Platinum telluride

Commonly used II-VI compounds include zinc sulfide, zinc selenide, zinc telluride, cadmium sulfide, cadmium telluride, and mercury cadmium telluride. These materials are not as widely used as the III-V compounds, one reason being that it is difficult to achieve p-type doping. Mercury cadmium telluride is used extensively in military night sights, which detect in the 8-13 im spectral band (a similar material, platinum silicide, is being developed for that purpose). The major applications ofCVD II-VI compounds are found in photovoltaic and electroluminescent displays. 

Crystals of platinum ditelluride can be grown when charges of platinum, sulfur, phosphorus, and tellurium in the molar ratio of 1 3 1 2 are held at 875° and the growth zone is cooled to 690°. In the preparation of both the sulfide and the telluride, adding chlorine to a pressure of 75-100 torr enhances the transport, but its presence is not essential. However, the presence of both phosphorus and sulfur is necessary. 

The octahedral radii of the table are applicable to complex ions such as [PtCle]—. The radius sum Pt(IV)—Cl is 2.30 A, and the several reported experimental values for salts of chloroplatinic acid range from 2.26 A to 2.35 A. The radii can also be applied to the sulfides, selen-ides, and tellurides of quadrivalent palladium and platinum (PdS2, etc.), which crystallize with the cadmium iodide structure, consisting of layers of MX octahedra so packed together that each X is common to three octahedral complexes. The average deviation between radius sums and reported distances for these substances is about 0.02 A. 

PGM Concentration. The ore mined from the Merensky Reef in South Africa has a maximum PGM content of 8.1 g/1, of which 50—60% is platinum, and 20—25% palladium. The PGMs are in the form of a ferroplatinum alloy, or as their sulfides, arsenides, or tellurides. The aim of the concentration process is to separate from the ore a cmde metal concentrate, having a PGM content of 60%. The majority of other metals, such as nickel and copper, are separated out at this stage for further refining. 

Dibenzyl telluride, (C6H5.CH2)2Te, forms a compound with platinum chloride, PtCl2.2(C6H5.CH2)2Te, an orange powder which decomposes in solution with the separation of tellurium, platinum and dibenzyl, but on rapid crystallisation from chloroform is obtained as a microcrystalline powder of greenish-gold colour which darkens and softens at 115° to 120° C.2... 

It may also be obtained by heating an intimate mixture of finely divided tellurium (100 parts) and platinum (150 parts) in a glass tube until combination takes place. The tube and its molten contents are now melted together and dropped into cold water. The telluride then yields quite good crystals. 

Platinum Ditelluride, PtTe2, results on heating an intimate mixture of finely divided platinum with a slight excess of tellurium above that theoretically required.1 The product is treated with concentrated potash solution to remove excess of tellurium, and the telluride remains as a grey, crystalline, insoluble powder. 

Seebeck experimented with a number of metals including antimony, iron, zinc, silver, gold, lead, mercury, copper, platinum, and bismuth. Later, the observation was made that the electromotive force (EMF) generated is proportional to the temperature difference between the junctions. Today, TE couples are often made from semiconductor alloys of bismuth antimony telluride, Bi Sb2- cTe3 (x 0.5), that have been suitably doped to possess distinct n- or p-type characteristics. A practical TE cooler consists of one or more couples that are connected electrically in series and thermally in parallel. 

The bathophenanthroline method was used for determining iron in blood plasma [157], in plant materials [158], in waters [159], in niobium, tantalum, molybdenum, and tungsten [42,160], in molybdenum compounds [161], in cobalt [162], in cadmium and cadmium telluride [5], platinum [163], synthetic rubies and sapphires [164], silicon tetrachloride [165], and in boiler water [166]. 

Diaryl telluride reacts with Pt(PEt3)3 to produce a complex with Pt-G and Pt-Te bonds as the oxidative addition products.Phenyl(isopropyl)telluride forms the m-phenyl(isopropyltellurido)platinum complex 217 as the kinetic... 

The reaction of dithienyl ditelluride with Pt(PPh3)4 in GH2CI2 yields the chloro(thienyl)platinum(ii) complex 219, and a trinuclear Pt complex whose metal centers are bridged by two telluride ligands (220, Equation (57)). Activation of the Te-Te and G-Te bonds takes place during the reaction. 

A number of relevant review articles have appeared. Their subjects include the chemistry of antitumor platinum complexes, complexes of platinum metals with weak donor ligands, and transition metal complexes of sulfide, selenide, and telluride ligands (which includes much material on square-planar compounds). A review by Chanon and Tobe " on electron transfer catalysis relates to many reaction types, including ligand replacements at square planes. 

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