferences on Concrete with Mineral Admixtures at Istanbul and Athens (Istanbul and Athens, 3-13 May, 35. Lars-Olof Nilsson, Kristina Norling, Bedömning av 1992) intorkning hos Swedeck-ribbjälklag (Göteborg, Maj 1991) 48. Xu Aimin, The Shrinkage and Bulk Modulus of 36. Mats Rodhe, Tcletorn i Bergsjön (Uppdragsgivare: Cement-Fly Ash Mortar (Bidrag till "Fourth Consultadministration AB, Göteborg, Juni 1991) CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Neutral Poz/.olans in Concrete", 37. Elisabeth Atlassi, The Influence of Silica Fume and Istanbul, 10-13 May 1992) Some other Parameters on the Compressive strength of Concrete (Bidrag till "Blended Cements in Construction", 49. Adrian Radocca, A New Method for Studying Sheffield, September 1991) Blccnding of Cement Paste (Artikel i "Cement and Concrete Research", Vol 22, nr 5,1992) 38. Elisabeth Atlassi, Kristina Norling, Adrian Radocca, Fuktfri betong - en fråga om ratt material- kombination 50. Satish Chandra, Durability of Concrete with Mineral (Artikel införd i "Betong", Nr 3,1991) Admixtures Mixing (Ett kapitel till en bok om "Minc- raliska tillsatsmedel i betong", skall publiceras i Indien, 39. Xu Aimin, Kristina Norling, Tång Luping, Jön Möller, ABI Books, New Dcti) Methods for structural study of Cement Paste and Their Application in Highpcrformancc Concrete (September 51. Stefan Hjort, Undvik rötskador genom att använda rätt 1991) färg (Bidrag Ull Gullfibers "fuktdag", Maj 1992)

40. Satish Chandra, Reserapport International Congress on 52. Shondeep L. Särkar, Satish Chandra, Microstruciura! "Polymer in Concrete" och besök på University of Investigation of Masonry Deterioration in an Historical Chicago, September 1991 Church Tower, Gothenburg, Sweden (7th International Congress on Deterioration and Conservation of Stone, 41. Elisabeth Atlassi, Influence of Cement Type on the Lisabon, Portugal 15-18 Juni 1992) (Proceedings, Dcsorption Isotherm of Morur Jnfört i "Nordic Volume 2) Concrete Research", Nr. 10,1991) 53. Salish Chandra, Water Absorbing Polymer in Cement 42. Elisabeth Atlassi, Some Moisture Sorpu'on Properties Mortar (Bidrag till "Congress on Polymers in Con- of Silira Fume Mortar (Bidrag till "Fourth CANMET/ crete", September 1992) ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete", Istanbul 10- 54. Kristina Norling-Mjömell, Uttorkning av plastgjutna 13 May 1992) T-bjälklag fullskaleförsök och datorsimulering (Göteborg, Oktober 1992) 43. Lars-Olof Nilsson, Mincraliska material, grundläggan- de forskning, material och metodutveckling (Läges- 55. Stefan Hjort, Rötskadade träfasader. Orsaker och rapport till BFR för perioden Juli 1989 - Februari 1991) åtgärder. (Fuktinformation)

44. Satish Chandra, Xu Aimin, Influence of Presaiurauon 56. Kristina Norling-Mjömell, Fuktmätningar vid Arvika and Frecze-Thaw Test Conditions on Length Changes sjukhus Byggfuktfri betong of Portland Cement Mortar (Införs i "Cement and Concrete Research", Vol 22, Nr 4, May 1992) 57. Elisabeth AUassi, Dcsorption isotherms of silica fume mortar (9th International Congress on the Chemistry of Cement, New Delhi, India, 23-28 November 1992)

