Phase equilibria in the systems SrS-Cu2S-Ln2S 3 (Ln = la or Nd)

Article abstract of DOI:10.1134/S0036023607040237

Phase equilibria in the systems SrS-Cu₂S-Ln₂S ₃ (Ln = La or Nd) have been studied along the isothermal section at 1050 K and vertical sections CuLnS₂-SrS and Cu₂S- SrLnCuS₃, which are partially quasibinary joins. Compounds SrLnCuS₃ with Ln = La or Nd have been synthesized for the first time. They crystallize in orthorhombic space group Pnma, the BaLaCuS₃ structure type, with the following unit cell parameters: for SrLaCuS ₃, a = 1.1157(2) nm, b = 0.41003(6) nm, c = 1.1545(2) nm; for SrNdCuS₃, a = 1.1083(1) nm, b = 0.40887(7) nm, c = 1.1477(2) nm. Noticeable homogeneity regions for SrLnCuS₃ are not found. The compounds melt congruently by the reaction SrLnCuS₃ SrS + L at 1365 K for SrLaCuS₃ and 1400 K for SrNdCuS₃. The tie-lines at 1050 K in the systems SrS-Cu₂S-Ln₂S₃ radiate from SrLnCuS₃ toward phases SrS, Cu₂S, CuLnS₂, and SrLn₂S₄, lying between the phases CuLnS₂ and compositions from the γ-Ln₂S₃-SrLn ₂S₄ solid-solution field. Eutectics are formed between the compounds CuLaS₂ and SrLaCuS₃ at 21.0 mol % SrS, T = 1345 K; between the compounds CuNdS₂ and SrNdCuS₃ at 31.0 mol % SrS, T = 1310 K; and between the phases Cu₂S and SrLnCuS ₃ at 14.0 mol % SrLaCuS₃, T = 1075 K and 8.0 mol % SrNdCuS₃, T = 1055 K. Nauka/Interperiodica 2007.