Thermodynamic Study of Ag8GeTe6 and Ag8GeTe6 – xSex Solid Solutions by the EMF Method with Solid Ag+-Conducting Electrolyte

The thermodynamic properties of the Ag8GeTe6 compound and Ag8GeTe6 – xSex solid solutions are studied by means of EMF measurement of concentration cells with a solid Ag electrode relative to the Ag4RbI5 electrolyte in the temperature range 300–400 K. From the EMF measurement data, the partial thermodynamic functions of silver in the alloys are calculated. Based on the solid-phase equilibria data in the Ag–Ge–Se–Te system, the potential-forming reactions responsible for these partial molar functions are determined and the standard thermodynamic functions of formation and standard entropies of the Ag8GeTe6 compound and Ag8GeTe5Se, Ag8GeTe4Se2, Ag8GeTe3Se3, Ag8GeTe2Se4, and Ag8GeTeSe5 solid solutions are calculated.