Thermodynamic properties of saturated solid solutions of Ag7SnSe5Br and Ag8SnSe6 compounds in the Ag–Sn–Se–Br system measured by the EMF method

Abstract

Triangulation of the Ag–Sn–Se–Br system in the part of Ag2Se–SnSe–SnSe2–AgBr was carried out using the X-ray diffraction and differential thermal analysis methods. The spatial position of the established four-phase regions regarding figurative point of silver was used in order to write the equations of virtual potential-forming chemical reactions. Potential-forming processes were performed in electrochemical cells (ECCs) of the type (−) C |Ag| Ag3GeS3Br glass |D| C (+) where C are the inert (graphite) electrodes; Ag and D are the electrodes of the ECCs; D represents the equilibrium four-phase alloys, and Ag3GeS3Br glass is a membrane with purely ionic Ag+ conductivity. The linear dependencies of the EMF of cells on temperature in the range of 480–520К have been used in order to calculate the standard thermodynamic values of saturated solid solutions of Ag7SnSe5Br and Ag8SnSe6 compounds in the four-element part of the Ag–Sn–Se–Br system.