Effects of Ordering in Nonstoichiometric Interstitial Compounds
Theoretical and experimental findings regarding the effect of atomic ordering on the structure and properties of non-stoichiometric interstitial compounds, namely transition metal carbides, nitrides and oxides, are generalized. The types of possible superstructures of non-stoichiometric compounds and the corresponding distribution functions of interstitial atoms are considered. Diffraction spectra of possible superstructures are calculated. The problem of superstructural and correlational short-range order and their admissible variation regions is discussed in detail. The application of the order parameter functional method for description of atomic ordering in non-stoichiometric compounds and for calculation of non-equilibrium phase diagrams of M – X (X = C, N, O) systems is considered. The results relating to the effect of ordering on the lattice and electronic properties of non-stoichiometric compounds are explained with allowance for structure peculiarities of disordered and ordered phases. It is shown that the effects of nonstoichiometry and ordering are comparable in value. Figures80. Tables 42. References 291.
