Physical-chemical characterization of the processes occurring in extrusion and their effect on phase diagram and thermoelectric properties of the materials in Bi2Te3-Bi2Se3 and Sb2Te3-Bi2Te3 systems

By methods of differential thermal and X-ray-phase analysis it has been proved that after the implementation of the process of hot extrusion of Bi2Te3-Bi2Se3 solid solutions, in the fusibility diagram for 33.3 %mole Bi2Se3 compound, below the solidus line, Bi2Te2Se compound is not formed. In the samples of the material containing up to 25 mole% of Bi2Se3 the presence of excess tellurium is observed. The effect is described of the gaseous medium (hydrogen, inert gas, air) on thermoelectric properties of extruded rods. Thermoelectric properties of non-doped extruded compositions of Sb2Te3-Bi2Te3 system have been investigated and the recommendations have been produced on their application in cooling modules in the temperature range from 100 K to 340 K.