DOI: 10.17188/1273804
title: Materials Data on KSm2Sb3Se8 by Materials Project

description: KSm2Sb3Se8 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of K–Se bond distances ranging from 3.37–3.67 Å. There are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to seven Se2- atoms to form distorted SmSe7 pentagonal bipyramids that share a cornercorner with one SbSe6 octahedra, edges with two equivalent SbSe6 octahedra, and edges with four equivalent SmSe7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. There are a spread of Sm–Se bond distances ranging from 2.89–3.11 Å. In the second Sm3+ site, Sm3+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Sm–Se bond distances ranging from 2.99–3.45 Å. There are three inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded to five Se2- atoms to form SbSe5 square pyramids that share corners with six SbSe6 octahedra, edges with two SbSe6 octahedra, and edges with two equivalent SbSe5 square pyramids. The corner-sharing octahedra tilt angles range from 4–93°. There are a spread of Sb–Se bond distances ranging from 2.63–2.91 Å. In the second Sb3+ site, Sb3+ is bonded to six Se2- atoms to form SbSe6 octahedra that share corners with two equivalent SbSe5 square pyramids, edges with four SbSe6 octahedra, edges with two equivalent SmSe7 pentagonal bipyramids, and an edgeedge with one SbSe5 square pyramid. There are a spread of Sb–Se bond distances ranging from 2.75–3.05 Å. In the third Sb3+ site, Sb3+ is bonded to six Se2- atoms to form distorted SbSe6 octahedra that share a cornercorner with one SmSe7 pentagonal bipyramid, corners with four equivalent SbSe5 square pyramids, edges with four SbSe6 octahedra, and an edgeedge with one SbSe5 square pyramid. There are a spread of Sb–Se bond distances ranging from 2.67–3.36 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to five Sm3+ atoms to form distorted SeSm5 square pyramids that share corners with eight SeK2Sm2Sb square pyramids, a cornercorner with one SeKSm2Sb2 trigonal bipyramid, edges with six SeSm5 square pyramids, and edges with two equivalent SeKSm2Sb2 trigonal bipyramids. In the second Se2- site, Se2- is bonded to two equivalent K1+, two equivalent Sm3+, and one Sb3+ atom to form distorted SeK2Sm2Sb square pyramids that share corners with nine SeSm5 square pyramids, corners with two equivalent SeKSm2Sb2 trigonal bipyramids, edges with two equivalent SeKSb5 octahedra, edges with five SeSm5 square pyramids, and edges with two equivalent SeKSm2Sb2 trigonal bipyramids. In the third Se2- site, Se2- is bonded to one K1+, two Sm3+, and two equivalent Sb3+ atoms to form distorted SeKSm2Sb2 trigonal bipyramids that share corners with three equivalent SeKSb5 octahedra, corners with four SeSm5 square pyramids, corners with two equivalent SeKSm2Sb2 trigonal bipyramids, an edgeedge with one SeKSb5 octahedra, and edges with eight SeSm5 square pyramids. The corner-sharing octahedra tilt angles range from 8–53°. In the fourth Se2- site, Se2- is bonded in a 4-coordinate geometry to three Sm3+ and one Sb3+ atom. In the fifth Se2- site, Se2- is bonded to one Sm3+ and four Sb3+ atoms to form SeSmSb4 square pyramids that share corners with four equivalent SeKSb5 octahedra, corners with four SeSm5 square pyramids, a cornercorner with one SeKSm2Sb2 trigonal bipyramid, an edgeedge with one SeKSb5 octahedra, and edges with five SeSmSb4 square pyramids. The corner-sharing octahedra tilt angles range from 3–78°. In the sixth Se2- site, Se2- is bonded to two equivalent K1+ and three Sb3+ atoms to form distorted SeK2Sb3 square pyramids that share corners with two equivalent SeKSb5 octahedra, corners with seven SeK2Sm2Sb square pyramids, edges with two equivalent SeKSb5 octahedra, edges with five SeK2Sm2Sb square pyramids, and edges with two equivalent SeKSm2Sb2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 39°. In the seventh Se2- site, Se2- is bonded to one K1+ and five Sb3+ atoms to form SeKSb5 octahedra that share corners with six SeSmSb4 square pyramids, corners with three equivalent SeKSm2Sb2 trigonal bipyramids, edges with two equivalent SeKSb5 octahedra, edges with seven SeK2Sm2Sb square pyramids, and an edgeedge with one SeKSm2Sb2 trigonal bipyramid. In the eighth Se2- site, Se2- is bonded to two equivalent K1+, two equivalent Sm3+, and one Sb3+ atom to form distorted SeK2Sm2Sb square pyramids that share corners with six SeK2Sb3 square pyramids, edges with two equivalent SeKSb5 octahedra, edges with seven SeSm5 square pyramids, and edges with two equivalent SeKSm2Sb2 trigonal bipyramids.