Molecular models of polymorphs modifications of zinc chalcogenides have been designed. Based on the results of ab initio quantum chemical calculations of the crystal structure of clusters the temperature dependences of the Gibbs energy of sphalerite and of wurtzite have been found. Phase transformations "sphalerite-wurtzite" temperatures have been evaluated.

On the basis of the results of radiographic researches and measurements of thermoelectric parameters of antimony-doped lead telluride, such as the thermoelectric coefficient and the conductivity, the penetration mechanisms of impurity atoms into the crystal lattice of the matrix are established. The influence of impurity on the charge carrier mobility is revealed. The introduction of impurities up to 0.3 at.% is shown to favor the electron mobility owing to the filling of tellurium vacancies, which are active scattering centers, by antimony ions, the effect of which on the electron mobility is lower. K e y w o r d s: lead telluride, doping, scattering mechanisms.

The features of the experimental dependences of the concentration of charge carriers on the temperature and chemical composition of germanium telluride with NaCl-type structure at temperatures T = 550-850 K and concentrations of excess tellurium X Te = 0.01-0.1 at.% Te are interpreted, and a crystal chemical model is proposed for the defect subsystem. It was found that the dominant defects under these conditions are doubly ionized metal vacancies, which define the character of the dependences p(T), p(X Te ). At temperatures above 750 K and for excess tellurium concentrations above 0.04 at.% Te, also antistructural chalcogen atoms have a significant impact on the concentration of free holes. The concentrations of other defects are much lower and do not affect the electrical properties of the material. Germanium telluride / Electrical properties / Point defects

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We grew single crystals of cadmium telluride, doped with bromine by the Bridgman method, annealed them under a cadmium overpressure (P Cd = 10 2-10 5 Pa) at 800-1100 K, and investigated their electrical properties at high-and low-temperature. The influence of impurities on 2 Cd) 0. Their content varies with the annealing temperature and the vapor pressure of the component; the concentration of other defects is much smaller and almost does not affect the electron density.