Cu<sub>8</sub>GeSe<sub>6</sub>-Ag<sub>8</sub>GeS<sub>6</sub> System: Phase Equilibria and High-Entropy Alloys
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY, vol.70, no.11, pp.1779-1785, 2025 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 70 Issue: 11
- Publication Date: 2025
- Doi Number: 10.1134/s0036023625602132
- Journal Name: RUSSIAN JOURNAL OF INORGANIC CHEMISTRY
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex
- Page Numbers: pp.1779-1785
- Azerbaijan State University of Economics (UNEC) Affiliated: Yes
Abstract
Argyrodite family compounds and their based phases are of interest as environmentally friendly functional materials. This work presents new phase equilibria data in the Cu8GeSe6-Ag8GeS6 system obtained by differential thermal analysis (DTA) and X-ray powder diffraction (XRD). The system was found to be not quasi-binary due to the incongruent melting of Cu8GeSe6, yet it maintains thermodynamic stability at below the solidus temperature. A continuous solid solution series (delta phase) between the high-temperature phases with both cationic and anionic substitutions was identified. The low-temperature phases were shown to have limited homogeneity regions. Solid solution formation lowers the polymorphic transitions temperatures and extends the homogeneity range of the ion-conducting cubic delta phase down to room temperature and below. At room temperature, the homogeneity range of the delta phase spans 10-70 mol % Ag8GeS6. The delta phase in the range 36-64 mol % Ag8GeS6 can be classified as a high-entropy alloy (HEA), which offers additional facilities for tailoring its properties through entropy-driven structural stabilization.