Hybrid Mn–iXn –i superstructures in compounds with atomic vacancy ordering

The existence of a special class of M_{n – i} X_{n – i} superstructures (n – integer constant, i – rational variable) formed as a result of incomplete second order equilibrium order–order phase transitions in compounds with atomic vacancy ordering has been theoretically substantiated. The superstructure M_{5 – i}X_{5 – i} (i = 1; 11/18; 14/18) of the high-temperature ordered titanium monoxide phase β-TiO has been described in detail as an example.