DOCSLIB.ORG

Structure of Ice VI Barclay Kamb

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Structure of Ice VI Barclay Kamb KAMB-B 65-0860 Structure of Ice VI Barclay Kamb Repriated frent Science. Oct.her 8, IH.'). Vel. 150, Xe. 3693, ...." .i-", powder data, to search the capillaries for crystals suitable for single-crystal study, and to orient and collect com­ plete diffraction data from such crys­ tals. Ice VI, prepared and examined in this way, gives a powder pattern (Ta­ ble 2) in general agreement with data obtained at high pressure and also with data from other experiments on quenched samples (6). Single crystals are easily obtained and are found to be tetragonal with unit cell dimensions a = 6.27 ± 0.01 A, c = 5.79 ± 0.01 Structure of Ice VI A. The diffraction patterns show extinc­ tions for reflections of type hkO with Abstract. Ice VI, a high-pressure form of density 1.31 g cm-J , has a tetrag­ h + k odd and for hhl with I odd. The onal cell of dimensions a = 6.27 A, c = 5.79 A, space group P4jnmc, each space group is thus uniquely determined cell colltaining ten water lIlolecules. The structure' is built up of hydrogen-bonded as P4~ / nmc (7) . The foregoing cell c//{lins of water molecules that are analogs of the tectosilicate chains out of which accounts well for the observed powder the fibrous zeolites are constructed. The chains in ice VI are linked laterally' to spacings (Table 2). one another to form an 0 en; zeolite-like framework. The cavities in this r ne­ Recently single crystal data for ice war ' are filled with a second fralllewor I enflca Wit 1 t 7e rst. The two frame­ VI, obtained at high pressure by means l . pene ra e £It 0 not interconnect and the complete structure call thus of a pressure cell mounted on a pre­ be con.fldered a "sell-clathrate." 1 h~ctural feature is a natural way to achieve cession camera, have been published high density in tetrahedrally linked framework structures. by Block, Weir, and Piermarini (8). These authors report an orthorhombic The stability conditions of the quenched by immersing the cylinder in cell with dimensions a' = 8.38 A, b' known forms of ice (Fig. 1) are a re­ liquid nitrogen, the pressure is released, = 6.17 A, and c' = 8.90 A, and for flection of the thermodynamic relations and the sample is forced out of the this cell they report diffraction extinc­ among the various phases, and these cylinder and into a bath . of liquid tions for reflections of type h' k'O with relations are in turn a macroscopic re­ nitrogen. At the temperature of liquid h' odd (diffraction aspect p •• a). This flection of the molecular architecture nitrogen (-196°C), high-pressure ice identification of the unit .cell is errone­ of the individual forms. Conversely, samples are metastable and can be OLIS. The cell chosen by Block el al. the structural features of the indi­ kept indefinitely at atmospheric pres­ (8) is related to the true tetragonal vidual forms in relation to their stabil­ sure. When the capillaries are removed cell as follows. The b' axis is one of ity fields and to the thermodynamic into the open aii', they explode, because the tetragonal a-axes, and the a' axis variahles provide some insight into the of the volume increase upon inversion is the tetragonal cell diagonal [10 I], forces of interaction between water of the high-pressure ice to ordinary that is, a' = a + c. The c' axis chosen molecules, and in particular into the ice J. by Block et al. (8) should evidently disruption of these forces that is caused Individual capillaries were mounted correspond to the other cell diagonal by packing the molecules more closely for x-ray study in a precession camera, [lOT]. The angle between the a' and c' together, as is achieved under high where they were maintained at a tem­ axes is 94.5°, according to the dimen­ pressure. Some structural information perature of -175°C by a stream of sions of the tetragonal cell, rather than for most of the forms of ice is now cooled nitrogen gas. The precession 90° as apparently assumed by Block availahle (Table 1), and the detailed camera can he used to obtain x-ray et al. (8). structures of ice T. Ie, II, I If, and VTJ are known (1-5). I here describe the structure . of ice VI, determined by x­ Table I. X-ray structural data for ice polymorphs. ray diffraction, and give preliminary x-ray .structural information for ice V Density" Crystal Space Cell dimen- Ice Zt Reference (Table 1). (g cm"" ) syste{J1 group sions (A)" The samples were prepared as fol­ lows. Short glass capillaries, filled with I 0.92 Hexagonal P6,, / nZlllc a 4.48, c 7.31 4 (I) l. Ie 0.92 Cubic Fd3m a 6.35 8 (2) water, were placed in a hollow steel II 1.17 Rhombo- R3 a 7.78, Ot Il3.to 12 (3) cylinder fitted with pistons at both hedral ends. The chamber thus formed was III 1.14 Tetragonal P4,212 a 6.79, C 6.79 12 (4) filled with gasoline, to transmit pres­ IV 1.28 (14) sure from the pistons to the water sam­ V 1.23 Monoclinic A2/ a a 9.22, b 7.54 28 ~ C 1035, {J 109.2· ples. By loadirig the pistons and control­ VI 1.31 Tetragonal P4"/ llmc a 6.27. e 5.79 10 :j: ling the cylinder temperature appropri­ VII 1.50 Cubic . PI/3m a 3.41 2 (5) ately (Fig. 1), the desired i~e phase • At atmospheric pressure and -175°C. i Number of molecules in the unit cell. :j: Data given can be formed. The sample is then in accompany ing text. Fig. I. Phase diagram for water. The solid phases (ice polymorphs) are identi­ fied by the roman numeral designations assigned by Bridgman (14, 9, 15), upon 20 whose data the diagram is based. The field of ice IV in relation to ice VI and liquid is plotted by dotted lines within the ice V field, and is plotted by analogy to 0,0 ice, for which the field was ac­ tually measured (14); ice IV is everywhere unstable relative to ice V. Ice Ic ("cubic ; ice") is shown sc hematically below the tem­ If) 15f- 0 L perature of about _105 C, below which 0 -<> it forms by vapor condensat.ion (16) and 0 above which it inverts to ice I (17) : it is Y: not known to have afield of actual sta­ <ll bility. L ::J If) If) <ll L 1-0 0.. Proof of the correct unit cell is es­ sential to determination of the struc­ ture; hence in Fig. 2 there is shown a precession photograph of the hkO plane of ice VI. The photograph was made i without use of a layer-line screen and 5:- hence shows also the symmetry of the II Li quid upper layers parallel to hkO. It is thus analogous to a Laue photograph in ex­ hibiting the diffra~tion symmetry of Ie I the crystal ' about its c-axis. The 4 -fold oL------~OL-O-----------5~O----------~O-----------5~O----------~100 axis and the mirror planes are clearly visible. There are no 4-fold axes paral­ Temperature (OC) lel to the plane of the photograph . Their absence cannot be judged from the photograph itself, but is determined by manipulating the original crystals. It is unlikely that the crystals studied by Block el al. (8) at high pressure were essentially different from the quenched samplcs of ice VI described here. The unit cell chosen by these au­ thors is compatible with essentially the same powder pattern as is given by the quenched samples (Table :2), and the dimensions of the "orthorhombic" and tetragonal cells are compatible, taking into accou nt the differing cell orienta­ tions and the different experimental conditions and possible sources of ex­ perimental error. The lI'k'O photo­ graph published by Block el at (Fig. 1 of Ref. 8) appears identical, to the ex­ tent that the diffraction pattern can be seen in the photograph, with precession photographs of the hkh plane of the tetragonal crystals. The two crystals (icc vr under pressure, and quenched) can therefore differ at most by a slight distortion. It is unlikely that a low- Fig. 2. Precession photograph about the c-axis of ice VI, made with unfiltered molybuen'um radiation and without a 0 layer-line screen, /L = 15 • The II kO plane shows as single spots in the central por­ tion of the photograph. ilk I and higher layers as double spots and hyperbolic streaks in the oute r portion. Note 4-folu symmetry about the c-axis. 2 temperature (quenched) form would tail. The parameter values x and z Table 2. X-ray powder data for ice VI. be more symmetrical (tetragonal) than given must be accurate (probably to hkl the high-temperature form (supposedly ± 0.002), since the "fractional dis­ orthorhombic) from which it inverted crepancy" ~ I ~F ! /~IF()I is only 0.07, 4.44 4.47 110 by a displacive transfor~ation upon which is about as low as is commonly 81z 4.3 4.27 4.26 101 81z 3.6 cooling. achieved for refined structures based 51t 3.4 The density of ice YI at 6175 at­ on photographically measured x-ray 13 3.12 3.14 3.14 200 m~ospheres and 0 2°e (the triple point intensities. 8 2.91 2.92 2.90 002 3 90 2.75 2.76 2.76 201 ice V-ice VI-Ii ui cm- Positions of the hydrogen atoms 50 2.63 2.64 2.63 102 .
