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Journal Archive

Platinum Metals Rev., 1965, 9, (1), 26

ABSTRACTS: January 1965

of current literature on the platinum metals and their alloys



Magnetic Susceptibility and Electronic Specific Heat of Transition Metals and Alloys. VI. Pt Metal and Pt-Au and Pt-Ir Alloys

m. shimizu and a. katsuki, J. Phys. Soc. Japan, 1964, 19, (7), 1135-1141.

The density of states curve of Pt metal was derived from low temperature specific heat measurements on Pt, Pt-Au and Pt-Ir alloys. Calculation then gave the electronic specific heat CE and spin paramagnetic susceptibility of Pt and the alloys between 0 and 2000°K. Estimates for Pt gave the molecular field coefficient α=0.64~0.74 ×104 mole/e.m.u. and the orbital paramagnetic susceptibility zorb =0.13-0.48 × 10-4 e.m.u./mole. Results confirmed that Ce<γ (0)T at higher temperatures, where y is the temperature coefficient of electronic specific heat.

Equiatomic Transition Metal Alloys of Manganese. I. The Tetragonal PtMn Phase

k. brun, a. kjekshus and w. b. pearson, Phil. Mag., 1964, 10, (104), 291–299

CuAu I-type tetragonal PtMn has a and c axes with maximum and minimum size respectively, close to equiatomic composition because of the relative atomic sizes of Pt and Mn.

On the Structure of the Platinum-Silicon System

r. gohle and k. schubert, Z. Metallkunde, 1964, 55. (9), 503–511

X-ray and microscopic studies of the Pt-Si system showed the phase transformations and equilibria of Pt3Si, Pt7Si3, Pt2Si, Pt6Si5 and PtSi. Structures are: Pt3Si(r), Pt3Ge-type; Pt3Si(h2), U3Si-type; Pt2Si(h), Fe2P-type; Pt2Si(r), tetragonally distorted CaF2-type.

The Vapour Pressure of Palladium

p. d. zavitsanov, J. Phys. Chem., 1964, 68, (10), 2899–2901

The vapour-pressure of Pd from 1537 to 1841°K is represented by log Patm = 5.99 —18,898/T. Its mean heat of sublimation at 298°K is 89.8±0.9 kcal/mole and its normal boiling point is estimated as 3150±100°K.

Absorption of Hydrogen by Gold/Palladium Alloys

a. maeland and t. b. flanagan, Abs. Papers, 148th Meeting, Am. Chem. Soc, 1964, 12V-30

Absorption of H2 by Au-Pd alloy wires from H2-stirred HC1 solutions caused changes in the relative resistance R/R0 and electrode potential of specimens. R/R0 is related to the H/metal ratio. Tests at 25°C showed maxima in the relationship which shifted to smaller H/metal and R/R0 values as Au content increased. The equilibrium amounts of absorbed H2 at 1 atm., 25°C are: 5.7% Au-Pd, H/metal=0.55; 11.9%, 0.45; 18.8%, 0.33; 26.5%, 0.22; 35.1%, 0.12.

Effect of Temperature on the Lattice Parameters of Some Silver-Palladium Alloys

c. n. rao and k. k. rao, Canad.J. Phys., 1964, 42, (7)= 1336–1342

63 and 80 wt.% Ag-Pd alloys showed a straight-line relationship between lattice parameters and temperature from room temperature to 790°C. Deviations from the straight line for 25, 39 and 50 wt.% Ag-Pd may be due to electronic structure changes.

The Influence of Annealing on the Electrical Properties of Cold-worked Ag-Pd Alloys

w. k. chen and m. e. nicholson, Acta Met., 1964, 12, (6), 687–696

Annealing affects the resistivity, Hall constant, magnetic susceptibility and thermo-electric power of Ag-Pd alloys. The anomaly in the electrical resistivity change accompanying cold working in Ag-rich alloys is explained by a short-range order mechanism.

The Palladium-Tantalum System

e. m. savitskii, v. p. polyakova, m. a. tylkina and g. s. burkhanov, Zh. Neorg.Khim., 1964, 9, (7), 1645–1649

Melting-point, microstructural, and X-ray studies of the Pd-Ta system showed the existence of four intermetallic compounds: Pd3Ta, Pd2Ta, PdTa and σ-phase. The constitution diagram indicates an eutectic between a and PdTa at 68 wt.% Pd, 1720 ±25°C. PdTa has f.c. tetragonal structure with a =3.28, σ -6.00 Å, c/a = 1.84. Tetragonal Pd3Ta has a = 3.87, c=7.94 Å, c/a=2.05. a-phase has 8=9.64, 0=5.02 Å, c/a=0.522. The system was compared with the Pd-V and Pd-Nb systems. (11 micrographs.)

