Materials Data on Pm2MgS4 by Materials Project

Abstract

MgPm2S4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded to five S2- atoms to form MgS5 square pyramids that share corners with four PmS6 octahedra, edges with four PmS6 octahedra, and edges with four equivalent MgS5 square pyramids. The corner-sharing octahedral tilt angles are 5°. There are a spread of Mg–S bond distances ranging from 2.51–2.65 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 three equivalent PmS6 octahedra, corners with two equivalent MgS5 square pyramids, edges with six PmS6 octahedra, and an edgeedge with one MgS5 square pyramid. The corner-sharing octahedra tilt angles range from 55–59°. There are a spread of Pm–S bond distances ranging from 2.76–2.91 Å. In the second Pm3+ site, Pm3+ is bonded to six S2- atoms to form PmS6 octahedra that share corners with three equivalent PmS6 octahedra, corners with two equivalent MgS5 square pyramids, edges with four PmS6 octahedra, and edges with three equivalent MgS5 square pyramids. The corner-sharing octahedra tilt angles range from 55–59°. There are a spread of Pm–S bond distances ranging from 2.70–2.95 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to three equivalent Mg2+ and two equivalent Pm3+ atoms to form a mixture of edge and corner-sharing SPm2Mg3 square pyramids. In the second S2- site, S2- is bonded in a rectangular see-saw-like geometry to four Pm3+ atoms. In the third S2- site, S2- is bonded in a 3-coordinate geometry to three Pm3+ atoms. In the fourth S2- site, S2- is bonded to two equivalent Mg2+ and three Pm3+ atoms to form SPm3Mg2 square pyramids that share corners with two equivalent SPm2Mg3 square pyramids and edges with five SPm3Mg2 square pyramids.