DOI: 10.17188/1700722
title: Materials Data on Er4US7 by Materials Project

description: UEr4S7 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. U is bonded to six S atoms to form US6 octahedra that share corners with three ErS6 octahedra, corners with six ErS7 pentagonal bipyramids, edges with two equivalent US6 octahedra, edges with three equivalent ErS6 octahedra, and an edgeedge with one ErS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 1–56°. There are a spread of U–S bond distances ranging from 2.70–2.81 Å. There are four inequivalent Er sites. In the first Er site, Er is bonded to seven S atoms to form distorted ErS7 pentagonal bipyramids that share corners with four equivalent US6 octahedra, corners with four ErS6 octahedra, an edgeedge with one US6 octahedra, edges with three equivalent 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 22–65°. There are a spread of Er–S bond distances ranging from 2.72–2.93 Å. In the second Er site, Er is bonded to seven S atoms to form distorted ErS7 pentagonal bipyramids that share corners with two equivalent US6 octahedra, corners with six 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 2.71–2.94 Å. In the third Er site, Er is bonded to six S atoms to form ErS6 octahedra that share a cornercorner with one ErS6 octahedra, corners with two equivalent US6 octahedra, corners with six ErS7 pentagonal bipyramids, edges with two equivalent ErS6 octahedra, edges with three equivalent US6 octahedra, and an edgeedge with one ErS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 1–57°. There are a spread of Er–S bond distances ranging from 2.66–2.77 Å. In the fourth Er site, Er is bonded to six S atoms to form ErS6 octahedra that share a cornercorner with one US6 octahedra, a cornercorner with one ErS6 octahedra, corners with four ErS7 pentagonal bipyramids, edges with two equivalent ErS6 octahedra, and edges with six ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 56–57°. There are a spread of Er–S bond distances ranging from 2.65–2.72 Å. There are seven inequivalent S sites. In the first S site, S is bonded to one U and three Er atoms to form distorted SEr3U tetrahedra that share corners with three SEr3U tetrahedra, corners with nine SEr5 trigonal bipyramids, and edges with four SEr5 trigonal bipyramids. In the second S site, S is bonded to four Er atoms to form distorted SEr4 tetrahedra that share corners with three SEr3U tetrahedra, corners with nine SEr5 trigonal bipyramids, and edges with four SEr5 trigonal bipyramids. In the third S site, S is bonded to five Er atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent SEr3U tetrahedra, corners with six SEr5 trigonal bipyramids, edges with three SEr3U tetrahedra, and edges with six SEr5 trigonal bipyramids. In the fourth 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 SEr3U tetrahedra, and edges with six SEr5 trigonal bipyramids. In the fifth S site, S is bonded to one U and four Er atoms to form SEr4U trigonal bipyramids that share corners with five SEr3U tetrahedra, corners with four SEr5 trigonal bipyramids, an edgeedge with one SEr4 tetrahedra, and edges with five SEr5 trigonal bipyramids. In the sixth S site, S is bonded to two equivalent U and three Er atoms to form SEr3U2 trigonal bipyramids that share corners with five SEr3U tetrahedra, corners with four SEr5 trigonal bipyramids, an edgeedge with one SEr3U tetrahedra, and edges with five SEr5 trigonal bipyramids. In the seventh S site, S is bonded in a rectangular see-saw-like geometry to two equivalent U and two equivalent Er atoms.