Materials Data on Er2Ge2S7 by Materials Project

Abstract

Er2Ge2S7 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share a cornercorner with one GeS6 octahedra, corners with four ErS7 pentagonal bipyramids, corners with two equivalent GeS4 tetrahedra, an edgeedge with one GeS6 octahedra, edges with two equivalent ErS7 pentagonal bipyramids, an edgeedge with one GeS4 tetrahedra, and a faceface with one GeS6 octahedra. The corner-sharing octahedral tilt angles are 23°. There are a spread of Er–S bond distances ranging from 2.67–2.93 Å. In the second Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share a cornercorner with one GeS6 octahedra, corners with four ErS7 pentagonal bipyramids, corners with two equivalent GeS4 tetrahedra, an edgeedge with one GeS6 octahedra, edges with two equivalent ErS7 pentagonal bipyramids, an edgeedge with one GeS4 tetrahedra, and a faceface with one GeS6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are a spread of Er–S bond distances ranging from 2.67–3.07 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to six S2- atoms to form distorted GeS6 octahedra that share corners with two ErS7 pentagonal bipyramids, edges with two ErS7 pentagonal bipyramids, faces with two equivalent GeS6 octahedra, and faces with two ErS7 pentagonal bipyramids. There are a spread of Ge–S bond distances ranging from 2.31–2.81 Å. In the second Ge4+ site, Ge4+ is bonded to four S2- atoms to form GeS4 tetrahedra that share corners with four ErS7 pentagonal bipyramids and edges with two ErS7 pentagonal bipyramids. There are a spread of Ge–S bond distances ranging from 2.20–2.28 Å. There are seven inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to two Er3+ and two equivalent Ge4+ atoms. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to two Er3+ and two equivalent Ge4+ atoms. In the third S2- site, S2- is bonded in a 4-coordinate geometry to two Er3+ and two equivalent Ge4+ atoms. In the fourth S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Er3+ and one Ge4+ atom. In the fifth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Ge4+ atom. In the sixth S2- site, S2- is bonded in an L-shaped geometry to one Er3+ and one Ge4+ atom. In the seventh S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to two Er3+ and one Ge4+ atom.