Study of Metallic Carbides by Electron Diffraction Part II. Crystal Structure Analysis of Nickel Carbide

Abstract

The crystal structure of nickel carbide, Ni₃C, was studied by the electron diffraction method. The observed intensity showed considerable primary extinction and this was corrected, using Wilson’s intensity statistics combined with the theory of primary extinction (S. Nagakura, Acta Cryst. 10 (1957) 601). The actual procedure was described in detail and it was concluded that the structure of nickel carbide belongs to the space group R\bar3c and nickel atoms occupy 18e positions with the parameter x=1⁄3 and carbon atoms 6b positions. It was found also that the carbon atoms take a kind of one-dimensionally disordered arrangement in the carbide lattice.