Malakhovska-Rosoha T. Systems Tl-Sn(Pb)-S(Sе, Те): phases equilibria, single crystals growth of the ternary compounds and their properties.

The dissertation contains the results of the phase equilibrium in the quasibinary and isothermic sections of the Tl-Sn-S and Tl-Sn-Se systems were carried out. The physicochemical interactions type in the Tl2S(Se, Te)-SnS(Se, Te), Tl2Se(Te)-PbSe(Te) and TlSе-SnSе systems were specified. Corresponding phase diagrams have been elaborated to Tl4SnS3(Se3,Te3), Tl4PbSe3(Te3), Tl4SnS4, Tl2SnS3 near to optimal, their thermoelectic properties have been studied. The crystal structure of Tl4PbSe3 was determined. The regularities of properties changes relative to crystal structure, chemical bonds type, phenomenon of polarization were analyzed for ternary compounds of studied systems. The single crystals of Tl4SnS3, Tl4PbSе3, Tl4SnS4 can be used as working part of medium-temperature thermoelectric devices.