Structure transitions in A4B6 compounds

The paper is devoted to investigation of structural transitions in A4B6 compounds directly from analysing the band structure formed on a pseudopotential in a many wave approximation. The conditions of structural transition are determined by overlapping indirect gaps of the forbidden band. Experimental dependences of the lattice period on temperature, pressure and composition, and also experimental values of the Debye-Waller factor have been used for investigating the behaviour of the forbidden band. For A4B6 compounds the main effect upon the band structure is produced by changes in the lattice period. P-T phase diagrams for tin telluride are constructed, the existence of temperature phase transition is discussed. Approximate phase diagrams for lead and germanium tellurides are presented the problem of structural stability in SnTe-GeTe alloys is considered. Structural stabilities of the fifth group elements are evaluated