Silver nickel oxide

Fig. 8. Current characteristic of a silver-nickel oxide sandwich (79). (Copyright by the Universite de Liege. Reprinted with permission.)...

Another additive that can serve a dual function is silver nickel oxide (AgNi02>. Silver nickel oxide is produced by the reaction of nickel oxyhydroxide (NiOOH) with monovalent silver oxide in hot aqueous alkaline solution - ... 

A third group includes silver—nickel, silver—cadmium oxide, and silver—graphite combinations. These materials are characterized by low contact resistance, some resistance to arc erosion, and excellent non sticking characteristics. They can be considered intermediate in overall properties between silver alloys and silver or copper—refractory compositions. Silver—cadmium oxide compositions, the most popular of this class, have wide appHcation in aircraft relays, motor controllers, and line starters and controls. 

Eigure 11 illustrates the superior conductivity of P/M silver—nickel or silver—cadmium oxide contacts when compared with contacts made by standard melting techniques and formed from soHd-solution alloys. 

Other alkaline primary cells couple zinc with oxides of mercury or silver and some even use atmospheric oxygen (zinc—air cell). Frequendy, zinc powder is used in the fabrication of batteries because of its high surface area. Secondary (rechargeable) cells with zinc anodes under development are the alkaline zinc—nickel oxide and zinc—chlorine (see Batteries). 

Fig. 1. Schematic representation of a battery system also known as an electrochemical transducer where the anode, also known as electron state 1, may be comprised of lithium, magnesium, zinc, cadmium, lead, or hydrogen, and the cathode, or electron state 11, depending on the composition of the anode, may be lead dioxide, manganese dioxide, nickel oxide, iron disulfide, oxygen, silver oxide, or iodine.

Thus films can be divided into two groups according to their morphology. Discontinuous films are porous, have a low resistance and are formed at potentials close to the equilibrium potential of the corresponding electrode of the second kind. They often have substantial thickness (up to 1 mm). Films of this kind include halide films on copper, silver, lead and mercury, sulphate films on lead, iron and nickel oxide films on cadmium, zinc and magnesium, etc. Because of their low resistance and the reversible electrode reactions of their formation and dissolution, these films are often very important for electrode systems in storage batteries. 

Hydrogen sulfide is rapidly oxidised, and may ignite in contact with a range of metal oxides, including barium peroxide, chromium trioxide, copper oxide, lead dioxide, manganese dioxide, nickel oxide, silver(I) oxide, silver(II) oxide, sodium peroxide, and thallium(III) oxide. In the presence of air, contact with mixtures of calcium oxide or barium oxide with mercury oxide or nickel oxide may cause vivid incandescence or explosion. 

Nickel is a silver-white, lustrous, hard, malleable, ductile, ferromagnetic metal that is relatively resistant to corrosion and is a fair conductor of heat and electricity. Nickel is a ubiquitous trace metal that occurs in soil, water, air, and in the biosphere. The average content in the earth s crust is about 0.008%. Nickel ore deposits are accumulations of nickel sulfide minerals (mostly pentlandite) and laterites. Nickel exists in five major forms elemental nickel and its alloys inorganic, water-soluble compounds (e.g., nickel chloride, nickel sulfate, and nickel nitrate) inorganic, water-insoluble compounds (e.g., nickel carbonate, nickel sulfide, and nickel oxide) organic, water-insoluble compounds and nickel carbonyl Ni(CO). ... 

Typically, coatings most often in use as intermediate layers are silver, nickel, copper, and gold however, silver is used by far the most often. This is so because of the low dissociation temperature of silver oxide, making it relatively easy to obtain clean surfaces. Also, the typical thickness range of electroplates used, in practice, for diffusion welding is about 15 to 40/rm, but thicknesses as great as 130 )um must sometimes be used. A considerable variety of steel types as well as aluminum and a host of other difficult-to-join metals and even beryllium have been and continue to be diffusion bonded with the use of electroplated intermediate layers. 

In (1) the electrolytic process, a nickel of 99.9% purity is produced, along with slimes which may contain gold, silver, platinum, palladium, rhodium, iridium, ruthenium, and cobalt, which are subject to further refining and recovery. In (2) the Mond process, the nickel oxide is combined with carbon monoxide to form nickel carbonyl gas, Ni(CO)4. The impurities, including cobalt, are left as a solid residue. Upon fuitlier heating of the gas to about 180°C, the nickel carbonyl is decomposed, the freed nickel condensing on nickel shot and the carbon monoxide recycled. The Mond process also makes a nickel of 99.9% purity. 

Several, different, electrochemical oxidations of 26 to 27 have been reported. Using a variety of electrodes (copper, Monel metal, nickel, or silver), 26 was oxidized in aqueous potassium hydroxide solution containing potassium chromate or potassium permanganate, to afford 27 in 70-85% yield.118,119 This electrochemical oxidation has been conducted in aqueous, alkaline solution in the presence of a surfactant, but with added metal catalyst, to give 27 in 85-95% yield.120 Alternatively, the oxidation has been performed by using an anode on which nickel oxide was deposited. This anode, in a solution of 26 at pH >9, with or without nickel salts, afforded 27 in >90% yield.121 A number of additional publications described122-140 other modifications of the... 

The electrical conductivity was measured by W. H. Ross, who found that in all cases the conductivity of the salt soln. was increased with time, especially with the more dil. soln. This is due to the decomposition of the salts under the influence of the platinum-black of the electrodes with polished electrodes, the effect is considerably smaller. The base itself is oxidized even more rapidly than the salts. The soln. are in all cases decomposed by the platinum electrodes, and G. M. J. MacKay showed that tin does not decompose the soln. at all, while copper decomposes the soln. completely. The order in which the metals were found to decompose the soln. is tin, platinum, silver, nickel, mercury, and copper. The electrical conductivity of hydroxylamine, using tin electrodes, in terms of mercury at 18°, with v vols. of soln. per mol, is as follows ... 

It is, of course, well known that metal-semiconductor interfaces frequently have rectifier characteristics. It is significant, however, that this characteristic has been confirmed specifically for systems that have been used as inverse supported catalysts, including the system NiO on Ag described above as catalyst for CO-oxidation. In the experimental approach taken, nickel was evaporated onto a silver electrode and then oxidized in oxygen. A space charge-free counter-electrode was then evaporated onto the nickel oxide layer, and the resulting sandwich structure was annealed. The electrical characteristic of this structure is represented in Fig. 8. The abscissa (U) is the applied potential the ordi-... 

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