254 THE CENTRE FOR BUILDING MATERIALS

P-88:4 P-90:7 58. Lats-Olof Nilsson, Fukttransportegenskaper hos trä och 70. Bengt Dcllming, Fuktbalans i lockpanelvägg målad träbaserade skivor - en byggnadsfysikalisk inventering med olika färgsystem - en laboratorieförsök och analys av kunskaper och kunskapsbehov. (Omarbetad version) (STU-ansIag86-O484P) P-90:8 P-88:5 70. Ralejs Tepfers, Fatigue of concrete structures (Paper 59. Lars-Olof Nilsson, Juhan Aavik, Utredning av fukt- presented at a Nordic seminar in Göteborg 1989) och mögelproblem, Torslanda. Undersökning av tio fastigheter i kv Trollrunan, Lönnrunan och Ö Lönnrunaa P-90-.9 71. Xu Aimin, The Structure and some Physical Properties P-88:6 of Cement Mortar with Fly Ash (Lic.uppsats) 60. Mats Rodhe, Fuktvandring i silovägg av betong. (Uppdragsgivare: Hallands lantmän, okt 1988) P-90:10 72. Tomas Kutti, Juhan Aavik, Rötskador i träpanel. Etapp P-88:7 II: Husbesiktning 61. Lars-Olof Nilsson, Juhan Aavik, Undersökning av flytspackelproblem i flcrbostadshus, BRF Mariestads- P-90:ll hus 10, Mariestad 73. Satish Chandra, British Swedish Seminar on Concrete Repairs (CTH, Göteborg, 10-11 December 1990) P-89:l 62. Tomas Kutti, Skador på ytputs i serporocksystcm. P-91:2 (Uppdragsgivare: Emströrn & Co. AB, Mars 1989) 74. Tang Luping, Tomas Kutti, Parkcringsdäck av betong. Skadestatus och reparationsbehov. Reparationsmetoder. P-89:2 Etapp I: Inventering. Del 1: Repair methods for 63. Tomas Kutti, Rötskador i träpanel. Etapp I: Husinvcn- parking decks - a literature survey tcring. P-91:3 P-89:4 75. Lars-Olof Nilsson, Parkeringsdäck av betong. Skadesta- 64. Stefan Hjort, Rötskadade träfasader i en klimatiskt tus och reparationsbehov. Reparationsmetoder. Etapp I: utsatt miljö. En utredning av rötskador med speciell Inventering. Del 2: Inventering av P-husbeståndct i inriktning mot småhusområdet Torpet, Lysekil, Etapp H. Göteborg P-90:2 P-91:4 65. Tomas Kutti, Skador på ytputs i serporocksystcm - 76. Stefan Hjort, Kristina Norling, Fuktbalans i lockpanel- Fortsättning. (Uppdragsgivare: Emström & Co, AB, vägg målad med fyra olika färgsystem - en fältmätning Febru: i 1990) P-91:5 P-9O:3 77. Adrian Radocea, Porvattcntryckförhållanden i ung 66. Bengt Dcllming, Fuktbalans i lockpanclvägg målad cementpasta. Mätmetod, preliminära modeller och med olika färgsystem - en laboratorieundersökning parameterstudier (Lic.uppsats) (Delrapport, intern för Alcro-Beckers AB) P-91:8 P-90:4 78. Juhan Aavik, "90-lalets golv" 67. G Ekman, T Yokoyama, T Kutti, Metoder att hålla betongen varm vid gjutning vintertid P-91:9 79. Bengt Dcllming, Ilias Limani, Fuktbalans hos träpanel P-90:5 målad enligt hydrolin-metodcn - Inverkan av baksides- 68. Lars-Olof Nilsson, Fukttransportegenskapcr hos furu, bchandling gran och träbaserade skivor - Vcrifieriiig och komplet- terande bestämning (STU-anslag 86-04894P) P-91:10 Preliminär utgåva 80. Bengt Dcllming, Ilias Limani, Fuktbalans i lockpanclvägg P-90:6 69. Tomas Kutti, Alkali activated slag mortar- mechanical strengths, shrinkage and structure (Doktorsavhandling) 81. Leif Bcmtsson, Lars-Olof Nilsson, Betongteknologi, Fukt i porösa Byggnadsmaterial. Kompendium i Byggnadsmaterial för V3

MATERIALS SCIENCE, 1993 255 BUILDING MATERIALS

P-91:12 P-92.-8 82. Xu Aimin, Vapour sorption theories, Seminaricuppgift 90. Stefan Hjon, Mätning av fuktbalans i mälad lockpancl till doktorandkurs. 'Transportprocesser i byggnads- -jämförande provning mellan olika färgsystcm och material" olika konstruktiva utföranden

P-92:l P-92:9 83. Xu Aimin, A mincralogical-microscopical study of 91. Adrian Radocca, A study on the mechanism of plastic cement pastc/mortar incorporated with fly ash shrinkage of cement-based materials

P-92:2 P-92:10 84. Takashi Yokoyama, A field study on winter concreting 92. Leif Bcmlsson, Lars-Olof Nilsson, 3etongteknologi, methods. Part I: Main report (Hobcrg site, Göteborg Fukt i porösa byggnadsmaterial (Kompendium i 1988/89) (Lic.uppsats) byggnadsmaterial för V3)

P-92:3 P-92:ll 85. Takashi Yokoyama, A field study on winter concreting 93. Leif Berntsson, Lars-Olof Nilsson, Exempelsamling i methods. Part II: Data report (Hobcrg site, Göteborg byggnadsmaterial (Byggnadsmaterial för V3) 1988/89) (Lic.uppsats) P-92:12 P-92:4 94. Takashi Yokoyama, A field study on winter concreting 86. Takashi Yokoyama, A field study on winter concreting methods. Part I: Main Report, Part II: Dala Report, Part methods. Pan III: Two dimensional analysis (Hobcrg III: Dimensional Analysis (Hobcrg site, Göteborg site, Göteborg 1988/89) (Lic.uppsats) 1988/89) (Lic.uppsats)

P-92:5 P-9?:13 87. Lars-Olof Nilsson, Tang Luping, Relationships 95. Lars-Olof Nilsson, A theoretical study on the effects of between flow coefficients for moisture, water, gases nonlinear chloride binding on chloride diffusion and ions in concrete measurements in concrete (Toulouse i Maj 1992)

P-92:6 P-92:14 88. Tang Luping, Lars-Olof Nilsson, Test methods for 96. Lars-Olof Nilsson, The replica technique of Insa- transport of ions in concrete Toulouse - a powerful tool for studying the develop- ment of microcracks in high-performance concrete? P-92:7 (Toulouse i Juni 1992) 89. Xu Aimin, Structure of hardened cement - fly ash systems and their related properties (Doktorsavhandling)

