DOE OSTI2020
Lu4MnS7 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are four inequivalent Lu3+ sites. In the first Lu3+ site, Lu3+ is bonded to seven S2- atoms to form distorted LuS7 pentagonal bipyramids that share corners with four LuS6 octahedra, corners with four equivalent MnS6 octahedra, an edgeedge with one MnS6 octahedra, edges with three equivalent LuS6 octahedra, edges with two equivalent LuS7 pentagonal bipyramids, and faces with two equivalent LuS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 21–71°. There are a spread of Lu–S bond distances ranging from 2.66–2.99 Å. In the second Lu3+ site, Lu3+ is bonded to seven S2- atoms to form distorted LuS7 pentagonal bipyramids that share corners with two equivalent MnS6 octahedra, corners with six LuS6 octahedra, edges with four LuS6 octahedra, edges with two equivalent LuS7 pentagonal bipyramids, and faces with two equivalent LuS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 22–68°. There are a spread of Lu–S bond distances ranging from 2.65–2.93 Å. In the third Lu3+ site, Lu3+ is bonded to six S2- atoms to form LuS6 octahedra that share a cornercorner with one LuS6 octahedra, a cornercorner with one MnS6 octahedra, corners with four LuS7 pentagonal bipyramids, edges with two equivalent LuS6 octahedra, and edges with six LuS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 53–54°. There are a spread of Lu–S bond distances ranging from 2.61–2.67 Å. In the fourth Lu3+ site, Lu3+ is bonded to six S2- atoms to form LuS6 octahedra that share a cornercorner with one LuS6 octahedra, corners with two equivalent MnS6 octahedra, corners with six LuS7 pentagonal bipyramids, edges with two equivalent LuS6 octahedra, edges with three equivalent MnS6 octahedra, and an edgeedge with one LuS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 2–53°. There are a spread of Lu–S bond distances ranging from 2.62–2.71 Å. Mn2+ is bonded to six S2- atoms to form MnS6 octahedra that share corners with three LuS6 octahedra, corners with six LuS7 pentagonal bipyramids, edges with two equivalent MnS6 octahedra, edges with three equivalent LuS6 octahedra, and an edgeedge with one LuS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 2–54°. There are a spread of Mn–S bond distances ranging from 2.53–2.68 Å. There are seven inequivalent S2- sites. In the first S2- site, S2- is bonded to four Lu3+ and one Mn2+ atom to form distorted SLu4Mn trigonal bipyramids that share corners with five SLu3Mn tetrahedra, corners with four SLu5 trigonal bipyramids, an edgeedge with one SLu4 tetrahedra, and edges with five SLu4Mn trigonal bipyramids. In the second S2- site, S2- is bonded to three Lu3+ and two equivalent Mn2+ atoms to form distorted SLu3Mn2 trigonal bipyramids that share corners with five SLu3Mn tetrahedra, corners with four SLu5 trigonal bipyramids, an edgeedge with one SLu3Mn tetrahedra, and edges with five SLu4Mn trigonal bipyramids. In the third S2- site, S2- is bonded to five Lu3+ atoms to form distorted SLu5 trigonal bipyramids that share corners with four equivalent SLu3Mn tetrahedra, corners with six SLu4Mn trigonal bipyramids, edges with three SLu3Mn tetrahedra, and edges with six SLu3Mn2 trigonal bipyramids. In the fourth S2- site, S2- is bonded to five Lu3+ atoms to form distorted SLu5 trigonal bipyramids that share corners with four equivalent SLu4 tetrahedra, corners with six SLu4Mn trigonal bipyramids, edges with three SLu3Mn tetrahedra, and edges with six SLu4Mn trigonal bipyramids. In the fifth S2- site, S2- is bonded to three Lu3+ and one Mn2+ atom to form distorted SLu3Mn tetrahedra that share corners with three SLu3Mn tetrahedra, corners with nine SLu4Mn trigonal bipyramids, and edges with four SLu3Mn2 trigonal bipyramids. In the sixth S2- site, S2- is bonded to four Lu3+ atoms to form distorted SLu4 tetrahedra that share corners with three SLu3Mn tetrahedra, corners with nine SLu4Mn trigonal bipyramids, and edges with four SLu4Mn trigonal bipyramids. In the seventh S2- site, S2- is bonded in a rectangular see-saw-like geometry to two equivalent Lu3+ and two equivalent Mn2+ atoms.