ANALYSIS OF CRYSTAL STRUCTURES OF THE OUTPUT PHASES OF THE QUASITERNARY Y2S3 – LA2S3 – PBS SYSTEM

Abstract

The articles present a theoretical and experimental approach to the study of the quasi-ternary Y2S3 – La2S3 – PbS system. The synthesis of the initial samples of the systems was carried out using solid-phase reactions in vacuum quartz ampoules at a residual pressure of 10-2. The maximum synthesis temperature is 1323 K. Analysis of the initial components of the quasi-ternary Y2S3 – La2S3 – PbS system indicates may be components of the studied quasi-ternary system. Their crystal structure is described by an octahedral filling. The ternary Y2PbS4 phases – Cmc21 (a = 7.9301 Å; b = 28.6966 Å; c = 12.0511 Å), La2PbS4 – I 4 3d (a = 8.767 Å) are determined by the base concentration and the volume-centered cell, respectively. A mobile decrease in the amount of cationic composition leads to an increase in the elementary cell parameters and at the same time the Y and Pb atoms occupy separate positions in the structure, and the La and Pb atoms form a mixture of {0.667 La + 0.333 Pb}, which is localized at site 12a. At the experimental stage, the existence of ternary phases was confirmed and it was determined that quasi-binary equilibria Y2S3 – La2PbS4 and Y2PbS4 – La2PbS4 are carried out in the quasi-triple system. The wide two-phase region Y2S3 – La2PbS4 is due to the existence of a solid solution of La2+2/3xPb1-xS4 (x = 0 ÷ 0.69). Based on the results of a set of studies, an isothermal section was constructed, which conducts experimental research activities. The diffraction pattern of powder samples was taken at room temperature on DRON-4-13. The crystal structure was analyzed using the WINCSD software package (Version 2016).