256 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE Building Technology

Research summary els. Of special interest is chloride penetration and Applied and to some extent basic research is per- frost resistance. formed mainly in the field of wood and woodbased Concrete mortar and other inorganic materials materials, cement and concrete but also where ma- are studied by using microscopical methods. In a sonry, stone and other inorganic building materials EUROCARE-project mortar from up to 1000 years are concerned. An important goal of the research is old churches are studied, mainly by microscopical to develop test methods. Performance testing and methods but also by chemical methods and by using non destructive testing techniques (NDT) are of strength and durability testing. The aim of the project special interest. In order to calibrate the test methods is to learn from the past in order to improve the against "reality" and to develop new material mod- properties of the mortars produced today. els, field exposure tests play an important role in our research. Another speciality is microscopical studies of materials by use of the so called thin section Address technique and by scanning electron microscopy. Swedish National Testing and Research Institute NDT-techniques are developed for classifying P.O. Box 24036 timber (automatic stress grading). Equipment for S-400 22 Göteborg, Sweden three different stress grading techniques are avail- Phone+46 312008 70 able at the laboratory. In a BCR-project a method of Fax+46 31 1612 95 calibrating stress grading machines is developed. In a field test glued pieces of wood are exposed to Swedish outdoor climate. Different types of glue are Staff used and the pieces have been subjected to various types of surface treatment. The results can be used Senior members for classifying the glues and the surface treatments Lars Boström Doctor of Science and also for calibrating laboratory methods against KentGylltoft Professor real exposure conditions. Carl-Johan Johansson Licentiate of Technology Research regarding frost and scaling resistance of Per-Erik Petersson Doctor of Science concrete is established since a number of years. A Björn Schouenborg PhD test method has been developed which today is Lennart Ågårdh Associate professor accepted as a standard test method in Sweden. In a newly started project the frost resistance of old concrete structures will be studied. This will, among Major instrumentation other things improve the possibility to predict the • MFL UP2000 compression testing machine, service life of new structures. 1977, with a load capacity of 20 MN static and In a field exposure test on the Swedish west coast 13 MN dynamic (1 Hz). about 50 concrete qualities are tested in a marine environment. This is a joint project where beside SP • Instron 1253 universal strength testing ma- also LTH (Lund University of Technology), CTH chine, 1977, with a load capacity of 50 kN (Chalmers University of Technology) and CBI dynamic and 100 kN static. (Swedish Cement and Concrete Research Institute) • Cook-Bolinder stressgrading machine 1991; participate. The aim of the project is to test new types prediction of bending strength of timber with of concrete, to calibrate existing test methods and sizes up to 75 x 250. material models and to develop new material mod-

MATERIALS SCIENCE, 1993 257 SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - BUILDING TECHNOLOGY

Computer Matic strcssgrading machine 1991; Newmethodsarealsostudied, for instance strength prediction of bending strength of timber with predictions based on a combination of density and sizes up to 75 x 150. knot size measurements. In a European co-operation project (BCR) we are developing calibration sys- Micromeritics X-ray SediGraph 5100,1991; tems for stress grading machines. determination of grain size distribution of Traditionally timber has been graded in dry con- pulverized materials with particle size between dition. The economy could, however, be improved if 300 and 0,1 mm (equivalent spherical diam- the grading was carried out prior to the rather costly eter). Materials commonly analysed are liming kiln drying as no drying of the rejects would be materials, cement and additives, aggregate necessary then. In our project we establish the rela- filler and industrial minerals. tion between strength and stiffness for wet timber in Leitz Polarizing microscope, 1978, with order to obtain correct setting values for the ma- Innovativ Vision AB LabEye Image-analysis chines. system 3,1992; thin-section analysis of build- ing materials and quantitative analysis of air- pore structure and size distributions of various Structure and composition of old lime mor- components in concrete. tars and renderings with good durability; examination, sampling and analysis The knowledge for choosing methods and materials Financial support for restoration and conservation of the architectural • The Swedish Board for Building Research, BFR heritage is not always available. •NORDTEST Nordic Lime is a joint inter-Nordic project on old •NUTEK building limes. The primary aim of the project is to •BCR develop new lime mortars mainly for conservation • Swedish materials industry purposes. The project also deals with the develop- • Swedish National Road Administration ment of guidelines for field examination and sam- •SBUF pling. The project will also increase our knowledge • Nordisk Industrifond about which properties that have a major influence on the durability of present mortars and renderings for other building purposes. Three medieval churches in Scania have been Research projects sampled in order to study the structural, chemical, Machine stress grading of timber physical and mechanical properties of ancient mor- Machine stress grading is a technique where the tars and to correlate these parameters with a.o. the timber is classified based on a prediction of the durability against frost action. strength. The most common method is to determine Well established methods for testing of frost the bending stiffness and to use known relations resistance, compressive strength, density, porosity, between strength and stiffness. In the most common water absorption coefficient and permeability are grading machines the timber is subjected to three modified to suit the small-scale samples of the old point loading in the weak direction and the load- mortars. Chemical analysis and thin-section deflection relation is determined for every 100 to 150 microscopy are used in order to characterise the mm along the timber except for 0.6 m at the ends. chemical composition of the binder phase and the In our project we study different ways of improv- composition of the aggregates. Image-analysis is ing the strength prediction. This, for instance, in- used to quantify the air-pore content and structure volves adding information about knot size using and also the content of aggregate versus the binder optic sensors and image processing technique. One phase. important task is also to find methods of damping the A progress report with results from the ongoing vibrations that easily occur in the timber during the analyses will be submitted in the spring, 1993. The passage through the machine and that affects the project will thereafter focus on the development of strength predictions.

