Фізико-хімічна взаємодії в системі Ti4PbTe3–TI9BiTe2–TIBiTe2

Abstract

Using DTA, XRD and mathematical modelling methods the character of physicochemical interaction in the Tl4PbТe3–Tl9BiTe6–TlBiTe2 quasiternary system was studied, the isothermal section at the temperature of 473 K, projection of the liquidus surface and 3D state phase diagram was investigated. The detailed course of the lines of monovariant equilibria is established by the using of polynomial analysis. Formation of the new compounds in the Tl4PbТe3–Tl9BiTe6–TlBiTe2 system is not found. The main purpose of this scientific work was to establish the possibility of modifying the composition of the initial ternary compounds of thallium (I) Tl4PbTe3, Tl9BiTe6 та TlBiTe2, by experimentally studying of physico-chemical interaction on the basis of their. This quasiternary system is formed by three quasibinary sections, two of which belong to eutectic type Tl4PbТe3–TlBiTe2 (the eutectic е2 – 36 mol.% TlBiТe2, 756 К) and Tl9BiTe6–TlBiTe2 (the eutectic е1 – 52 mol.% Tl9BiTe6, 775 К), and the Tl4PbТe3–Tl9BiTe6 system, which is characterized by the formation of unlimited solid solutions without extreme points on the liquidus and solidus curves. To study the physico-chemical interaction in the Tl4PbТe3–Tl9BiTe6–TlBiTe2 system was synthesed a number of points. The synthesis of binary, ternary compounds and the number of alloys was carried out in evacuated (0.13 Pa) quartz ampoules using a direct one-temperature method. The maximum synthesis temperature on 50-70 K exceeds the melting point of the most initial component. Annealing was performed for 480 hours at a temperature of 473 K. Cooling to room temperature – in the mode of the off oven. On the basis of the obtained results it was established that the fields of primary crystallization intersect along the line of monovariant eutectic equilibrium e1-e2. This monovariant eutectic process L«(Tl4PbTe3)х(Tl9BiTe6)1–х+(TlBiTe2) takes place in the temperature range from 778 K (eutectic e1) to 763 K (eutectic e2). The character of the physico-chemical interaction in the quasiternary system Tl4PbТe3–Tl9BiTe6–TlBiTe2 describes well the plot space phase diagram. Keywords: Thermal analysis; X-ray diffraction; Physico-chemical interaction; Quasiternary system; Quasibinary sections; Isothermal section; Projection of liquidus surface; Solid solution.