Materials Data on Er2MgS4 by Materials Project

MgEr2S4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded to four S2- atoms to form MgS4 tetrahedra that share corners with six ErS6 octahedra and edges with three ErS6 octahedra. The corner-sharing octahedra tilt angles range from 60–66°. There are a spread of Mg–S bond distances ranging from 2.39–2.48 Å. There are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share corners with four equivalent ErS6 octahedra, corners with two equivalent MgS4 tetrahedra, edges with four ErS6 octahedra, and edges with two equivalent MgS4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Er–S bond distances ranging from 2.68–2.76 Å. In the second Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share corners with eight ErS6 octahedra, corners with four equivalent MgS4 tetrahedra, edges with two equivalent ErS6 octahedra, and an edgeedge with one MgS4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–54°. There are a spread of Er–S bond distances ranging from 2.69–2.80 Å. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Er3+ atoms. In the second S2- site, S2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Er3+ atoms. In the third S2- site, S2- is bonded to one Mg2+ and three Er3+ atoms to form distorted corner-sharing SEr3Mg tetrahedra.