Phase equilibria in the reciprocal system 3Tl2S + Bi2Te3 ↔ 3Tl2Te + Bi2S3

Phase equilibria in the reciprocal system 3Tl 2 S + Bi 2 Te 3 ↔ 3Tl 2 Te + Bi 2 S 3 (A) have been studied by differential thermal analysis, X-ray diffraction, microhardness tests, and emf measurements using thallium concentration cells, and a number of vertical sections, the 300-K isothermal section of its phase diagram, and the liquidus projection have been mapped out. The system is shown to be reversibly reciprocal, with broad solid solution regions in the Tl 2 S-Tl 2 Te-Tl 9 BiTe 6 subsystem and along the TlBiS 2 -TlBiTe 2 join. We have determined the homogeneity ranges and primary crystallization fields of the phases and identified the nature and coordinates of invariant equilibria in system A.