Magnetic Properties of Dilute Alloys Based on Palladium with Some Transition Metals

j.-p. burger, Ann. Physique, 1964, 9, (5-6), 345–372

Magnetic moments and interactions were measured for Pd diluted with small amounts of Fe, Co, Cr, Mn or Ni. For alloys saturated with H2, paramagnetic Curie points are proportional to the amount of dilution but magnetic moments are independent of it up to 10%. The polarisation of Pd atoms in non-hydrogenated alloys occurs in two stages. Electron transfer explains results for Pd-Cr and Pd-Mn. A molecular field model was derived to explain the mechanisms.

Magnetic Properties of the Pd3Mn2 Alloy

h. yamauchi, J. Phys. Soc. Japan, 1964, 19, (5), 652–657

X-ray, magnetic and thermal studies of PdaMn2 showed that the ζ-phase has b.c.t. lattice with CsCl-type superstructure and that this is modified in the n-phase. Both phases are antiferromagnetic. Susceptibility of μ-phase below the 210°C Neel point depends strongly on field strength. Excess heat absorption at this point is 510 cal./ mol. and is 890 cal./mol. (Pd1.5Mn) for the •-phase. Heat of transformation (μ→ζ)is 180 cal./mol. (Pd0.6Mn0.4).

On the Interaction of Titanium with Iridium

v. n. eremenko, t. d. shtepa and m. m. churakov. Dopovidi Akad. Nauk Ukr. R.S.R., 1964, (6), 763–766

1-55 at.% Ir-Ti alloys were studied by metallo-graphic, X-ray and microhardness methods. Three intermediate phases were detected: γ -phase has Cr30-type structure with a = 5.00 kX; δ-phase has CsCl-type structure with a = 3.10 kX; δ-phase has an undetermined structure. The three phases are based on or are modifications of Tilr.

Constitution Diagram and Some Physical Properties of Alloys of the Nickel-Ruthenium System

i. i. kornilov and k. p. myasnikova, Izv. Akad. Nauk S.S.S.R., Metallurgiya i Gornoe Delo, 1964, (4), 159–165

The Ru-Ni constitution diagram was built up from microstructural, X-ray and thermal analyses, together with tests of hardness, microhardness and specific resistivity. Crystallisation occurred peritectically at 1823±10°K, when the mutual solubilities of Ru and Ni were 41 and 53 at.% respectively. Mutual solubility decreased at lower temperatures. Ru increased the cell size of Ni but Ni decreased a and c for Ru, although c/a remained constant.

A Constitution Diagram for the Niobium-Ruthenium System above 1100°C

g. f. hurley and j. h. brophy, J. Less-Common Metals, 1964, 7, (4), 267–277

The Nb-Ru constitution diagram from solidus, metallographic, X-ray, and diffusion couple measurements shows a minimum m.p. at 39 at.% Ru, 1870°C, a maximum m.p. at 50 at.%, 1942°C, an eutectic between the terminal solid solutions at 65 at.% Ru, 1774°C, and an h.c.p. intermediate phase formed peritectoidally at 75 at.% Ru, 1540°C. Maximum solubilities are 29 at.% Nb in Ru and 58 at.% Ru in Nb but at room temperature the b.c.c. terminal solid solution exists only up to 40 at.% Ru.

The Effect of Pressure on the Volume and Lattice Parameters of Ruthenium and Iron

r. l. clendenen and h. g. drickamer, J. Phys. Chem. Solids, 1964, 25, (8), 865–868

Ru and Fe were subjected to 400 kbars pressure at 25°C. Ru has compressibility similar to Rh and Mo. c/a decreases slightly at lower pressures and then rises rapidly to the highest pressure.

Phase Equilibrium Diagram of the Chromium-Osmium System

v. n. svechnikov, g. p. dmitrieva, g. f. kobzenko and a. k. shurin, Dokl. Akad. Nauk S.S.S.R., 1964,158, (3), 668-670.

The composition diagram of the Cr-Os system was built up from X-ray, metallographic and differential thermal analysis tests. Conditions for the formation of the intermetallic compounds Cr2Os and Cr3Os were derived. An eutectic reaction occurred at 33 at.% Os, 1840 ± 10°C. Os additions raised the hardness and lattice size of Cr. Hardnesses measures were: Cr3Os, 600 kg/mm2; σ-phase, 1800-2000 kg/mm2; (β-phase, 800 kg/mm2.

