Platinum Metals Review

PLATINUM METALS REVIEW

A quurterly survey of reseurch on the platinum metuls urrd of dwelopments in their applications in industry

VOL. 16 OCTOBER 1972 NO. 4

Contents

The Fluorine Compounds of the Platinum Metals

Precision Fabrication in Platinum

The Production of Ultra-pure Hydrogen

Cobalt-Platinum Permanent Magnets

Fifth International Congress on Catalysis

The Work of James Lewis Howe

Abstracts

New Patents

Index to Volume 16

Communications should be addressed to The Editor, Platinum Metals Review Johnson, Matthey & Co Limited, Hatton Garden, London EClP 1AE The Fluorine Compounds of the Platinum Metals

THE NATURE AND IMPORTANCE OF RECENT WORK

By John H. Holloway Chemistry Department, The University of Leicester

This review summarises some of the chemistry of the platinum metal fluorides and outlines the part they have played in developments in inorganic chemistry. A number of new compounds in thisjeld have been identijed only recently for the jrst time.

The last fifteen years has seen a revision historically significant in inorganic fluorine and considerable extension of the fluorine chemistry in the last sixty years. In order to chemistry of the platinum metals. In the form this type of compound an electron must earlier part of the period the new hexa- be removed from oxygen and transferred to fluorides PtF, (I), RuF, (2) and RhF, (3) RF,. The surprising thing about the were reported and the fluoride previously reaction is that the first ionisation potential thought to be OsF, was shown to be OsF, for oxygen is quite high. Until 02+PtF6-was (4). More recently OsF, itself has been made no compound containing 02+had ever prepared and characterised and the possible been reported. The discoverer of this unique existence of OsF, has been suggested (5). compound, Neil Bartlett, realised that the Unusual polymeric smctures have been fist ionisation potential of xenon is almost found in the crystalline pentduorides of identical with that of molecular oxygen: ruthenium (6), osmium (7), rhodium (8), iridium and platinum all of which I 177kJmol-l (g), (10), Op -Oa+ :-e have been either discovered or properly I 16glcJmol-l characterised for the first time since 1960. Xe *Xe++- e The first oxide fluorides have been discovered, but so far only RuOF, (11), Os09F, This led him to wonder if the reaction of (12), OsOF, (13), OsOF, (14), and PtOF, platinum hexafluoride with xenon would (IS) have been reported and some of these produce a xenon compound analogous to the are still not well characterised. oxygen compound. A simple experiment, In 1962 a compound of formula ROBF, the mixing of xenon with PtF, vapour, (16) was found among the products of the dmedthat it did (18). This first com- reaction of platinum and platinum salts with pound of xenon, Xe+PtF,-, was the pre- fluorine in glass and silica apparatus. Sub- cursor to the discovery of the whole new sequently it was shown that this same sub- chemistry of the noble gases (19). Now stance could be synthesised by oxidising compounds of krypton, xenon and radon are molecular oxygen with an equimolar quantity known (19) and there are hints (20) that of PtF, vapour (16, 17) and that the correct argon compounds may be discovered soon. formulation is Oa+PtF,- (17). This dis- Perhaps the most interesting recent aspect covery is without doubt one of the most of platinum metal fluoride chemistry has

Platinum Metals Rev., 1972, 16, (4), 118-122 118 Fig. 1 The hexajuorides of the platinurn mads are highly volatile and er- tremely corrosive. Con- sequently their discovery awuited the deuelopment of special Mend and nickel uacuum and high-pressure systems for handling them under anhydrous conditions and such apparatus is shown here

been the discovery of a new class of com- The variety of types of oxide fluoride and pounds, the transition metal carbonyl the fact that oxide fluorides are known only fluorides. Carbonyl fluorides of molyb- for three metals are indications that this is denum (21) and ruthenium (22) have been not the case. In fact, the chemistry of the claimed but only the ruthenium compound, platinum metals is quite diverse. This is difluorotricarbonylruthenium(I1) (22) has well illustrated by the fluorides, and trends been fully characterised and this has been are best determined by considering the shown to have a closely related structure to elements as members of the second and third those of the platinum metal pentafluorides transition series (See Table I). As is usual (see later). with transition elements each exhibits a variety of oxidation states. Through the Binary Fluorides series up to the first members of Group VIII Because the six platinum metals are usually the highest attainable oxidation state is referred to as a single “group”, it is often equal to the group number. Ruthenium and assumed that they are chemically similar. osmium both exhibit octavalence in their

Platinum Metals Rev., 1972, 16, (4) 119 Table I The Platinum Metals as Members of the Second and Third Transition Series

Group IIIA IVA VA VIA VIIA VIII IB

Element Y Zr Nb Mo Tc Ru Rh Pd Ag

Electronic Configuration Element La Hf Ta W Re 0s Ir Pt Au

Electronic 5d16s2 5d26s2 5d36s3 5d46s2 5d56sz gd66s2 5d76sZ 5d96s1 5d106s1 Configuration tetroxides and some hint of the existence of In 1966, Glemser and his co-workers (5) OsF, has also been obtained (5). Beyond these succeeded in preparing OsF, by heating first members of Group VIII, however, the osmium plus fluorine mixtures at high oxidation state maximum diminishes dramati- temperatures (500 to 600°C) and pressures cally from Ru to Ag and from 0s to Au in (350 to 400 atm.). As expected the pale spite of the availability of the necessary yellow compound loses fluorine at room numbers of valence electrons. There is no temperature to give OsF,. Osmium hepta- firm evidence for Rh(1X) and Ir(1X) compounds or for decavalent palladium or Table II platinum. Indeed, even hepta- and octa- The Known Fluorides and Oxide Fluorides valent states for the elements beyond of the Platinum Metals and the Highest ruthenium and osmium have not been Oxidation-state Oxides attained. I In Table I1 the known fluorides and Ru RuF, Rh RhF, oxide fluorides of the platinum metals are RuF, RhF5 listed along with the highest oxidation-state RuF, RhF, PdF, oxides. A number of interesting features RuF, RhF, PdF, are at once apparent. For example, although PdF, RhF, is known Rho, is not; the highest RuOF, known fluoride of ruthenium is RuF, in RuO, Rho, Pd,O, spite of the fact that RuO, exists. Some explanations for observations such as these 0s OsF, Ir Pt have been derived from thermodynamic OsF, IrF, PtF, considerations (23). OsF, IrF, PtF, Octafluorides and Heptafluorides OsF, IrF, PtF, In spite of the demise of so-called “OsFs” IrF, in 1958 (4) there has always been hope that OsO,F, PtOF, a higher osmium fluoride than OsF, might OsOF, be formed since, unlike RuF,, OsF, is OsOF, stable and the preceding element in the oso, IrO, PtO, third transition series forms a heptafluoride,

Platinum Metals Rev., 1972, 16, (4) J 20 fluoride was shown to have a pentagonal bipyramidal (D5h symmetry) structure. n During these experiments mass spectro- metric, magnetic susceptibility, e.s.r. and i.r. evidence was accumulated which suggested the possible existence of some OsF, in the reaction product. However no con- clusive evidence for OsF, has yet been obtained. Hexafluorides The discovery of the hexafluorides RuF,

0-F~ (2)~OsF6 (4)~~FG (3h and PtF6 (1) was I the work of one research group under the Fig. 2a (above) leadership of Bernard Weinstock at Argonne Fig. 26 (below) National Laboratory in the U.S.A. Their success came largely through their development of special Monel and nickel vacuum and high-pressure systems for the handling of these highly volatile and corrosive materials. (Similar apparatus is shown in Fig. I.) With the exception of palladium then, a hexafluoride is known for each of the platinum metals. The physical properties of some of these molecules have been carefully studied but very little is known of their chemistry (24, 25). Although there are no good heat of formation data available, fundamental vibra- tion frequencies for the algmode in the infrared and Raman spectra (26, 23) indicate a decrease in bond strength from left to right in Fig. 2 (a) Tetrameric crystalline pentajuorides of each series and this is confirmed by the the platinum metals with metal atoms M at the corners of a rhombus and with non-linear bridging increasing tendency for the hexafluoride to jhorine atoms between the metals. F=$uorine atom dissociate to lower fluoride and fluorine with (b) The tetramer from the side showing clearly increasing atomic number. This decrease in the close packed layers of fluorine atoms stability has been explained in terms of there being an increase in the electron withdrawing The structures are based on a hexagonal power of the central atom across each series close-packed arrangement of fluorine atoms, (23). and the tetramer seen from the side clearly shows the close packed layers of fluorine Pentafluorides and Lower Fluorides atoms (see Fig. zb). Unusual tetrameric structures were dis- Other recent interesting aspects of platinum covered in the crystalline pentafluorides of metal pentafluoride chemistry include adduct Ru (6), 0s (71, Rh (81, Ir (9), and Pt (10) formation of RuF, and OsF, with XeF,. The (see Fig. za) in the early 1960s. In these MFj.XeF,, MF,.(XeF,), (M=Ru or 0s) tetramers the metal atoms lie at the corners and (RuF,),.XeF, adducts are known and of a rhombus and there are non-linear may be prepared in BrF, solution (28) or, bridging fluorine atoms between the metals. in most cases, directly from the parent

Platinum Metals Rev., 1972, 16, (4) 121 fluorides (27). X-ray evidence on the OsF,. References (XeF,), compound has been interpreted I B. Weinstock, H. H. Claassen and J. G. Malm, J. Am. Chem. Soc., 1957, 79, 5832 on the basis of an ionic formulation con- 2 H. H. Claassen, H. Selig, J. G. Malm, C. L. taining the XeeF,+ cation (28) and it has Chernick and B. Weinstock, J. Am. Chem. been assumed that the remaining adducts Soc., 1961, 83, 2390 3 C. L. Chernick, H. H. Claassen and B. can be formulated in terms of similar ionic Weinstock, J. Am. Chem. Soc., 1961, 83, 3165 adducts [XeF]+[MF,]- or [XeF]+[M,F,,]-. 4 B. Weinstock and J. G. Malm,J. Am. Chem. Generally speaking the lower fluorides Soc., 1958, 80, 4466 5 0. Glemser, H. W. Roesky, K. H. Hellberg can be most readily prepared when the and H. U.Werther, Chem Ber., 1966,99,2652 related higher fluorides are least stable, 6 J. H. Holloway, R. D. Peacock and R. W. H. e.g., PdF, is known but PdF, has not been Small, J. Chcm. Soc., 1964,644 7 S. J. Mitchell and J. H. Holloway, J. Chem. made; attempts to make PtF, and PtF, Soc. (A),1971, 2789 have failed (29). Little is known of the 8 J. H. Holloway, P. R. Rao and N. Bartlett, Chem. Comm., 1965, 306 properties of these compounds though the 9 N. Bartlett and P. R. Rao, Chem. Comm., structures for some of the trifluorides are 1965,252 known (30) and the “trifluoride” of palladium I0 N. Bartlett and D. H. Lohmann, J. Chem. SOC., 1962, 5253 has been shown to be PdZ+[PdF,]2-, pal- I1 J. H. Holloway and R. D. Peacock,J. Chem. ladium(I1) hexafluoropalladate(1V) (3I). Sot., 1963, 527 I2 M. A. Hepworth and P. L. Robinson, 3. Xnorg. Nuclear Chem., 1957,4,24 Complex Fluorides I3 N. Bartlett, N. K. Jha and J. Trotter, Proc. Bartlett has drawn much attention to the Chem. Soc., 1y58,80,4466 I4 G. B. Hargreaves and R. D. Peacock, J. reactivity of the higher fluorides of the Chem. Soc., 1960, 2618 platinum metals by reference to their complex 15 N. Bartlett and D. H. Lohmann, J, Chem. formation with such things as nitric oxide SOC.,1964,619 16 N. Bartlett and D. H. Lohmann, Proc. Chem. (23). He has shown that the electron affnity Soc., 1962,115 of the hexafluorides increases with atomic I7 N. Bartlett and D. H. Lohmann, J. Chem. Sac., 1962, 5253 number and that PtF, is the only hexa- 18 N. Bartlett, Proc. Chem. Soc., 1962, 218 fluoride capable of oxidising oxygen (i.e. to I9 J. H. Holloway, “Noble-Gas Chemistry”, give 02+PtF,- (17)). This correlates well Methuen, London, 1968 20 J. Berkowitz and W. A. Chupka, Chem. Phys. with the increased readiness of hexafluorides Lett., 1970,7,447 to dissociate to fluorine and a lower fluoride 21 T. A. O’Donnell and K. A. Phillips, Znorg. with increasing atomic number. Chem., 1970~9,2611 22 C. J. Marshall, R. D. Peacock, D. R. Russell He has also shown that the quinquevalent and I. L. Wilson, Chem. Comm., 1970, 1643 state is increasingly difficult to attain as 23 N. Bartlett in “Preparative Inorganic Reactions”, Vol. 2, Ed. W. L. Jolly, Inter- atomic number is increased across each science, New York, 1965 series, as the following reactions illustrate (23). 24 J. E. Canterford, R. Colton and T. A. 0’ Donnell, Rev. Pure Appl. Chem., x967,17,123 6CsBr+60sBr4 I 1zBrF,+6Cs0sF~ I 21Br, 25 T. A. O’Donnell, Rev. Pure Appl. Chem., 6CsBr+6IrBr,+ 1zBrF,+6Cs1rF, t 21Br, 1970, 20, I59 26 H. H. Claassen, G. L. Goodman, J. H. Cs,PtBr, -2BrF3+Cs,PtF6 +4Br, Holloway and H. Selig, J. Chem. Phys., 1970, 2CsBr 1 2Ru+4BrF3+zCsRuF,+ 3Br, 53,341 4CsC1 t 2RhC1,+~BrF,+2CszRhF,+2Brz 27 J. H. Holloway and J. G. Knowles,J. Chem. t5CL Sot. (A), 1969, 756 2CsBr : PdBr, 12BrF,+CszPdF, i 3Brz 28 F. 0. Sladky, P. A. Bulliner and N. Bartlett, J. Chem. Soc. (A), 1969, 2179 29 N. Bartlett and D. H. Lohmann, J. Chem. In fact, this decrease in the maximum SOC.,1964, 619 attainable oxidation state with increasing 30 M. A. Hepworth, K. H. Jack, R. D. Peacock atomic number parallels the case of the and G. J. Westland, Actu Cryst., 1957, 10, 63 31 N. Bartlett and P. R. Rao, Prac. Chem. simple fluorides. SOC., 1964,393

Platinum Metals Rev., 1972, 16, (4) 122 Precision Fabrication in Platinum BLACK-BODY CAVITY ASSEMBLIES

The concept of the perfect black-body cavity can never be achieved in practice because such an object would have no opening in it through which observations could be made. However, providing that an opening is small enough the emission of radiation from such a cavity through the hole gives an accurate indication of the temperature inside the cavity, when a good radiation pyrometer is used to measure the radiation. T. J. Quinn and T. R. D. Chandler have described (Platinum Metals Rev., 1972, 16, (I), 2-9) work at the National Physical Laboratory aimed at compiling reference tables for platinum : 10 per cent rhodium- platinum and platinum : 13 per cent rhodium- platinum thermocouples to meet IPTS-68 with common acceptance by both U.K. and U.S. manufacturers and users. Using the N.P.L. photoelectric pyrometer they were able to check four thermocouples at a time from the gold point up to 1748'C in a black-body cavity fabricated entirely from platinum in the workshops of Johnson Matthey Metals Limited. The three sections forming the black-body cavity consist qf R bafle assembly (foreground) with a A similar black-body has now been made small hole in its end-plate, a cylinder into which by JMM for use in Norway and this is shown the assembly fits, and a stopper (background) in the illustration before final assembly. which screws into the latter. The four holes in the cylinder and stopper accommodate the It consists of three parts, all of which pre- thermocouples under test sented special problems of fabrication. The baffle assembly is an obviously intricate closed by the third section of the apparatus. piece of work, consisting of eleven platinum The third section also required continuations rings, each threaded at three points on to of the four thermocouple bore holes parallel platinum rods, together with a terminal to its axis, a male screw thread on the end to platinum disc pierced by the hole through be inserted into the cavity, and a non- which radiation is emitted. reflective surface on the end of this insert. The cylinder into which this assembly fits The whole piece of equipment is an in- required the formation of four small bores, structive example of what can be done in the all exactly parallel to the main axial bore, to way of machining operations on platinum, carry the thermocouples under test. It also which is sometimes regarded as not the needed a female thread at the end to be easiest metal to work. F. J. S.

Platinum Metals Rev., 1972, 16, (4), 123-123 123 The Production of Ultra-pure Hydrogen

QUALITY CONTROL OF PALLADIUM ALLOY DIFFUSION UNITS

By D. A. Stiles and P. H. Wells Johnson Matthey Metals Limited

The successful development of Johnson Matthey Metals palladium alloy difusion units for the production of ultra-high purity hydrogen is largely dependent on comprehensive testing of all units before they are released to customers. This articEe describes the test procedures and the equipment used in testing.