258 THE CENTRE FOR SWEDISH NATIONAL TESTING AND RESEARCH INSTITUTE - BUILDING TECHNOLOGY methods for testing objects in situ and the manufac- precipitation are recorded and studies will be made turing of new mortars, short time testing (accelerated of frost resistance, chloride penetration, alkalinity ageing) and field applications. and rate of corrosion. Normally freeze-testing starts in the laboratory Frost resistance of concrete when the concrete is 28 days old. Results from these To rate the salt-frost resistance of concrete the Swed- tests cannot be expected to be in full agreement with ish standard 13 72 44 has proved to be very depend- results obtained from drilled-out cores from old able and to give reproducible results. It is a laboratory structures. A procedure or formula to "translate" method where the resistance of the concrete is as- laboratory results to safe predictions of concrete sessed after the amount of material that has scaled durability in aggressive environments is highly de- after a number of well-defined freeze-thaw cycles. sirable and work is in progress with this purpose. However, the method is sometimes considered Laboratory experiences with the freeze-testing too strict and to give results with a large margin of method are quite extensive as regards testing with a safety. Consequently, concrete structures might be- salt solution (3 % sodium chloride). This is not the come unnecessarily expensive. The reason for these case, however, when freezing takes place in pure doubts is that nobody has taken pains to correlate the water. Comparisons with other freeze-testing meth- results to outdoor circumstances. ods are necessary to arrive at a recommended method To ascertain the relevance of the method, i.e. to for testing and to put forward relevant assessment show how the accurately defined freeze-thaw cycles criteria for concrete in moderately aggressive envi- of the standard correspond to outdoor conditions, it ronment. is necessary to expose concrete to aggressive envi- The relations between various parameters that ronments outside the laboratory. For this purpose govern the frost resistance of concrete are poorly field stations have been established, the largest one understood. These parameters might be the water- at Träslövsläge on the Swedish west coast. This cement ratio, air content, size and distribution of air station, which was inaugurated in December of bubbles, cement content and type of cement. Work 1991, consists of two connectal pontoons. Along the has started with the aim to increase the knowledge of sides of the pontoons, concrete slabs of more than 40 relations between these parameters, hopefully re- different qualities are fastened, half-way subwezed sulting in considerably increased capabilities in de- into the water. The slabs are provided wilh reinforce- sign for concrete durability. ment. Temperature, wind velocity, humidity and

MATERIALS SCIENCE, 1993 259 Production and materials processing

Production Engineering 262 IVF, The Swedish Institute of Production Engineering Research 264

MATERIALS SCIENCE, 1993 261 Production Engineering Division of Manufacturing Engineering

Address Major Reids of Research Department of Production Engineering A: Maching and tool wear Chalmers University of Technology participants: Ralph Crafoord, Jacek Kaminski, S-41296 Göteborg, Sweden Per Öhl, Hans-Börje Oskarson, Hans Vogt Phone+46 31 772 1270 collaborators:SKF (Swedish Ball Bearing Fax+46 31 772 3819 Company) B: Surface roughness participants: Ralph Crafoord, Bengt-Göran Staff Rosén, Robert Ohlsson, Magnus Jonasson Senior Members: collaborators: Volvo Car Corporation Ralph Crafoord Professor Hans Vogt Docent Jacek Kaminski Tech.Dr. Research Projects Graduate Students: A: Wear Mechanism when Machining with Robert Ohlsson Civ.Eng. Whisker-reinforced Ceramic Cutting Tools. Christian Qjmertz Civ. Eng. This project will study the wear mechanism when Magnus Jonasson Civ.Eng. cutting with whiskerreinforced ceramic cutting tools, Bengt-Göran Rosén Tech.lic. especially in work material Inconel 718 and V2906. PerÖhl Tech.lic. In part A (1990-1991) of the project the notch wear Hans-Börje Oskarson Tech.lic. mechanism has been examined. The notch wear in a ceramic cutting tool when machining heat resistant Technical Staff: alloys is often the factor which decides the tool life RolfNoniström Eng. and consequently the tool economy will be depend- Dick Olofsson Eng. ent on it. In this study, DOC notch at the whisker- Secretary: reinforced ceramic (A12O3 + SiCw) will be studied Ann-Charlotte Hansson when turning in Inconel 718. Some comparison studies are made in steel V2906. The position of the notch and the geometry of the tool are measured Major Instrumentation closely. The notch is situated outside the theoretical • 525 ton hydraulic r•™;ss. Manufacturer: chip width with all its extension. The friction condi- Carbox. Field of application: High pressure tions in the cutting area and the cutting parameters research, cold forging. have a determining influence on the degree to which the notch will appear on the rake and flank face. Chip 5 axis milling machine. Manufacturer: Maho. studies are made and the chip formation mechanism Field of application: Milling, tool wear, adap- is discussed. The ragged edge of the chip is an tive control. important factor for the notch formation. The wear Surface roughness measurement equipment. mechanism in the notch area is a combination of Rebuild for 3D measurements. mechanical and chemical processes. The two types of mechanism are confirmed in SEM studies and studiesofcuttool.Theinfluence of the oxygen on the process will be mentioned in wear studies with different cutting media. The influence of whisker orientation on notch wear is studied in some special

