Phase diagram of the Sb-Te-I system and thermodynamic properties of SbTeI

The Sb-Te-I system was investigated by using differential thermal analysis, X-ray diffraction analysis and electromotive force measurements with an antimony electrode. 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 equilibriums were determined. It is shown that the quasi-binary sections SbI3-Sb2Te3, SbI3-Te, and SbI3-TeI4 triangulate the Sb-Te-I system, leading to four independent subsystems. From the electromotive force measurements, the partial molar functions of antimony as well as the standard integral thermodynamic functions of SbTeI were calculated. The latter were found to have the following values: Delta G(f,298)(0) = 55.77 +/- 1.7 kJ . mol(-1): Delta H-f,298(0) = -55.72 +/- 1.39 kJ . mol(-1); S-298(0) = 153.5 +/- 2.8 J . K-1 . mol(-1).