Квазібінарні перерізи в системі Tl-Sb-P-Se

Abstract

The purpose of this work was to establish quasibinary cross sections based on the TlSbP2Se6 quaternary phase, in order to study the nature of the physico-chemical interaction in the system Tl–Sb– P–Se. To achieve this, it was necessary to conduct both analysis of literary data and to provide an experimental research using the Gütler method. In the course of the study, only the above complex, thermally stable compounds, which are implemented in the system Tl–Sb–P–Se, were taken into consideration. Thus, with the participation of TlSbP2Se6 and complex compounds in the system, formation of eight quasi-binary systems is possible. Only three (TlSbP2Se6–Tl4P2Se6, TlSbP2Se6– Sb4(P2Se6)3, TlSbP2Se6–Tl3PSe4) of eight possible quasibinary systems based on TlSbP2Se6 do not cross the cross-sections based on stable compounds and are quasibinary according to polyhedration rules. The quasibinarity of the other five sections required an experimental study. For this, it was necessary to carry out synthesis and phase analysis of samples corresponding to the intersection points of the corresponding sections. The synthesis of samples was performed in vacuumed to 0.13 Pa quartz ampoules. The maximum temperature exceeded about for 50 K the melting point of the most refractory component and amounted to 900 K. Annealing was carried out at 573 K for 10 days. The samples were hardened to ice water. The obtained samples were investigated by X-ray powder diffraction (XRD). The phase analysis of samples lying at the points of intersection of possible quasibinary cross sections confirmed the quasibinarity of only two (TlSbP2Se6–TlSbSe2 and TlSbP2Se6–Sb2Se3) from five possible systems involving TlSbP2Se6. Additionally the quasibinarity of Tl4P2Se6–TlSbSe2 and Tl3PSe4–Sb4(P2Se6) was established. The generalization of these data made it possible to establish a number of quasi-ternary systems. To quasiternary systems refer to systems formed by three quasibinary systems. Based on obtained and literature data analysis on the interaction in Tl–Sb–P–Se system quasiternary systems based on complex compounds can be divided into formed by quasibinary sections of which were established experimentally (TlSbP2Se6–TlSbSe2–Sb2Se3 and TlSbP2Se6– Tl4P2Se6–TlSbSe2) and formed by sections the quasibinarity of which follows from the general rules of polyhedration. It should be noted that for the latter it is also necessary to experimentally confirm the quasibinarity of the system-forming cross-sections. Keywords: Physico-chemical interaction; Quasibinary system; X-ray powder diffraction; Quasi-ternary system.