The Total Emissivity of Rhenium, Rhodium, Palladium and Titanium

w. landensperger and d. stark, Z. Phys., 1964, 180, (2), 178–183

Total emissivities of Re, Rh, Pd and Ti were determined between 1100°K and their m.p. The purity and surface of the wire specimens affected the results, which are compared with those of other workers.

Dispersion-hardening of Laminated Platinum Sheet

w. betteridge, Powder Metallurgy, 1964, 7, (14), 142-151

Hardness and annealing characteristics were studied for laminated sheet produced from unalloyed Pt by stacking pieces of normal sheet, bonding them by hot forging, cold rolling them and repeating the process to obtain the required lamination thickness. Stress-rupture strength at 1450°C for 100 h life is maximum for ~1000 Å lamination thickness but is not increased by putting Tho2 between the laminations.


Sulphospinels Containing Rhodium

g. blasse and d. j. schipper, j. Inorg. Nucl. Chem., 1964,26, (8), 1467–1468

CuRh2S4 has cell edge 9.72 Å. Similar compounds containing Fe and Co instead of Cu were obtained in an impure state but X-ray studies detected complicated patterns with Mg, Mn, and Zn. CuRh2S4 showed a weak paramagnetism of about 320.10-6 e.m.u./g.mol. spinel which was nearly independent of temperature.

Crystal Chemistry and Some Magnetic Properties of Mixed Metal Oxides with Spinel Structure

g. blasse. Philips Res. Rept. Suppl., 1964, (3), 139 pp.

The fifth chapter describes oxidic spinels containing Rh. Their formulae are NiFe2-tRhto4, Li0-5Fe2.5-t Rhto4, CoFe2-tRhto4, and CuFe2-t Rhto4. Saturation moments, Curie temperatures and lattice parameters were determined for various values of t.

The Preparation of Rhodium (III) Halide Complexes with Tertiary Phosphines and Tertiary Arsines

j. chatt, n. p. johnson and b. l. shaw, J. Chem. Soc, 1964, (Aug.), 2508–2513

Mononuclear complexes of the type [RhX3(MR3)3], where X=halogen, MR3=phosphine or arsine, and binuclear halo-bridged complexes of types [Rh2X6(MR3)3] and [Rh2X6(MR3)4] have been prepared. Dipole-moment data are given and some of their reactions are described.

Co-ordination Compounds of Iridium (III) with Biguanide

s. p. ghosh and a. i.p. sinha, J. Inorg. Nucl. Chem., 1964, 26, (10), 1703–1705

Trisbiguanidinium Ir (III) sulphate, chloride, nitrate, and thiosulphate were prepared. They are almost colourless, are diamagnetic and have octahedral structure with dssp3 bonding. They are slightly more stable than the analogous Co and Rh complexes.

The Formation of Hydrido- and Carbonyl Complexes of Ruthenium by Reaction of Certain of its Complexes with Alcohols

J. chatt, b. l. shaw and a. e. field, j. Chem. Soc, 1964, (Sept.), 3466–3475

A mechanism is suggested for the reaction of RuCl3-tertiary phosphine complexes with alcohols to give very stable hydrido-carbonyl complexes of Ru, with degradation of the alcohol. CO reacts on the complexes to give new Ru carbonyl tertiary phosphine or arsine complexes. Br and I complexes were also prepared.

Further Investigations of RuC and OsC

c. p. kempter, j. Chem. Phys., 1964, 41, (5), 1515–1516

Syntheses using Ru: 10C and Os: 10C at 2600°C for 4 h produced WC-type phases of RuC and OsC, which were examined by spectrography, block diffraction and electron probe scanning.

Recent Investigations into the Structure of Noble-Metal Compounds

k. brodersen, Angew. Chem. Internat. Ed. Engl, 1964, 3, (7)’ 519

The monoclinic form of IrCl3 forms platelets with a=5.99, b=10.36, c = 5.98 Å, β = 109°27’. PtCl2 forms needle-like hexagonal prisms with rhombo-hedral unit cell of a = 8.09 Å, α =108° 15’. The six Pt atoms are arranged octahedrally with twelve Cl atoms in front of the twelve edges of the Pt6 octahedron. PtCl2 has a structure with Pt6Cl12 complexes and weak metal-metal bonds.


