Structural vacancy distribution in the crystal lattice of the tetragonal V52O64 superstructure which was formed on the basis of disordered super-stoichiometric cubic vanadium monoxide VOy≡VxOz was experimentally determined and the presence of significant local atomic displacements and large local microstrains in a crystal lattice of real ordered phase was established. It was shown that the relaxation of local microstrains takes place owing to the basic disordered cubic phase grain refinement and a formation of ordered phase domains. The ordered phase domains grew in the direction from the boundaries to the centre of grains of the disordered basic cubic phase. Isothermal evolution at 970K of the average domain size <D> in ordered VO1.29 vanadium monoxide was established. It was shown that the short-range order was present in a metal sub-lattice of disordered cubic VOy vanadium monoxide. The character of the short-range order was such that vanadium atoms occupying tetrahedral positions were in the environment of four vacant sites of the vanadium sub-lattice. This meant that the disordered VOy vanadium monoxide, especially super-stoichiometric VOy>1.0 monoxide, had a cubic (space group Fm¯3m) D03-type structure differing from the B1-type structure typical for most of the strongly non-stoichiometric cubic compounds carbides, nitrides and oxides.

Vacancy Distribution in Nonstoichiometric Vanadium Monoxide. A.I.Gusev, D.A.Davydov, A.A.Valeeva: Journal of Alloys and Compounds, 2011, 509[5], 1364-72