Phase Equilibria in the Ag2Te-PbTe-Sb2Te3 System and Thermodynamic Properties of the (2PbTe)(1-x)(AgSbTe2)(x) Solid Solutions

摘要

Phase equilibria in the Ag2Te-PbTe-Sb2Te3 system were experimentally investigated by means of differential thermal analysis, powder X-ray diffraction techniques and electromotive force (EMF) measurement method. A liquidus surface projection of the system, 750 K and 300 K isothermal sections, as well as five vertical sections of the phase diagram, were constructed. The primary crystallization fields of phases and homogeneity range of phases were also determined. The character and temperature of the various nonvariant and monovariant equilibria were identified. The studied system is characterized by the formation of a wide continuous band of a high-temperature cubic structured solid solution (beta-phase) between PbTe and Ag1-xSb1+xTe2+x intermediate phase. The partial molar thermodynamic functions of lead telluride in alloys and standard integral thermodynamic functions of the beta-solid solutions along the 2PbTe-"AgSbTe2" section were calculated based on the EMF measurements results.