Load more

Recommended publications
  • Proton Ordering and Reactivity of Ice
    1 Proton ordering and reactivity of ice Zamaan Raza Department of Chemistry University College London Thesis submitted for the degree of Doctor of Philosophy September 2012 2 I, Zamaan Raza, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. 3 For Chryselle, without whom I would never have made it this far. 4 I would like to thank my supervisors, Dr Ben Slater and Prof Angelos Michaelides for their patient guidance and help, particularly in light of the fact that I was woefully unprepared when I started. I would also like to express my gratitude to Dr Florian Schiffmann for his indispens- able advice on CP2K and quantum chemistry, Dr Alexei Sokol for various discussions on quantum mechanics, Dr Dario Alfé for his incredibly expensive DMC calculations, Drs Jiri Klimeš and Erlend Davidson for advice on VASP, Matt Watkins for help with CP2K, Christoph Salzmann for discussions on ice, Dr Stefan Bromley for allowing me to work with him in Barcelona and Drs Aron Walsh, Stephen Shevlin, Matthew Farrow and David Scanlon for general help, advice and tolerance. Thanks and also apologies to Stephen Cox, with whom I have collaborated, but have been unable to contribute as much as I should have. Doing a PhD is an isolating experience (more so in the Kathleen Lonsdale building), so I would like to thank my fellow students and friends for making it tolerable: Richard, Tiffany, and Chryselle. Finally, I would like to acknowledge UCL for my funding via a DTA and computing time on Legion, the Materials Chemistry Consortium (MCC) for computing time on HECToR and HPC-Europa2 for the opportunity to work in Barcelona.
    [Show full text]
  • Ice Ic” Werner F
    Extent and relevance of stacking disorder in “ice Ic” Werner F. Kuhsa,1, Christian Sippela,b, Andrzej Falentya, and Thomas C. Hansenb aGeoZentrumGöttingen Abteilung Kristallographie (GZG Abt. Kristallographie), Universität Göttingen, 37077 Göttingen, Germany; and bInstitut Laue-Langevin, 38000 Grenoble, France Edited by Russell J. Hemley, Carnegie Institution of Washington, Washington, DC, and approved November 15, 2012 (received for review June 16, 2012) “ ” “ ” A solid water phase commonly known as cubic ice or ice Ic is perfectly cubic ice Ic, as manifested in the diffraction pattern, in frequently encountered in various transitions between the solid, terms of stacking faults. Other authors took up the idea and liquid, and gaseous phases of the water substance. It may form, attempted to quantify the stacking disorder (7, 8). The most e.g., by water freezing or vapor deposition in the Earth’s atmo- general approach to stacking disorder so far has been proposed by sphere or in extraterrestrial environments, and plays a central role Hansen et al. (9, 10), who defined hexagonal (H) and cubic in various cryopreservation techniques; its formation is observed stacking (K) and considered interactions beyond next-nearest over a wide temperature range from about 120 K up to the melt- H-orK sequences. We shall discuss which interaction range ing point of ice. There was multiple and compelling evidence in the needs to be considered for a proper description of the various past that this phase is not truly cubic but composed of disordered forms of “ice Ic” encountered. cubic and hexagonal stacking sequences. The complexity of the König identified what he called cubic ice 70 y ago (11) by stacking disorder, however, appears to have been largely over- condensing water vapor to a cold support in the electron mi- looked in most of the literature.