262 THE CENTRE FOR PRODUCTION ENGINEERING

tool materials with a controlled whisker orientation. have confirmed the usefulness of our ISM-concept. Whiskers standing all over the material flow give the In cooperation with Volvo and NUTEK, we in the best wear resistance, while the worst wear resistance surface measuring group till continue our work with will be given with whiskers laying all over the flow ISM to increase the quality of the basic knowledge direction of the material. Reported to NUTEK fund for the cylinder liner surface with the focus on 910927. In pan B (1992-1994), the time-dependent the manufacturing process. chemical reactions and wear mechanism will be examined. Aspectsof intermittent cutting conditions will be included in the study. FEM will be used to Publications determine the temperture gradient in the cutting zone. Investigation methods such as SEM, Auger Ph.D. Dissertations spectroscopy and element mapping will be used. Bengtsson, Anders, On Three-Dimensional Measurement Cutting tools, work material and analyzing support of Surface Roughness. September 1991. Kaminski, Jacek, Positional Accuracy of Drilled Holes. will be furnished by Volvo Flygmotor and Sandvik December 1992. Coromant. Licentiate Dissertations B: Interactive Surface Modelling Rosén, Bengt-Göran, Interactive Surface Modelling and Making surface roughness a useful tool for dealing Representation of Surface Roughness and Topography. November 1991. with functional surfaces points to the need for a high- Oskarson, Hans-Börje, Wear Mechanism when Machining quality foundation for surface decisions. Errors in with Whisker-reinforced Ceramic CuttingTools (in specifications in many cases lead to costly produc- Swedish). December 1991. tion and perhaps nonfunctional surfaces. Decision- Ohl, Per, Harder Ball Surfaces: Thermal and Mechanical makingverymuchreliesonthequality of retrievable Processes (in Swedish). October 1992. and collected information. A recognized problem Papers today is that compared to older systems, today's 1) Rosén, B-G. and Crafoord, R., "Interactive Surface industry suffers from discontinuity in knowledge Modelling. Model of a Function-Oriented Expert communication due to reorganizations and the dy- System for Specification of Surface Properties", namics in the labor market. Often problems occur in Industrial Metrology, Vol. 2 No. 2,1992 pp. 107-119. making available proper and select information Rosén, B-G., "Representation of Thrcc-Dimensional (standards, expert knowledge and laws). Interactive Surface Topography in CAD-Systems and Image- Processing Software", Machine Tools and Manufac- Surface Modelling, ISM, addresses those problems ture, Vol. 12,1992. with an approach where functional demands control the route from specification of parameters through 2) Planning Expert". Proceedings of the CIRP Seminars - manufacturing preparation to measuring of the ma- Manufacturing System 20(1991)1, WISU Verlag, chined surface. Aachen, 1991 ISSN 0176-3377. Vogt, H.G., "Skiktbeläggningar på verktyg - några For two years, we have been working with Volvo fysikaliska synpunkter vid skärande bearbetning", to build a prototype Interactive Surface Modelling CTH, Inst f Produktionsteknik, Verkstäderna (1992) system for expert support in specification, manufac- Oct. 1992, Stockholm. turing preparation, and measuring of surface rough- Vogt, H.G. and Zaring, P., "Planning of Operation Se- ness and topography. In this first version, the system quences with an Al-based Knowledge-Aquisition Tool", in Kochan, D., Complex Machining and AI- is implemented for two obviously different func- methods. Proceedings of the IFIP TC5/WG5.3 Work- tional surfaces: cylinder liners for car engines, and ing Conference, 27-29 Nov. 1991, Gaussig/Drcsden, leather imitation textures and (ongoing) metal sheet Elsevier, Nov. 1991, ISBN 0^44-89326-1. surfaces for deep drawing and painting. The imple- Crafoord, R., "Proposal for a Fast and Accurate Software mentation is done on an ordinary PC with the support for Sheet Metal Bending", ERC/NSM Report, Ohio State University, Columbus OH, USA, Dec. 1991. of commercially available softwares for database Crafoord, R. and Lee, J.K., "Bending Experiments", handling, CAD multimedia and calculations. A lot Engineering Mechanics, Ohio Stale University, of effort has been put into making the system user- Columbus OH, USA, Jan. 1992. NADDRG Confer- friendly. Demonstrations to industry and other uni- ence, May, 1992. versities in Sweden, Denmark and Great Britain

MATERIALS SCIENCE, 1993 263 1V1% The Swedish Institute of Production Engineering Research

IVF - The Swedish Institute of Production Engi- Address neering Research - was founded in 1964 and con- The Swedish Institute of Production Engineering ducts applied research and technological develop- Mölndalsvägen 85 ment. The objective is to improve the efficiency and S-412 85 Göteborg, Sweden competitive strength of engineering companies by Phone+46 31 83 8600 developing and disseminating new technological Fax 446 31 40 78 76 know-how. IVF has a turnover of SEK 105 million (about 10 MGBP) and has 180 employees (1992).