Ultra-pure hydrogen is being used today Some recent unpublished work even sug- in an increasing number of industrial ap- gests that a dramatic reduction of wear plications as diverse as gas chromatography in wire-drawing dies can be achieved by and the furnace atmospheres required for the annealing wires in very pure hydrogen to sintering and annealing of refractory metals. prevent the formation of abrasive oxide

Dimensions and Recommended Operating Conditions of J.M.M. Diffusion Units

Model Physical Recom- Recommended Pure H, Dimensions, mm mended Feed Gas output Operat- Pressure In2 Tcmp. “C W DH Ibf/in2 kgf/cm2 ft3/h I/h

Laboratory H 28/1 203.2 203.2 558.8 300 300 21.0 1 28 Range H 14015 203.2 203.2 558.8 300 300 21.0 5 140 Units H 480;17 203.2 203.2 558.8 300 300 21.0 17 480 H 1260145 203.2 203.2 558.8 300 300 21.0 45 1,260 250 7,000 Integral HK 7 531 577 1399 300 150 10.5 14,000 Units HK 14 531 577 1399 300 150 10.5 500

Large HK 21 console Units 531 577 1399 300 150 10.5 750 21,000 with pressure frame Separate 1371 686 1015 Console and HK 2% console Pressure 531 577 1399 300 150 10.5 1,000 28,000 Frame pressure frame 1371 686 1015

W=width D=depth H=height

Platinum Metals Rev., 1972, 16, (4), 1244128 124 Fig. 1 The rear of the pressure frame of an HK 28 diLffusion unit, showing the compact arrangement of four difusion modules and the ease of access for servicing

surface films. However, the major usage significant contribution to improved reliability continues to be in the manufacture of semi- and service life, particularly under con- conductor devices where the highest standards ditions of thermal stress cycling. of purity and operating safety are required. Johnson Matthey Metals caters for all Intrinsic Safety these applications with its ranges of H and All Johnson Matthey Metals diffusion HK diffusion units (I). The table shows the cells are built to the British Standard Code of principal dimensions and operating character- Practice CP.1003 Parts I and 11, relating to istics of all standard JMM units. the safety of electrical appliances in the Performance of these diffusion units has presence of explosive or flammable atmos- been recently still further improved. A few pheres. Diffusion cells must be intrinsically early models were found to have a tendency safe, particularly the larger units such as the to leak where the tubular alloy membranes HK 28 shown in Fig. I since such a unit were joined to the manifold or header plate may be producing pure hydrogen at more but a new and advanced brazing technique than 28,000 I/h (1,000 ft3/h). Johnson has now virtually eliminated this source of Matthey Metals engineers are continually leakage. The method consists of forming a seeking to improve the efficiency and safety controlled fillet of braze metal on each side of their diffusion units, and considerable of the joint while preventing the brazing care goes into the design of operating and alloy from undercutting into the thin-walled safety features. For example, current HK palladium tubes and thus causing pinhole units are now operated by illuminated push perforations. This development has made a buttons linked to an interlocked sequential

Platinum Metals Rev., 1972, 16, (4) 125 Fig. 2 An IIK 28 diffusion unit viewed from the front, showing the ergonomic layout of the controls on tho pressure frame (left) and on the control console (right)

control system, making the units virtually IOO per cent purity. In practice very high foolproof in use. The push button control purity can only be achieved by skilful design system can be seen on the front of an HK 28 and by stringent quality control procedures unit in Fig. 2. Other safety devices include during fabrication to minimise the occurrence both strategically placed thermal fuses and of leaks in components and assemblies. Each automatic purging with nitrogen to ensure H or HK diffusion unit consists of assemblies that the units fail safe in the event of fire of silver-palladium tubes, all of which are or of the failure of gas or power supplies. eddy current-tested for flaws or for manu- Solid state temperature controllers are used facturing defects before closure at one end to to regulate the operating temperature (nor- form diffusion membranes. Each tubular mally 300°C) of the units and these control- membrane is then pressure-tested to 6,900 lers incorporate over-temperature detection kN/mZ (1,000 lb/in2) to detect leaks at the devices. closure weld. Membranes passing this test In theory palladium alloy diffusion mem- are assembled into a manifold or header branes are capable of supplying hydrogen of plate to form a diffusion module and the

Platinum Metals Rev., 1972, 16, (4) 126 Fig. 3 A typical diffusion module being evacuated in preparation for leak testing on the helium mass spectrometer. Only modules with leak rates less than 2~10-"cm~/secat 1 x 1fFtorr are passed for installation in I1 and IIK units tubes are sealed into the manifold by the of pure hydrogen is checked there against method described on page 125. This stage of the design requirements and during this assembly having been completed, the modules latter test the pure hydrogen being produced are given their most searching test by evacua- is sampled and checked for its moisture tion and leak testing on a helium mass content, using a Shaw dew-point meter. The Spectrometer. A module on test is shown dew-point of the gas produced must be less in Fig. 3. Only modules with a leak rate of than -60°C (equivalent to a moisture content less than 2x10-l~cm3/sec at an operating of 10 p.p.m. of water vapour), although pressure of I x IO-~torr can be passed for experience has shown that the dryness and installation into H and HK units. purity of the gas improves steadily with time, and after three hours operation the dew- Testing of Assembled Units point can be expected to approach -80°C Completedunits are subjected to a thorough (I p.p.m. water vapour). The relationship testing and inspection before leaving the between water vapour content and cell works. After testing to ensure correct running time is shown in Fig. 5. Further functioning of the complex electrical circuits, improvement is only limited by the overall each unit is coupled to a suitable gas supply leak rate of the system in which the unit is and is run up to its normal operating tem- operating. On completion of flow and perature and pressure on a special flow test purity tests, each complete unit is returned rig. Figure 4 shows both H and HK units to the mass spectrometer and is rechecked under test connected to this rig. The output to the same high standard of leak tightness.

Platinum Metals Rev., 1972, 16, (4) 1 27 Fig. 4 Performance testing of Hand HK diffusion units on a specially developed $OEU test rig. The operator is adjusting an H series unit while an HK series unit is OR test OR the right

The value of such thorough quality control developed these highly reliable units but can be seen in the remarkable performance they also supplement them with a compre- achieved by Johnson Matthey Metals dif- hensive range of advice and maintenance fusion units, some of which have produced services to ensure continuous operation. more than 42,500 m3 (1.5x 106 ft3) of pure Reference hydrogen in the Of their norma1 course I p. M. Roberts and D. A. Stiles, Platinum service life. JMM engineers have not only Metals Rev., 1969, 13 (4), 141-145

Platinum Metals Rev., 1972, 16, (4) 12% Cobalt =PlatinumPermanent Magnets MODELS FOR STUDY AND TECHNICAL DEVELOPMENT By D. J. Craik Department of Physical Chemistry, Nottingharn University

The 50 atomic per cent cobalt platinum ulloy continues to hold a special place as an outstanding permanent magnet material and to receive considerable scientijc study. It is suggested that much remains to be done before its properties can be fully understood and some reasonable models for study are proposed. Technological development could improve its properties still further and the implications of this with respect to specialised applications are discussed.

The equiatomic cobalt-platinum alloy is a Magnetic Properties fascinating and challenging material. It There are two classes of magnetic proper- constitutes, when properly treated, one of ties; the technical properties, coercivity H,, the highest quality permanent magnet remanent magnetisation M, or induction materials in currem use, with special proper- B,( =4zM,), susceptibility M/H, and perties which justify its continued application in meability B/H; and the intrinsic properties spite of the obviously substantial cost. For including saturation magnetisation M,, aniso- this reason it has undergone a considerable tropy coefficient K and exchange coefficient amount of technical development and has also A. These latter are in turn related to quantum been subjected to careful scientific study. mechanical effects at an atomic level, and the In spite of this it is far from certain that its intrinsic properties interact with the micro- technical properties could not be improved structure of any particular specimen to give still further, and absolutely certain that more rise to the technical properties. Thus we may study will be required before its behaviour write, formally: is fully understood. quantum state &intrinsic properties +micro- Before discussing the technical properties a structure +technical properties. brief outline of the relevant magnetic prin- Clearly the intrinsic properties may be ciples may be helpful. An attempt will then regarded as those of a perfect crystal, while be made to decide just which of the principles the technical properties can only relate to are the most relevant to this material in its specimens in a particular form. From this familiar form or in alternative forms in point of view there are no “hard” and “soft” which it might be produced; a certain amount magnetic materials, just magnetically hard of flexibility seems to be called for in the and soft specimens. However it will be present situation and if one cannot reach seen that high values of K indicate the definite conclusions concerning the behaviour feasibility of preparing good permanent of the material in one condition it might well magnets if the appropriate structure can be be advisable to consider lines of experimen- achieved. tation which include the preparation of The spinning electrons in the ions of a specimens with a simpler structure. magnetic material can be represented as

Platinum Metals Rev., 1972, 16, (4), 129-137 129 n minute current loops which thus have EH= - H-Ms-: - HMs cos(HMs) magnetic moments. The spins are coupled and thus M, rotates towards H to minimise within any one ion to give a net ionic magnetic EH (= -HM, when 0 =o) but is restrained moment, and in a ferromagnetic metal all the by the anisotropy so that the final orienta- ionic moments are coupled together to give a tion balances the two effects. However the spontaneous magnetisation M, which is the magnetic and anisotropy interactions are so magnetic moment per unit volume. The much weaker than the exchange interactions strength of this so-called exchange coupling that it can generally be assumed that M, is indicated by a parameter A, such that there rotates as a whole, or at least remains uniform is an exchange energy per unit volume of over small distances.

E*- A (2) Magnetic Behaviour : Coherent Rotation where dejdx represents the rate of change of orientation of the spins along a particular Suppose a field is applied normal to the axis OX. Clearly E,=o if the ionic spins easy axis of a spherical crystal (to avoid are all parallel and, generally, exchange has complications from demagnetising effects) as the effect of smoothing out any variations in Fig. Ia. Ms rotates through an angle 8, in the direction of' M,. so that the total energy involved is It is relevant to note one very important EK+EH=KsinafJ-HMs cos (go-O)=KsinaO- and almost unique feature of exchange HMs sin 6 interactions. They have a quantum mech- and the actual value of 0 will be that which anical derivation which relates them to the minimises E, +EH: direct overlap of the charge clouds represent- ZK sin 0 cos O-HMs cos 0-0 ing the orbits of the electrons in the neigh- 0 =-sin-l (HMs/zK) bouring ions, and so they have a very short range. This is a major distinction from The induced magnetisation, measured as the magnetostatic interactions, which are long- component along the direction of H is range. A hypothetical slot one atom wide M=Ms sin O=HM:/2K cut through a crystal constitutes a real barrier to exchange. so that the susceptibility %=M/His constant, Exchange alone gives rise to a net mag- %=M;/zK, up to saturation (M=M,) at netisation vector which points in an arbitrary H=2K/MS. This gives the magnetisation direction, but there are also interactions curve shown in Fig. Ib. The particular between the charge clouds or orbitals and value of H=2K/M, is called the anisotropy the electrostatic fields of neighbouring ions field H, since it is the field which has an in the crystal lattice which, via the spin-orbit equivalent effect to that of the anisotropy, coupling, constrain the spins and thus M, for small rotations. It is noted that the to lie in a particular direction with respect remanent magnetisation in zero field, and to the lattice. Thus easy directions arise and thus the coercivity or field required to cause the strength with which M, is coupled to an demagnetisation, are both zero. easy direction is indicated by an anisotropy Very different results are obtained when constant K such that there is an energy per fields are applied parallel to the easy axis, unit volume Ex-K sinz 0, where 0 is the opposing the initial direction of M, (Fig. IC). angle between M, and the easy direction. The torque due to the field, which is the Suppose that a field is applied at an angle rate of change of - H.Ms or HM,sin0, is to an easy direction. The energy of inter- zero when O=o so the situation is at least action of the magnetisation vector with H is metastable whatever the value of H. However,

Platinum Metals Rev., 1972, 16, (4) 130 Fig. 1. (a) Coherent rotation in a spherical crystal with uniaxial anisotropy, in jields normal to the easy axis. (b) The reversible magnetisation loop for (a). (c) Field applied parallel to the easy axis. (d) Loop for (c) shouiq compEete reversal when Easy €I= HK-= axis 2K/Mx

the anisotropy torque, which is zKsinOcosO spontaneously in zero applied field and or K sin 20, has a maximum when 0-45" H, -0). and also approaches zero as O+o, and if one plots out the torques as a function of 0 it can Partially Ordered Material be seen that the net torque is always in the When cobalt-platinum is quenched from field direction so long as H>zK/M,. Thus about IOOO"Cit has a cubic crystal structure complete reversal occurs at H-H,, giving with low crystal anisotropy, and also a low the loop shown in Fig. Id with M,=M, and coercivity. After prolonged heating at H,-HK. 600 to 700°C X-ray diffraction shows that Anisotropy fieIds can be extremely high; there is a tetragonal distortion of the lattice specifically for ordered cobalt-platinum and that this is due to the production of a 2K/M,~80,ooo Oe, so very large coercivities regular arrangement of the cobalt and may be expected whenever magnetisation platinum atoms, i.e. to ordering. The reversal does occur by coherent rotation. The ordered material has a very high uniaxial mode of reversal depends largely on the size anisotropy but since it occurs coherently of the crystal or crystallites, but coherent in the form of large uniform "sub-crystallites" rotation should apply below a critical dia- it is not surprising that the coercivity is meter of the order of IO-~cm for this material. again low. It is a general observation that (This is well above a second critical size relatively low coercivities occur, whatever at which reversal is aided by thermal fluctua- the anisotropy, in any crystalline regions tions to the extent that the remanence decays which are large enough to contain domain

Platinum Metals Rev., 1972, 16, (4) 131 Fig, 2 Transmission electron micrograph uf a thin fuil of high coercivity material, reducrd to the required thickness by ion bombardment (by 1W. Paulus ojC.N.R.S., Rrllevue, France). The jine structure indicated, with l00A spacing, is assumed to be a consequence qf the ordering, although a detailed interpretatiort is nut yet possible. x 50,000 walls which represent a gradual transition as field-ion microscopy. The author has from one direction of magnetisation to the taken a different approach, and Fig. 2 shows other. These walls have a characteristic what is thought to be the first straightforward width (6- .\/A/K) and energy (y- 4AK) transmission electron micrograph of optimum since within them the ionic moments or cobalt-platinum to be published. spins must be directed out of an easy direc- This was only obtained with the kind tion and also there must be an angle between assistance of Max Paulus, in charge of micro- neighbouring spins giving an exchange energy structural and synthesis studies at C.N.R.S., contribution. In a perfect crystal the energy Bellevue. The difficulty is mainly one of will not be a function of position and thus preparing specimens which are transparent the walls will move freely in small fields to to the electron beam, i.e. -100 a thick, change the overall state of magnetisation, and since this material is difficult to thin by demagnetisation is readily achieved. The electropolishing: the specimen illustrated walls can be caught up on imperfections but was prepared by the ion polishing technique this usually gives coercivities far below those pioneered by Paulus, and it is hoped that it expected for coherent rotation. marks the beginning of a systematic study It is generally only for an intermediate using these techniques. state of order between the two extremes, So far it can only be said that the micro- which can be achieved by controlled heat graphs give direct visual confirmation of an treatment, that the highest coercivities of extremely finely-divided structure in the 5000 Oe or more occur. It seems quite partially ordered material, with an oriented natural to suggest that in this condition the texture which occurs systematically through- ordering has occurred in such a way as to out certain regions within each grain. At give very small tetragonal regions, which the same time it is readily demonstrated that are too small to contain domain walls and domains on a relatively enormous scale thus have very high coercivities or switching exist in this material, by simple powder fields. Naturally there is great interest in the patterns such as that in Fig. 3, and this has exact manner in which the ordering occurs, led some workers to introduce simple models and in this state in particular. Much excel- for the impedance of domain walls which lent work has been done, by Southworth pass through both the “disordered matrix” for example, using advanced techniques such and the “ordered precipitate particles”.

Platinum Metals Rev., 1972, 16, (4) 132 Fig. 3 (a) Electron micrograph of a magnetic powder pattern replica, produced by the author’s method, showing extensive domain walls at LOW magnification in high eo- ercivity material. It is also clear that M, is not uniform within each domain but that some fine magnetic structure exists. x 5,000

These could be relevant, but since the period of the structures shown in Fig. 2 is similar to the predicted domain wall widths the following alternative “mic- romagnetic” approach is suggested. This is basically to start with non-interacting particle assemblies and then to see how the interactions depend upon the dimensions of the system. The simplest situation is a pair of non-interacting discs of the two phases, as shown in Fig. 4a. Particle I (softer phase) switches in a field of 2K,/MSI and particle 2 then switches at H-7 2K /Ms2. Introducing magnetostatic interactions we see that I switches at

Fig. 3 (b) As (a)at very high magnification, indicating that the striations shown within the domains hare themselves an ultra-fine structure with a spacing of about lOOA which it is tempting to associate directly with the ordering structures shown in Fig. 2. x 32,000

Platinum Metals Rev., 1972, 16, (4) 133 Fig. 4 Models for analysis of exchange-coupled jhe- particle behaviour. (a) with H’H~ino exchange coupling: after (1) switches its stray fields stabilise M,, in its original direction. (b)with exchange coupling and K,$Kl, tl>S1, a domain tuall forms in (I). (c) the exchange torque may be assumed to add to the direct effect of li and cause coherent rotation in (2) (b) (Kp$nite). (d) according to dimensions the rotation in (2) might occur gradually (more sloiuly than in (1) since K,>K,) and if t,=S, a modijied wall structure will occur: as t, becomes less than the normal S1 coherent switching of the pair should be (‘) approached at a jield ap- proaching 2 KJM,,

(d)

H<2Kl/M,, and z at H>2K2/Ms, and so reduce the overall switching field to below these are “decoupling” interactions which zK2/MS1. It should then be quite feasible have the reverse of the desired effect. to relax the above conditions, permitting a (One object of the analysis is to show why partial rotation in z due to the switching of I reversal of the whole assembly occurs in a (Fig. 4d) and studying the increasing effects of fairly narrow field range and certainly in the coupling as tl+S1 or becomes less than Sl. fields < 2K,/MS2.) We now introduce ex- The main points to be made are that even change coupling across the interface and formulating the problem leads to some initially consider that K,/M,%-K,/M, and sensible conclusions and, more important, that t,>Z1. Particle I now switches at one can see how the full analysis of the model H+zK1/MsIover most of its volume but a could in fact be carried out (even if the fmal domain wall must form towards the interface energy minimisation has to be done nurneric- with 2. This exerts an exchange torque on z ally). The negative effect of the rnagnetostatic which thus switches at H

Platinum Metals Rev., 1972, 16, (4) 134 theory proposed and the observed domain properties of fully ordered specimens. There structures must be made when extending the is indeed evidence that the coercivity of theory to encompass many particles or fully ordered specimens can remain high, interacting pairs of particles. although this is certainly not inevitably the It should be stressed that the computations case. This retention of coercivity is presum- themselves would require a considerable ably associated with the persistence of a effort and also that much more structural finely-divided structure due to the distri- work is required by a variety of methods to bution of the tetragonal axes of the ordered determine whether the model is in fact regions among the different cube axes of the appropriate or whether one should be dealing disordered crystal structure. However, this with regions differing in their degree of order distribution of easy directions implies that or indeed equally ordered but, as suggested the remanence cannot be optimum. previously by the author, still having an Thus it seems that an entirely different identity as fine particles from the magnetic structure, and method of preparation, is point of view due to the variation of the easy called for: i.e. an oriented compact of wholly directions created. ordered material in the form of particles apparently, but not perhaps necessarily, Applications and Scope for below the critical single-domain size. It Development is readily admitted that this rather obvious Following the speculation on the origins of suggestion is only made seriously because the coercivity of conventional cobalt-plati- there seems now to be indirect evidence at num, it is no less interesting to speculate on least that it should be feasible, stemming the possibilities of further development of from recent studies on rare-earth cobalt this material. This type of undertaking has a alloys. Furthermore it would be very short- serious purpose, because development is sighted in general to ignore these latter generally quite costly and any possible studies in any account of any permanent outcome must be evaluated with care. magnet material. It may well be possible to achieve further We will first survey the potential properties improvements in the properties of tempered of this ideal material. By comparison with alloys, but since their behaviour is not fully the anisotropy field of 80,000 Oe it will be understood it seems advisable for the moment assumed that a coercivity of 8,600 ( =4nM,) to consider an ideal microstructure and then can be achieved. Assuming, also, perfect to ask whether this could be approached in orientation and IOO per cent packing the practice. From a scientific point of view a remanent induction will also be equal to truly flexible approach implies a readiness to 4xM,, giving an exceptionally simple and fabricate an alternative type of specimen symmetrical demagnetising curve as shown which might respond more readily to study in Fig. 5. This is compared with the de- and analysis than existing ones. Any results, magnetising curve for a similarly idealised or conclusions drawn, might then help to SmCo, specimen, and the similarity in elucidate the behaviour of the original properties is notable by contrast with the specimens. broken line for a typical alloy magnet of Alnico Perhaps the only conclusion to be drawn type and the dotted line for an oxide magnet. with any confidence, from the preceding There are several major features of such section, is that with mixed phases the idealised magnets. First a negligible recoil presence of a low-Hk phase is always likely effect is implied since there is no change in the to reduce the overall coercivity. Since M, magnetisation until H, is reached, i.e. such a only falls from 696 to 687 on ordering it magnet would be extremely stable in dynamic would appear advisable to consider the conditions with the flux returning to its

