Turovska L. Point defects and physicochemical properties of crystals in Pb-Ga (In, Tl)-Te, Pb-Sb (Bi)-Te, Pb-Cr (Co, Ni)-Te systems

Based on the proposed crystal-quasichemical formulae, the analysis of quasichemical reactions of point defects formation, the method of minimization of thermodynamic potentials and the results of the complex experimental data defective subsystem of pure lead telluride and crystals in Pb-Ga (In, Tl)-Te, Pb-Sb (Bi)-Te, Pb-Cr (Co, Ni)-Te systems have been investigated. The types of dominant point defects, their charge states have been specified. In the crystals of Pb-M-Te system (M = Ga, In, Tl) the range of physicochemical properties is due to different charge state of metallic component 1+, 2+, 3+, and conductivity type of PbTe:X crystals (X = Sb, Bi) is determined by amphoteric action of dopant. Dominant point defects in doped crystals PbTe:Cr are impurity defects, the concentration of which increases with the impurity content. Based on the developed crystal-quasichemical equations of solid solutions in Pb-Ga (In, Tl)-Te, Pb-Sb (Bi)-Te, Pb-Cr-Te systems the mechanisms of their formation have been established. Dependence of the concentration of point defects on the magnitude of the deviation from the stoichiometric composition in lead telluride and chemical composition of solid solutions have been defined, the conditions of formation of materials with predetermined conductivity type and concentration of charge carriers have been defined.