Nickel continued structure

Nickel (continued) polysulfide complex, 31 98 half chair conformation, 31 115 porphyrin complexes, 32 13 in proteins, 47 284-285 quadruply bridged dimers, 40 211-214 steric structures, 40 190-194 quaternary phosphonium salts of, 6 31-32 redox chemistry probes of structure, 32 243-245 steric and electronic requirements, 32 242-243... 

An even more extreme example of nonstoichiometry is provided by the Co—Te (and the analogous Ni—Te) system. Here, a phase with the nickel arsenide structure is stable over the entire composition range CoTe to CoTe2. It is possible to pass continuously from the former to the latter by progressive loss of Co atoms from alternate planes (see Fig. 12-4) until, at CoTe2, every other plane of Co atoms present in CoTe has completely vanished. 

Instrumentation. The experimental setup is similar to that employed for in situ X-ray diffraction. The material under investigation is pressed into a thin sheet and mounted together with suitable counter and reference electrodes into a silica cell. In order to decrease the large incoherent scattering contributions from protons in aqueous electrolyte solutions, deuterated solutions are used. In a typical study, the reaction mechanism of Ni(OH)2 (employed in nickel accumulators) was studied with neutron powder diffraction NPD [46]. A direct and continuous structural transformation of both the y- and jS-NiOOH phases into j8-Ni(OH)2 was observed during reduction with no direct relationship or discontinuity related to the transition from the first discharge electrode potential to the second one, which was located about 0.4 V lower. 

The nickel-polonium system resembles the analogous tellurium system in that compounds of composition varying continuously between NiPo and NiPo2 are formed, with structures between the NiAs and Cd(OH)2 types (134). 

Bayer AG has addressed this problem by patenting [152] electrodes fabricated from nickel or coated with nickel [153] having a columnar structure. Since these electrodes are said not to corrode, they allow long-term, continuous fluorination and require lower voltages, making the process more economical. 

Petrov and co-workers polymerized acetylene with simultaneous hydrogenation over nickel or nickel plus zinc chloride and obtained saturated and olefinic products. The ratio of products boiling in the gasoline range to heavier products depended upon the catalyst as well as the pressure. The liquid obtained from nickel consisted of a gasoline obtained in 50 % yield in the runs under atmospheric pressure, and in 70 % yield under 20 atm. pressure. The rest comprised diesel fuel hydrocarbons (292). The structure of the liquid hydrocarbons formed was unaffected by the presence of phosphoric acid or zinc in the catalyst. The gas contained up to 80% butenes, depending upon the conditions. This work of Petrov on the synthesis of hydrocarbons is apparently being continued at the present time. 

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