Platinum Metals Rev., 1972, 16, (4) 135 H hoe Fig. 5 Idealised demagnetisation curves, for single domain behaviour, for Copt and SmCo,, with the energy product eurvefor the Copt. Typical curves for Alnico and barium ferrite are shown for comparison. The load lines drawnfor the two shapes illustrated indicate that with such shapes large energy products are still obtained for the high K materials although they have fallen substontially for the other materials equilibrium value after application of fields construction, i.e. by drawing a line from the below H,. Secondly, it should be possible to origin with a slope B/H which indicates the work at the theoretical (BH),, point and also relative magnitude of the reverse fields (self to obtain a large energy product* with what demagnetising fields and possibly additional would generally be considered as very un- reverse fields of external origin). favourable geometries. It is recalled that the Demagnetising fields can only be estimated demagnetising curve may be considered as for uniformly rnagnetised specimens, and the response of a block of material which is generally uniform magnetisation is only in a complete magnetic circuit, with no obtained for specimens which have the form demagnetising effects or zero demagnetising of ellipsoids of revolution. Thus it is very factor, to reverse fields of external origin, difficult to estimate the demagnetising effects or as the response of the material in the form and thus the load lines for cylindrical or of an isolated block to its own demagnetising square section blocks of a material such as fields. The first situation is that in which the Alnico with relatively low coercivity or curve would be measured while the second anisotropy. However, for cobalt-platinum is that in which the magnet is actually used to the anisotropy fields are so much higher than produce fields. The working point of a the largest demagnetising fields (4rMS) that magnet may be represented by a load line the magnetisation can be treated as uniform even in non-ellipsoidal specimens. The *Energy product BH, measured in mega-gauss-oersted or MGO, is an indication of the ability of a particular demagnetising fields are not uniform but at magnet to produce a useful field. It clearly depends upon the shape of the magnet and is zero for an infinitely long least one can now use an approximate de- cylinder (demagnetising H = zero) and for a thin sheet (Hi 4rrM. and B -zero) and in the idealised case has its maxi- magnetising factor which gives a mean mum value (BH),,, at H=2Mx,; BH=4xaM,a=(BH),.,. demagnetising field, and thus associate a

Platinum Metals Rev., 1972, 16, (4) 136 particular shape of specimen with a particular their realisation has a genuine interest. The load line or working point on the demag- encouraging factor is that specimens ap- netising curve. proaching such an ideal have in fact been For example, take a cylinder magnetised achieved for other materials, by carefully along its cylindrical axis of length L, and controlled grinding, orienting a powder with cross-sectional diameter D. It happens compact in a strong applied field and sin- that for D=2L the demagnetising factor is tering. Whether the same could be achieved approximately 2x and the demagnetising for fully ordered cobalt-platinum remains to field is 2xM,. The load line has a slope B/H be seen. It may be that the response to (~prM,-zxM,)/zxM,= I and this clearly grinding would not be quite the same and puts the magnet at its point of highest that special procedures would have to be efficiency, (BH) =(BH),ax=(2r;M,)Z-qr;ZM~. developed, perhaps leading to a lower particle The predicted value for the ideal specimen is size and true single-domain behaviour. It 18.7 MGO, and nearly all other materials may not even be possible to grind cobalt- would give a much lower value because (a) platinum since SmCo, is particularly brittle, the value of (BH),,, is much lower and (b) and after all the mechanical properties are a for this geometry the specimens would be substantial factor favouring cobalt-platinum. far from their maximum energy product Yet again one must balance the possibility condition, i.e. much more elongated speci- that this feature would be impaired in a mens would be required to work at (BH),,. specimen produced by powder metallurgy. Now take a second example: a disc five (In the comparison of these two outstanding times as wide as it is deep: i.e. LID-0.2. materials, note that they represent extremes The demagnetising factor is nearly z/3(4n) of chemical reactivity so far as permanent and the demagnetising field (8/3)zM5. Thus magnets are concerned, cobalt-platinum being

B =4xMs-(8/3)nM, ~ (4/3)’cM,; the load line extremely passive while the properties of has a slope of B/H-0.5 and the energy SmCo, are very responsive to the atmosphere, product is (p/9)n2Msa. Thus (BH) is only particularly while it is finely divided, and its reduced by a factor of (8/9) below its maxi- stability remains a matter for study.) mum value by this strongly demagnetising geometry, but this stresses the value of Conclusions achieving a really high H, and not being In its usual form cobalt-platinum con- obsessed by the (BH),,, requirement itself. tinues to present scientific problems, the It is noted that load lines with slopes of as solutions of which may well lead to a fuller little as 0.5 are involved in such specialised understanding of magnetic behaviour gen- designs as focusing magnets in travelling erally and possibly suggest principles for the wave tubes, which are in fact placed face to synthesis of new materials. It is also of face so that each is subject to stray fields considerable scientific and technological in- from neighbours as well as self-demagnetising terest to speculate on the properties and fields. Also, the advantages with regard to behaviour of specimens with a classical fine- flexibility of design, where miniaturisation is particle structure which could in principle concerned as in the production of bias fields have such outstanding properties as energy for microwave components, are very obvious; products of 16-17 MGO in strongly de- with such a material the shape is almost magnetising configurations. However, as is immaterial and great economy results from so often the case, a true estimate of the the use of flat geometries in such applications chances of success for further development as miniature microphones, and wrist watches. can only be made with difficulty, although one Faced with these indications of the possi- gains encouragement from the advances made bilities of real improvements the question of with materials with similar intrinsic properties.

Platinum Metals Rev., 1972, 16, (4) 137 Fifth International Congress on Catalysis DOMINANT ROLE OF THE PLATINUM METALS

The four-yearly International Congress on Catalysis provides a welcome opportunity to review the state of the art and to exchange ideas and experiences. A review of the papers relevant to the platinum metals is given in this article.

The Fifth International Congress on spillover” is demonstrated by work with Catalysis was held at the Breakers Hotel, mechanical mixtures of platinum black with Palm Beach, Florida, in the last week of CeY zeolite and various oxides including August. It was attended by over five hundred ruthenium dioxide (Neikam and Vannice). participants from thirty countries-the great majority, however, coming from the United Reactions of Hydrocarbons States. The papers presented at this Congress We have witnessed in recent years a revolu- show the dominant role that the platinum tion in our thinking concerning the kinds of group metals play in catalysis, for of the IIO hydrocarbon transformation which platinum papers at least thirty-six were concerned can bring about; at least fourteen papers wholly or in part with these metals. The more discussed various aspects of hydrocarbon significant of these papers are reviewed below. reactions on the platinum metals. It is now well established that unsupported Adsorption platinum can catalyse the skeletal isomerisa- The adsorptive properties of very clean tion of hydrocarbons; this was, of course, platinum surfaces are proving to be very formerly thought to be the prerogative of different from those of slightly contaminated dual-function catalysts, and that there was a surfaces; thus the sticking probability of carbonium ion intermediate. On platinum oxygen on the ( 11 I) face of clean platinum iilms at 275 to 300°C multiple isomerisation has the remarkably low value of about IO-~, occurs in one residence; thus 2,3-dimethyl- which is much lower than previously reported butane yields 3-methylpentane, n-hexane, values (Weinberg, Lambert, Comrie, and methylcyclopentane, and benzene as primary Linnett). Three papers treat adsorption on products (Muller and Gault). Hydrogenolysis platinum/alumina catalysts. Thermochemical to smaller molecules occurs simultaneously, studies (Basset, Theolier, Primet, and Prettre) and the proportion of hydrogenolysis products demonstrate strong and weak forms of decreases with increasing particle size adsorbed hydrogen, while temperature- (Anderson and Shimoyama). Reactions on programmed desorption of adsorbed hydrogen dual-function catalysts continue to be of (Aben, van den Eijk and Oelderik) suggests interest. The direct dehydrocyclisation of three forms, the amount adsorbed in the linear alkanes to aromatics, a reaction which weakest state correlating with catalytic activity has long been mechanistically obscure, has for benzene hydrogenation. The enhance- now been shown to proceed independently ment of hydrogen adsorption caused by on platinum and on alumina (Callender, preadsorption of oxygen is shown to be due Brandenberger and Meerbott). Over plati- to a surfixe area increase (Darensbourg and num/CaY zeolite, methylcyclopentane suffers Eischens). The generality of “hydrogen cationic ring-opening at 275”C, yielding

Platinum Metals Rev., 1972, 16, (4), 138-139 138 products of higher molecular weight (Schulz, ethylene to acetaldehyde at IOO'C with high Weitkamp and Eberth). selectivity, and without the necessity of a Some quite novel hydrocarbon reactions redox component (Fujimoto and Kunugi). were reported. The disproportionation of Propylene oxidation on palladium/carbon alkanes and alkyl benzenes is achieved by use gives acrolein and acrylic acid, the reaction of a mechanical mixture of a dehydrogenation proceeding in the presence of water whose catalyst such as platinum/alumina and an oxygen atom becomes incorporated in the olefin disproportionation catalyst (tungsten product (Moro-oka and Takita). trioxide on silica) (Hughes, Bumett and Wall). Linear mono-olefins have been Novel Catalysts observed to disproportionate into the alkane The heterogenisation of homogeneous and diolefin over supported palladium cata- catalysts is now an active field of research. lysts between 100 and 200"C, although yields The idea is to mount organometallic com- are low (Bhasin). plexes on supports so that they may be used Palladium foil at 0°C rapidly loses activity as heterogeneous catalysts. Rhodium corn- for ethylene hydrogenation but the activity is plexes may be linked to phosphorus atoms stabilised by pre-adsorption of acetylene incorporated into polymers such as poly- (Yasumori, Shinohara and Inoue). The styrene and polyvinyl chloride, and through a addition of deuterium to 4-fBu-cyclohexanone reactive silaphosphine also to silica (Allum, results in simple addition over ruthenium, Hancock, McKenzie, and Pitkethly). These osmium, iridium, and platinum, but over catalysts are active for hydrogenation and rhodium and palladium substitution occurs hydroformylation of olefins. A further paper at the 2- and 6-positions (Takagi, Teratani (Haag and Whitehurst) treated other aspects and Tanaka). The reactions of deuterium of polymer-supported catalysts. with norbornadiene and norbornane do not High dispersion of metals in zeolites has exhibit structure sensitivity (Clarke, been claimed before, but it has now been McMahon and O'Cinneide). The ruthenium- shown conclusively that careful preparation catalysed hydrogenolysis of isopentane and through ion exchange of Pt(NH,):' into Y of neopentane gives methane as the primary zeolite gives particles containing less than product in both cases, but the former is much six platinum atoms (Dalla Betta and Boudart): more reactive (Kempling and Anderson). the catalyst shows high activity and the particles are thought to be electron-deficient. Oxidation Catalysis The use of palladium alloys as hydrogen- In a further search for structure-sensitive permeable membrane catalysts has been reactions, the oxidation of carbon monoxide developed and product yields from dehydro- on the low index planes of a palladium mono- genation reactions are shown to be sig- crystal has been examined by LEED and nificantly better than thermodynamics would Auger spectroscopy (Ertl and Koch); how- suggest (Gryaznov, Smirnov and Slinko). ever, strengths of adsorption and activity Although the activity of ruthenium in were found to be similar on all planes. The ammonia synthesis has long been known, it is formally simple hydrogen-oxygen reaction now shown that this activity can be powerfully on platinum, when studied by field-emission promoted by alkali metals (Ozaki, Aika and microscopy, proves to be rather complex Morikawa). A 5 per cent ruthenium/carbon (Gorodetski and Savchenko). catalyst promoted with 22 per cent potassium Interest continues in the ability of pal- is some four times more active than a con- ladium and its salts to oxidise olefins selec- ventional doubly-promoted iron catalyst, tively to useful products. Various palladium and it possesses the advantage of not being salts when adsorbed on active carbon oxidise retarded by the product ammonia. G. c. B.

Platinum Metals Rev., 1972, 16, (4) 139 The Work of James Lewis Howe

BIBLIOGRAPHER OF THE PLATINUM GROUP METALS

By Professor George B. Kauffman California State University, Fresno, U.S.A.

This year marks the seventy-fifth an- buryport he became interested in chemistry. niversary of the publication of James Lewis He received his B.A. degree in 1880 from Howe’s classic “Bibliography of the Metals Amherst College. of the Platinum Group 1748-1896”, an As was customary in those days, Howe appropriate occasion for a brief examination went to Germany after graduation to com- of his life and work, with special emphasis plete his studies. From 1880 to 1882 he on his bibliography. studied at the Universitat Gottingen under James Lewis Howe was born in Hans Hiibner, J. Post, and the legendary Newburyport, Massachusetts, U.S.A., on Friedrich Wohler. In 1882 he was awarded August 4th, 1859, the son of Dr. Francis his doctorate with the dissertation “Ueber Augustine Howe, a physician, and his wife, die Athylderivate des Anhydrobenzdiami- Mary Frances Howe (nee Lewis). The Howe dobenzols und uber ein Nitril desselben”, family was noted for its progressive and based on research carried out under Hiibner’s liberal outlook and for its longevity. Howe direction. These results were published as lived to be ninety-six and at the time of his two short separate papers (I) and constitute death was one of the American Chemical both his first publications and his only works Society’s oldest members. He was thus a in organic chemistry. After returning to the transitional figure in chemistry; he was born one year after Kekule proposed the self- linking of carbon atoms, yet he lived to witness the hydrogen bomb. Howe originally intended to become a physician like his father, but during high school in New-

James Lewis Howe 1859-1955 America’s foremost authority on ruthenium and author of the classic bibliography on the platinum group metals. (Photograph by courtesy of James L. Howe, Jr., and Guendolen Howe.)

Platinum Metals Rev., 1972, 16, (4), 140-144 140 The title page of the Jirst volume of I3owe’s Biblio- graphy. It contained 2,438 entries by more than 1,300 authors. It has been referred to as an ideal bibliography. An edition revised to 1917 appeared in 1919, a volume couering 1918 to 1930 ap- peicred in 1947, and drcennial indmes for 1931-1940 and 1941-1950 were published in 1949 und 1956, respectivply

United States, Howe became Instructor of Guendolen and Frances. In 1886 Howe Science at Brooks Military Academy, Cleve- received an honorary M.D. from the Hospital land, Ohio (1882-1883), Professor of College of Medicine, Louisville, Kentucky, Chemistry (later of Physics and Geology as where he was Professor of Medical Chemistry well) at Central College, Richmond, Kentucky and Toxicology. (1883-1894, and finally in 1894 Professor For the first fifteen years of his tenure of Chemistry and Head of the Chemistry at Washington and Lee University, Howe Department at Washington and Lee Uni- was a one-man chemistry department. The versity, Lexington, Virginia, one of the entire chemistry laboratory was merely a South’s leading liberal arts colleges for men, single room located over the power plant where he remained for almost half a century. with Howe’s office and a balance room par- On December 27th, 1883, Howe married titioned off at one end and a small research Henrietta Leavenworth Marvine of Scranton, laboratory at the other. It was in these Pennsylvania. The couple had one son, cramped and noisy quarters that Howe James Lewis, Jr., himself a chemist who carried out the research on the element with spent a number of years in China involved which his name is so closely identified- in missionary work, and two daughters, ruthenium. His lecture style was informal,

Platinum Metals Rev., 1972, 16, (4) 141 and although he was sparing in his use of nitrosochloride solutions ([Ru(NO)ClJ-) demonstrations, hc made liberal use of with various reagents and devised means for anecdotes and reminiscences, many about the distinguishing them from hexachloride immortals of chemistry that he had known ([RuC1J3-) solutions. He made a study of in Europe. the cyanide complexes (6), investigating As a well-known bibliographer, Howe was ten methods for the preparation of naturally a wide and avid reader of the litera- K4[Ru(CN),].gH,0. He also described the ture, and he kept his lectures thoroughly preparation of new salts of this series (7). up to date with the latest chemical advances. The major portion of Howe’s research on He insisted on personally supervising his ruthenium concerned the chlorides and their students’ laboratory work, and he was complexes. In a series of papers (8), he rigorous in his standards and firm in his investigated three important classes of discipline, His bibliography and his un- complexes : (i) hexachlororuthenates(IV), challenged position as the leading American M ,[RuCl,] ;(ii) tetrachlorooxoruthenates(VI), authority on the chemistry of the platinum M,[Ru02C14]; and (iii) pentachloroaquo- metals led directly to his appointment in ruthenates(III), M,[Ru(H,O)Cl,1. He also 1917 as Chairman of a special sub-committee attempted to unravel the extremely complex on platinum of the National Research Council, relationships between the salts of the three and he subsequently received three series M,[RU’~CI M,[RuTV(OH)C1J, and presidential appointments to commissions for M,[Ru”’(H,O)Cl,]. Howe also investigated assaying the coinage of the United States. analytical methods for the quantitative A member of, and participant in, many determination of ruthenium (9) and made professional and honorary organisations, studies of ruthenium(I1) chloride (10). For Howe also engaged in numerous civic and a more detailed and critical discussion of fraternal activities. He was particularly Howe’s life and work, the reader is referred active in the Presbyterian Church and ranked to another paper by the present author (11). religion equal to science in his life. Although he retired from teaching in 1938, Howe The Great Bibliography remained active and continued to w-ork on his Despite his fundamental research on the bibliography. During World War I1 he was chemistry of ruthenium, Howe’s magnum recalled from retirement to teach chemistry opus and best known contribution to chemistry and German. He retired for a second time was his “Bibliography of the Metals of the in 1946. He died on December zoth, 1955. Platinum Group” (IZ), which eventually covered the literature from 1748, when Howe’s Chemical Research platinum was first described, to the end of Howe’s early work, aside from the two 1950, a span of more than two centuries. papers based on his organic dissertation This monumental bibliography was cited as research (I), was primarily inorganic (za) the major basis on which Howe was awarded and analytical (zb). In his first work on the in 1937 the American Chemical Society chemistry of ruthenium (3), dated March, Georgia Section’s “Charles H. Herty Medal” 1894, Howe sought a simple, reproducible for the advancement of science in the southern method for preparing the exceptionally United States. Professor M. Guy Mellon stable so-called “ruthenium tetrachloride” of Purdue University, long a recognised described by Claus (4). Howe confirmed authority on the literature of chemistry, Joly’s conclusion (5) that the compound was always referred to Howe’s work as an ideal RuC1,NO rather than RuC1, and emphasised bibliography. the necessity for complete analytical data. In a letter of January 18th, 1897, to Mr Howe also investigated the reactions of Samuel Pierpoint Langley (I 834-1906), the

