DOE OSTI2020
Er3ScS6 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are three inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Er–S bond distances ranging from 2.78–2.96 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 ScS6 octahedra, corners with two equivalent ErS6 octahedra, edges with two equivalent ScS6 octahedra, and edges with four equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 35–51°. There are a spread of Er–S bond distances ranging from 2.65–2.92 Å. In the third Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share corners with three equivalent ScS6 octahedra, corners with two equivalent ErS7 pentagonal bipyramids, and edges with four equivalent ErS6 octahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Er–S bond distances ranging from 2.62–2.74 Å. Sc3+ is bonded to six S2- atoms to form ScS6 octahedra that share corners with three equivalent ErS6 octahedra, a cornercorner with one ErS7 pentagonal bipyramid, edges with four equivalent ScS6 octahedra, and edges with two equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Sc–S bond distances ranging from 2.55–2.67 Å. There are six inequivalent S2- sites. In the first S2- site, S2- is bonded to five Er3+ atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent SEr5 square pyramids, corners with two equivalent SEr3Sc2 trigonal bipyramids, an edgeedge with one SEr5 square pyramid, and edges with seven SEr5 trigonal bipyramids. In the second S2- site, S2- is bonded to three Er3+ and two equivalent Sc3+ atoms to form distorted SEr3Sc2 trigonal bipyramids that share corners with two equivalent SEr5 square pyramids, corners with four equivalent SErSc3 tetrahedra, corners with two equivalent SEr5 trigonal bipyramids, an edgeedge with one SEr5 square pyramid, an edgeedge with one SErSc3 tetrahedra, and edges with five SEr5 trigonal bipyramids. In the third S2- site, S2- is bonded in a 4-coordinate geometry to four Er3+ atoms. In the fourth S2- site, S2- is bonded in a 4-coordinate geometry to three equivalent Er3+ and one Sc3+ atom. In the fifth S2- site, S2- is bonded to one Er3+ and three equivalent Sc3+ atoms to form distorted SErSc3 tetrahedra that share corners with three equivalent SEr5 square pyramids, corners with two equivalent SErSc3 tetrahedra, corners with four equivalent SEr3Sc2 trigonal bipyramids, edges with two equivalent SErSc3 tetrahedra, and an edgeedge with one SEr3Sc2 trigonal bipyramid. In the sixth S2- site, S2- is bonded to five Er3+ atoms to form distorted SEr5 square pyramids that share corners with three equivalent SErSc3 tetrahedra, corners with six SEr5 trigonal bipyramids, edges with four equivalent SEr5 square pyramids, and edges with two SEr5 trigonal bipyramids.