Phase diagram of the Sb–Se–I system and thermodynamic properties of SbSeI

The Sb–Se–I system was investigated by using the DTA and XRD analyses and EMF measurements with an antimony electrode. The T–x diagram of the binary Sb–I system was accurately redefined. A number of polythermal sections and the projection of the liquidus surface were constructed. The fields of the primary crystallization, as well as the types and coordinates of non- and monovariant equilibria were determined. It is shown that the quasi-binary sections Sb2Se3–SbI3, Sb–SbSeI, SbI3–Se, and SbSeI–Se triangulate the Sb–Se–I system, leading to five independent subsystems. A broad area of immiscibility, that overlaps a certain part of the antimony primary crystallization field, was found. From the EMF measurements, the partial molar functions of antimony (ΔG¯,ΔH¯,ΔS¯) as well as standard integral thermodynamic functions of SbSeI were calculated. The latter were found to have the following values: ΔGf,2980=−80.12±1.81 kJ/mol; ΔHf,2980=−77.3±1.8 kJ/mol; S2980=155.2±9.5 J/(mol K).