Platinum Metals Rev., 1972, 16, (4) 142 American astronomer, physicist, and pioneer with X-rays. Howe’s 36-page subject index in aeronautics who was then Secretary of contains 66 separate headings and is remark- the Smithsonian Institution, Dr. Henry ably complete. In addition to the expected Canington Bolton (1845-1903), himself an chemical headings, it includes headings such eminent bibliographer of chemistry, wrote, as decomposition of ores, assay, physiological “The Committee of the American Association action, optical properties, exhibits at ex- for the Advancement of Science having positions, and various physical properties charge of Indexing Chemical Literature has such as those connected with light, heat, voted to recommend to the Smithsonian thermochemistry, magnetism, electricity, Institution for publication the following : ‘A thermoelectricity, polarisation, and electrolytic Bibliography of the Metals of the Platinum action. A 15-page author index listing the Group, 1748-1896’ by Professor Jas. Lewis more than 1,300 authors concludes the Howe, M.D., rh.D.”. In December of that volume. same year, the first volume of Howe’s great In preparing his bibliography, Howe bibliography appeared as No. 1084 in carefully searched one hundred journals, Volume 38 of Smithsonian Miscellaneous literally from A to Z (AllgemeinesJournal der Collections (12), less than three years after Chemie to Zeitschrift fur physiologische the completion of his first research paper on Chemie). He was also aided in this immense ruthenium (3). The work was a truly re- task by referring to a rare monograph markable achievement in view of the obvious “Fragment einer Monographie des Platin’s painstaking and meticulous care expended und der Platinmetalle” (20) by Carl Ernst in its compilation. Claus (Karl Karlovich Klaus) (1796-1864)~ Howe’s bibliography contains 2,438 sep- the discoverer of ruthenium, which con- arate entries by more than 1,300 authors. tained a fairly complete critical bibliography Many of these entries contain more than one of the platinum metals to 1861, but which reference citation, some as many as two contained many errors that Howe had to dozen! Dissertations as well as journal correct. articles are included, and many entries contain citations of reviews and abstracts of Succeeding Volumes articles. Each entry is unequivocally desig- Howe’s first volume met with great success, nated by two numbers-one for the year and and in 1919 a secondvolume @I), co-authored a second for the number within that year. with Dr. Hendrick Coenraad Holtz and The first entry is, appropriately enough, the covering the period 1748-1917, was published. first reference to platinum, by its discoverer Like its predecessor, it quickly established Don Antonio de Ulloa in 1748 (13). The itself as the standard bibliography on the first references for the other platinum metals subject. Twenty-eight years elapsed before are as follows: palladium (1803) (14), the third volume, entitled “Bibliography of iridium (1804) (15)~rhodium (1804) (16)~ the Platinum Metals” and covering the osmium (1804) (17), and ruthenium (1826) years 1918-1930 (22a), was published in 1947 (IS) and (1844) (19). From the single entry by Baker and Co., Inc. (now Engelhard for the year 1748, the number of entries Industries, Inc.). Since then, two further reaches a peak of sixty-eight in 1892, re- Howe-Baker decennial bibliographies (1931- flecting the increasing attention paid to the 1940, 1941-1950) have appeared (22b, c) platinum metals. The articles are primarily in the same attractive format with the lettering chemical, but for earlier references, other on the cover stamped in palladium leaf. divisions of the subject are included, for Howe was scrupulous in keeping up with example, the use of platinum in electrical the literature. Except when deterred by apparatus, in photography, and in connection illness and the infirmities of old age, he could

Platinum Metals Rev., 1972, 16, (4) 143 be found late at night in his upstairs room 9 J. L. Howe, Chem. News, 1898, 78, 269; Science, 192.7, 65, 503; J. Am. Chem. Soc., at the typewriter under a bare light bulb !927,49, 2393; J. L. Howe and F. N. Mercer, preparing index cards for the next decennial zbtd., 1925, 47, 2926 volume of the bibliography, which was 10 J. L. Howe, 3. Am. Chem. Sac., 1901, 23, 775; J. L. Howe, J. L. Howe, Jr., and S. C. to cover the period 1951-1960. He continued Ogburn, Jr., ibid., 1924, 46, 335 this activity until as late as the autumn of 11 G. B. Kauffman, J. Chem. Educ., 1968, 45, 1955, and upon his death in December of‘ 804-81 I that year his daughter Guendolen presented 12 J. L. Howe, “Bibliography of the Metals of the Platinum Group : Platinum, Palladium, the cards to Baker and Co. I was dis- Iridium, Rhodium, Osmium, Ruthenium, appointed to learn recently that these cards 1748-1896” (Smithsonian Miscellaneous Col- lection, Vol. 38 (No. 1084), Smithsonian had been “destroyed with permission” (23). Institution, Washington, 1897), octavo, 318 This is indeed unfortunate, for the contin- PP. uation of the decennial bibliographies would 13 Don Antonio de Ulloa, “Relacidn Histdrica del Viage a la America Meridional” (Antonio have constituted a fitting and perpetual Marin, Madrid, 1748), Vol. I, Book 6, tribute to the patience and foresight of the Chap. 10, p. 606 man who initiated the series-James Lewis 14 R. Chenevix, Phil. Trans., Roy. SOC.(London), 1803, 93, 290 Howe-a true pioneer in the chemistry and 15 A. F. Fourcroy and L. N. Vauquelin, Ann. literature of the platinum metals. Chim., 1804, 49, 188, 219; 50, 5 16 A. F. Fourcroy, Ann. Mus. Nut. Hist., Paris, Acknowledgements 1804j31 I49 The author is grateful for biographical informa- 17 S. Tennant, Phil. Trans., Roy. SOC.(London), tion obtained from Howe’s friends, students, 1804,941 411 colleagues, or relatives, particularly Mr James 18 G. Osann, Ann. Phys., 1826, 8, 505 Lewis Howe, Jr. and Miss Guendolen Howe. 19 C. Claus,J. prakt. Chem., 184, 32, 479 The assistance of the John Simon Guggenheim Memorial Foundation for a Guggenheim Fellow- 20 C. Claus, “Fragment einer Monographie des Platin’s und der Platinmetalle, 1865-1883” ship, of the California State University, Fresno, (Commissionare der Kaiserlichen Akademie for a sabbatical leave, and of the California State der Wissenschaften, St. Petersburg, 1883). University, Fresno Research Committee for help Only three hundred copies of this pamphlet in typing the manuscript is gratefully acknowl- were printed, and according to Donald edged. McDonald (Platinum Metals Review, 1964, 8, 67-69), the only copy still in existence 111 1946 outside the U.S.S.R. was Howe’s References own copy in the library of the Washington I J. L. Howe, Amw. Chem.J., 1833,5,415-418; and Lee University Chemistry Department. 418-424 This was microfilmed, and photocopies were z(a) J. L. Howe, Amer. Chem. J., 1886, 8, 75; presented by Johnson, Matthey and Co., J. L. Howe and S. G. Hamner,J. Am. Chem. Ltd. to the libraries of the British Museum, SOC., 1898, 20, 757; J. L. Howe and E. A. the Royal Society, the Chemical Society, O’Neal, ibid., 1898, 20, 759; (b) J. L. Howe and the Institute of Metals and P. S. Mertins, ibid., 1896, 18, 953; J. L. 21 J. L. Howe and H. C. Holtz, “Bibliography Howe and H. D. Campbell, Amer. 3. Sci., of the Metals of the Platinum Group: 1896, [4] 2, 413; J. L. Howe and J. L. Platinum, Palladium, Iridium, Rhodium, Morrison, J. Am. Chem. Soc., 1899, 21, 422 Osmium, Ruthenium, 1748-1917” (Depart- 3 J. L. Howe,J. Am. Chem. Sac., 1894, 16, 388 ment of the Interior, U.S. Geological Survey, Bulletin 694, Government Printing Office, 4 C. Claus, Bulletin de 1’Acade‘mie Impkriale des Washington, 1919), 558 pp. Sciences de St. Pe’tersbourg, 1847, [2] 5, 249; 1860, [3] I, 103;J. prakt. Chem., 1846, 39, 22 J. L. Howc and Staff of Baker and Co., Inc. 97; 1860>79>35 (a) “Bibliography of the Platinum Metals 5 A. Joly, Compt. rend., 1888, 107, 994; 1889, 1918-1930’’ (Baker and Co., Inc., Newark, N. J., 1947); (b) “Bibliography of the Platinum 108,854 Metals 1931-1940’’ (Baker and Co., Inc., 6 J. L. Howe,J. Am. Chem. Soc., 1896, 18, 981 Newark, N.J., 1949); (c) “Bibliography of 7 J. L. Howe and E. D. Campbell, 3. Am. the Platinum Metals 1941-1950’’ (Baker and Chem. SOC.,1898, 20, 29 Co., Inc., Newark, N.J:, 1956) 8 J. L. Howe, J. Am. Chenz. SOC., 1901, 23, 23 R. L. Meyer, Manager, Technical Infor- 775; 1904, 26, 543, 942; 1927, 49, 2381; mation Services, Engelhard Industries, in a J. L. Howe and L. P. Haynes, ibid., 19~5, letter of February Irth, 1972, to G. B. 473 2920 Kauffman

Platinum Metals Rev., 1972, 16, (4) 144 ABSTRACTS of current literature on the platinum metals and their alloys PROPERTIES obtained corresponding to the desorption of H, from Pd and Pd-Ag alloys. The heat of desorption Diffusion in Thin Film Couples of Platinum- was measured. Solid-state diffusion is not the Gold limiting step for palladised Ag-Pd but may be for W. B. NOWAK and R. N. DYER, J. Vacuunz Sci. unpalladised Ag-Pd. Technol., 1972, 9, (I), 279-283 The interdiffusion of Pt and Au films was studied On the Oxidation of Palladium, Silver, up to 550°C.Diffusion was monitored by plotting Silver-Palladium, and Silver-Palladinm- specrral reflectance against wavelength in the Copper Alloys band 500-100 nm. Analysis of Pt diffusion U. HARMSEN and W. MERL, Metall, 1972, 26, (7), through Au films gave an activation energy of 680-682 kcal ,Ig-atom and a pre-exponential factor of -38 The transition resistance of Pd, Ag, 3onbPd-Ag, the order IO-~ cm2/s, values close to those for 5oO/oPd-Ag, and 5 06Cu-z5y'J'd-Ag was measured volume diffusion. Results have particular rele- vance to microcircuit beam-lead technology. using a fully automatic apparatus. The contact resistance increases in the region of the stable The Low Temperature Electrical Resistivity PdO layer, but falls to its initial value at 800°C when the PdO evaporates. The alloy 5;/uCu- and Thermoelectric Power of Palladium- 25qoPd-Ag has a higher transition resistance Platinum Alloys owing to the oxidation of Cu above 800°C. P. BLOOD and D. GREIG, J. Phys. F:Metal Phys., 1972, 21 (11, 79-88 The electrical resistivity and thermoelectric power Ordered Alloys in the Cobalt-Palladium of Pd-Pt alloys were measured as a function of System temperature at I-IOOK. The low temperature Y. MATSuO, 3. Phys. SOC.Japan, 1972, 32, (4), thermopowers at the two ends of the alloy series 972-978 have opposite signs. Ordered phases on the 20-roo at.",Pd-Co alloy system were studied by electron diffraction using Significance of Electric Fields on the Growth evaporated single crystal films. Two types of of Thin Metal Films ordered state were found; one is of LI, type L. E. MURR and H. P. SINGH, Appl. phys. Lett., 1972, (Cu,Au type) and exists in 6-90 at.jl,Pd. For 80 at.'!;Pd-Co the order-disorder transition occurs 2% (I2), 512-514 Pt and Pd thin films were vapour-deposited on to at 830°C. The other has the LI, type structure (CuAuI type) and exists in a narrow composition air-cleaved NaCl (001)substrates in the absence of an electric field and in the presence of d.c. range around the equiatomic alloy. This phase fields in the plane of the substrate of 10-1o~V;crn. is accompanied by two phase regions over wide No significant effects of this field were apparent on composition ranges both sides of 50 at.?(, Pd-Co. examination of samples of the evaporated films. Constitution Diagram of the Titanium- High-temperature Transport Properties of Palladium System Palladium v. N. EREMENKO and T. D. SHTEPA, Porosh. Metall., M. J. LAUBXTZ and T. MATSUMURA, Can. J. Phys., 19729 (31, 75-81 19723 503 (313 196-205 The Pd-Ti system was investigated by X-ray, The thermal conductivity, electrical resistivity metallographic and differential thermal analyses and absolute thermoelectric power of pure Pd over the whole concentration range, and the phase were determined at 90-1300K. Results are diagram is given. Pd forms the intermediate compared with existing data and are analysed in phases Ti,Pd, Ti,Pd, TiPd, TiPdz and TiPd,. terms of a simple two-band model, where one The TilPd phase is formed at -600°C; the TiPd, band contains the carriers and the other acts as a phase is due to ordering of the @-solidsolution; trap into which phonons scatter the carriers. the TiPd phase melts congruently and the TiPd, phase appears in peritectic reaction at 14oo0C. Desorption of Hydrogen from Palladium and Palladium-Silver Alloys followed by Differ- The Deformation of Amorphous Palladium- ential Scanning Calorimetry 20 at.% Silicon D. ARTMAN and T. B. FLANAGAN, Can. 3. Chem., R. MADDIN and T. MASWMOTO, Muter. sci. Engng., 19729 5% (9), 1321-1324 1972, 9, (31, 153-162 Differential scanning calorimetric curves were The time-dependent mechanical properties of

Platinum MetalsRev., 1972, 16, (4), 145-151 145 amorphous 20 at. Si-Pd, i.e. fracture-strain CHEMICAL COMPOUNDS rate effect, load relaxation, creep and elastic after- effect characteristics, were measured as a function Electronic Energy Bands of Metal Hydrides - of stress and temperature. The viscous nature of Palladium and Nickel Hydride the amorphous phase is explained, and a qualita- A. C. SWITENDICK, Ber. Bunsenges. Phys. Chem., tive model for the change from the amorphous to 197% 763 (613 635-543 the crystalline phase is suggested. Energy band calculations for the Pd-H system were carried out with the H atoms occupying The Hf-Pd Constitution Diagram interstitial positions in the f.c.c. Pd lattice to A. K. SHURIN and v. v. PET'KOV, fzv.Akad. Nauk represent PdHx with x=0.25, 0.75, 1.0 and 2.0. S.S.S.K., Metally, 1972, (z), 166-168 The calculations show why P-phase PdH saturates Studies of the Hf-Pd system showed that Pd at higher H concentrations than the known con- lowers the melting point of Hf with the formation centration of holes in Pd d bands. of an eutectic and also lowers the temperature of allotropic conversion with the formation of an Conduction Mechanism in Square Planar eutectoid. The structures of Hf,Pd, HfPd, and Complexes of Platinum HfPd, were confirmed. HfPd and Hf,Pd, (Hf,Pd,) P. -EL, H. D. HAUSEN, K. KROGMA" and were detected. There were no laves phases. P. STAMPFL, Phys. Status Solidi A, 1972, 10, (z), Solubility of Hf in Pd is up to 22.5 at.:/, but of 537-541 Pd in Hf is only up to I at.";; in a-Hf and A strong dependence of conductivity upon lattice <5at.4; in (3-Hf. distortions and humidity was detected in square planar complexes of Pt. Both electronic conduc- Equiatomic Transition Metal Alloys of tion and ionic conduction were found. Observed Manganese. VIII. Structural and Magnetic results are probably related to the influence of Properties of Rh-Mn Phases humidity on electronic conductivity. K. SELTE, E. BJERKELUND, A. KJEKSHUS, A. F. ANDRESEN, W. B. PEARSON and V. MEISALO, Acta Confirmation of One Dimensional Metallic Chem. Scand., 1972, 26, (2), 719-732 Behaviour in K,Pt(CN)4Br0.3.(H20)n by The structural and magnetic properties of 44-72 Far Infrared Reflection at.?(, Mn-Rh were studied. The cubic RhMn P. BRUESCH and F. LEHMANN, Solid State Commun., phase with CsC1-type structure is stable at higher 1972J I0J (6), 579-Sg0 temperatures and 50-58 at.:$ Mn. It has not Far infrared reflection measurements on single been obtained in an ordered magnetic state. It crystals of K,Pt(CN),Br,.,.(H,O)n show an transforms on cooling to a tetragonal phase with unusually high anisotropy of the reflectivity and CuAu(1) type structure; this is in an antiferro- confirm the almost one dimensional metallic magnetically ordered state. behaviour of this compound. Some Structural and Physical Properties of Suppression of Graft-versus-Host Reaction 'As Cast' Molybdenum-Ruthenium Alloys by cis-Platinum(I1) Diamminodichloride P. E. J. FLEWITT and A. J. TATE, J. Len-common A. KHAN and J. M. HILL, Transplantation, 1972, Metals, 1972, 27, (3), 339-352 139 (I), 55-57 The microstructure, hardness and superconduct- The antitumour agent cis-Pt(NH,),CI, (5-10 ing transition temperature of high purity 'as cast' mgjkg, i.p.) decreased the graft-versus-host 10-45y0 Ru-Mo alloys are reported. The reaction in B6AF, mice. morphology and crystallography of the three phases (a,b, IS) which occur singly or in combina- Hydride Complexes of the Transition Metals tion within this composition range were analysed H. D. WSZand R. B. SAILLANT, Chem. Rev., 1972, using optical and electron microscopy. 72, (31, 231-281 Hydride complexes of transition metals including Alloys of Thorium with Certain Transition the Pt metals are reviewed. Methods of synthesis Metals. V. The ThOs,-ThJr, Pseudo-binary and properties and reactions are discussed to- System and Some Additional Results on the gether with spectroscopic characteristics and Thorium-IridiumSystem structure determinations. J. R. THOMSON, J. Less-common Metals, 1972, 27, (3)J 293-296 ELECTROCHEMISTRY The ThOs,-ThIr, pseudo-hinary system was studied using X-ray and metallographic methods. True Temperature Coefficients of the Electric The composition range of stability of the cubic Tension of Individual Electrodes. X. The C15-type phase was investigated and information Pt-H,,/H-'.Electrode was obtained on the stability of other phases. G. MILAZZO and V. K. SHARMA, Z. phys. Chem. Metallographic results on binary 66-83 wt.O/; (Frankjurt),1972, 79, (I-2), 41-61 Ir-In are reported. The non-isothermal temperature coefficient of

Platinum Metals Rev., 1972, 16, (4) 146 the Pt-H,/H+ electrode was measured in aqueous mechanism is proposed for N, and NH, formation HCI. The temperature coefficients are 859.6 at by way of intermediate products with adsorbed N 25T and 884.0 at 35°C. atoms.

