The phase equilibria in the Ag2S-Ag8GeS6-Ag8SnS6 system

The phase equilibria in the Ag2S-Ag8GeS6-Ag8SnS6 system were investigated experimentally by means of differential thermal analysis (DTA), X-ray diffraction (XRD) techniques, scanning electron microscopy (SEM) and electromotive force (EMF) measurements of the concentration chains with Ag4RbI5 solid electrolyte. The phase diagram of the boundary Ag8GeS6-Ag8SnS6 system, two isopleth sections as well as liquidus surface projection of the Ag2S-Ag8GeS6-Ag8SnS6 system was plotted. The continuous solid solution series between low and high temperature modifications of both initial compounds were found along the boundary Ag8GeS6-Ag8SnS6 system. It was found that the Ag2S-Ag8GeS6-Ag8SnS6 system is quasi-ternary plane of the quaternary system and relates to monovariant eutectic type. The partial molar thermodynamic functions (ΔG‾,ΔH‾,ΔS¯) of silver were calculated for the LTM-Ag8Ge1−xSnxS6 (for x = 0.2; 0.4; 0.6; 0.8) solid solution based on the results of the EMF measurements.