DOI: https://doi.org/10.36719/2707-1146/65/124-131
Phase Relations in the Ag8SiS6 - Ag8SiSe6 System and Characterization of Solid Solutions
Albina Poladova1* , Aynura Yagubova2
Abstract. Argyrodite-type compounds and the phases derived from them represent environmentally benign and valuable functional materials exhibiting a wide range of properties, including thermoelectric, photoelectric, and optical characteristics. In addition, these materials demonstrate ionic conductivity through Cu⁺ and Ag⁺ ions, which makes them promising candidates for application as electrode or electrolyte materials in ion-selective electrodes, various types of batteries, displays, and sensors. In this work, the phase equilibria of the Ag8SiS6–Ag8SiSe6 system were investigated using differential thermal analysis and X-ray diffraction methods, and the corresponding T–x phase diagram was constructed. The system was found to be quasi-binary and is characterized by the formation of an extended region of solid solutions between the HT-Ag8SiS6 and HT-Ag8SiSe6 compounds. The polymorphic transition temperature of Ag8SiS6 decreases with increasing formation of solid solutions. It was determined that at room temperature the homogeneity region of the δ-phase extends within the composition range of 70–90 mol% Ag8SiSe6. Furthermore, the lattice parameters of the obtained solid solutions were calculated from X-ray diffraction data, revealing a linear dependence on composition.
Keywords: silver-silicon sulfide, silver-silicon selenide, argyrodite-like compounds, DTA, XRD, phase equilibria, polymorphic transformation