Catalytic Decomposition of Nitrogen Dioxide ELECTRODEPOSITION AM) on a Heated Platinum Wire SURFACE COATINGS B. G. ONG and D. M. MASON, Id. Engng. Chem., Fund., 1972, 11, (2), 169-174 Deposition of Platinum by Chemical Re- In the study of natural convection heat transfer duction of Aqneous Solutions from a Pt wire to the endothermically reacting F. H. LEAMAN, Plating, 1972, 59, (s), 44-444 gaseous system tNO, + 2NO+O,, a large in- The most successful chemical plating processes crease in the heat flux is observed at a wire tem- which have been developed for depositing dense, perature -11ooK at 0.2-1 atm. This is probably adherent layers of Pt on to noble metals and because below IIOOK the wire is coated with alloys and on catalysed nonconductive substrates PtO,. Above IIOOKtheoxide decomposes to pure are described. Various applications of these Pt which catalyses the NO, decomposition and processes and the advantages and disadvantages of causes an increase in heat flux. each are outlined. Modelling and Opthisation of the Ammonia Precious-metal Coatings for the Protection Oxidation Process for Nitric Acid Manu- of Refractory Metals facture B. JONES, M. w. JONES and D. w. RHYS, 3. Inst. P. URONEN and F. KIUKANNIEM, Br. Chem. Engng. Metals, 1972, 100, (5), 136-141 Process Technol., 1972, 17, (4, 323-32s The use of Pt-Au and Pd-Au coatings for pro- A semi-empirical mathematical model for the tection from oxidation of Ir, Ru, W and Mo was oxidation of NH, over s-ro'i Rh-Pt catalyst was studied. The compatibility of the alloys was derived. A simulation study was carried out and assessed from the phase equilibria and direction the effect of feed temperature, NH, content of of the lines in the ternary systems of Pt-Au and feed, total gas charge and number and dimensions Pd-Au with the four refractory metals. Pt-Au of sieves has been studied. can be used to protect only Pt-rich Pt-Ru alloys; Pt-Au is suitable for unalloyed refractory metals. Catalyst Aids Selective Hydrogenation of Pd-Au has a tendency to diffuse 0, but could be Acetylene used for interdiffusion barriers between refractory w. K. LAM and L. LLOYD, oil Gas?., 1972, 70, metals and oxidation resistant coatings. (13, Mar. 27), 66-70 0.04 wt.% Pt/a-Al,O,, developed by ICL under Reduction of Pd(I1) with Sn(I1) in Hydro- the name 38-1, is used for the selective hydro- chloric Acid. Studies on the Metallisation of genation of C,H, to C,H, and C,H,. Catalyst Plastics. Part 1 formulation and reactor design, operating tem- M. TSUKAHARA, T. KISHI, H. YAMAMOTO and T. perature and catalyst performance are discussed. NAGAI, J. Metal Finish. soc. Japan, 1972, 23, [2), 83-89 Chemisorption on Supported Platinum. I. The reduction of Pd(1I) with Sn(I1) in HCl Evaluation of a Pulse Method. 11. Stoichio- solution was investigated by potentiometric, metry for Hydrogen, Oxygen and Carbon spectrophotometric and polarographic methods. Monoxide [Pd(II)Sn(II)mClx]n- ions (m=2 or 6) were formed during the process and gradually de- J. FREEL,~.Catalysis, 1972, 25, (I), 139-148, 149- composed to form free Pd(o) and Sn(1V). The 160 negatively charged Pd colloid - stabilised by A flow method was used to measure H, chemi- adsorption of Sn(I1) - was assumed to act as an sorption on Pt/Al,O, and Pt/SiO,. The results active sire in the electroless plating process. agreed with those obtained using static methods at room temperature. At 200-300°C a substantial volume of H, was reversibly chemisorbed which HETEROGENEOUS CATALYSIS was excluded from the flow determination. Reaction of Nitric Oxide with Hydrogen on Dehydrocyclisation of 1-Ethylnaphthalene Platinum Purified in Ultra-high Vacuum and Hydrogenolysis of Acenaphthene in the I. I. TRET'YAKOV, v. N. KORCHAK and B. R. SHUB, Presence of Pt-C Kinet. Kataliz, 1972, 13, (2), 512-514 L. A. ERIVANSKAYA, A. KHALIMA-MANSUR, YU. K. H, reacts with NO on Pt purified in ultra-high GRISHIN and A. F. PLATE, Neftekhimiya, 1972, 12, vacuum to form either N, or NH,. The selectivity (2), 183-187 of the process depends on both catalyst tempera- I-Ethylnaphthalene undergoes dehydrocyclisation ture and the partial pressures of the gases. A at 3m-42ooC over Pt/C to acenaphthene. Hydro-

Platinum Metals Rev., 1972, 16, (4) 147 genolysis of the latter forms naphthalene-I, impregnated with 0.8 wt.?; Pt in acidic solution I-methyl- and I-ethylnaphthalenes. Below 390°C at a5"C. the active surface of the catalyst is poisoned as dehydrocyclisation of ethylnaphthalene and hydro- Activity of Hydrogenation Catalysts in an genolysis of acenaphthene occur. Ultrasonic Field I. V. SOLOV'EVA and A. N. MAL'TSEV, Zh. Fiz. Khim., Preparation of a Well Dispersed Platinum- 19721 46, (511 1332-1333 Iron Alloy on Carbon Studies of the hydrogenation of acrylic acid C. H. BARTHOLOMEW and M. BOUDART,J. Catabsis, revealed that an ultrasonic field doubled the 1971>25>(I), 173-176 activity of Pt black and more than trebled that A method for the preparation of Pt-Fe alloy of Pd black. At 15-35"C the activation energies catalyst with average particles 3c-4o.k in dia- of Pt and Pd were 3.0 and 2.5 kca1,mole respec- meter supported on graphitised C is described. tively. The method consists of four steps: partial oxidation of the support, impregnation with H,PtCl, Characterisation of Palladium Blacks. I. A and Fe(NO,), in 4 : I C,H,-C,H,OH mixture, Novel Hydrogen Pretreatment and Surface drying the impregnated samples, and reduction Area Determination of Palladium at 500°C in H,. P. A. SERMON,J. Catalysis, 1972, 24, (3), 460-466 Hydrogenation of Ethylenes on Supported A method for the determination of Pd surface areas using H, chemisorption is described. The Platinum results obtained for a series of Pd blacks covering J. SCHLATTER and M. BOUDART, J. Catalysis, 1972, c. a wide range of surface areas are given. The 24, (31,482-492 method is independent of the extent to which 0, The rate of hydrogenation of C,H, on Pt/SiO, was is preadsorbed on the metal surface. studied at 207-371 K. The results agree with 11. Comparison of Various Methods of those of others on films of evaporated Pt. Enhanced activity was observed when Pt/SiO,- Estimating Surface Area or Particle Size r;Al,O, was used. There was no evidence for P. A. SERMON,J. Catabsis, I972,24, (3), 467-471 correlating spillover of H, from the metal to the Series of Pd blacks of widely differing surface A1,0, with enhanced rates of hydrogenation of area were characterised by techniques including C,H4 adsorbed on the Altoa. N, and Kr adsorption, H, chemisorption, electron microscopy, and X-ray diffraction. The precision Selective Hydrogenolysis of Methylcyclopro- of these techniques is estimated from a comparison of the results. pane over Bifunctional Catalysts J. c. SCHLATTER~~~M. BOUDART,J. Cata&sis, 1972, Carbon-supported Platinum Metal Catalysts 25, (119 93-98 for Hydrogenation Reactions. Mass Trans- Hydrogenation of methylcyclopropane proceeds at different rates to yield iso-C,H,, or n-C,H,,. port Effects in Liquid Phase Hydrogenation The ratio of these rates at 0°C (selectivity) was over PdjC G. J. K. studied on Pt/silica gel. The selectivity was -20 ACRES and B. J. COOPER, J. Appl. Chem. when the catalyst was used alone or with excess Biotechnol., 1972, 22, (6), 769-785 silica gel. When mixed with A1203or silica gel The efficient use of Pd/C catalysts in liquid phase diluents, selectivity dropped to -0.1. This is hydrogenation is shown to depend on H transport probably due to isomerisation on the diluent to limitations from the bulk liquid to catalyst n-C,H,,, followed by hydrogenation to n-C,H particles and on H, diffusion through the support on the metal. to the active crystallites. These processes limit the maximum hydrogenation rate and affect the The Anodic Oxidation of Hydrogen on selectivity. Factors controlling output are Platinised Tungsten Oxides. I. Composition examined. of Tungsten Blue in Platinised WO, Hydro- Effect of the Nature of the Solvent on the gen Electrocatalyst Kinetics of Hydrogenation of Dimethyl- B. s. HOBBS and A. c. c. TSEUNG, J. Electrochem. ethynylcarbinol on Palladium/Polyacrylonit- Soc., 1972, 119, (51, 580-583 The mechanism of the synergistic effect using rile Catalyst by Reduction in Optimum Pt/WO, catalysts in H, electrodes depends on Conditions the composition and mode of formation of a 0. A. TYURENKOVA, L. A. CHIMAROVA and F. I. reduced intermediate W oxide. Chemical analysis ALEKSANDROVA, Zh. Fix. Khim., 1972, 46, (4), and X-ray diffraction show it to consist of blue 885-889 bronze. Mechanical mixtures and impregnated The hydrogenation of dimethylethynylcarbinol powders were investigated at different tempera- over Pd /polyacrylonitrile was studied in iso- tures, Pt loadings and pH values. The greatest amyl alcohol, in H,O, in H,O-alcohol, in H,O- reduction (H0.41W03)was obtained using WO, acetone, and also in acid and alkaline media.

Platinum Metals Rev., 1972, 16, (4) 148 Adsorption Properties of Rhodium- bis-ic-allylpalladium yields n-hexadecapentaenes Ruthenium Catalysts in Relation to in high selectivity. The same catalyst was active Hydrogen for the codimerisation of 1,3,7-octatriene with T. I. KIM, T. M. GRISHINA and G. D. VOVCHENKO, other polyolefins such as 1,3,6-heptatriene and Zh. Fiz. Khim., 1972, 46, (4), 960-962 1,3,6-octatriene producing linear olefins in the Clo-Czzrange. The addition of phosphine ligands The adsorption capacity of Rh-Ru alloys increases alters the course of the reaction and branched as the content of Ru increases. Catalysts were dimers are formed. prepared by CO-deposition from salt solutions. Studies were by charging curves. Noble Metal Catalysis. I. Synthesis of Investigation of the Kinetics of the Catalytic Succinates from Olefins D. M. FENTON and P. J. STEIN WAND,^. Org. Chem., Dealkylation of Toluene 1972, 37~(121, 2034-2035 L. N. GRIGOR’EVA, G. N. MASLYANSKII, G. L. Dialkyl succinate yields of over 909; were achieved RABINOVICH and T. A. SLOVOKHOTOVA, Neftekhimiya, 1972, (2), 195-199 by the oxidative carbonylation of olefins in the 12, presence of alchohols with a Pd redox system Studies of the conversion of toluene with H,O involving Fe and Cu chlorides. FeCl,, in the vapour over 0.6% Rh/A1,0, at 44~480°C presence of Hf, was used, or CuCl added, to showed dealkylation of toluene and the formation prevent the formation of HC1 which slowed the of gaseous produas to complete the conversion. reaction and decreased the yield. NaOAc and The rate of demethylation is proportional to the alkyl orthoformates increased the yield. The amount of toluene present. The rate of CHI product distribution depended on the CO/olefin accumulation correlates with the rate of complete ratio. breakdown of the toluene. Hydroformylation of Propene under Mild Some Problems of the Kinetics and Mechan- Conditions Using Rh,(CO),, ism of Hydrogenolysis of Cyclopentane P. CHINI, s. MARTINENGO and G. GARLASCHELLI, Hydrocarbons on Rhodium/Carbon J. Chem. SOC.,Chem. Commum., 1972, (IZ), 709- 0. V. BRAGIN, T. G. OLFER’EVA and A. L. LIBERMAN, 710 Kinet. Kataliz, 1972, 13, (2), 380-384 Stoichiometric amounts of H, and Rh,(CO),, in The selectivity of hydrogenolysis of trans- tolulene were used to catalyse the hydroform- 1,z-dimethyl- and ethylcyclopentane over 20$4 ylation of C,H,. The reaction probably involves Rh/C is considerably displaced towards the the dissociation of the catalyst. In polar solvents unshielded bonds compared with hydrogenolysis acyl derivatives were formed. Treatment of over Pt/C. The apparent activation energy over Rh,(CO),, with a 1-2 fold excess of PPh, gave a Rh/C for hydrogenolysis of trans-1,2-dimethyl- phosphine complex which catalysed the hydro- cyclopentane is 24 kcal/mole; for ethylcyclo- formylation of olefms. pentane it is 18 kcal/mole. These results broadly agree with the ribbed doublet mechanism of cyclane hydrogenolysis. Investigation of the Course and Mechanism of the Homogeneous Hydrogenation of Diene Dehydrocyclisation of 2-n-Butylnaphthalene Hydrocarbons in the Presence of in the Presence of Rhodium-Alumina Tris(tripheny1phospbine)chlororhodium Catalyst L. KH. FRBIDLIN, E. F. LITVIN and L. F. TOPURIDZE, Zh. Org. Khim, 1y72,8, (4), 669-674 L. A. ERIVANSKAYA, G. A. SHEVTSOVA and A. F. PLATE, Neftekhimiya, 1972, 12, (3), 329-333 RhCI(PPh,), catalyses the reduction of C=C 2-n-Butylnapthalene at 370-560°C in the presence bonds in dienes successively and more selectively of 0.5 wt. yi Rh/AI,O, undergoes C,-dehydro- than does Rh black. The reduction of various cyclisation to form mainly phenanthrene, C,- butadienes is described. dehydrocyclisation, dehydrogenation, and hydrogenolysis of alkyl groups. The latter reaction is Isomerisation of Bis Olefinic Acids with predominant as successive terminal methyl Rhodium Compounds groups are split off. H. SINGER, W. STEIN and H. LEPPER, Fette Seifen Anstrichmitt., 1972, 74, (4), 193-198 The reaction mechanism and effect of catalyst HOMOGENEOUS CATALYSIS composition and conditions were studied for the conjugation of isolated double bonds of bis-olefinic Linear Dimerisation and Codimerisation of acids and esters by Rh compounds. RhCl(PPh,), 1,3,7-Octatriene and RhCOCI(PPh,), in the presence of SnCI,. W. KEIM and H. CHUNG,J. org. Chem., 1972, 37, 2H,O were used to isomerise linoleic acid and its (71, 947-950 esters to conjugated cis-trans and trans-trans The linear dimerisation of 1,3,7-octatriene using dienoic acids.

Platinum Metals Rev., 1972, 16, (4) 149 Investigation of Catalysis of Hydrogenation and Ru(O,)(NCS)(NO)(PPh,), (11) are efficient and Isomerisation of Pentenes by the catalysts for the oxidation of PPh, to OPPh,. In Chlorodimethylsulphoxide Complex of xylene the rate was proportional to the catalyst Rhodium concentration. The rate depends on the partial L. KH. FREIDLIN, YU. A. KOPYTTSEV, N. M. NAZAROVA pressure of Ozfor (I) but not for (11). A mcchan- ism is proposed. and T. I. VARAVA, Izv. Akad. Natrk S.S.S.R., Ser. Khim., 1972, (6), 1420 Reduced Rh chlorodimethylsulphoxide complexes catalyse homogeneous hydrogenation and iso- FUEL CELLS merisation of pentenes at rates of conversion in The Electrochemical -4ctivity of Dispersed the order: pentene-1 > 3-methylbutene-I > trans- Platinum pentene-2 > cis-pentene-a. The reduction and isomerisation of a-methylbutene-2 are probably K. F. BLURTON, P. GREENBERG, H. G. OSWIN and prevented by steric problems. 2-Methylbutene-I D. R. RUTT, J. Electrochem. soc., 1972, 119, (5), is not hydrogenated; it deactivates Rh catalysts 559-564 for the conversion of olefins. Rh complexes do A highly dispersed Pt catalyst (Pt crystallite size not catalyse reduction of dimethylsulphoxide by less than 15 a) on a conductive C support was H, in the chosen conditions. prepared. These doped carbons were made into Teflon-bonded fuel cells electrodes and the Pt The Isomerisation of l,4-Diarylbutenes by surface area and the dispersed Pt specific activity Ruthenium-Phosphme Complexes for 0 electroreduction in acid electrolyte were determined. The specific activity was E 20 times J. BLUM and Y. BECKER, J. Chem. Sac., Perkin less than that of crystalline Pt black. The lower Trans. ZI, 1972, (8), 982-989 activity may be duc either to the difference in Pt The catalytic double-bond migration in 1,4-diaryl- crystallite sizes or to the support, or to both. butenes and in 2-methyl- 1,4-diphenylbutenes by RuCl,(PPh,), was studied. The electronic nature of the substituents does not affect the reaction ELECTRICAL AND rate but affects the ratio of the isomers formed. The reaction is sensitive to steric effects and to ELECTRONIC ENGINEERING the electronic nature of the aryl ligands in the Conductive Ternary Oxides of Ruthenium, PPh, group of the catalyst. and Their Use in Thick Film Resistor Glazes Investigation of the Reduction of Cyclo- P. R. VAN LOAN, Am. Ceram. SOC.Bull., 1972, 51, hexanones by Alcohols in the Presence of (3),231-233,242 Six ruthenitcs, CaRuO,, SrRuO,, BaRuO,, Tris( triphenylphosphine)dichlororuthenium Tl,Ru,O,, Bi,Ru,O, and Pb,Ru,O,, were L. KH. FREIDLIN, v. z. SHARF, v. N. KRUTII and investigated for use in thick-film resistive glazes s. I. SHCHERBAKOVA, Zh. Org.Khim., 1972, 8, (9, for microelectronics. The first three have 979-981 perovskite structures and the others have pyro- RuCl,(PPh,), catalyses cyclohexanone reduction chlore structures. They exhibit metallic conduc- by addition of H from primary and secondary tivity, with resistivities of 10-~10-*ohm cm at alcohols. The alcohols’ reactivity depends on the room temperature, and excellent stability. the number and structure of the hydrocarbon radicals at the carbonyl hydrocarbon atom. Reliability Studies on Ti-Pd-Au Metallisation J. J. GELFAND and B. s. ou, Extended Abstr., 141st Homogeneous Hydrogenation of Diene Natl. Mtg., Electrochem. SOC.,1972, 72-1, 67-68, Hydrocarbons in the Presence of Tri- abstr. 22 phenylphosphine Complexes of Ruthenium The resistivity of Ti-Pd-Au systems was measured E. F. LITVIN, L. KH. FREIDLIN and K. G. KARIMOV, and compared with Ti-Pt-Au systems. An in- Neftekhimtva, 1972, 12, (3), 318-323 vestigation of the interaction of Pd with Au or In the presence of RuCl,(PPh,), and of Ti alone showed a greater resistance change for RuH(CF,CUO)(PPh,), diene hydrocarbons are a thicker Pd interlayer. This indicates that Pd is hydrogenated with high selectivity and stereo- not a barrier layer in the same sense as Pt. specificity for the formation of cis-form p-olefins. Diffusion of Pd into Au is the predominant mechanism for the observed resistance change. Dioxygen Complexes of Ruthenium as Homogeneous Catalysts for the Oxidation of Preparation, Structure and Electrical Pro- Triphenylphosphine perties of Thick Ruthenium Dioxide Films B. W. GRAHAM, K. R. LAING, C. J. O’CONNOR and S. PIZZINI, G. BUZZANCA, C. MARI, L. ROSS1 and S. W. R. ROPER, .7. Chem. soc., Dalton Trans., 1972, ToRcnIo, Muter. Res. Bull., 1972, 7, (5), 449-462 (121, 1237-1243 Results of measurements of X-ray diffraction, The complexes Ru(NCS)(CO)CNO)(PPh,), (I) electron scanning microscopy and electrical

Platinum Metals Rev., 1972, 16, (4) 150 conductivity of thick, polycrystalline RuO, films Fine Line Printing for Consumer Electronics obtained by decomposing RuCl, are presented R. A. VOGEL, Solid State Technol., 1972, 15, (9, and discussed. The influence of the preparation 51-54 procedure, process temperature, C1 content and A system for printing Ag-Pd fine lines is des- nature of substrate on the electrical and structural cribed. Rheology and inks are discussed, together properties is also considered. with printer characteristics and requirements.