X-ray Studies of Hydrogen-Silver-Palladium Electrodes

s. d. axelrod and a. c. makrides, J. Phys. Chem., 1964, 68, (8), 2154–2159

Ag-Pd alloys of up to 25 at.% Ag, when charged with H2, showed a potential plateau corresponding to the α-β transformation in the H-Pd system but no plateau was observed for 30 at.% Ag and the lattice expanded continuously. Lattice parameter-potential curves of H-Ag-Pd alloys with varying Ag content were coincident in general after β -phase formation despite differences in dissolved H2 concentration. A model of the system shows dissolved H2 as protons and the corresponding electrons entering the d-band of the alloy.

Absorption of Hydrogen by Silver-Palladium Alloys

a. c. makrides, Ibid., 2160–2169

Ag affects absorption isotherms of H2 on Ag-Pd electrodes by decreasing the pressure p0 of the α-β transition as Ag content rises to about 25at.%.No α-β transition occurs above 30 at.% Ag. Solubility of H2 increases with Ag content for p ≤ po and heat of solubility at p0 increases with Ag content. Maximum solubility for p ≫ p0 decreases with Ag content.


Recent Developments Concerning Electrolytic or Chemical Deposits of the Platinum Group Metals

Traitements de Surface, 1964, 5, (42), 25–40

Small quantities of selenic acid added to the sulphate plating solution reduce stress cracking of Rh deposits. A method of stress measurement is described. Electrolytes based on the salts Pt(NH3)2(NO2)2, Na2Pt(OH)6, and H2PtCl6 for Pt plating are compared. Pd electrolytes compared are Pd(NH3)2(NO2)2 and Pd(NH3)4(N03)2. Ru and Ir are briefly discussed. Chemical plating of Pd, Pt, Rh, and Ru is described. Applications, particularly in electronics, are illustrated.


An Afterheater for Use with High-temperature Vertical Crystal Pulling

j. d. ridley and b. cockayne, J. Sci. instrum., 1964= 41,(10), 647

An afterheater above the melt in the Ir crucible reduces the temperature gradient, and hence the strain level, of laser single crystals. It consists of three concentric A12O3 tubes in a jacket of Mgo2, the innermost lined with Pt sheet, which is heated by induction coupling to the r.f. field, by infrared radiation from the crucible and by convection of gases from the melt. Melt temperatures up to 2000°C could be allowed if an Ir liner and other heating methods were used.


Hydrogenation of Olefins. Part I. Hydro-genation of Ethylene, Propylene and the n -Butenes over Alumina-supported Platinum and Iridium

g. c. bond, j. j. phillipson, p. b. wells and j. m. winterbottom, Trans. Faraday Soc, 1964, 60, (10), 1847–1864

Interactions of C2H4 and C3H6 with D2 and of I-C4H8, cis-2-C4H8 and trans-2-C4H8 with H2 and D2 over Pt/Al2O3 and Ir/Al,O3 from —20 to 150°C were studied in a static system. Only small amounts of deutero-olefins and HD were obtained; P(deutero-olefins)/P(paraffins) was generally <0.1. Double-bond migration and cis-trans isomerisation rates were low compared to the hydrogenation rate. Relative rates of olefin exchange and isomerisation generally increased as Ph2,d2/P0 decreased and as temperature increased. The low relative rate of olefin exchange was due to the virtual inability of an absorbed C2H4 molecule to desorb and not to failure of C2H5 radicals to revert to absorbed C2H4.

Specific Rates and Competitive Rates of Hydrogenation of Cycloalkenes

a. s. hussey, r. h. baker and g. w. keulks, Abs. Papers, 148th Meeting, Anx. Chem. Soc, 1964, 60S-109

Rates at 25°C in the liquid phase on Pt/Al203 were determined. Catalysts can be prepared with very high activity, which is reproducible from batch to batch. Specific reaction rates (mole, min.-1.mole Pt-1.atm.-1) ranged from 210 for bicyclo-[2,2,l]-heptene to 10 for cyclooctene.

Isomerisation of n-Pentane and n-Hexane on Platinum Supported on Borofluorinated Aluminium Oxide

r. i. izmailov, Izv. Akad. Nauk S.S.S.R., Ser. Khim., 1964, (9), 1713–1715

n -Pentane and n-hexane fractions separated from Romashkin petroleum were isomerised over Pt/Al2O3, promoted by F and B, at 350°C. n -Hexane was 64% converted into iso-hexane with 0. 91 selectivity. n -Pentane was 54% converted to isopentane with 0.94 selectivity. The apparent activation energy for the hexane isomerisation was 19 kcal/mole.

