Ag–Sn–Se SYSTEM: PHASE DIAGRAM, THERMODYNAMICS AND MODELING

A comparative analysis of works on the study of phase equilibria, structures and thermodynamic properties of intermediate phases of the Ag–Sn–Se ternary system has been carried out. It was shown that two ternary compounds Ag8SnSe6 and AgSnSe2 are formed in the system, melting congruently at 1015 K and incongruently at 860 K, respectively. The most reliable data for enthalpy, entropy, free formation energy, and heat capacities of AgSnSe2 and the argirodit phase of Ag8SnSe6 are recommended. Thermodynamic functions of mixing liquid solutions are approximated by an asymmetric version of the model of regular solutions. To determine the boundaries of the separation of liquid alloys, the function of the internal thermodynamic stability of the homogeneous phase was used. With the help of the program OriginLab, multi 3D visualization of Ag2Se, SnSe2, SnSe, Ag8SnSe6 crystallization surfaces and immiscibility surfaces in the Ag ̶ Sn ̶ Se system was carried out