DOI: 10.17188/1730620
title: Materials Data on Er9Al5S21 by Materials Project

description: Er9Al5S21 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are six 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 AlS6 octahedra, corners with three ErS7 pentagonal bipyramids, corners with two AlS4 tetrahedra, edges with two ErS7 pentagonal bipyramids, an edgeedge with one AlS4 tetrahedra, and a faceface with one AlS6 octahedra. The corner-sharing octahedral tilt angles are 22°. There are a spread of Er–S bond distances ranging from 2.73–2.89 Å. In the second Er3+ site, Er3+ is bonded in a 7-coordinate geometry to eight S2- atoms. There are a spread of Er–S bond distances ranging from 2.72–3.34 Å. In the third Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share a cornercorner with one AlS6 octahedra, corners with three ErS7 pentagonal bipyramids, corners with two AlS4 tetrahedra, an edgeedge with one AlS6 octahedra, an edgeedge with one ErS7 pentagonal bipyramid, and an edgeedge with one AlS4 tetrahedra. The corner-sharing octahedral tilt angles are 37°. There are a spread of Er–S bond distances ranging from 2.74–2.91 Å. In the fourth Er3+ site, Er3+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Er–S bond distances ranging from 2.70–2.93 Å. In the fifth Er3+ site, Er3+ is bonded in a 7-coordinate geometry to eight S2- atoms. There are a spread of Er–S bond distances ranging from 2.72–3.33 Å. In the sixth Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share a cornercorner with one AlS6 octahedra, corners with four ErS7 pentagonal bipyramids, corners with two AlS4 tetrahedra, an edgeedge with one AlS6 octahedra, an edgeedge with one ErS7 pentagonal bipyramid, and an edgeedge with one AlS4 tetrahedra. The corner-sharing octahedral tilt angles are 37°. There are a spread of Er–S bond distances ranging from 2.74–2.92 Å. There are six inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with three ErS7 pentagonal bipyramids and edges with two ErS7 pentagonal bipyramids. There are a spread of Al–S bond distances ranging from 2.22–2.25 Å. In the second Al3+ site, Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with three ErS7 pentagonal bipyramids and an edgeedge with one ErS7 pentagonal bipyramid. There are a spread of Al–S bond distances ranging from 2.22–2.25 Å. In the third Al3+ site, Al3+ is bonded to six S2- atoms to form AlS6 octahedra that share corners with three equivalent ErS7 pentagonal bipyramids, a faceface with one AlS6 octahedra, and faces with three equivalent ErS7 pentagonal bipyramids. There are three shorter (2.41 Å) and three longer (2.47 Å) Al–S bond lengths. In the fourth Al3+ site, Al3+ is bonded to six S2- atoms to form AlS6 octahedra that share edges with three equivalent ErS7 pentagonal bipyramids and a faceface with one AlS6 octahedra. There are three shorter (2.31 Å) and three longer (2.61 Å) Al–S bond lengths. In the fifth Al3+ site, Al3+ is bonded to six S2- atoms to form AlS6 octahedra that share corners with three equivalent ErS7 pentagonal bipyramids, edges with three equivalent ErS7 pentagonal bipyramids, and a faceface with one AlS6 octahedra. There are three shorter (2.32 Å) and three longer (2.62 Å) Al–S bond lengths. In the sixth Al3+ site, Al3+ is bonded to six S2- atoms to form AlS6 octahedra that share corners with three equivalent ErS7 pentagonal bipyramids and a faceface with one AlS6 octahedra. There are three shorter (2.40 Å) and three longer (2.47 Å) Al–S bond lengths. There are fourteen inequivalent S2- sites. In the first S2- site, S2- is bonded to three Er3+ and one Al3+ atom to form distorted SEr3Al tetrahedra that share corners with three SEr3Al2 square pyramids and corners with three SEr3Al trigonal pyramids. In the second S2- site, S2- is bonded to three Er3+ and one Al3+ atom to form distorted SEr3Al tetrahedra that share corners with three SEr3Al2 square pyramids and corners with three SEr3Al trigonal pyramids. In the third S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Al3+ atom. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Al3+ atom. In the fifth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Al3+ atom. In the sixth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Al3+ atom. In the seventh S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Al3+ atom. In the eighth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Al3+ atom. In the ninth S2- site, S2- is bonded in a 4-coordinate geometry to four Er3+ and one Al3+ atom. In the tenth S2- site, S2- is bonded to three Er3+ and two Al3+ atoms to form distorted SEr3Al2 square pyramids that share corners with three SEr3Al tetrahedra, a cornercorner with one SEr3Al trigonal pyramid, edges with two equivalent SEr3Al trigonal pyramids, and faces with two equivalent SEr3Al2 square pyramids. In the eleventh S2- site, S2- is bonded to three Er3+ and one Al3+ atom to form distorted SEr3Al trigonal pyramids that share a cornercorner with one SEr3Al2 square pyramid, corners with three SEr3Al tetrahedra, edges with two equivalent SEr3Al2 square pyramids, and edges with two equivalent SEr3Al trigonal pyramids. In the twelfth S2- site, S2- is bonded to three Er3+ and two Al3+ atoms to form distorted SEr3Al2 square pyramids that share corners with three SEr3Al tetrahedra, a cornercorner with one SEr3Al trigonal pyramid, edges with two equivalent SEr3Al trigonal pyramids, and faces with two equivalent SEr3Al2 square pyramids. In the thirteenth S2- site, S2- is bonded to three Er3+ and one Al3+ atom to form distorted SEr3Al trigonal pyramids that share a cornercorner with one SEr3Al2 square pyramid, corners with three SEr3Al tetrahedra, edges with two equivalent SEr3Al2 square pyramids, and edges with two equivalent SEr3Al trigonal pyramids. In the fourteenth S2- site, S2- is bonded in a 4-coordinate geometry to four Er3+ and one Al3+ atom.