Materials Data on Pm2MgS4 by Materials Project

MgPm2S4 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 PmS6 octahedra and edges with three PmS6 octahedra. The corner-sharing octahedra tilt angles range from 59–64°. There are a spread of Mg–S bond distances ranging from 2.41–2.49 Å. There are two inequivalent Pm3+ sites. In the first Pm3+ site, Pm3+ is bonded to six S2- atoms to form PmS6 octahedra that share corners with four equivalent PmS6 octahedra, corners with two equivalent MgS4 tetrahedra, edges with four PmS6 octahedra, and edges with two equivalent MgS4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–57°. There are a spread of Pm–S bond distances ranging from 2.80–2.85 Å. In the second Pm3+ site, Pm3+ is bonded to six S2- atoms to form PmS6 octahedra that share corners with eight PmS6 octahedra, corners with four equivalent MgS4 tetrahedra, edges with two equivalent PmS6 octahedra, and an edgeedge with one MgS4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–57°. There are a spread of Pm–S bond distances ranging from 2.80–2.89 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 Pm3+ atoms. In the second S2- site, S2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Pm3+ atoms. In the third S2- site, S2- is bonded to one Mg2+ and three Pm3+ atoms to form distorted corner-sharing SPm3Mg trigonal pyramids.