The crystal structures of the complex sulfides SrLnCuS3 (Ln = Sm, Gd, Er and Lu) have been determined and refined using powder X-ray diffraction. The crystals are found to be orthorhombic, with the structure type changing consecutively in the order BaLaCuS3 → Eu2CuS3 → KZrCuS3 as the Ln3+ ionic radius decreases in the order La/Pr → Sm/Gd → Er/Lu. Variations of the structure parameters along the series of compounds studied are analyzed, and an effect caused by crystallochemical contraction on the stabilization of the respective structure types is demonstrated.
Keywords: SrLnCuS3; crystal structure; crystallochemical contraction; derivative difference minimization method; powder diffraction; sulfides of rare earth elements.