NEW PATENTS METALS AND ALLOYS coated with Pt group metals, e.g., Pt itself, optionally plated on over Ni. DisperRion Strengthening of Metals JOHNSON MATTHEY & CO. LTD. Iridium Plating British Patent 1,280,815 INTERNATIONAL NICKEL CO. INC. Platinum group metals are dispersion strengthened U.S. Patent 3,639,219 by spraying the metal or alloy with -0.1 wt.% An Ir electroplating bath is prepared by digesting reactive metal, e.g. Zr, through an atmosphere an aqueous solution of IrCl, and sulphamic acid which reacts Dreferentiallv with the reactive metal at rooT for an extended period, then adjusting to form a dispersion strengthening material, e.g. the Ir content of the bath to about 3-20 g/1 and ZrO,. adding about 3-20 g/1 ammonium sulphamate. Dispersion Hardening of Pt Group Metals LABORATORY APPARATUS JOHNSON MATTHEY & CO. LTD. U.S. Patent 3,640,705 AND TECHNIQUE An oxidation resistant and high mechanical Palladium Alloy strength alloy is made by alloying a Pt group metal with an element capable of forming a stable DEUTSCHE GOLD- 82 SILBER-SCHEIDEANSTALT German Offen.2,043,492 refractory compound, and heating the alloy in a gas, e.g. air or 0,, to form the refractory com- Torsion strips in electrical meters are made from pound within the alloy. This corresponds to an alloy of Pd with 0.6--20/; B. British Patent 1,139,897. HETEROGENEOUS CATALYSIS Treatment of Metals and Alloys JOHNSON MATTHEY & 60. LTD. Hydrogenation Catalyst German Offen. 1,533,481 MARUZEN OIL CO. British Patent 1,272,728 The mechanical properties of metals, alloys and Selective hydrogenation of polyunsaturated hydro- compounds are improved by cold working and carbons can be carried out in the presence of annealing. Recrystallisation, which takes place specified proportions of CO and a catalyst which during annealing, results in an elongated crystal is preferably supported, Cu-free Pd. or grain structure orientated in the direction of working. Hydrogenation Catalyst F.M.C. COW. British Patent 1,273,280 In the production of H,O, by the anthraquinone ELECTRODEPOSITION AND process, the hydrogenation catalyst is Pd metal SURFACE COATINGS supported on A1,03 spheres of specified dimensions. Plated Polymers GULF & WESTERN INDUSTRIAL PRODUCTS CO. Hydrogenation Catalyst British Patent 1,277,145 B.P. CHEMICALS INTERNATIONAL LTD. It has been found that in the electroless plating British Patent 1,273,874 of polypropylene articles, much better results are 12-Aminododecanoic acid (for use in the manu- obtained if Pd(NO,), rather than PdCl, is used facture of nylon- 12) is obtained by hydrogenation as the activator. of I I-cyano-undecanoic acid in the presence of Ru metal deposited on a SiO, support. Platinum Coatings on Cobalt Alloys DEUTSCHE EDELSTAHLWERKE A.G. Dehydrogenation Catalyst British Patent 1,282,530 V.E.B. LEUNA-WERKE 'WALTER ULBRICHT' Turbine blades and other metal parts exposed to British Patent 1,275,830 high temperatures are made from Co alloys Normal paraffins are dehydrogenated to linear

Platinum Metals Rev., 1972, 16, (4), 151-154 151 monoolefins in the presence of a catalyst which Aromatic Hydrocarbon Hydrogenation contains 0.5-5 wt.% Pt and 0.3-0.6 wt.% alkali UNIVERSAL OIL PRODUCTS CO. metal. US.Patent 3,637,879 Cycloparafbs are produced from aromatics by Rhodium Catalysts reduction in contact with a catalyst containing MONSANTO CO. British Patent 1,277,242 0.01-2"/, Pt group metal, 0.02-57b Ge component, Carboxylic acids and esters are obtained by 0.01-1.5% alkali metal compound and a porous reaction of alcohols with CO in the presence of a carrier. Pt and Pd are preferred. solid catalyst containing (a) a support, (b) a Rh component and (c) another metal. Reforming Catalyst CHEVRON RESEARCH GO. U.S. PUte?Zt 3,639,273 Hydroreforming Catalyst A catalyst useful particularly for reforming is a COMPAGNIE FRANCAISE DE RAFFINAGE particulate mixture of ( I) a layered crystalline clay British Patent 1,278,001 type aluminosilicate and (2) a Pt group The catalyst is a porous refractory inorganic oxide component in association with an Alto3 carrier support carrying 0.02 to 2 wt.y& of a metal or a SiO, carrier, e.g. Pt. catalyst which is a Pt group metal with 0.02-2 wt.% of Pb and/or Sn. Ethylene Oxidation GULF RESEARCH & DEVELOPiMENT CO. Ammonia Oxidation Catalyst U.S. Patent 3,641,139 M. A. MINIOVICH et al. British Patent 1,282,000 C,H, is oxidised to CH3COOH without 0, in the A catalyst for the oxidation of NH, to NO consists presence of Ir metal. See also U.S. Patents of 7542% Pt, 15-22% Pd, 2-3.5% Rh and 3,641,510 and 3,641,511. 0.05-0.15 Au, Fe and Ir. This catalyst is more active but costs less than known catalysts. Hydrocarbon Isomerisation Process UNIVERSAL OIL PRODUCTS CO. Catalytic Hydrogenation of Hydrocarbon US.Patent 3,642,925 oils Hydrocarbons are isomerised using a catalytic SHELL INTERNATIONALE RESEARCH MIJ. N.V. composite of a Pt group component, a Sn com- British Patent 1,282,774 ponent and a Re component on a porous carrier, A catalyst for the hydrogenation of hydrocarbon e.g. Pt, Sn and Re/Al,O,. oils consists of 0.25-5 wt.% Pt or Rh on an Al,03 carrier the total alkali content of which is less Hydrocarbon Hydroprocessing than 0.01 wt.y&. UNIVERSAL OIL PRODUCTS CO. U.S. Patent 3,644,198 Catalysis The hydroprocessing of hydrocarbons is catalysed ACCUMULATORENWERK HOPPECKE CARL ZOELLNER by a supported mixture of Ni, Group VIII metal & SOHN K.G. British Patent 1,283,138 and GIOUPIVA metal, e.g. Ni, Pt and Ge on a H, and 0, generated by electrical accumulators crystalline alurninosilicate. are catalytically re-formed into H,O using a Pt metal catalyst, thus minimising the need for Catalytic Reforming Process periodic topping up. UNIVERSAL OIL CO. U.S. Patent 3,645,888 A gasoline fraction is catalytically reformed Exhaust Gas Treatment together with H, and H,O over a catalyst con- ESSO RESEARCH & ENGINEERING CO. taining a Pt group component, Ge and a halogen U.S. Patent 3,637,344 on a porous support; e.g. Pt, Ge and CI. A new improved catalyst for the treatment of ICE exhaust gases is a mixture of Ru and Ir. Dehydrogenation Catalyst UNIVERSAL OIL PRODUCTS CO. US.Patent 3,647,719 Exhaust Gas Treatment The dehydrogenation of hydrocarbons is catalysed OXY-CATALYST INC. U.S. Patent 3,637,353 by a mixture of Pt group metal, Ge and an alkali ICE exhaust gases are treated in three coaxial or alkaline earth metal on a porous support. A chambers. The central chamber contains a Pt- typical catalyst contains Pt, Ge and Li. plated catalyst. Dehydrogenation Catalyst Multicomponent Catalyst UNIVERSAL OIL PRODUCTS CO. CHEVRON RESEARCH CO. U.S. Patent 31637,527 U.S. Patent 3,647,911 Hydrocracking and denitrification multicompon- Saturated hydrocarbons are dehydrogenated over ent catalysts are produced by co-precipitating a Pd an Al,O,-supported mixture of As and Pt with compound (e.g. sulphide) with a Zr, Ti, Th, etc. 0.01-1.576 Li. The ratio of As to Pt is 0.15- compound and also a metal chloride. 0.45 : I. Other Pt group metals can replace Pt.

Platinum Metals Rev., 1972, 16, (4) 152 Selective Hydrogenation of Acetylenic Dicarboxylic Acid Production Hydrocarbons MONSANTO CO. British Patent 1,278,353 UNIVERSAL OIL PRODUCTS GO. Dicarboxylic acids are produced by reacting a U.S. Patent 3,651,167 non-vicinal glycol (or one of its derivatives) with Selective hydrogenation of 4C acetylenes. for CO in a solution containing a halogen-promoted example ethylacetylene and /or dimethylacetylene, Rh or Ir compound and H,O (where both OH mixed with butadiene, is carried out in a fixed-bed groups of the glycol are substituted). Rh carbonyl system using a Group VIII noble metal com- bromides and chlorides and their phosphine ponent catalyst. A preferred catalyst contains complexes are described in the examples. 0.01-0.2~~,Pd. Adipic Acid Production Hydrocarbon Isomerisation Catalyst MONSANTO CO. British Patent 1,278,354 UNIVERSAL OIL PRODUCTS CO. Adipic acid is produced by the reaction of butane- U.S. Patent 3,652,697 1,4-diol with CO in the presence of a halogen- Hydrocarbons are isomerised using a Pt group promoted Rh or Ir catalyst. The preferred metal-Ge-Friedel Crafts halide catalyst. A catalysts are phosphine or phosphine/carbonyl typical catalyst contains Re, Ge and Pt on A1,0, complexes of Rh monohalides. treated with the chlorides of these metals to produce AlCl, as the Friedel-Crafts halide. Production of Octadienes IMPERIAL CHEMICAL INDUSTRIES LTD. Hydroisomerisation Catalyst British Patent 1,278,806 TEXACO INC. U.S. Patent 3,652,709 1,6- and/or rpoctadienes are produced by con- Hydroisomerisation of 4-7 C hydrocarbons is tacting one or more acyclic conjugated dienes with carried out in the presence of a chloride-activated a metallic Pt, Pd, Os, Rh or Ru or one of their metal-Al,O, catalyst, the metal being Ru, Rh, Pd compounds in the presence of a polar solvent and or Pt. The selectivity of the catalyst is improved a reducing agent. by treating it with a C oxide at 50-400CF. Catalytic Carbonylation of Nitro Compounds Refractory Catalyst Supports OLIN CORP. U.S. Patent 3,636,027 JOHNSON MATTHEY & CO. LTD. An organic isocyanate is produced by reacting an German Offen. 2,149,663 organic nitro compound with CO in the presence Refractory catalyst supports, e.g. of honeycomb of a catalyst system containing a S-containing structure, are produced from an A1,0, structure heteroaromatic compound and a halide of a noble coated with AI,O,’SiO, fibres. Pt may then be metal. Thiophene and dibenzothiophene are the deposited on the support. preferred heteroaromatic compounds, and the noble metal halide is preferably a halide of Pd, Rh, Ir andlor Pt, e.g. RhC1,-thiophene. See also HOMOGENEOUS CATALYSIS US.Patents 3,636,028 and 3,636 029. OX0 Catalysts Unsaturated Ester Production BADISCHE ANILIN- & SODA-FABRIK A.G. MOBIL OIL COW. U.S. Patent 3,646,115 British Patent 1,273,042 Unsaturated esters are prepared from an olefin, Aldehydes and alconols are produced by reaction carboxylic acid and 0, in the presence of a Rh of olefins with CO and H, in the presence of a or Ir catalyst complexed with CO, phosphine, tertiary phosphine adduct of a Group VIII metal arsine or stibine. carbonyl complex of preferably Rh or Pt. Aromatic Isocyanate Production Oxidation Catalyst OLIN MATHIESON CHEMICAL CORP. SHELL INTERNATIONALE RESEARCH MI]. N.V. U.S. Patent 3,637,785 British Patent 1,275,370 Aromatic isocyanates are produced by the reaction Methyl esters of aliphatic carboxylic acids are of an aromatic nitro compound with CO in the obtained by reaction of mixtures of C,H, and presence of a noble metal halide and an amide or CH,OH in the presence of a complex of Ru with thioamide, e.g., Pd halide and dimethyl form- CO and a triaryl phosphine. amide. See also U.S. Patent 3,637,786. HydrosiIylation Catalyst Diene Synthesis Catalyst TORAY INDUSTRIES INC. British Patent 1,278,072 E. I. DU PONT DE NEMOURS & CO. An organosilicon compound is produced by U.S.Patent 3,640,898 reaction of an olefinically unsaturated compound Dienes are synthesised from olefins and conjugated with a hydrosilane in the presence of a catalyst dienes in the presence of Rh(I1I) salt catalysts which is a zerovalent complex of Pd with a P-, complexed with amides, phosphoramides, phos- As- or Sb-containing ligand. phine oxide, etc.

Platinum Metals Rev., 1972, 16, (4) 153 Cyclic Olefin Isomerisation Semiconductor Device SUN OIL co. U.S. Patent 3,647,896 TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. Exocyclic-unsaturated olefins are produced by Brirish Patent 1,274,500 isomerisation in the presence of a Group VIII A solar cell includes a semiconductor body and a complex, especially an 0s or Ru phosphine halide contact which consists of a layer of Ag, a layer of and/or carbonyl. Ti and a layer of a noble metal othcr than Ag (e.g. Pd or Pt). Palladium Complexes OLIN MATHIESON CHEMICAL CORP. Heater Elements US.Patent 3,654,279 JOHNSON MATTHEY & CO. LTD. New catalysts, especially for isocyanate produc- British Patent I ,27841 I tion, have the formula PdL(CO)X,, where X An electrical heater element is made from a is halogen and L is a Lewis base and particularly a high temperature resistant non-conducting sub- heteroaromatic N compound such as pyridine. strate with a layer of the resistor composition of British Patent 1,210,493. This consists of 91-20?1, Stabilised Rhodium Carbonyl Complexes finely divided glass and g-809/, of the product of BADISCHE ANILIN- & SODA-FABRIK A.G. heating RuO, with one or more Group V oxides, German Offen.2,044,651 e.g. Nb,O,. Rh carbonyl complexes used in the 0x0 synthesis are stabilised by a formylalkyl ester. Resistor Composition TOHNSON MATTHEY & CO. LTD. U.S. Patent 3,637,530 FUEL CELLS AND BA'M'ERIES A resistor composition suitable for firing on to a ceramic substrate has the form of an oxide con- Fuel Cell Electrodes taining Nb and Ru in which the atomic ratio of ALLMANNA SVENSKA ELEKTRISKA A.B. metal to 0, is I : 2 and in which the atomic ratio British Patent 1,273,045 of Nb to Ru is within the range I:~OOO-I:I. The fuel electrode in a fuel cell is a porous Ni plate coated with a mixture of Pd, Pt and Ru and Palladium FiIms on Silicon Semiconductors the air electrode has an active layer consisting of a MATSUSHITA ELECTRONICS CORP. mixture of Ag and Ni particles sintered together. U.S. Patent 3,642,528 Pd films on SO2layers peel off when exposed to H,. This discovery is used in making selective CHEMICAL TECHNOLOGY deposits on Si semiconductors. The area not to be coated is treated to produce a layer of SiO,. Platinum in Silicone Elastomers The whole body is coated with Pd and treated DOW CORNING CORP. US.Patent 3,652,488 with H, so that the Pd over the oxide peels off. A flame resistant elastomer is obtained from a mixture of IOO parts silicone polymer, 10-100 Palladium Phosphide Chalcogenidcs parts SiO, reinforcing agcnt and 0.05-2 parts E. I. DU FONT DE NEMOURS & CO. S-free C black cured with 10-150 p.p.m. Pt. U.S. Patent 3,655,348 At high pressures and -I,ooo~C, Pd, P and a chalcogen, S or Se, combine to form compounds GLASS TECHNOLOGY of formula PdPyX,..y in which y is 0.67 when X is S and y is 0.4-0.8 when X is Se. The compounds Glass Fibre Production have a pyrite-type crystal structure. They are CERTAIN-TEED PRODUCTS CORP. electrical conductors with a zero temperature U.S. Patent 3,647,382 coefficient of resistance from liquid He tempera- A cooling tube assembly for use in a glass fibre ture to room temperature. They are useful as spinneret is made from commercial Pd metal. electrical resistors.

ELECTRICAL AND TEMPERATURE ELECTRONIC ENGINEERING MEASUREMENT Anode Resistance Thermometer Alloys ELECTRONOR CORP. British Patent 1,273,486 CALIFORNIA INSTITUTE RESEARCH FOUNDATION A Ti anode for use in electrolysis of brine is U.S. Patent 3,644,863 coated with an electrocatalytic layer of a semi- Alloys with a negative temperature coefficient of conductor composition. The composition con- electrical resistance contain a Pt group metal, tains a major portion of TiO, and a minor Si or Ge and a first series transition metal. A portion of an oxide of a Pt group metal. preferred alloy is Pd80-xSi,oCrx,where x is 1-8.

