The Ag2Te-SnTe-Bi2Te3 system and thermodynamic properties of the (2SnTe)1-x(AgBiTe2)x solid solutions series

Abstract

Phase relations and ternary solubility of the binary and ternary compounds in the Ag2Te-SnTe-Bi2Te3 system were experimentally investigated by means of differential thermal analysis (DTA) and powder X-ray diffraction (PXRD) techniques, as well as microhardness and electromotive force measurements (EMF) of concentration chains with Ag4RbI5 solid electrolyte. Five isopleth sections SnTe-AgBiTe2, Ag2Te-0.5SnBi2Te4, [AgSn0.5Te]-AgBiTe2, 0.5SnBi2Te4-AgBiTe2 and [AgSn0.5Te]-Bi2Te3 and two isothermal sections at 300 and 800 K as well as liquidus surface projection of the system were constructed. The primary crystallization fields of phases and homogeneity range of binary and ternary phases were also determined. The character and temperature of the various non- and monovariant equilibria were identified based on solidifications behavior of several key alloys. The system includes high-temperature cubic structured solid solutions series (γ-phase) along the SnTe-AgBiTe2 section. The partial molar thermodynamic functions for silver in the (2SnTe)1-x(AgBiTe2)x (where x = 0.1; 0.2; 0.4; 0.6 and 0.8) solid solutions were calculated based on the EMF measurements results.