Crystal Structures of Complex Lanthanide Sulfides With Built-in Non-Commensurability

Abstract

Non-commensurability on the boundaries of adjacent structural layers (rods, blocks) represents an important structure-building principle for several structural families of complex lanthanide sulfides. In the layer-misfit sulfides 'ABS₃', pseudotetragonal layers with lanthanide ions alternate with octahedral layers or trigonal prismatic layers. Among more complex, fragment-recombination structures based on similar layer strips, (A) a family of derivatives of the structure of Yb₃S₄, (B) structures that represent anti-(out-of-)phase modulated non-commensurate layer sequences, and (c) lanthanide sulfosalts (with bismuth and antimony) are described in some detail. Layer-match modes, their relationships to the ratios of cation radii, and relations to simpler archetypal structures are analysed.