RARE EARTH NICKEL OXIDES,
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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LaNi03, containing nickel in the trivalent state was prepared and its structure studied by X-ray diffraction methods. The dimensions of the rhombohedral pseudo-cell are a 7.6760.002 A., alpha 90 degrees 43 minutes. The dimensions of the primitive rhombohedral cell are alpha sub p 60 degrees 49 minutes, a 5.461 A. The hexagonal form of this cell has the following dimensions a 5.456 A., c 13.122 A. Neodymium oxide reacts with nickel II oxide, in the presence of sodium carbonate, to form a single phase whose composition may vary between Nd 1.67Ni2 0.72Ni3 0.41 03.84 and Nd 1.75Ni2 0.57 Ni3 0.43 03.84. An increase in the ratio NdNi results in the formation of more trivalent nickel. With the exception of one very weak line at 2 theta 31. 2 degrees, all the lines of the X-ray diffraction patterns out to 2 theta 75 degrees could be indexed satisfactorily on the basis of a monoclinic unit cell with a 3.92 A., b 6.16 A., c 3.77 A. and beta 92.4 degrees. Samarium, gadolinium and yttrium oxides do not appear to form stable compounds with nickel II oxide under the conditions used to form the other rare earth nickel oxides. The product of reaction between lanthanum oxide, samarium oxide and nickel II oxide, in the mole ratio 11.4, was a new phase which seemed to be isomorphous with the phase obtained from the reaction of mixtures having compositions between 2Ni0.1.5Nd203 and 2Ni0.1.75Nd203.