Phase Diagrams of the Systems CuBiS2-LnBiS3 (Ln = La, Nd)

Phase relations in the CuBiS2-LaBiS3 and CuBiS2-NdBiS3 systems were studied for the first time using physicochemical analysis, and the T-x phase diagrams of these systems were constructed. Both systems contain quaternary compounds with the Cu2LnBi3S7 stoichiometry, which melt incongruently at 815 and 910 K, respectively. Cu2LaBi3S7 and Cu2NdBi3S7 are isostructural with one another and crystallize in orthorhombic symmetry. The lattice parameters of Cu2LaBi3S7 are a = 14.66 Å, b = 21.60 Å, and c = 4.12 Å, and those of Cu2NdBi3S7 are a = 14.60 Å, b = 21.56 Å, and c = 4.10 Å.