    [Show full text]
  • Glaciers and Their Significance for the Earth Nature - Vladimir M
    HYDROLOGICAL CYCLE – Vol. IV - Glaciers and Their Significance for the Earth Nature - Vladimir M. Kotlyakov GLACIERS AND THEIR SIGNIFICANCE FOR THE EARTH NATURE Vladimir M. Kotlyakov Institute of Geography, Russian Academy of Sciences, Moscow, Russia Keywords: Chionosphere, cryosphere, glacial epochs, glacier, glacier-derived runoff, glacier oscillations, glacio-climatic indices, glaciology, glaciosphere, ice, ice formation zones, snow line, theory of glaciation Contents 1. Introduction 2. Development of glaciology 3. Ice as a natural substance 4. Snow and ice in the Nature system of the Earth 5. Snow line and glaciers 6. Regime of surface processes 7. Regime of internal processes 8. Runoff from glaciers 9. Potentialities for the glacier resource use 10. Interaction between glaciation and climate 11. Glacier oscillations 12. Past glaciation of the Earth Glossary Bibliography Biographical Sketch Summary Past, present and future of glaciation are a major focus of interest for glaciology, i.e. the science of the natural systems, whose properties and dynamics are determined by glacial ice. Glaciology is the science at the interfaces between geography, hydrology, geology, and geophysics. Not only glaciers and ice sheets are its subjects, but also are atmospheric ice, snow cover, ice of water basins and streams, underground ice and aufeises (naleds). Ice is a mono-mineral rock. Ten crystal ice variants and one amorphous variety of the ice are known.UNESCO Only the ice-1 variant has been – reve EOLSSaled in the Nature. A cryosphere is formed in the region of interaction between the atmosphere, hydrosphere and lithosphere, and it is characterized bySAMPLE negative or zero temperature. CHAPTERS Glaciology itself studies the glaciosphere that is a totality of snow-ice formations on the Earth's surface.
    [Show full text]
  • Thermodynamic Stability of Hydrogen Hydrates of Ice Ic and II Structures
    PHYSICAL REVIEW B 82, 144105 ͑2010͒ Thermodynamic stability of hydrogen hydrates of ice Ic and II structures Lukman Hakim, Kenichiro Koga, and Hideki Tanaka Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima, Kitaku, Okayama 700-8530, Japan ͑Received 6 August 2010; published 13 October 2010͒ The occupancy of hydrogen inside the voids of ice Ic and ice II, which gives two stable hydrogen hydrate compounds at high pressure and temperature, has been examined using a hybrid grand-canonical Monte Carlo simulation in wide ranges of pressure and temperature. The simulation reproduces the maximum hydrogen-to- water molar ratio and gives a detailed description on the hydrogen influence toward the stability of ice structures. A simple theoretical model, which reproduces the simulation results, provides a global phase dia- gram of two-component system in which the phase transitions between various phases can be predicted as a function of pressure, temperature, and chemical composition. A relevant thermodynamic potential and statistical-mechanical ensemble to describe the filled-ice compounds are discussed, from which one can derive two important properties of hydrogen hydrate compounds: the isothermal compressibility and the quantification of thermodynamic stability in term of the chemical potential. DOI: 10.1103/PhysRevB.82.144105 PACS number͑s͒: 64.70.Ja I. INTRODUCTION relative to other water-hydrogen composite phases in a wide range of thermodynamic conditions has been scarcely ex- Storage of hydrogen has been actively investigated to plored. On the other hand, constructing a global phase dia- meet the demand on environmentally clean and efficient gram is a tedious task from experimental view point, consid- hydrogen-based fuel.1 A search for practical hydrogen- ering the number of thermodynamic states to be explored.