Change of Rate and Direction of Hydro-genolysis of Methylcyclopentane by High Temperature Treatment of Platinum-Alumina Catalyst with Hydrogen

i. i. levitskii, m. g. gonikberg, kh. m. minachev and v. i. bogomolov, Dokl. Akad. Nauk S.S.S.R., 1964, 158, (5), 1123–1126

High temperature treatment of Pt/Al2O3 catalyst by H2 eliminated O2 and H2O from it. After treatment at 350°C, the catalyst caused conversion of methylcyclopentane to iso-hexane but, after treatment at 550°C, n -hexane was the principal product.

Study of Atomic Platinum Dispersion on a Zeolite Support

J. a. rabo, p. e. pickert and v. schomaker, Abs. Papers, 148th Meeting, Ann. Chem. Soc, 1964, 5U-9

½% Pt/calcium Y zeolite prepared by cation exchange, pre-treated by heating to 350°C and reducing with H2 at 300°C, was not poisoned by 10 p.p.m. thiophene but isomerised n – C6H14 to produce > 14% of 2,2-dimethylbutane at 350°C. Zeolite impregnated with ½% Pt in anionic form from H.2PtCl6, and similarly pretreated was deactivated rapidly by 10 p.p.m. thiophene and 2,2-dimethylbutane output dropped to 7% in 24 h. The mechanism by which Pt becomes loaded on the catalyst in each case indicates atomic dispersion of Pt after cation exchange and a reduction in the tendency to poisoning by S compounds.

Reductive Animation of Acetone. III. Study of the Hydrogenation of Acelone-Isopropylamine Mixtures in Ethanol and Water

a. le bris, g. lefebvre and f. coussemant, Bull. Soc Chim. France, 1964, (7), 1584–1600

Reductive amination of acetone by isopropyl-amine took place over 5% Pt/C at 29°C in ethanol in two stages; formation of an intermediate imine homogeneously and heterogeneous hydrogenation of this to diisopropylamine.

The Catalytic Oxidation of Methyl Alcohol and Formaldehyde in Aqueous Solutions

t. c. franklin and y. c. emu, Abs. Papers, 148th Meeting, Am. Chem. Soc, 1964, 40V-101

CH3OH and HCHO were oxidised by O2 in aqueous NaOH and H2S04 solutions over platinised Pt. The catalyst area was measured by its H2- absorption. The oxidation rate for CH3OH was first order with respect both to CH3OH and to Pt area. The rates per unit area were similar in both solutions indicating identical mechanisms. The rate of oxidation of HCHO was negligible but the application of a potential to the catalyst increased rates of oxidation for both CH3OH and HCHO. The rate for HCHO was then first order with respect both to HCHO and to Pt area.

Kinetics of the Hydrogen Transfer Reaction of Cyclohexene on Palladium Powder

s. carra, p. beltrame and v. ragiani, J. Catalysis, 1964, 3, (4), 353–362

Pd powder catalysed the disproportionation of cyclohexene to C6H12 and C6H6 in tetrahydrofuran solution at 50-60°C. 1,3-Cyclohexadiene was more reactive under similar treatment and may be an intermediate in the cyclohexene disproportionation.

Kinetics and Mechanism of the Catalytic Oxidation of Ethylene in the Presence of Aqueous Solutions of Palladium and Copper Salts

k. i. matveev, i. f. bukhtoyarov, n. n. shul’ts and O. a. emel’yanova, Kinetika i Kataliz, 1964, 5, (4), 649–657

There are two mechanisms for oxidation of C2H4 to CH3CHO in the presence of PdCl2/CuCl2 in aqueous solution via a complex of C2H4 and PdCl2. An equilibrium reaction with Cu(II) ions and subsequent irreversible reaction with OH-has a higher rate of reaction than direct reaction with OH-. On this basis, an empirical reaction relationship is derived which agrees well with results of the process.

Kinetics of the Oxidation of Ethylene by Aqueous Palladium (II) Chloride

p. m. henry, J. Am. Chem. Soc., 1964, 86, (16), 3246–3250

C2H4 oxidation to CH3CHO in aqueous HClO4-NaClO4 solution in the presence of PdCl2 consisted of initial rapid C2H4 uptake followed by a slow reaction, first order in Pd (II) but inhibited by CI-, for which the rate expression, isotope effect, and reaction parameters were derived. A π-complex →σ-complex mechanism is proposed.

