X-ray diffraction study of phases in the system CaS-Lu2S3 (0-50 mol % Lu2S3)

Thirteen samples were synthesized in the system CaS-Lu2S3 in the range 0-50 mol % Lu2S3 and studied by X-ray powder diffraction (phase analysis, determination and refinement of unit cell parameters, Rietveld structure refinement). The phases crystallizing in the system have NaCl-type structures (space group Fm3m, unit cell parameter a (0)) with a cubic, hexagonal, or orthorhombic superstructure, the respective structure types being Yb0.875S (space group F (4) over tilde 3m, a similar to 2a(0) ), CaY2Se4 (space group R (3) over tildem, a similar to a(0) root 2, c similar to 2a(0) root 3), and Tm0.76Se (space group Pnnn; a similar to a(0)root 2, b similar to a(0) c similar to 2a(0)), and a phase with a Yb3S4- type orthorhombic unit cell (space group Pnma).