Platinum Metals Rev., 1972, 16, (4) 154 AUTHOR INDEX TO VOLUME 16

Page Page Page Page Abramova, L. I. 105 Chasanov, M. G. 107 Gornm, P. S. 107 Kaesz, H. D. 146 Acres, G. J. K. 74, 148 Chen, H.-S. 106.11 1 Gostunskaya, 1. V. 32 Kahan, G. J. 111 Agarwala, Y. S. 11 1 Chen, W. Y. K. 105 Graham, B. W. 150 Kane-Maguire, L. A. P. Akhtar, M. 63 Chimarova, L. A. Graham, J. H. 32 62 Aldag, A. W. 27 32,65,148 Grasserbauer, M. 30 Kauffman, G. B. 101,140 Alekseeva, V. I. 30,33 Chini, P. 149 Greenberg, P. 150 Keim, W. 149 Al’t, L. Ya. 66 Chizhikov, D. M. 28 Greenspan, L. 29 Kempling, J. C. I10 Anderson, R. B. 1 10 Chung, H. 149 Greig, D. 145 Kennedy, G. C. 35 Andreeva, 0. V. 109 Constable, D. C. 34 Grigor’eva, L. N. 149 Kern, D. W. 35 Arai, H. 62 Conti, F. 33 Grishina, T. M. 149 Khalima-Mansur, A. 147 Arakawa, T. 33 Cooper, B. J. 74,148 Grubbs, R. H. 33 Khan, A. 146 Aref’ev, 0. A. 30 Craik, D. J. 129 Gryaznov, V. M. 31 Khan, H. R. 61 Artman, D. 145 Gubieva, D. N. 106 Kikuchi, E. 13 Asami, Y. 31 Dautzenberg, F. M. 1 OX Guertin, R. P. 61 Kim, T. 1. 149 Atkins, L. T. 65 Davis, B. H. 108 Guialyuk, N. I. 110 Kirsanota, T. S. 34 Atroslichenko, V. I. 108 Dekhtyar, I. Ya. 27 KiseleFa, T. S. 31 Avery, N. R. 109 Dietz, R. L. 112 Kishi, T. 147 Dimitrenko, V. E. 107 Hall, W. K. 32 Kishore, B. I 06 Halpern, J. 62 Kiukanniemi, E. 147 Bagotskii, V. S. 63 Domanskaya, K. K. 32 Harmsen, U. 145 Klabunovskii, E. I. 32 Baier, E. 67 Donati, M. 33 Drobek, J. Hartley, F. R. 22 Klammer, H. 67 Bailar, J. C. 63, 11 1 60 Harvey, G. A. 33 Klvana, D. I09 Balenkora, E. S. 30,33 hffy, J. A. 34 Duggan, R. 105 Hasegawd, R. 61 Kogan, S. B. 31 Banks, R. L. 32 Hashimoto, E. 27, 105 Baranowski, B. 10 Dutchak, Ya, I. 112 Kiihling, A. 63,66 Hata, G. 33 Kolboe, S. I08 Bartholomew, C. H. 148 Duwez, P. 61 Hausen, H. D. 146 Koons, F. J. 34 Bartlett, W. 105 Dyer, R. N, I45 R. Havel, J. J. 62 Kopyttscv, Yu. A. 66, 150 Bartosik, D. C. 60 Heckelsberg, L. F. 32 Korchak, V. N. 147 Beamer, R. L. 32 Entezami, A. 111 HCault, D. 65 Kosenko, V. A. 62 Becker, Y. 150 Eremenko, V. N. 145 Herr, A. 105 Kovtun, G. P. 62 Bell, P. M. 35 Erivanskaya, L. A. Heyne, W. 67 Kozlov, N. S. 3 I, 64 Benesi, H. A. 65 147.149 Hill, J. M. 146 Kroll, L. C. 33, 64 Berenbaum, M. C. 29 Evans, J. P. 34 Hobbs, B. S. 148 Kropotota, N. V. 64,107 Besnus, M. J. 105 Hockings, E. F. 28 Krupenya, N. G. 109 Besprozvannyi, M. A. 65 Fadeev, V. S. 32 Holbrook, L. 109 Kudryavtsev, N. T. 29 Biefer, G. J. Ill Farr, J. P. G. 105 Holdoway, M. J. 38 Kulishkin, N. T. 65 Binder, H. 63,66 Fedorov, G. V. 105 Holleck, G. L. 106 Biswas, S. R. 34 Kiindig, P. 62 Feldstein, N. 63 Holloway, J. H. 28, 118 Bjerkelund, E. 146 Kunz, L. 27 Fenton, D. M. 149 Honzu, J. 34 Kuz’mina, N. N. 107 Blood, P. 145 Flanagan, T. B. 145 Houghton, R. W. 106 Blum, J. 150 Kuzora, T. V. 109 Flewitt, P. E. J. 146 Houska, C. R. 60 Blurton, K. F. 150 Fomichev, Yu. V. 31 Hotre, J. A. 29 Boidenko, V. S. Frankel, 111 28, 1OS, 106 E. N. Hubbard, A. T. 63 Ladozhina, Z. I. 111 Fredrickson, R. 107 Boronin, V. S. 108, 109 Huber, H. 62 Laing, K. R. 150 Freel, J. 147 Bouchard, R. J. 62 Hulbert, B. J. 30 Lam, W. K. I47 Freidlin, I,. Kh. Hunt, C. E. 65 Laucsek, T. S. 63 Boudart, M. 148 66,110,149,150 Huntley, D. J. 61 Lange, H. 30 Boyd, F. R. 35 Fujimoto, K. 32 Hutchens, R. D. 61, 106 Laroy, B. C. 60 Bradford, C. W. SO, 62 Fuschillo, N. 27 Bragin, 0. V. 149 Hutchinson, J. M. 88 Lau, A. L. Y. 63 Brookbanks, D. M. 94 Lanbitz, M. J. 145 Gale, G. R. 29 Lauder, I. 28 Brown, W. D. 32 Ilyushchenko, N. G. 106 Gankin, E. A. 62 Lazarus, D. 67 Briiesch, P. I46 Irani, S. 48 Ganlt, F. G. 110 R. Lazutkina, A. 1. 66 Burch, D. S. 107 Itatani, H. 111 Gelfand, J. J. 150 Leaman, F. H. 147 Burnett, M. G. 34 Ivanova, G. V. 27 Geraudelle, A. 111 Lecrone, F. N. 63 Buzzanca, G. 150 Izmailov, R. I. 109 Getting, I. C. 35 Lehmann, F. 146 Cahn, R. W. 48 Gibbens, H. R. 108 Leonard, €3. J. 15 Cant, N. W. 32 Gimpl, M. L. 27 Jako, G. J. 29 Lesueur, D. 28 Chaldecott, J. A. 57 Glushenkova, A. I. 32 Jeffery, R. N. 67 Levin, D. Z. 65 Chandler, T. R. D. 2 Goldstein, M. 106,111 Jones, B. 147 Levinter, M. E. 108 Chao, C. C. 61 Golomb, M. G. 108 Jones, M. W. 147 Levitskii, I. I. 30

Platinum Metals Rev., 1972, 16, (4), 155-156 155 Page Page Page Puge Lisorskii, P. V. 110 Ong, B. G. 147 Sen’kov, G. M. 31,64 Timofee%, 27,28 Litvin, E. F. 149,150 Otterson, D. A. 27 Sergutkina, 0. R. 30 Toibaev, I. K. 107 Lloyd, L. 147 Ou, B. S. 150 Sermon, P. A. 148 Tomashov, N. D. 11 1 Loebich, 0. 61 Owston. P. G. 107 Shah, J. S. 94 Tomkins, F. C. 63 Losee, J. R. 107 Sharf, V. Z. 150 Tracey, V. A. 105 Luss, D. 30 Sharma, V. K. 146 Trease, R. E. 112 L’vov, S. N. 106 Pajonk, G. 64,65 Sharon, T. E. 61 Treizer, L. M. 110 Lyons, J. E. 34 Pak, A. M. 33 Sharp, D. J. 29 Tret’yakov, I. I. 31, 147 Palkin, V. A. 107 Shevtsova, G. A. 149 Treverton, J. A. 61 Maatman, R. W. 64 Pandey, P. C. 33 Shibata, S. 29 Triplett, B. B. 61 MacConnell, J. D. 16 Panteleimonov, L. A. 106 Shimizu, S. 27, 105 Trofimova, A. A. 107 Macdonald, W. J. D. 34 Parravano, G. 110 Shtepa, T. D. 145 Tseung, A. C. C. 148 Madatova, E. G. 27 Pavlova, L. F. 31 Shue, R. S. 66 Tsuei, C. C. 61,105 Maddin, R. 145 Perlstein, J. H. 63 Shul’man, A. R. 34 Tsukahara, M. 147 Magat, L. M. 27,28,105 Perree-Fauvet, M. 65 Shur, Ya. S. Tsurumi, M. 33 Maguire, C. F. 34 Pet’kov, V. V. 146 27,28, 105,106 Tsvetkov, Yu. V. 28 Mahaffy, P. 64 Phillips, N. E. 61 Shurin, A. K. 146 Turner, I. 61 Mais, R. H. B. 107 Pilbrow, M. F. 107 Siegel, S. 66 Tynrenkova, 0. A. Maitlis, P. M. 56 Pizzini, S. 150 Singer, H. 149 32,65,148 Makushina, V. M. 30 Platteeuw, J. C. 108 Singh, H. P. 145 Mal’tsev, A. N. 148 Podvyazkin, Yu. A. Singh, V. N. 33 Underhill, A. E. 107 Margrave, J. L. 61 30,110 Sinha, A. K. 60 Uronen, P. 147 Martinengo, S. 149 Polak, J. 27 Sinyak, G. S. 110 Uzbekov, A. A, 11 I Martynova, E. N. 64 Polikarpov, V. A. 3 1,64 Skell, P. S. 62 Martyshkina, L. E. 30 Pollitzer, E. L. 42 Sklyarov, A. V. 31 Mashkina, A. V. 65 Polyakova, V. P. 62 Smith, R. J. 27 Van Loan, P. R. Maslyanskii, G. N. Pope, D. 32 Smith, W. L. 32 150 31,65,110,149 Popov, N. I. 31,110 Sokolova, N. P. 32, 105 Vasev, A. V. 64 Mason, D. M. 147 Vasiliev, Yu. B. 63 Popova, I. L. 110 Sokolovskaya, E. M. 106 Masumoto, T. 145 Prokhorenko, V. Ya. 112 Sokol’skii, D. V. Vatolin, N. A. 27,28 Matsumura, T. 145 31, 33,63, 107, 109, 110 Velho, L. R. 105 Matsuo, Y. 145 Solov’eva, I. V. 148 Verkhorobin, L. F. 62 Matthews, J. W. 60 Sonn, M. 29 Vinogradov, S. N. 29 Matveeva, T. V. 111 Quinn, H. A. 32 Stadnik, P. M. 108 Vlasov, V. G. 31 Matyjewski, P. 65 Quinn, T. J. 2 Stanitski, C. 28 Vogel, R. A. 151 Merl, W. 145 Stein, W. 149 Von Benda, K. 63 Metcalfe, A. 31 Steinwand, P. J. 149 Milazzo, G. 146 Rabinovich, G. L. Stelts, P. D. 35 Minachev, Kh. M. 30 65,110,149 Stepanov, F. N. 64 Weiher, J. F. 62 Mitchell, S. J. 28 Rao, V. U. S. 61,106 Stiles, D. A. 124 Wells, P. H. I24 Mitrofanova, A. N. 109 Raub, C. J. 49,61 Stolyarenko, L. I. 64 Wentorf, R. H. 35 Miyake, H. 33 Raub, E. 61 Strel’nikova, Zh. V. 30 Wenzel, E.-M. 27 Morrison, R. J. 34 Reinacher, G. 60 Sukhotin, A. M. 62 Whan, D. A. 65 Moss, R. L. 32, 108 Riskin, I. V. 111 Sumino, M. P. 29 White, J. G. 28 Moyer, R. 0. 28 Robertson, A. R. 67 Sun, R. C. 60 Wise, H. 109 Mukerji, J. 34 Riischel, E. 49 Suzuki, T. 60 Witekowa, S. 65 Muller, J. M. 110 Rouleau, D. 109 Svajel, 0. 30 Wood, S. D. 34 Murr, L. E. 145 Rowden, M. W. 31 Swanson, J. L. 108 Wurfel, P. 146 Rushford. 11. G. 65 Switendick, A. C. 146 Nagasawa, H. 106 Sykora, M. 65 Naidn, S. V. N. 60 Yakovlev, V. I. 28 Nakajima, H. 66 Saillant, R. B. 146 Yakovleva, T. I. 107 Nakamura, S. 111 Saleh, J. M. 29 Takahashi, K. 33 Yasui, T. 111 Nazarova, N. M. 66,150 Samsonov, G. V. 28,62 Takahashi, T. 32 Nemchenko, V. F. 106 Sarachik, M. P. 106 Tallman, C. R. 35 Newman, D. J. 30 Savage, R. 105 Tanaka, M. 60 Zabotin, L. I. 108 Nikulina, V. S. 108,109 Savitskii, E. M. 62 Tatarkina, A. L. 106 Zakarina. N. A. 63 Notley, J. M. 90 Schindler, A. I. 60 Tate, A. J. 146 Zakumbaeva, G. D. 63 Nowak, W. B. 145 Schlatter, J. C. 148 Teichner, S. J. Ci4,65 Zasorin, A, P. 108 Nyholm, R. S. 62 Schmidt, L. D. 27,30 Thomas, J. Y. 28 Zharkov, B. B. 31 Schmitz-Pranghe, N. 106 Thompson, H. S. 29 Zhubanov, K. A. 109 Ohrt, D. 66 Schroder, R. H. 106 Thomson, J. R. 146 Zhubanova, L. D. 109 Okada, M. 31 Selte, K. 146 Thomson, S. J. 33 Zwingmann, G. 27 Olfer’eva, T. G. 149 Semenova, A. D. 64,107 Thulin, A. 67 Zysk, E. D. 67

Platinum Metals Rev., 1972, 16, (4) 156 SUBJECT INDEX TO VOLUME 16 a=abstract Page Catalysts, Pd/AI,O, (contd) Page Brazing, Pd-Ni and Pd-Mn-Ni alloys for, a reduction of N oxides in exhaust gases 30 toN,on,a 108 Catalysis, 5th International Congress on 138 PdjC, dispersion of Pd in, a 32 Catalysts, H,PtCI,, hydrogenation of Hpchemisorption on, a 65 methylocadecadienoate, a 111 hydrogenation on, liquid phase, a 148 Iridium, black, heat of adsorption of Haon, a 1 10 Pd/kieselguhr, hydrogenation of C,Haon, a 65 black, hydrogenation of cyclo-olefins Pd/pnlyacrylonitrile, effect of KOH additions on, a 33 on, a 32 complexes, IrH(CO)(PPhJ ?, hydrogenation of IrH J(CO)(PPh lrH(CO)(PPh,) 2, dimethylethynylcarbinol on, a 148 hydrogenation of CaH, with, a 34 Pdlpnly-S-leucine, hydrogenation of complexes, IrCl(CO)(PPh,) *, methylcinnamic acid on, a 32 isomerisation of vinylcycloalkenes Pdlpoly-S-valine, hydrogenation of and alkanes with, a 34 metliylcinnamic acid on, a 32 reactionofn-C5HI2withH2on,a 33 Pd/pnlyvinyl alcohol, with added alkali, Ir/A120a, hydrogenation of hydrogenation of dimethylethynylcarbinol dimethylethynylcarbinol on, a 110 on, a 65 Ir/suppnrt, alkylation of PhH, PhCH, and Pd/SiOz,DjH exchange over, a 32 cyclohexane, a 110 electrical conductivity of, a 33 Osmium. black. heat of adsorotion of H Heuptakc by hydrocarbons on, a 109 on, a 110 Pdlzenlite, CaA, KA, NaA, structure and black, hydrogenation of butynediol on, a 33 hydrogenation activity of, a 109 Palladium-Osmium. hvdrogenation of OsOl, oxidation of acetaldehyde, a 33 I_ - Palladium, black, hydrogenation of acrylic butynediol on, a 33 acid in ultrasonic field, a 148 Palladium-Rhodium, films of, CO oxidation hlack. hydrogcnation of huryncdiol on, L( 33 on, a I08 hlack. hydrogcnation ofcyclo-oletins, a 33 Pd salt/C, reactivation of, a 32 black. surface area and particle SIX ot. LI 148 Palladium-Silver, hydrogenation of PhNO complexes, z-allylpalladium bromide, on, a 31 pol? merisation of butitdiene, N 66 Pd-Rh/Al,O, hydrogenation of C,Hoon, a 110 complexes. z-allylpalladium chloride, Pd-RulAl.0, hydrogenation of CeHeon, a 110 polymerination of butadicnc. (I 66 Platinum, black, heat of adsorption of H, complexes, bis---allylpalladium. on, a 110 dimerisation of I.3,'i-octatriene on, n 149 black, hydrogenation of acrylic acid complexes, oxycjanatioii of C,11, and on, a 148 C,H. with. o 66 black, hydrogenation of butynediol on, a 33 complexes. Pd(CN) : (PPIi,) ., black, hydrogenation of cyclohcxene, h) drogenation of -nonene and -dodeccnc, a 30 mrthyloc~adrcadirnoate,n Ill black, hydrogcnation of cyclo-olefins complexes. dirncthylsulpho.tidc, olctin on, a 33 h).drogcnation using, '7 66 black, sorption properties of, a 107 complexes. ditertiary hutoxy Pd(ll), black, thermal treatment effect on, a 64 dimerisation of dicnci, n 33 complexes, reaction of 1,3-d1eneson, a 33 complcxcs. reaction of 1,3-diencs on, a 33 complexes, PtCln(PPhr),hydrogenation complexes, PdCI(C,,H solvent of methyloctadecadienoate, a 111 elTects on, a 33 complexes, PtCIP(PPhD)l,isomerisation films, D 'If exchange over, (I 32 of vinylcycloalkanes and -alkencs, a 34 films, deliydrocyclisation of methyl complexes, PtCl ,(Ph sAs) + SnCl pentaiies on, (I 110 hydrogcnation of foil, dehydrogenation ofcyclohcuane methyloctadecadienoate, a 111 on, t7 31 dchydrocyclisation of hjdrogcnation of dimcthylcthynyl- dimethylcyclo-octanes over, a 30 carbinol on, a 65 effect of heat on, a 30 oxidation of CO on, (I 31 effect of Hg poisoning on, a 30 reaction ofn-C,II,, with tf? on. a 33 exhaust purification using 74 redo? system, s) nthesis of succinates films, dehydrocyclisation of methy1 tising, (I I49 pentanes on, a 110 supported, Iiydrogcnarion of fatty acids films, effect of presorption on, and area on, a 32 determination of, a 63 synthesis of\ inyl acctatc on, a Ill films, H,/O,titration of, a 63 Piilladium Acrtate,couplingofC',I~,and heated wire. decomoosition of NO, on, a 147

olcfins. LI 66 hydrogenation of ~ dimcrisation ofdiencs, o 33 dimethylenebicyclononane on, a 64 Palladium Acetnacctate, dimeriwrion of lead-free gasoline production using 42 dienes, a 33 metals, supported, reduction of nitro PdCl?,solvent effects on, (I 33 compounds, a 31 Palladium-Gold, wires, hydrogenation of oxidation of gases from pyrolysis of but-2->lie, u 65 human wastes, a 110 Palladiem-Niclicl-.Aluniinium,hydrogcnation reaction of NO with Hzon, a I47 ofcottonsccd oil on, a 109 reactionofn-C,H,,with H20n,a 33 Pd'.Al.O,, hutcne isomerisation on, a 10') PtCI,, solvent effects on, a 33 combustion of HhO I pollutants on. a 30 Platinum-Iridium, H, adsorption on, a 64 dchydrocyclisation of alkcncs and Headsorption on, a 107 alkadiencs, a 32 Pt-FeiC, preparation of, a 148 dch)drogenation ofcyclohexane on, a 109 Pt/AI, catalytic activation of, 4 65 dispcrsion and activity of, a 65 Pt/AlpOs,,C2He hydrogenation on, a 147 effect of Mn, Cr and Zn on, a I09 activity for C2H,hydrogenation, a 64 electrical conductivity of, a 33 aromatisation of alkanes and alkenes H chemisnrption on. a 65 on, a 65 hydrogenation ofC,H on. II 65 aromatisation of n-hexane on, a 108