IVF's main work consists of The department of • monitoringandevaluatinginternationaldevelop- Electronic Production ments in the engineering industry; The department of Electronic Production consists of • initiating and implementing research projects in 18 employees of which 15 are research engineers (7 close co-operation with industry and other re- Ph.D.s, 7 engineers holding M.Sc. degrees and 1 search institutes, both nationally and interna- engineer). The research volume is SEK 15 •nillion. tionally; More than 70 companies support (financially and technically) joint projects conducted by the depart- • turning technological advances into practical ment of Electronic Production. Manager of the de- applications; partment is Ph.D. Bill Brox. • helping to introduce new technology in indivi- Five areas are identified as main research areas. dual companies; A: Support for design, M.Sc. Håkan Svärd • spreading information about new methods of B: Assembly and materials technique, product development and production engineering M.Sc. Per Hedemalm - particularly to small and medium-sized C: Material and failure analyses, companies. M.Sc. Göran Wetter D: Chemistry and environment, IVF perform works within the following areas Ph.D. Per-Erik Tegehall Machining Adhesives E: Production, Engineer Peter Wahlberg Assembly Quality management Robotics Working Major equipment CAD/CAM environments research The laboratory facilities consist of a micro joining Electronics Vibration lab in a clean room, surface mount lab, thermal lab, Forging Ventilation chemical and specimen preparation lab, environ- Hot isostatic pressing Workplace planning mental testing lab, material analysis lab and lab for Heat treatment Ergonomics chemical analysis. This includes Welding Machine safety Surface treatment Small companies • Scanning Electron Microscope, SEM, JEOL Sheet metal working service 840 A, resolution approx. 50 Å, test object size New materials max. 10 cm. including composite fibres • Energy Dispersive Spectrometer, EDS, Two of these areas, "Electronics" and Surface treat- TRACOR, connected to the SEM equipment ment", are described more in detail below. for quantitative and semiquantitative elemental analysis (also carbon, oxygen and nitrogen).

264 THE CENTRE FOR IVF THE SWEDISH INSTITUTE OF PRODUCTION ENGINEERING RESEARCH

5 - Sulfat

I I I II I I I I I I i i i i 11 5 6 8 10 Diagram from Minutes ion chromatograph

Ion chromatography, Dionex 300, with con- Thermo camera, Agema Thermovision 870. ductivity detector and spectral array detector. Resolution approx. 15 |jm, sampling time 70 Computer controlled. ms, temperature sensivity 0,1 K. Production equipment, such as IR reflow soldering equipment, semiautomatic screen printer, wedgebonder, ballbonder and pull and Projects Below are examples of projects ongoing within the shear tester. department that in some respects are related to the Environmental testing equipment, such as field of materials science. temperature cycling chamber, humidity cabi- nets and pressure cooker. Al: EMC Several projects are ongoing in this area which X-ray microscope, Feinfocus FXS 200.72. includes the electromagnetic interaction between Real time X-ray with image processing. Accel- the electronics and the surroundings as well as the eration voltage 10-200 kV. Resolution approx. electrical properties of materials. 3 pm. Penetration thickness 20 mm Fe, 80 mm Al. Test object size: max. 0,5 m, 10 kg. A2: Thermal design and cooling of electronics Thermal parameters of individual components, printed circuit boards and electronics installed in racks have been studied for many years at the depart- ment. Today, much attention is focused on thermal parameters of different materials.

Bl: International programme for Rip-Chip Interconnection Technique Flip-chip is a technique to mount chip directly onto the printed wire board instead of using components. The project includes evaluation of the reliability for different cowibinations of materials. The evaluation itself consists of e.g. strength tests and environ- mental tests. Surface mounted chip capacitor - voids in solder joint.

MATERIALS SCIENCE, 1993 265 iVF, THE SWEDISH INSTITUTE OF PRODUCTION ENGINEERING RESEARCH

B2: Conductive adhesives as solder replacement 7 Flexibel och kostnadseffektiv teknik för framställning The driving forces to use adhesives as replacement av metallkontakter hos chip - Nya sätt att skapa bumpar for solder is higher reliability of printed circuit för flip-chip-förbindningar. Johan Liu, IVF-rapport 91025,1991,52 sidor. boards, no use of lead (environmentally hazardous), fewer process steps in the production of electronics. 8 Mciallmigralion mellan uttag på elektronikkomponenter med liten bendelning. Per Johnsson och Anne Tillström, Dl: The International conformal coating IVF-resultat 91602,1991,28 sidor.

The objective is to increase the reliability of printed 9 Brandskadad elektronik: Sanering och tillförlitlighet BEST-projektet Lennart Cider, IVF-rapport 92/20, circuit board assemblies using conformal coatings at 1992,34 sidor. minimal additional cost The evaluation includes the properties of the conformal coatings in different 10 The relation between the halide and alkali concentra- environments, the influence of the surface state tions and the electrochemical migration on printed before coating as well as the influence of method of circuits boards. Per Carlsson and Lennart Cider, 2nd International symposium on corrosion of electric application. materials and devices. Electrochemical Society Conference, Toronto 1992. D2: Evaluation of commercially available electro lessly golcHXated printed circuit boards 11 TAB outer lead bonding alternatives for small batch The main purpose of the project is to evaluate the and flexible production. Martin Udden, IVF-skrift properties of electrolessly plated FR-4 PCBs made 90814,1990,40 pages. by different manufactures using different processes. The project includes evaluation of thickness, hard- ness, porosity, strength, solder ability, bond ability, The Surface Treatment group environmental tests as well as analyses of inter The Surface Treatment group consists of 12 employ- metallic phases in the solder joint. ees of which all are research engineers (1 Ph.D., 1 M.Sc, 6 engineers holding M.Sc. degrees and 4 engineers). The research voiume is SEK 7 million. Publications More than 60 companies support (financially and 1 Handbok i lermisk konstruktion av elektronik i technically) joint projects within the Surface Treat- apparaimiljö. Göran Rodman och Anders Sihlbom, ment group. Manager of the department including IVF-skrift 88822,1988,258 sidor. the Surface Treatment group is M.Sc.Lic Per Boije. 2 Elektrisk dimensionering av kretskort. Strålning - Three areas are identified as main research areas. regler och hjälpmedel. Hakan Svärd, IVF-rcsultat 90622, A: Electroplating/Hot dip galvanizing 199C. 51 sidor. (M.Sc. Richard »c.glund) 3 Concurrent Engineering - Resultat och utvärdering av B: Painting (M.Sc. Lars Österberg) enkät. Peter Gustafsson och Håkan Svärd, IVF-skrift C: Thermal spraying (M.Sc. Lars Österberg) 92818.1992,48 sidor.