    [Show full text]
  • Searching for Crystal-Ice Domains in Amorphous Ices
    PHYSICAL REVIEW MATERIALS 2, 075601 (2018) Searching for crystal-ice domains in amorphous ices Fausto Martelli,1,2,* Nicolas Giovambattista,3,4 Salvatore Torquato,2 and Roberto Car2 1IBM Research, Hartree Centre, Daresbury WA4 4AD, United Kingdom 2Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA 3Department of Physics, Brooklyn College of the City University of New York, Brooklyn, New York 11210, USA 4The Graduate Center of the City University of New York, New York, New York 10016, USA (Received 7 May 2018; published 2 July 2018) Weemploy classical molecular dynamics simulations to investigate the molecular-level structure of water during the isothermal compression of hexagonal ice (Ih) and low-density amorphous (LDA) ice at low temperatures. In both cases, the system transforms to high-density amorphous ice (HDA) via a first-order-like phase transition. We employ a sensitive local order metric (LOM) [F. Martelli et al., Phys. Rev. B 97, 064105 (2018)] that can discriminate among different crystalline and noncrystalline ice structures and is based on the positions of the oxygen atoms in the first- and/or second-hydration shell. Our results confirm that LDA and HDA are indeed amorphous, i.e., they lack polydispersed ice domains. Interestingly, HDA contains a small number of domains that are reminiscent of the unit cell of ice IV,although the hydrogen-bond network (HBN) of these domains differs from the HBN of ice IV. The presence of ice-IV-like domains provides some support to the hypothesis that HDA could be the result of a detour on the HBN rearrangement along the Ih-to-ice-IV pressure-induced transformation.
    [Show full text]
  • Modeling the Ice VI to VII Phase Transition
    Modeling the Ice VI to VII Phase Transition Dawn M. King 2009 NSF/REU PROJECT Physics Department University of Notre Dame Advisor: Dr. Kathie E. Newman July 31, 2009 Abstract Ice (solid water) is found in a number of different structures as a function of temperature and pressure. This project focuses on two forms: Ice VI (space group P 42=nmc) and Ice VII (space group Pn3m). An interesting feature of the structural phase transition from VI to VII is that both structures are \self clathrate," which means that each structure has two sublattices which interpenetrate each other but do not directly bond with each other. The goal is to understand the mechanism behind the phase transition; that is, is there a way these structures distort to become the other, or does the transition occur through the breaking of bonds followed by a migration of the water molecules to the new positions? In this project we model the transition first utilizing three dimensional visualization of each structure, then we mathematically develop a common coordinate system for the two structures. The last step will be to create a phenomenological Ising-like spin model of the system to capture the energetics of the transition. It is hoped the spin model can eventually be studied using either molecular dynamics or Monte Carlo simulations. 1 Overview of Ice The known existence of many solid states of water provides insight into the complexity of condensed matter in the universe. The familiarity of ice and the existence of many structures deem ice to be interesting in the development of techniques to understand phase transitions.
    [Show full text]
  • Estimation of the Dependence of Ice Phenomena Trends on Air and Water Temperature in River
    water Article Estimation of the Dependence of Ice Phenomena Trends on Air and Water Temperature in River Renata Graf Department of Hydrology and Water Management, Institute of Physical Geography and Environmental Planning, Adam Mickiewicz University in Poznan, Bogumiła Krygowskiego 10 str., 61-680 Poznan, Poland; [email protected] Received: 6 November 2020; Accepted: 9 December 2020; Published: 11 December 2020 Abstract: The identification of changes in the ice phenomena (IP) in rivers is a significant element of analyses of hydrological regime features, of the risk of occurrence of ice jam floods, and of the ecological effects of river icing (RI). The research here conducted aimed to estimate the temporal and spatial changes in the IP in a lowland river in the temperate climate (the Note´cRiver, Poland, Central Europe), depending on air temperature (TA) and water temperature (TW) during the multi-annual period of 1987–2013. Analyses were performed of IP change trends in three RI phases: freezing, when there appears stranded ice (SI), frazil ice (FI), or stranded ice with frazil ice (SI–FI); the phase of stable ice cover (IC) and floating ice (FoI); and the phase of stranded ice with floating ice (SI–FoI), frazil ice with floating ice (FI–FoI), and ice jams (IJs). Estimation of changes in IP in connection with TA and TW made use of the regression model for count data with a negative binomial distribution and of the zero-inflated negative binomial model. The analysis of the multi-annual change tendency of TA and TW utilized a non-parametric Mann–Kendall test for detecting monotonic trends with Yue–Pilon correction (MK–YP).