Platinum Metals Rev., 1972, 16, (4) 157- 160 157 Catalysts, Pt/AI,O, (conrd) Page Catalysts (contd) Page aromatisation of methylhcptane and Rh/AI,O,, dealkylation of toluene dimetliylhcxanc, a 31 on, a 66,110,149 chemisorption on, a 147 dehydrocyclisation of 2-N- 149 combustion of HNOs pollutants on, a 30 butylnaphthalene on, a 149 dehydrocyclisation of paraffins on, a 108 electrical conductivity of, a 33 effect of CI and H20on, a 30 C2H,and C,H, oxidation on, a 32 effect of Clon 3-methylheptane Rh,’C, hydrogenation of cyclohcxadiene dehydrocyclisation, a 108 on, a 110 cffect of H, pressure and H,O on, a 30 hydrogenolysis of cyclopentanes on, a 149 effcct of preparation method on, a 31 Rh/SiOe,electrical conductivity of, a 33 effects of rare earths on, a 31 Rhodium-Platinum, NH, oxidation on, a 108,147 effect of S on, a 31 gauzc, NH, oxidation on, a 64 electrical conductivity of, a 33 gauze, conccntrated HNOl production H2chemisorption on, a 65 on, a 64 hydrogenation of CaHI and rso-CIH, gauze, properties of, a 30 on, a 108 gauzc, reduction of Pt loss from, a 30 isomerisation of n-hexane on, a 108 Rhodium-Ruthenium, H ,adsorption preparation of an cyclohexane properties of, a I49 dehydrogenation on, a 64 Rh-Ru/Al,O,, hydrogenation of CsH, on, a 110 promoted by Y and Cc. petroleum Ruthenium, black, heat of adsorption of H rcforming on, a 64 on, a 110 reduction of U(V1) and Pu(1V) with complcxcs, RuCI”(PPh$)?, N,H,on,a I08 hydrogenation of dienes using, a 150 Y-promoted, hydrogenation of C,H li complexes, RuCl2(PPhh3, on, a 64 isomerisation of 1,4-d1arylbutenes PtjC, dehydrocyclisation of by, a 150 1 -ethylnaphthalene on, a 147 complexes, RuCI,(PPha)a, H, chemisorption on, a 65 isomerisation of vinylcycloalkenes hydrogcnolysis of acenaphthcne on, a 147 and -alkanes, a 34 in fuel cells, a 150 complexes, RuC12(PPh,)r,reduction of PtjSiO,, active area measurement of, a 65 cyclohexanones by alcohols using, a 150 activity for dehydrogenation of, a 109 complexes, RuH(CF,COO)(PPha)a, chemisorption on, a 147 hydrogenation of dienes using, a 150 electrical conductivity of, a 33 complexes, Ru(NCS)(CO)(NO)(PPh 8) *, Hnchemisorption and Pt dispersion oxjdation of triphenylphosphine on, a 109 using, a 150 hydrogenation of ethylenes on, a I48 complexes, Ru(02)(NCS)(NO)(PPha) hydrogenolysis of methylcycIopropane ox!dation of triphenylphosphine over. a 148 using, a 150 Pt surface area of, a 108 reaction of n-CsHI2with Haon, a 33 Pt/Si0-Alr0,hydrogenation of ethylenes Ru/AI,O,, electrical conductivity of, a 33 on, a 148 C2H1and CsHcoxidation, a 32 synthesis of xylene on, a 31 hydrogenolysis of butane on, a 110 Ptlsupport, alkylation of PhH, PhCH, and Ru/SiO,, electrical conductivity of, a 33 cyclohexanc, a 110 hydrogenation of acetoacetic esters on, a 32 Pt/WO,, H, electrocatalyst, composition isomerisation of 1-butene on, a 32 of, a 148 Ru/support, alkylation of PhH, PhCHI and Platinum-Osmium, hydrogenation of cyclohexanc, a I10 butyncdiol on, a 33 Ru-Pt/TiO,hydrogenation using, a 109 Pt-Pd/AlpO,hydrogenation of COHOon, a 110 Ruthenium-Rhodium, Haadsorption Platinum-Rhenium, lead-free gasoline propcrtics of, a 149 production using, 42 Cathodic Protection, Pt/Ti anodes for, review of, a 67 Platinum-Rhodium,NH, oxidation on, a 108,147 Cells, galvanic, KI.BPPt(C204)rxHo0, proton gauze, NH, oxidation on, a 64 injection in, a 63 gauze; concentrated HNOs production on, a 64 Chemical Plating, Pt, a 147 gauze, properties of. a 30 Coatings, Pt-Au, Pd-Au on Ir, Ru, W, Mo, a 147 gauze, reduction of Pt loss from, a 30 Corrosion, Pd-Ti in HCI, study of, a 111 Pt-Rh/A1203,hydrogenation of C8Hoon,a 110 Pd-Ti in HCI, study of Pd loss of, a 111 Pt-Ru/Al,O, hydrogenation of CsH,on, a 110 Ru-Ti in HCI, study of, a Ill Rhodium, black, hydrogenation of stainless steels, Pd and Pd-Mo additions to, a 1 1 1 cyclo-olefins, a 33 Crucibles, Pt, corrosion in, a 30 complexes, Rh,(CO), hydroformylation Pt, melting optical glasses in, a 34 of propcne using, a I49 complexes, RhCOCI(PPh J Diffusion Units, Hz,ultra-pure 124 isomerisation of bis-olefinic acids with, a 149 Elcctrical Contacts, Pt group metals, properties and applications of, a 67 complexes, RhCI(PPh $) 3r hydrogenation ofcyclohexane with, a 66 Electrodeposition of Osmium, from osmic acid, a 29 complexes, RhCI(PPh3)3, hydrogenation Osmium 90 of diencs by, a 149 Palladium-Cobalt, from mixed-ligand complexes, RhCI(PPh 8) 3, isomerisation electrolytes, a 29 of bis-olefinic acids with, a 149 Platinum, on Ni-based turbine blades 87 complexes, RhCI(PPh,) Jdivinyl- Platinum Metals, laboratory unit for, a 64 henzenestyrenc, reduction of Electrodes, Platinum, adsorption of gases on, a 29 olefins on, a 33 black, in biogalvanic cell, a 107 complcxcs, Rh chlorodimcthylsulphoxide, cffect of chemisorbcd species on Pt complex hydrogenation and isomerisation reactions, a 63 of pentenes by, a 150 heat-treated, clcctrochcmical activity of, a 29 complexes, Rh(N02)%.2H80, hydrogenation of propargyl alcohol on, a 63 polymerisation of isoprene and porous, manufacture of, a 107 butadiene, a 111 Raney, autogcnic H2reference, a 66 reaction of n-CbHI2with H, on, a 33 structural effccts of, a 63

Platinum Metals Rev., 1972, 16, (4) 158 Electrodes, Platinum (confd) Page Palladium Alloys (contd) Page with adsorbed surface films, a 63 Palladium-Copper-Nickel, structure at Pt-Hp/H+,coefficients of electric tension 400-7OO0C,a 61 of, a 146 Palladium-Gold, coatings on Ir, Ru, W, Mo, a 147 PtlC, in fuel cells, a 150 thermodynamic properties of, a 60 Electroless Plating of, Palladium, on thick film pastes of, u 112 adsorbed Sn(l1) laver. a 63 Palladium-Gold-SiIwr, Debye temperature Palladium,~photbselectivcprocess using, a 29 and expansion of, a 60 Palladium-Gold-Tellurium, superconductivity Fuel Cells, activity of dispersed Pt in, a 150 in, a 105 Pt cathodes for, stability of, a 34 Palladium-Gold-Titanium, metallisation, a 150 Palladium-Hafnium, Constitution diagram, a 146 Palladium-Hydrogen, high pressure study of 10 Gihbs, Wolcott, life and work of 101 Palladium-Iron, atomic ordering and Glass, Pd-Si compounds, properties of, a 111 magnetic hardening in, a 105 liquid, activity of, a 28 liquid, vapour pressure of, a 21 Heater, Catsheat catalytic, Pt metals in 16 magnetic properties of, a 105 Howe, James Lewis, work of 140 magnetic properties and phase state Hydrogen, ultra-pure, production of 124 of, a 106 powder, magnetic properties of, a 28 temperature dependence of resistance Iridium, Ettinghausen-Nernst coefficient of, a 106 of, a 105 compounds, CaJrH,, SrJrHs, preparation Palladium-Iron-Silicon, magnetic states in, a 61 and structurc of, a 28 Mossbauer spectra of, a 61 Iridium Alloys, Iridium-Platinum, i.r. spectra of 105 Palladium-Manganese, liquid, activity of, a 28 CO adsorbed on, a 105 Palladium-Molybdenum, addition to stainless Iridium-Thorium, ThOs ,-ThIr , steels,~ 111 pseudobinary system, a 146 Palladium-Nickel, liquid, activity of, a 28 Iridium Beryllide, Ir ?Be,, structure of, a 62 liquid, vapour pressure of, a 27 50 paramagnon scattering in, a 60 Iridium Carbonyls, preparation and properties of Palladium-Platinum, Fe-doped, magnetic Iridium Trisilicide, crystal structure of, a 28 scattering in, a 61 low temperature resistivity and thermoelectric power of, a 145 Metallisation, Ti-Pd-Au system, a 150 Palladium-Platinum-Iron, atomic ordering and magnetic hardening in, a 105 Nitric Acid, concentrated, Pt-Kh gauze for, a 64 ordering and magnetic properties in, a 27 manufacture, NH3oxidation for, a 147 Palladium-Rhodium, Fc-doped, magnctic scattering in, a 61 magnetic and electrical properties of, a 27 Osmium, complexes, with CO and PPh,, a 62 Palladium-Rhodium:Iron, magnetic and Ettinghausen-Nernst coefficient of, a 106 electrical properties of, a 27 Osmium Alloys, Osmium-Thorium, ThOs Palladium-Ruthenium-Gold, fabrication of, a 105 ThIr, pseudobinary systems, a 146 Palladium-Silicon 49 amorphous, deformation of, a 145 Osmium Beryllide, Os2BeL7,structure of, a 62 amorphous, resistance of 91 Osmium Carbonyl, reactions with PPh,, a 62 liquid, activity of, a 28 preparation and properties of 50 variation of expansion coefficient Osmium Pentafluoride, preparation and structure with stress, a 28 of, a 28 viscoelastic properties of glasses of, a 106 Oxidation of, NH d, HNO, manufacture by, a 147 Palladium-Silicon-Chromium, amorphous, rcsistivity of 91 Palladium-Silver, desorption of H, from, a 145 Palladium, compounds, K ,PdCI,, crystal structure diffusion units 124 of, a I07 line printing for electronics, a 151 desorption of Hpfrom, a 145 liquid, vapour pressure of, a 27 high-temperature transport properties of, a I45 magnetic and electrical properties of, a 27 liquid, thermodynamic propcrties of, a 61 oxidation of, a 145 metallisation of plastics, a I47 thick film pastes of, a 112 organic chemistry of, book review 56 thin foils of, H, absorption effects on, a 105 oxidation of, a 145 Palladium-Silver-Copper, oxidation of, a 145 oxidation states in glass, a 34 Palladium-Titanium, constitution diagram Ag films on, misfit dislocations in, 60 of, a 145 tensile properties of, effect of H on, a 27 corrosion in HCI, a 111 thin films, growth of, a 145 Palladium-Tungsten, liquid, vapour pressure thin films on Si, interdiffusion of, a 60 of. a 27 thin foils of, Hzabsorption effects on, a 105 phase diagram of, a 61 wire, adsorption of H, on, a 27 Palladium Borides, preparation of, a 62 Palladium Alloys, Palladium-Aluminium, Palladium Hydride, electronic energy bands of, a 146 transformations of, a 106 Palladium Tetracarbonyl, preparation of, a 62 Palladium-Aluminium-Comer,__ ,-phase diagram of, a 106 Petroleum Reforming, Pt-Re catalysts for, Palladium-Barium, composition of vapour lead-free gasoline production using 42 over, a 28 Platinum, black-body 123 Palladium-Cerium-Lanthanum, clcctronic chemical plating of, a 147 specific heat of, a 106 coating on Ni turbine blades 87 Kondo effect in, a 61 complexcs, K ,Pt(CN),Br,. ,.2.3HZO, Palladium-Cohalt, liquid, activity of, a 28 electrical conductivity of, a 107 lianid, vauour pressure of, a 27 complexes, KIPt(CN)rBr,. *.(H,O)n, oidered alloys,-a 145 one-dimensional metallic behavlour of, a I46 Palladium-Copper, liquid, activity of, a 28 complexes, K2Pt(CN)&I,. ,2.2.6H,0, liquid, vapour prcssurc of, a 27 electrical conductivity of, a 107

Platinum Metals Rev., 1972, 16, (4) 159 Platinum (confd) Page JPage complexes, K1.elPt(CIO,)lxH %O, proton Resistance Sensor, Pt wire in, stability of, a 67 injection in, a 63 Resistance Thermometers, Pd-Si-Cr, low complexes, cis-Pt(NH3IsBr,, two temperature measurements using 91 modifications of, a 107 Pd-Si-Cr, low temperature sensitivity of, a 35 complexes, cis-Pt(NH,) 83,. antileukaemia Pt, comparison with thermocouples, a 34 properties of 15 Pt, performance of,a 67 complexes, cis-Pt(NHJ *CI2, Rh-Fe, cryogenic work using 9 immunosuppression by, a 29 Resistors, PdO/Ag-Pd, conductivity of, a 111 complexes, cis-Pt(NH 8),Cl,, inhibition of Ru ternary oxide thick film, a 150 DNA synthesis by, a 29 Rhodium, complexes, (PPh,),CIRh(I), complexes, cis-Pt(NH ,),Cl,, suppression dissociation in solution, a 62 of graft-host reaction, a 146 compounds, Ca,RhH, and Sr,RhHs, complexes, Pt(NH 3)sCl,,antileukaemia preparation and structure of, N 28 properties of 15 oxidation states in glasses, a 34 complexes, Pt(NHJ Kl,, immunosuppression .. reaction of S with, a 27 by, a 29 sputtered, coating on plastic 26 complexes, cis-Pt(py),C1 p. antitumour thermoelectric power of, a 61 properties of, a 29 with magnetic impurities, resistance complexes, square planar, conduction anomaly in, a 106 mechanism in, a 146 Rhodium Alloys, Rhodium-Iron, cryogenic complexes, with olefins and dienes, a 62 resistance thermometer 9 compounds, K,PtCI,, crystal structure of, a 107 properties of metastable phases, a 61 diffusivity and solubility of 0, in, a 105 Rhodium-Manganese, structural and fabrication, precision in 123 magnetic moperties of, a 146 freezing point of, new measurement of 9 Rhodium-Nickel, electrical resistivity of, a 106 oxidation states in glasses, a 34 heat capacity at low temperatures, a 61 purification of, and resistance ratio of 94 Rhodium-Palladium, Fe-doped, magnetic substrate for BaO film adsorption, a 34 scattering in, a 61 thin films, growth of, a 145 magnetic and electrical properties of, a 27 thin films on Si, interdiffusion in, a 60 Rhodium-Palladium-Iron, magnctic and wires, annealed and quenched, resistance of, a 27 electrical properties of, a 27 Platinum Alloys, Platinum-Barium, composition Rhodium-Platinum-Zirconium, internal of vapour over, a 28 oxidation of, a 60 Platinum-Chromium-Nickel-Phosphorus, Rhodium Beryllide, Rh,Bel,, structure of, a 62 resistivity and susceptibility of, a 60 Rhodium Carhonyls, preparation and properties of ' 50 Platinum-Cobalt,orderingand coercivityof, a 27 Ruthenium, complexes, with Ne,a 62 permanent magnets 129 compounds, LaRuO,, solid solutions with Platinum-Copper, structure of 48 SrRu08,a 62 Platinum-Gold, coatings on Ir, Ru, W, Mo, a 147 compounds, La& E-xRuOa,properties of, a 62 diffusion in thin films, a 145 compounds, preparation and structure of, a 28 dispersion hardening in, a 27 oxidation states in glasses, a 34 getter gauze for Pt capture, a 30 tcrnary oxides in thick film resistor glazes, a 150 Platinum-Iridium, i.r. spectra of CO Ruthenium Alloys, Ruthenium-Molybdenum, as-cast, structure and physical properties of, a 146 adsorbed on, a 105 Ruthenium-Niobium, phase transformations Platinum-Iron-Manganese, age-hardening in, a 106 nf n An_I Ruthenium-Niobium-Zirconium, study of, a 106 Pl~~~n~m-Iron-NickeI,ordering and magnetic Ruthenium-Palladium-Gold, fabrication of, a 105 properties in, a 27 Ruthenium-Platinum, solubility relationships Platinum-Nickel, diffusivity and solubility in 88 ofOzin,a 105 Ruthenium-Scandium, phases in, a 62 ferro- to paramagnetic transition in, a 105 Ruthenium-Titanium, corrosion in HCI, a 111 Platinum-Palladium, Fe-doped, magnetic Ruthenium Beryllide, Ru .Bel,, structure of, a 62 scattering in, a 61 Ruthenium Carbonyls, preparation and propertics low temperature resistivity and of thermoelectric power of, a 145 50 Platinum-Palladium-Iron, ordering and Ruthenium Oxide, RuO,, enthalpy of, a 107 magnetic hardening in, a 105 RuO,, thick films, a 150 ordering and magnetic properties in, a 27 Ru09,volatilisation of, a 28 Platinum-Rhodium, reaction of S with, a 27 Platinum-Rhodium-Zirconium, internal Semiconductors, Pt-Si layer on, a 34 oxidation of, a 60 Sputtering of, Platinum, on Teflon or parylene, a 29 Platinum-Ruthenium, solubility relationships Rhodium, on polyester strips 26 in 88 Platinum-Zirconium, internal oxidation of, a 60 Thermocouples, Pt:Rh-Pt, comparison with Platinum Carbonyls, preparation and propertics of 50 resistance thermometers, a 34 Platinum Metals, bibliography by Howe 140 Pt:Rh-Pt, correction graph for, a 35 complexes, development in U.S.A., a 63 Pt :Rh-Pt, effect of pressure on e.m.f. of, a 35 complexes, with olefins, synthesis, structure Pt :Rh-Pt, furnace temperature control and reactions of,a 62 using, a 67 effect on W sintering, a 28 Pt:Rh-Pt, international reference tables for 2 F compounds of 118 Pt:Rh-Pt, pressure dependence of, a 67 hydride complexes of, a 146 Pt:Rh-Pt, sensor-lance for BOF control, a 35 lattice parameters of, a 106 Pt:Rh-Pt, thermal noise measurement, a 35 organometallic complexes of, report of Pt, Rh, Ir, W and Re in, measurement 67 Moscow conference on 22 above I5OO0C,a 67 physical properties of. table of 59 Rh-Pt:Kh-Pt, sensor-lance for BOF Platinum Oxide, Pt,O,, preparation and structure control, a 35 of, a 62 Thick Films, Pd-Au and Pd-Ag, pastes, rheology Pt02,gaseous, thermodynamics of, a 28 of, a 112 Platinum Tetracarbonyl, preparation of, a 62 RuO #, a 150 Platinum Tetrachloride, crystal structure of, a 107 Pollution, car exhaust, Pt catalysts for 74 WoIlaston, William Hyde, Pt thermometer of 57

Platinum Metals Rev., 1972, 16, (4) 160