578a. CLARK, J., AND JACK, K. H. Preparation and the Crystal Structures of Cobalt Nitride, CO2N, of Cobalt, Carbonitrides, Co2 (C, N), and of Cobalt Carbide. Chem. and Ind., 1951, pp. 1004-1005; Chem. Abs., vol. 46, 1952, p. 2948.

578a. CLARK, J., AND JACK, K. H. Preparation and the Crystal Structures of Cobalt Nitride, CO₂N, of Cobalt, Carbonitrides, Co₂ (C, N), and of Cobalt Carbide. Chem. and Ind., 1951, pp. 1004-1005; Chem. Abs., vol. 46, 1952, p. 2948.

Co₂N was prepared by passing anhydrous NH₃ over pure Co powder (380 mesh) at 350° with the partial pressure of H₂ kept at a minimum. A Co nitride approximating Co₃N can be obtained by thermal decomposition of Co₂N. CO at 340° gradually reacts with Co₂N and Co₂N to form the corresponding Co carbonitrides. The Co₂C of Hofer and Peebles (abs. 1440) is apparently identical with that prepared by the complete replacement of N in Co₂N. X-ray powder photographs of Co₂N, Co₂C_0.53N_0.47 and Co₂C show that the unit-cell dimensions and the positions of the atoms within the unit cell change gradually as C replaces N. The space group is D¹²₂h-P m n n. For Co₂N the unit cell dimensions are a=2.8535, b=4.6056, c=4.3443 A., and for Co₂C, a=2.8969, b=4.4465, c=4.3707 A.