    [Show full text]
  • Ice Ic Without Stacking Disorder by Evacuating Hydrogen from Hydrogen Hydrate
    ARTICLE https://doi.org/10.1038/s41467-020-14346-5 OPEN Ice Ic without stacking disorder by evacuating hydrogen from hydrogen hydrate Kazuki Komatsu 1*, Shinichi Machida2, Fumiya Noritake3,4, Takanori Hattori5, Asami Sano-Furukawa5, Ryo Yamane1, Keishiro Yamashita1 & Hiroyuki Kagi1 Water freezes below 0 °C at ambient pressure ordinarily to ice Ih, with hexagonal stacking sequence. Under certain conditions, ice with a cubic stacking sequence can also be formed, 1234567890():,; but ideal ice Ic without stacking-disorder has never been formed until recently. Here we demonstrate a route to obtain ice Ic without stacking-disorder by degassing hydrogen from the high-pressure form of hydrogen hydrate, C2, which has a host framework isostructural with ice Ic. The stacking-disorder free ice Ic is formed from C2 via an intermediate amorphous or nano-crystalline form under decompression, unlike the direct transformations occurring in ice XVI from neon hydrate, or ice XVII from hydrogen hydrate. The obtained ice Ic shows remarkable thermal stability, until the phase transition to ice Ih at 250 K, originating from the lack of dislocations. This discovery of ideal ice Ic will promote understanding of the role of stacking-disorder on the physical properties of ice as a counter end-member of ice Ih. 1 Geochemical Research Center, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. 2 Neutron Science and Technology Center, CROSS, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan. 3 Graduate Faculty of Interdisciplinary Research, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan.
    [Show full text]
  • Mechanical Characterization Via Full Atomistic Simulation: Applications to Nanocrystallized Ice
    Mechanical Characterization via Full Atomistic Simulation: Applications to Nanocrystallized Ice A thesis presented By Arvand M.H. Navabi to The Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Master of Science in the field of Civil Engineering Northeastern University Boston, Massachusetts August, 2016 Submitted to Prof. Steven W. Cranford Acknowledgements I acknowledge generous support from my thesis advisor Dr. Steven W. Cranford whose encouragement and availability was crucial to this thesis and also my parents for allowing me to realize my own potential. The simulations were made possible by LAMMPS open source program. Visualization has been carried out using the VMD visualization package. 3 Abstract This work employs molecular dynamic (MD) approaches to characterize the mechanical properties of nanocrystalline materials via a full atomistic simulation using the ab initio derived ReaxFF potential. Herein, we demonstrate methods to efficiently simulate key mechanical properties (ultimate strength, stiffness, etc.) in a timely and computationally inexpensive manner. As an illustrative example, the work implements the described methodology to perform full atomistic simulation on ice as a material platform, which — due to its complex behavior and phase transitions upon pressure, heat exchange, energy transfer etc. — has long been avoided or it has been unsuccessful to ascertain its mechanical properties from a molecular perspective. This study will in detail explain full atomistic MD methods and the particulars required to correctly simulate crystalline material systems. Tools such as the ReaxFF potential and open-source software package LAMMPS will be described alongside their fundamental theories and suggested input methods to simulate further materials, encompassing both periodic and finite crystalline models.
    [Show full text]
  • © Cambridge University Press Cambridge