Isomerisation and Hydrogenation of n- Paraffins on Palladium Catalysts

m. hartwig, Brennstoff-Chem., 1964, 45, (8), 234–239

70% of n-hexane was isomerised over Pd/Al2O3-B203 and only 1% was cracked. 0.1% Pd gave the best yield of isohexane and A12O3-B2O3 was superior to ThOa, ZrO2, A12O3, and TiO2. Larger amounts of Pd reduced the temperature for isomerisation but increased the amount of cracking. 33.5% of C11-C12 n -paraffins were isomerised at 300°C, 25 atm., H2: hydrocarbon =4:1 without measurable formation of cracking products.

Catalytic Dehydrocyclisation of Diethyl Ether with the Formation of a Five-Membered Heterocyclic System

a. l. liberman, o. v. bragin and t. v. vasina, Izv. Akad. Nauk. S.S.S.R., 1964, (7),1352-1354

Tetrahydrofuran and its decomposition products were formed by the dehydrocyclisation of diethyl ether in the presence of 20 wt.% Pt, Pd, Ir, Os, or Rh/C at 250-300°C. Also observed was dehydrocyclisation of C5 hydrocarbons and cyclisation of secondary amines into pyrrolidine.

Deuteration of Pyridine and the Azines with Heavy Water and Transition Metal Catalysts Prepared by Self-activation, Hydrogen, and Borohydride Reduction

g. e. calf and j. l. garnett, J. Catalysis, 1964, 3, (5), 461–463

Catalytic deuteration and tritiation of pyridine and diazines is recommended rather than radiation methods. Pt was most active of the metals tested: Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt. H2 reduction or NaBH4 reduction of oxide catalysts gave better results than with chloride catalysts. Self-activated PtO2 is better than H2PtCl6 for reaction with pyridine.

On the Selectivity of Metallic Catalysts and Stereoselectivity of Platinum and Palladium Catalysts in the Reaction of Butadiene with Deuterium

z. leszczynski and p. b. wells, Przemysl Chem., 1964, 43, (9), 508–515

Differences in the stereoselectivity of Pt and Pd catalysts for the reaction of butadiene-1,3 with D2 were expressed by the cis-trans ratio of butene-2 isomers and the amount of D2 in the isomers. Reaction mechanisms on the catalysts are the same. Differences in action depend on the syn- and anti-configurations of butadiene on the catalysts and on the importance of the reactions C4X6⇄C4X8⇄C4X9.


Experimental Use of Platinised Titanium for Ground-Beds

j. r. walters, Corrosion Prevention & Control, 1964, 11, (10), 18–21

Platinised Ti mesh has been used as the anode connecting telecommunications cables to ground beds of coke breeze. Anodes have operated at 2A and at 5A since 1961 without corrosion of the platinised area. The mesh was platinised with 50 μ in. Pt. Tests on platinised Ti driven directly into the earth are in progress. Platinised Ti rods are used as ground electrodes for repeatered submarine cables. Their construction and installation are described and they are in use over several routes with satisfactory performance.


Thermocouples for Measurement of High Temperatures

b. i. stadnyk and g. v. samsonov, Teplofiz. Vysokikh Temp., 1964, 2, (4), 634–637

Thermocouple materials and sheaths are reviewed. Pt metal combinations are Pt: 10% Rh-Pt, 20% Rh-Pt: 40% Rh-Pt, 5% Rh-Pt: 20% Rh-Pt, 6% Rh-Pt: 30% Rh-Pt, Rh: 20% Rh-Pt, Rh: 30% Rh-Pt, Rh: 8% Re-Pt, Pt: Re, Ir: 40% Rh-Ir, and Ir: 60% Rh-Ir.

Results Obtained from Measurements on Platinum Resistance Thermometers at the Thermometry Section of the Kamerlingh Onnes Laboratorium, Leiden

h. van dijk, Physica, 1964, 30, (8), 1498–1512

Tests on 27 Pt resistance thermometers at 1.5-4.3°K, 9-20.3°K and 54-90°K gave the temperature dependence of reduced resistance ω=R/Ro°C for the range 1.5-90°K. Calibration at more than a few temperatures is needed, particularly for 4.2-10°K. ω = ω0+AT2+BT5 for 1.5-4.2°K, where ω0, A and B varied accordingly to the origin and purity of the Pt.