Phase equilibria in the Ag 2 Te-PbTe-Sb 2 Te 3 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 (β-phase) between PbTe and Ag 1-x Sb 1 + x Te 2 + x intermediate phase. The partial molar thermodynamic functions of lead telluride in alloys and standard integral thermodynamic functions of the β-solid solutions along the 2PbTe-"AgSbTe 2 " section were calculated based on the EMF measurements results.

2PbTe-AgSbTe 2 system was investigated by measuring the electromotive force of the concentration with respect to PbTe chains in the temperature range of 300-450 K. A wide region of PbTe-based solid solutions (20-100 mol% PbTe) was found in the title system. The partial thermodynamic functions of PbTe and lead in the alloys are calculated from the equations of the temperature dependences of the EMF. Standard thermodynamic functions of formation and standard entropies of solid (2PbTe) x (AgSbTe 2) 1-x (х=0.2, 0.4, 0.6, 0.8) solids are calculated by integrating Gibbs-Duhem equation along the 2PbTe-AgSbTe 2 section using literature data on the relevant thermodynamic data for Ag 2 Te, PbTe and Sb 2 Te 3 compounds.