Phase equilibria in the Cu2S–La2S3–EuS system

• Published in: Russian journal of inorganic chemistry 2017-05, Vol.62 (5), p.610-618
• Main Authors: Ruseikina, A. V., Andreev, O. V.
• Format: Article
• Language: English
• Subjects: Annealing; Chemistry; Chemistry and Materials Science; Copper sulfides; Diffraction; Eutectic temperature; Inorganic Chemistry; Melts; Phase equilibria; Phases; Physicochemical Analysis of Inorganic Systems; Triangles
• ISSN: 0036-0236; 1531-8613
• DOI: 10.1134/S0036023617050199

Phase equilibria in the isothermal (970 K) and polythermal LaCuS 2 –EuS, Cu 2 S–EuLaCuS 3 , LaCuS 2 –EuLa 2 S 4 , and EuLaCuS 3 –EuLa 2 S 4 sections of the Cu 2 S–La 2 S 3 –EuS system have been studied. EuLaCuS 3 (annealing at 1170 K) is of orthorhombic system, space group Pnma , a = 8.1366(1) Å, b = 4.0586(1) Å, c = 15.9822(2) Å, is isostructural to Ba 2 MnS 3 , and incongruently melts by the reaction EuLaCuS 3cryst (0.50 EuS; 0.50 LaCuS 2 ) ↔ 0.22 EuS SS (0.89 EuS; 0.11 LaCuS 2 ) + 0.78 liq (0.39 EuS; 0.61 LaCuS 2 ); Δ Н = 52 J/g. The Cu 2 S–La 2 S3–EuS system has been found to contain five major subordinate triangles. At 970 K, tie-lines lie between EuLaCuS 3 and the Cu 2 S, EuS, LaCuS 2 , and EuLa 2 S 4 phases and between the LaCuS 2 phase and the γ-La 2 S 3 –EuLa2S4 solid solution. Eutectics are formed between LaCuS 2 and EuLaCuS 3 at 26.0 mol % of EuS and T = 1373 K and between EuLaCuS3 and EuLa 2 S 4 at 29.0 mol % of EuLa 2 S 4 and T = 1533 K.