DOI: 10.17188/1695798
title: Materials Data on Er2MgS4 by Materials Project

description: MgEr2S4 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share corners with three equivalent ErS6 octahedra, corners with four equivalent ErS7 pentagonal bipyramids, edges with two equivalent MgS6 octahedra, edges with three equivalent ErS6 octahedra, and edges with three equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 10–54°. There are a spread of Mg–S bond distances ranging from 2.54–2.65 Å. 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 corners with four equivalent MgS6 octahedra, corners with four equivalent ErS6 octahedra, edges with three equivalent MgS6 octahedra, edges with three equivalent ErS6 octahedra, and faces with two equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 17–66°. There are a spread of Er–S bond distances ranging from 2.69–3.05 Å. In the second Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share corners with three equivalent MgS6 octahedra, corners with four equivalent ErS7 pentagonal bipyramids, edges with two equivalent ErS6 octahedra, edges with three equivalent MgS6 octahedra, and edges with three equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 10–54°. There are a spread of Er–S bond distances ranging from 2.68–2.74 Å. There are four inequivalent S2- sites. In the first 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 five equivalent SEr3Mg tetrahedra, edges with four SEr3Mg2 square pyramids, an edgeedge with one SEr3Mg tetrahedra, and edges with two equivalent SEr4Mg trigonal bipyramids. In the second S2- site, S2- is bonded to two equivalent Mg2+ and three Er3+ atoms to form SEr3Mg2 square pyramids that share corners with two equivalent SEr3Mg2 square pyramids, corners with two equivalent SEr3Mg tetrahedra, corners with six equivalent SEr4Mg trigonal bipyramids, edges with five SEr3Mg2 square pyramids, edges with two equivalent SEr3Mg tetrahedra, and an edgeedge with one SEr4Mg trigonal bipyramid. In the third S2- site, S2- is bonded to two equivalent Mg2+ and three Er3+ atoms to form distorted SEr3Mg2 square pyramids that share corners with two equivalent SEr3Mg2 square pyramids, corners with five equivalent SEr3Mg tetrahedra, corners with two equivalent SEr4Mg trigonal bipyramids, edges with five SEr3Mg2 square pyramids, an edgeedge with one SEr3Mg tetrahedra, and edges with three equivalent SEr4Mg trigonal bipyramids. In the fourth S2- site, S2- is bonded to one Mg2+ and three Er3+ atoms to form distorted SEr3Mg tetrahedra that share corners with seven SEr3Mg2 square pyramids, corners with two equivalent SEr3Mg tetrahedra, corners with five equivalent SEr4Mg trigonal bipyramids, edges with three SEr3Mg2 square pyramids, and an edgeedge with one SEr4Mg trigonal bipyramid.