4 Polymer (hick film technology - A reliability study of an additive PCB technology. Per Johnsson, Jan Major equipment Eliasson and Martin Udden, IVF-rcport GE9OO4,1990, The lab facilities consists of chemical surface treat- 134 pages. ment equipment (pilot scale), industrial production equipment for painting and thermal spraying besides 5 Mot miljövänligarc elektronik - avveckling av b!y och bromerade flamskyddsmedcl. Per Hedemalm, IVF - analyses facilities already mentioned. This includes skrift 91823,1991,30 sidor. • Pilot Plating Plant, flexible and fully auto- mated with bathes 70 1401. 6 Chip-on-boarc' - Grundläggande teknik för trådboiidad chip-on-board. Anne Tillström, IVF-skrift 91831,1991, • Pilot Painting Fac u for powder and wet 70 sidor. spray painting. • Thermal Spraying Faci fy, including HVOF (High Velocity Oxygen 1 ucl).

266 THE CENTRE FOR IVF, THE SWEDISH INSTITUTE OF PRODUCTION ENGINEERING RESEARCH

IVF:s flexible, fully automated pilot plant

Surface Carbon Analyzer (IMC-method). Cl: The adhesion of thermally sprayed coatings Atomic Absorbtion Spectroscopy. The adhesion is a critical property of a thermally SCAB Corrosion Testing sprayed coating. The study showed that when the substrate was properly blasted the preheating tem- perature was the most critical one. The difference Projects between preheating temperature and the maximum Below are examples of the about 30 major projects temperature of the substrate during spraying shall be ongoing within the group that in some respects are as small as possible. In contrary to the common related to the field of materials science. opinion the influence of time between blasting and spraying was negligable. Al: Quality assurance in surface treatment Musty The work covers how to build quality systems in small surface treatment companies. An important Publications field is to investigate how different process param- eters influence the properties of the coating. 1 Konstniktionsanvisningar för ytbehandling. (Design guide-lines for surface treatment). Lars österberg, Göran Ahlin, IVF-resuliat91604 (1901) 57 pages. A2: Hard chromium with Increased corrosion resistance 2 Yure miljö vid oorganisk ytbehandling. Vad händer pä The main interest has been to optimize the param- 90-talet? Lars Clarin. IVF-skrift 91816 (1991). eters in the hard chromium process in order to get hard and wear resistant coatings with good corrosion 3 Pulvcrlackering - användningsområden. (Powder Coatings - Fields of Application). Sture Lttckner, IVF- protection. resuliat 92501 (1992) 27 pages. It has been shown that pulse plating increases the corrosion protection with a very small drop in hard- 4 Renhetsmätning - en uppslagsbok om mätmetoder. ness. The ir cs for causing blistering in the coating (Cleanliness measurement - a reference manual of when using wetting agents in the bath have been measuring methods). Cecilia Norrby och Jan Skogsmo, studied. The main result is that the hard chromium IVF-resultat 92603 (1992) 71 pages. process is tolerant to relatively hifcii amounts of 5 Teknisk utvärdering av väunedlets inverkan pa wetting agents. hårdkromskiki. (Evaluation of wetting agent on the quality of hard chromium coatings). Svante Nordänger, Bl: Powder coating for corrosion protection IVF-skrift 92815,23 pages. The ability of a powder paint film to act as a barrier 6 Kvalitetssystem i ytbehandlande industri, en handbok. to the environment has been studied. Among the Richard Berglund, Ytforums Förlags AB 1992,48 sidor. parameters which can be changed during the appli- cation of the paint, the film thickness has the greatest 7 The journal Ytforum: 15-20 IVF-papers published each influence on the water permeability. At the same year. film thickness all powder paints studied showed less water permeability compared with the wet paints studied.

MATERIALS SCIENCE, 1993 267 Keywords

Keyword Chapter Page A adhesives IVF 264 analytical electron microscopy Microscopy and Micr analysis 228 annealing Semiconductor Physi ;s and Heterostructures.... 157 atom-probe field ion microscopy Microscopy and Microanalysis 228

B batteries Materials Physics 70 brazing Engineering Metals 216 buckminsterfullerenes Molecular Physics 126 building materials Building Materials 246 bulk polymers Polymer Technology 78

C catalysis Materials and Surface Physics 2 Surface Physics 114 Molecular Physics 126 catalyst Engineering Chemistry 139 ceramic materials Engineering Metal* 216 ceramics SCI 202 chlorine-free bleaching Engineering Chemistry 139 chromogenic materials Experimental Physics 32 clusters Molecular Physics 126 combustion Surface Physics 114 concrete Building Materials 246 condensed matter theory Materials and Surface Physics 2 Condensed Matter Theory 196 coordination chemistry Inorganic Chemistry 46 corrosion Engineering Metals 216 corrosion chemistry Inorganic Ciunistry 46 corrosion resistance materials SCI 202 IVF 264

D disordered systems Materials Physics 70 durability Building Materials 246 Mechanics, SP 240 Building Technology, SP 257

