DOE OSTI2020
Sr(ErS2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Sr–S bond distances ranging from 3.09–3.32 Å. There are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Er–S bond distances ranging from 2.69–2.74 Å. In the second Er3+ site, Er3+ is bonded to six S2- atoms to form a mixture of edge and corner-sharing ErS6 octahedra. The corner-sharing octahedra tilt angles range from 48–64°. There are a spread of Er–S bond distances ranging from 2.67–2.76 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Er3+ atoms. In the second S2- site, S2- is bonded to two equivalent Sr2+ and three equivalent Er3+ atoms to form a mixture of distorted edge and corner-sharing SSr2Er3 square pyramids. In the third S2- site, S2- is bonded in a 5-coordinate geometry to two equivalent Sr2+ and three Er3+ atoms. In the fourth S2- site, S2- is bonded to two equivalent Sr2+ and three equivalent Er3+ atoms to form a mixture of distorted edge and corner-sharing SSr2Er3 trigonal bipyramids.