Phase Equilibria in the System Tl2Te-SnTe-TlBiTe2

The phase equilibria in the system Tl2Te-SnTe-TlBiTe2 (A) have been studied using differential thermal analysis, x-ray diffraction, and microhardness measurements. We have constructed the T-x phase diagrams along the SnTe-TlBiTe2, SnTe-Tl9BiTe6, and Tl4SnTe3-TlBiTe2 joins, the 600- and 800-K sections of the phase diagram of system A, and its liquidus diagram. The results demonstrate that the system contains broad ranges of Tl5Te3-structured and SnTe-based solid solutions (delta and gamma(1) phases, respectively). There are also relatively small fields of the Tl2Te-based phase (alpha) and low- and high-temperature TlBiTe2-based solid solutions (gamma(2) and gamma(2)'). The liquidus surface of system A comprises the primary crystallization fields of the delta, gamma(1), and gamma(2)' phases melts phases. The liquidus of the a phase is degenerate. The ternary eutectic between the delta, gamma(1), and gamma(2)' at 755 K.