    Cambridge University Press 978-0-521-80620-6 - Creep and Fracture of Ice Erland M. Schulson and Paul Duval Index More information Index 100-year wave force, 336 friction and fracture, 289, 376 60° dislocations, 17, 82, 88 indentation failure, 345 microstructure, 45, 70, 237, 255, 273 abrasion, 337 multiscale fracture and frictional accommodation processes of basal slip, 165 sliding, 386 acoustic emission, 78, 90, 108 nested envelopes, 377 across-column cleavage cracks, 278 pressure–area relationship, 349, 352 across-column confinement, 282 S2 growth texture, 246, 273 across-column cracks, 282, 306, SHEBA faults, 371 across-column loading, 275 SHEBA stress states, 377 across-column strength, 246, 249, 275 Arctic Ocean, 1, 45, 190, 361 activation energy, 71, 84, 95, 111, 118, 131 aspect ratio, 344 activation volume, 114, 182 atmospheric ice, 219, 221, 241, 243 activity of pyramidal slip systems, 158 atmospheric icing, 31 activity of slip systems, 168 atmospheric impurities, 113 adiabatic heating, 291, 348 atomic packing factor, 9 adiabatic softening, 291 audible report, 240 affine self-consistent model, 160 avalanches, 206 air bubbles, 38 air-hydrate crystals, 37 bands, 89 albedo, 363 basal activity, 162 aligned first-year sea ice, 246 basal dislocations, 77 along-column confinement, 282 basal planes, 214, along-column confining stress, 282, basal screw dislocations, 77, 87 along-column strength, 244, 275 basal shear bands, 163 ammonia dihydrate, 181 basal slip, 18, 77, 127, 228 ammonia–water system, 186 basal slip lines, 77 amorphous forms
    [Show full text]
  • The Mechanics of Ice
    COLD REGIONS SCIENCE AND ENGINEERING Monograph ll-C2b THE MECHANICS OF ICE John W. Glen December 1975 GB 2401 CORPS OF ENGINEERS, U.S. ARMY .U58m COLD REGIONS RESEARCH AND ENGINEERING LABORATORY no.ll-C2b HANOVER, NEW HAMPSHIRE 1975 Approved for public release; distribution unlimited. 5 fl rolomis The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized docume* s. 0 Unclassified BUREAU OF RECLAMATION pENVER UBRARY C/ 92099625 ^ Y REPORT DOCUMENTATION PAGE ...............Q ? n Q 9 f i ? 5 1. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPt_______________ - ..------------ Monograph II-C2b -> 5. TYPE OF REPORT ft PERIOD COVERED 4. TITLE (end Subtitle) j m MECHANICS OF ICE 6. PERFORMING ORG. REPORT NUMBER 8. CONTRACT OR GRANT NUMBER*» 7. AUTHORf» European Research Office r J.W. Glen ,r Contract DAJA37-68-C*0208 £ ■ '« • ' 1 "• - TO. PROGRAM ELEMENT, PROJECT, TASK 9. PERFORMING ORGANIZATION NAME AND ADDRESS AREA ft WORK UNIT NJUMBERS Dr. John W. Glen Department of Physics ^ DA Project 1T062112A130 University of Birmingham ( ^ Task 01 ____ Birmingham. England ____; '____ ; _______ — 11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Office, Chief of Engineers ^ December 1975 u 13. n u m b er o f p a g e s ' Washington, D.C. 47 14. MONITORING AGENCY NAME ft ADDRESS*?/ different from Controlling Office) 15. SECURITY CLASS, (of thie report) UvS ^Army Cold Regions Research and Engineering Laboratory-^ Unclassified Hanover, New Hampshire 03755 15«. DECLASSIFICATION/ DOWNGRADING SCHEDULE 16. DISTRIBUTION STATEMENT (of thla Report) Approved for public release; distribution unlimited.
    [Show full text]
  • Structure of Ice IV, a Metastable Highpressure Phase Hermann Engelhardt and Barclay Kamb
    Structure of ice IV, a metastable highpressure phase Hermann Engelhardt and Barclay Kamb Citation: The Journal of Chemical Physics 75, 5887 (1981); doi: 10.1063/1.442040 View online: http://dx.doi.org/10.1063/1.442040 View Table of Contents: http://scitation.aip.org/content/aip/journal/jcp/75/12?ver=pdfcov Published by the AIP Publishing This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP: 131.215.71.79 On: Thu, 23 Jan 2014 23:05:03 Structure of ice IV, a metastable high-pressure phase Hermann Engelhardt and Barclay Kamb Division ofGeological and Planetary Sciences. D) California Institute of Technology. Pasadena. California 91125 (Received 8 June 1979; accepted 31 August 1981) Ice IV, made metastably at pressures of about 4 to 5.5 kb, has a structure based on a rhombohedral unit cell of dimensions aR = 760± I pm, a = 70.1 ±0.2', space group R 3c, as observed by x-ray diffraction at I atm, 110 K. The cell contains 12 water molecules of type I, in general position, plus 4 of type 2, with 0(2) in a special position on the threefold axis. The calculated density at I atm, 110 K is 1.272 ±O.OOS g cm -3. Every molecule is linked by asymmetric H bonds to four others, the bonds forming a new type of tetrahedrally-connected network. Molecules of type I are linked by 0(1)···0(1') bonds into puckered six-rings of3 symmetry, through the center of each of which passes an 0(2)···0(2') bond between a pair of type-2 molecules, along the threefold axis.
    [Show full text]