Barium dierbium(III) tetra­sulfide

Barium dierbium(III) tetra­sulfide, BaEr₂S₄, crystallizes with four formula units in the ortho­rhom­bic space group Pnma in the CaFe₂O₄ structure type. The asymmetric unit contains two Er, one Ba, and four S atoms, each with .m. site symmetry. The structure consists of channels formed by corner- and edge-sharing ErS₆ octa­hedra in which Ba atoms reside. The resultant coordination of Ba is that of a bicapped trigonal prism.