PHASE RELATIONS IN THE Ag8SiS6–Ag8SiTe6 SYSTEM AND CHARACTERIZATION OF SOLID SOLUTIONS

Abstract

Argyrodite family compounds and phases based on them are valuable ecologically friendly functional materials that exhibit a number of functional propreties, such as thermoelectric, photoelectric, optical, and other. On the other hand, having Cu+ and Ag+ ion conductivity, they are ionic conductors, and can be used as electrochemical sensors, electrodes, or electrolyte materials in solid-state batteries, displays, etc. In the present paper, phase relations in the Ag8SiS6–Ag8SiTe6 system were studied by differential thermal analysis and X-ray diffraction phase techniques and a T-x phase diagram was constructed. It is established that the system is quasi-binary and is characterized by the formation of a continuous series of substitutional solid solutions between Ag8SiTe6 and HT- Ag8SiS6 compounds. With the formation of solid solutions, the temperature of the polymorphic transition of the Ag8SiS6 decreases. This leads to the stabilization of the ion-conducting cubic phase in the range of compositions 30 mol. % Ag8SiTe6 at room temperature and below. The homogeneity regions based on RT-Ag8SiS6 are 10 mol. %. According to XRD data, the crystal lattice parameters of the obtained solid solutions were calculated and a their linear dependence on the composition is shown