Materials Data on Er5S7 by Materials Project

Abstract

Er5S7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Er sites. In the first Er site, Er is bonded to six S atoms to form ErS6 octahedra that share corners with two equivalent ErS6 octahedra, corners with four equivalent ErS7 pentagonal bipyramids, edges with two equivalent ErS6 octahedra, and edges with six equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. There are two shorter (2.66 Å) and four longer (2.72 Å) Er–S bond lengths. In the second Er site, Er is bonded to six S atoms to form ErS6 octahedra that share corners with three ErS6 octahedra, corners with six equivalent ErS7 pentagonal bipyramids, edges with five equivalent ErS6 octahedra, and an edgeedge with one ErS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 0–56°. There are a spread of Er–S bond distances ranging from 2.66–2.79 Å. In the third Er site, Er is bonded to seven S atoms to form distorted ErS7 pentagonal bipyramids that share corners with eight ErS6 octahedra, edges with four ErS6 octahedra, edges with two equivalent ErS7 pentagonal bipyramids, and faces with two equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 22–68°. There are a spread of Er–S bond distances ranging from 2.72–2.94 Å. There are four inequivalent S sites. In the first S site, S is bonded in a square co-planar geometry to four equivalent Er atoms. In the second S site, S is bonded to five Er atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent SEr4 tetrahedra, corners with six SEr5 trigonal bipyramids, edges with three equivalent SEr4 tetrahedra, and edges with six SEr5 trigonal bipyramids. In the third S site, S is bonded to four Er atoms to form distorted SEr4 tetrahedra that share corners with three equivalent SEr4 tetrahedra, corners with nine SEr5 trigonal bipyramids, and edges with four SEr5 trigonal bipyramids. In the fourth S site, S is bonded to five Er atoms to form SEr5 trigonal bipyramids that share corners with five equivalent SEr4 tetrahedra, corners with four equivalent SEr5 trigonal bipyramids, an edgeedge with one SEr4 tetrahedra, and edges with five SEr5 trigonal bipyramids.