Nickel monoxide

Copper(I) oxide [1317-39-1] is 2lp-ty e semiconductor, Cu2 0, in which proper vacancies act as acceptors to create electron holes that conduct within a narrow band in the Cu i7-orbitals. Nickel monoxide [1313-99-17, NiO, forms a deficient semiconductor in which vacancies occur in cation sites similar to those for cuprous oxide. For each cation vacancy two electron holes must be formed, the latter assumed to be associated with regular cations ([Ni " h = Semiconduction results from the transfer of positive charges from cation to cation through the lattice. Conduction of this type is similar... 

Dinickel trioxide Nickel dioxide Nickel monoxide Nickel subsulphide Nickel sulphide Potassium chromate Potassium dichromate... 

R.B. Hall, C.A. Mims, J.H. Hardenbergh, and J.G. Chen, Structure and Reactivity of Nickel Monoxide Surface Films on Ni(lOO), in Surface Science of Catalysis, D. Dwyer and F. Hoffmaim, Editors. 1991, ACS Publishing Washington DC. 

Nickel metal, nickel monoxide and sulfide Less than 0.5 mg/m3 19... 

Green nickel oxide nickel monoxide nickel(II) oxide bunsenite Cl 77777... 

Both nickel monoxide, NiO, and nickelo-niokclic oxide, Ni304, are known, hut, as stated above, there is a doubt about nickelie oxide, Nia03, the substance usually described a,s such being in all probability the dioxide, NiOa. Barium nickelitc. Ba0.2Ni0a, has been prepared. 

Nickel readily dissolves nickel monoxide, the freezing-point being thereby depressed 6 and the metal becoming brittle. This brittleness is removed on addition of a small quantity of magnesium to the molten nickel. It distils in the electric furnace more readily than cobalt,7 and boils at 2840° C. under 30 mm. pressure.8 At white heat nickel can be welded with itself, with iron, or with various alloys. 

Exact Atomic Weight.—In. 1826 Rothoff,1 in a single experiment, found that 188 parts of nickel monoxide are equivalent to 718-2 parts of silver chloride whence2 Ni — 59-OS... 

The sublimed salt is slowly soluble in hot water, yielding a clear solution, which may be boiled without decomposition. Berthelot 6 states that the solution on standing in air deposits nickel monoxide. This, however, is not the case with the pure substance. The density of the sublimed salt is 4-64 at 28° C. 

The trihydrate, NiBr2.8H20, may he obtained by introducing finely divided nickel into bromine under water, or by dissolving nickel monoxide in aqueous hydrogen bromide. On concentrating the solution, the salt crystallises out in the form of deliquescent needles. 

It is possible that Tetra-nickel Suboxide, Ni40, is capable of existence, for Sabatier and Espil4 claim to have prepared it by reduction of nickel monoxide in a current of hydrogen at 155° to 250° C. 

The velocity curve for the reduction of nickel monoxide by hydrogen in the presence of a dehydrator to remove the evolved water possibly indicates the existence of a suboxide,7 Ni20, but this is not certain. 

Nickel Dioxide, NiOa.—Presumably the substance described as nickel sesquioxide and obtained when nickel nitrate or chlorate is gently heated, or when potassium chlorate is fused with nickel chloride, really consists of the dioxide in intimate association with more or less nickel monoxide, according to circumstances (vide supra). 

Norman, M. R., and A. J. Freeman (1986). Model supercell local-density calculations of the id excitation spectra of nickel monoxide. Phys. Rev. B33, 8896-98. 

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