268 THE CENTRE FOR KEYWORDS

electrochemistry Inorganic Chemistry 46 electronic excitation Reaction Dynamics 58 electronic calculation Molecular Physics 126 electron microscopy Microscopy and Microanalysis 228 electron structure Electronic Structure of Condensed Matter 13 Materials and Surface Physics 2 Condensed Matter Theory 196 electrooptics Liquid Crystals 164 energy related materials Materials Physics 70 Experimental Physics 32 Interdisciplinary Materials 26 energy transfer Reaction Dynamics 58 engineering ceramics SCI 202

F fabrics IFP-TEFO 102 ferroelectricity Liquid Crystals 164 fibers IFP-TEFO 102 frequency doubling Molecular Physics 126 fuel cells Materials Physics 70

G GaAs Semiconductor Physics and Heterostructures.... 157 glass transition Materials Physics 70

H hard materials SCI 202 high pressure Interdisciplinary Materials 26 high temperature materials SCI 202 high temperature superconductors Applied Solid State Physics 174

I IC-CAD Solid State Electronics 148 interdisciplinary materials research Interdisciplinary Materials 26 ion conducting polymers Materials Physics 70

MATERIALS SCIENCE, 1993 269 KEYWORDS

laser spectroscopy Molecular Physics 126 lattice mismatch Semiconductor Physics and Heterostructures.... 157 liquid crystals Liquid Crystals 164

M MBE Semiconductor Physics and Heterostructures.... 157 many-body effects Electronic Structure of Condensed Matter 13 materials characterization Interdisciplinary Materials 26 mechanical properties Engineering Metals 216 Polymeric Materials 87 Mechanics, SP 240 mesoscopic systems Materials and Surface Physics 2 Applied Solid State Physics 174 metal cutting Production Engineering 262 metallic materials Engineering Metals 216 microanalysis Microscopy and Microanalysis 228 microstructurc Microscopy and Microanalysis 228 Interdisciplinary Materials 26 moisture Building Materials 246 molecular physics Molecular Physics 126

N nanomiterstructures Applied Solid State Physics 174 nuclear magnetic resonance (NMR) Polymer Technology 78

0 oil refining Engineering Chemistry 139 optical computing Liquid Crystals 164 optoelectronics Semiconductor Physics and Heterostructures.... 157 photoelectron spectroscopy Electronic Structure of Condensed Matter 13 pollution control Engineering Chemistry 139 polymer synthesis Polymer Technology 78 polymer surfaces Polymer Technology 78 polymers Polymeric Materials 87 Polymer Technology, SP 95 IFP-PGI 106 powder metallurgy Engineering Metals 216 processing Polymeric Materials 87

270 THE CENTRE FOR KEYWORDS

quantum structures Semiconductor Physics and Heterostructures.... 157

reaction kinetics Reaction Dynamics 58 rheology Polymeric Materials 87

S STM Applied Solid State Physics 174 secondary ion mass speci- jmetry (SIMS) Interdisciplinary Materials 26 semiconductors Semiconductor Physics and Heterostructures.... 157 Solid State Electronics 148 semiconductor surfaces Electronic Structure of Condensed Matter 13 sensors Solid State Electronics 148 Applied Solid State Physics 174 silicon devices Solid State Electronics 148 silicon technology Solid State Electronics 148 small particle technology Engineering Chemistry 139 solid electrolytes Materials Physics 70 Experimental Physics 32 structural dynamics Materials Physics 70 superconductivity Applied Solid State Physics 174 superconductors Applied Solid State Physics 174 Materials Physics 70 superlatticts Inorganic Chemistry 46 surface analysis Electronic Structure of Condensed Matter 13 Surface Physics 114 Engineering Metals 216 surface coating Interdisciplinary Materials 26 surface physics Experimental Physics 32 Surface Physics 114 surface processes Materials and Surface Physics 2 surface roughness Surface Physics 114 synchrotron radiation Production Engineering 262 synthesis Electronic Structure of Condensed Matter 13 Polymer Technology 78

MATERIALS SCIENCE, 1993 271 KEYWORDS

textile technology IFP-TEFO 102 theory of materials Materials and Surface Physics 2 thermal insulation Building Technology 257 thermal transport properties Thermal Transport Properties of Materials 22 tool wear Production Engineering 262 trace analysis Interdisciplinary Materials 26

W wood Building Materials 246

X X-ray Microscopy and Microanalysis 228 Inorganic Chemistry 46 Electronic Structure of Condensed Matter 13

Y yarns IFP-TEFO 102

272 THE CENTRE FOR The Centre for Materials Science promotes materials research among the member organizations and provides a link with industry and with society as a whole. Members are:

School of Physics and Engineering Physics, CTH /GU Department of Theoretical Physics and Mechanics Department of Physics Department of Applied Physics

School of Chemical Engineering, CTH /GU Department of Inorganic Chemistry Department of Physical Chemistry Department of Engineering Chemistry Department of Polymer Technology

School of Mechanical and Vehicular Engineering, CTH Department of Engineering Metals Department of Polymeric Materials Department of Production Engineering Department of Theoretical and Applied Mechanics

School of Civil Engineering, CTH Division of Building Materials

School of Electrical and Computer Engineering, CTH Department of Solid State Electronics

Swedish Ceramic Institute, SCI

The Swedish Institute of Fibre and Polymer Technology

Swedish National Testing and Research Institute

The Swedish Institute of Production Engineering Research, IVF

The Centre for Materials Science Chalmers University of Technology S-412 96 Göteborg Sweden

!SSN 1104-3539 ISPN CTH-MC-PBS--1--SE