Phase Equilibria in the Ag8GeSe6−Ag7GeSe5I−GeSe2 System

Phase equilibria in the Ag8GeSe6−Ag7GeSe5I−GeSe2 system (system А) were studied by differential thermal analysis (DTA) and X-ray powder diffraction. The T–x diagrams of the Ag8GeSe6−Ag7GeSe5I and Ag7GeSe5I−GeSe2 boundary binaries, the liquidus surface projection, the 300-K isothermal section, and some polytherms of the phase diagram of system A were constructed. A continuous solid solution series between Ag7GeSe5I and the high-temperature cubic Ag8GeSe6 phase and limited solid solutions based on the low-temperature Ag8GeSe6 phase were found to exist in the Ag8GeSe6−Ag7GeSe5I boundary system. Solid solution formation decreases the polymorphic transition temperature in Ag8GeSe6 and stabilizes the high-temperature cubic phase at room temperature.