DOI: 10.17188/1727480
title: Materials Data on Er2MgS4 by Materials Project

description: MgEr2S4 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share a cornercorner with one ErS6 octahedra, corners with two equivalent MgS6 octahedra, corners with four ErS7 pentagonal bipyramids, an edgeedge with one MgS6 octahedra, edges with four ErS6 octahedra, and edges with three ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Mg–S bond distances ranging from 2.53–2.86 Å. In the second Mg2+ site, Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share a cornercorner with one ErS6 octahedra, corners with two equivalent MgS6 octahedra, corners with four ErS7 pentagonal bipyramids, an edgeedge with one MgS6 octahedra, edges with four ErS6 octahedra, and edges with three ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Mg–S bond distances ranging from 2.54–2.77 Å. There are four inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent ErS6 octahedra, corners with four ErS7 pentagonal bipyramids, an edgeedge with one ErS6 octahedra, edges with four MgS6 octahedra, and edges with three ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Er–S bond distances ranging from 2.67–2.74 Å. In the second Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent ErS6 octahedra, corners with four ErS7 pentagonal bipyramids, an edgeedge with one ErS6 octahedra, edges with four MgS6 octahedra, and edges with three ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Er–S bond distances ranging from 2.66–2.76 Å. In the third Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share corners with four MgS6 octahedra, corners with four ErS6 octahedra, edges with three MgS6 octahedra, edges with three ErS6 octahedra, and faces with two equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 16–70°. There are a spread of Er–S bond distances ranging from 2.71–3.02 Å. In the fourth Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share corners with four MgS6 octahedra, corners with four ErS6 octahedra, edges with three MgS6 octahedra, edges with three ErS6 octahedra, and faces with two equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 17–69°. There are a spread of Er–S bond distances ranging from 2.70–3.03 Å. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SEr3Mg2 trigonal bipyramids that share corners with two equivalent SEr3Mg2 square pyramids, corners with three equivalent SEr3Mg tetrahedra, corners with two equivalent SEr3Mg2 trigonal bipyramids, edges with five SEr3Mg2 square pyramids, and edges with three SEr3Mg2 trigonal bipyramids. In the second S2- site, S2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SEr3Mg2 trigonal bipyramids that share corners with six SEr3Mg2 square pyramids, corners with two equivalent SEr3Mg tetrahedra, corners with two equivalent SEr3Mg2 trigonal bipyramids, edges with three SEr3Mg2 square pyramids, an edgeedge with one SEr3Mg tetrahedra, and edges with three SEr3Mg2 trigonal bipyramids. In the third S2- site, S2- is bonded to one Mg2+ and three Er3+ atoms to form a mixture of distorted corner and edge-sharing SEr3Mg tetrahedra. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Er3+ atoms. In the fifth S2- site, S2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SEr3Mg2 square pyramids that share a cornercorner with one SEr3Mg tetrahedra, corners with eight SEr3Mg2 trigonal bipyramids, edges with four SEr3Mg2 square pyramids, an edgeedge with one SEr3Mg tetrahedra, and edges with two SEr3Mg2 trigonal bipyramids. In the sixth S2- site, S2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SEr3Mg2 square pyramids that share corners with two equivalent SEr4Mg square pyramids, a cornercorner with one SEr3Mg tetrahedra, corners with six SEr3Mg2 trigonal bipyramids, edges with three SEr3Mg2 square pyramids, an edgeedge with one SEr3Mg tetrahedra, and edges with three SEr3Mg2 trigonal bipyramids. In the seventh S2- site, S2- is bonded to one Mg2+ and four Er3+ atoms to form distorted SEr4Mg square pyramids that share corners with two equivalent SEr3Mg2 square pyramids, corners with two equivalent SEr3Mg tetrahedra, corners with two equivalent SEr4Mg trigonal bipyramids, edges with three SEr3Mg2 square pyramids, an edgeedge with one SEr3Mg tetrahedra, and edges with five SEr3Mg2 trigonal bipyramids. In the eighth S2- site, S2- is bonded to one Mg2+ and four Er3+ atoms to form distorted SEr4Mg trigonal bipyramids that share corners with eight SEr3Mg2 square pyramids, corners with three equivalent SEr3Mg tetrahedra, edges with two SEr3Mg2 square pyramids, and edges with four SEr3Mg2 trigonal bipyramids.