Experimental Study of the Tl4PbTe3-Tl9TbTe6-Tl9BiTe6 Section of the Tl-Pb-Bi-Tb-Te System

Abstract

The aim of the present study was to determine the phase relations in the Tl 4 PbTe 3 -Tl 9 TbTe 6 -Tl 9 BiTe 6 section of the Tl-Pb-Bi-Tb-Te system. Based on a set of the methods of the physicochemical analysis (differential thermal analysis, powder X-ray diffraction method as well as microhardness measurements), the phase diagram of the Tl 4 PbTe 3 -Tl 9 TbTe 6 boundary system, some isopleth sections, liquidus and solidus surfaces projections, as well as isothermal sections at 840 and 860 K, were plotted. Unlimited solid solutions with the Tl 5 Te 3 structure (δ-phase) were found in the system, which are of interest as a thermoelectric materials.

MODELING THE PHASE DIAGRAM OF THE Tl9TbTe6–Tl4PbTe3–Tl9BiTe6 SYSTEM

“…To equalize the number of atoms in the molecules, the thallium-lead-tellurium compound was taken as a dimer 2Tl 4 PbTe 3 . To modeling these systems, we used the experimental data of [38,40]. According to the results of the indicated papers, these cross sections are characterized by the formation of continuous solid solutions (δ-phase) with the Tl 5 Te 3 structure.…”

“…Due to the peculiarities of the crystal lattice, it has many ternary analogs of the types Tl 9 AX 6 and Tl 4 BX 3 (A -Sb, Bi, In, Au, rare-earth elements; B -Sn, Pb, Mo, Cu, rare-earth elements; X -Se, Te ) [15,[17][18][19][20][21][22][23], also possessing several functional properties, namely optical [24,25], thermoelectric [26][27][28][29], magnetic [30,31], as well as topological insulators properties [32,33]. In recent years, to improve thermoelectric performance, intensive work has been carried out to study solid solutions and doped phases based on these compounds [34][35][36][37] To obtain new variable composition phases with Tl 5 Te 3 -structure, we studied phase relations in a some systems consisting of Tl 5 Te 3 and its ternary analogs [38][39][40], in which continuous substitutional solid solutions were found. The constructed phase diagrams serve as the basis for choosing the composition of melts for growing single crystals of solid solutions of a given composition by the method of directional crystallization.…”

MODELING THE PHASE DIAGRAMS OF THE Tl9SmTe6–Tl4PbTe3 AND Tl9SmTe6–Tl9BiTe6 SYSTEMS

“…In order to obtain new phases of variable composition with a structure of the Tl 5 Te 3 type, we studied phase equilibria in a number of systems consisting of Tl 5 Te 3 and its ternary analogs [27][28][29], in which continuous substitutional solid solutions were revealed. The constructed phase diagrams serve as the basis for choosing the composition of melts for growing single crystals of solid solutions with a given composition by directional crystallization.…”