DOI: 10.17188/1203731
title: Materials Data on K6Sn2Se7 by Materials Project

description: K6Sn2Se7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are twelve inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 pentagonal pyramids that share corners with five KSe6 pentagonal pyramids, corners with two SnSe4 tetrahedra, corners with two equivalent KSe5 trigonal bipyramids, edges with two equivalent KSe6 octahedra, an edgeedge with one KSe6 pentagonal pyramid, an edgeedge with one KSe5 square pyramid, and edges with two SnSe4 tetrahedra. There are a spread of K–Se bond distances ranging from 3.34–3.69 Å. In the second K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 pentagonal pyramids that share corners with three KSe6 pentagonal pyramids, a cornercorner with one KSe5 square pyramid, corners with two SnSe4 tetrahedra, an edgeedge with one KSe6 octahedra, edges with three KSe6 pentagonal pyramids, an edgeedge with one KSe5 square pyramid, edges with two SnSe4 tetrahedra, and an edgeedge with one KSe5 trigonal bipyramid. There are a spread of K–Se bond distances ranging from 3.43–3.72 Å. In the third K1+ site, K1+ is bonded to five Se2- atoms to form KSe5 trigonal bipyramids that share corners with four KSe6 pentagonal pyramids, corners with two equivalent KSe5 square pyramids, corners with five SnSe4 tetrahedra, an edgeedge with one KSe6 octahedra, and edges with three KSe6 pentagonal pyramids. There are a spread of K–Se bond distances ranging from 3.38–3.48 Å. In the fourth K1+ site, K1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of K–Se bond distances ranging from 3.27–3.59 Å. In the fifth K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 octahedra that share corners with four KSe6 pentagonal pyramids, corners with two SnSe4 tetrahedra, edges with four KSe6 pentagonal pyramids, edges with two SnSe4 tetrahedra, and an edgeedge with one KSe5 trigonal bipyramid. There are a spread of K–Se bond distances ranging from 3.31–3.55 Å. In the sixth K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 pentagonal pyramids that share a cornercorner with one KSe6 octahedra, corners with four KSe6 pentagonal pyramids, corners with three SnSe4 tetrahedra, a cornercorner with one KSe5 trigonal bipyramid, an edgeedge with one KSe6 octahedra, an edgeedge with one KSe6 pentagonal pyramid, and edges with three SnSe4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. There are a spread of K–Se bond distances ranging from 3.36–3.70 Å. In the seventh K1+ site, K1+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are a spread of K–Se bond distances ranging from 3.25–3.67 Å. In the eighth K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 pentagonal pyramids that share corners with two equivalent KSe6 octahedra, corners with two KSe6 pentagonal pyramids, corners with two equivalent KSe5 square pyramids, corners with four SnSe4 tetrahedra, edges with two KSe6 pentagonal pyramids, an edgeedge with one SnSe4 tetrahedra, an edgeedge with one KSe5 trigonal bipyramid, and a faceface with one KSe6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 18–27°. There are a spread of K–Se bond distances ranging from 3.35–3.89 Å. In the ninth K1+ site, K1+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of K–Se bond distances ranging from 3.19–3.78 Å. In the tenth K1+ site, K1+ is bonded to six Se2- atoms to form distorted KSe6 pentagonal pyramids that share a cornercorner with one KSe6 octahedra, corners with six KSe6 pentagonal pyramids, a cornercorner with one KSe5 square pyramid, a cornercorner with one SnSe4 tetrahedra, a cornercorner with one KSe5 trigonal bipyramid, an edgeedge with one KSe6 pentagonal pyramid, edges with three SnSe4 tetrahedra, an edgeedge with one KSe5 trigonal bipyramid, and a faceface with one KSe6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 30°. There are a spread of K–Se bond distances ranging from 3.39–3.60 Å. In the eleventh K1+ site, K1+ is bonded to five Se2- atoms to form distorted KSe5 square pyramids that share corners with four KSe6 pentagonal pyramids, corners with three SnSe4 tetrahedra, corners with two equivalent KSe5 trigonal bipyramids, edges with two KSe6 pentagonal pyramids, an edgeedge with one KSe5 square pyramid, and an edgeedge with one SnSe4 tetrahedra. There are a spread of K–Se bond distances ranging from 3.27–3.67 Å. In the twelfth K1+ site, K1+ is bonded in a distorted pentagonal planar geometry to five Se2- atoms. There are a spread of K–Se bond distances ranging from 3.30–3.55 Å. There are four inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to four Se2- atoms to form SnSe4 tetrahedra that share corners with three KSe6 pentagonal pyramids, a cornercorner with one KSe5 square pyramid, a cornercorner with one SnSe4 tetrahedra, a cornercorner with one KSe5 trigonal bipyramid, an edgeedge with one KSe6 octahedra, and edges with three KSe6 pentagonal pyramids. There are a spread of Sn–Se bond distances ranging from 2.53–2.64 Å. In the second Sn4+ site, Sn4+ is bonded to four Se2- atoms to form SnSe4 tetrahedra that share corners with four KSe6 pentagonal pyramids, corners with two equivalent KSe5 square pyramids, a cornercorner with one SnSe4 tetrahedra, a cornercorner with one KSe5 trigonal bipyramid, and edges with three KSe6 pentagonal pyramids. There are a spread of Sn–Se bond distances ranging from 2.52–2.63 Å. In the third Sn4+ site, Sn4+ is bonded to four Se2- atoms to form SnSe4 tetrahedra that share a cornercorner with one KSe6 octahedra, corners with two KSe6 pentagonal pyramids, a cornercorner with one SnSe4 tetrahedra, a cornercorner with one KSe5 trigonal bipyramid, an edgeedge with one KSe6 octahedra, and edges with three KSe6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 15°. There are a spread of Sn–Se bond distances ranging from 2.54–2.66 Å. In the fourth Sn4+ site, Sn4+ is bonded to four Se2- atoms to form SnSe4 tetrahedra that share a cornercorner with one KSe6 octahedra, corners with three KSe6 pentagonal pyramids, a cornercorner with one SnSe4 tetrahedra, corners with two equivalent KSe5 trigonal bipyramids, edges with two KSe6 pentagonal pyramids, and an edgeedge with one KSe5 square pyramid. The corner-sharing octahedral tilt angles are 59°. There are a spread of Sn–Se bond distances ranging from 2.54–2.65 Å. There are fourteen inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to five K1+ and one Sn4+ atom to form distorted SeK5Sn octahedra that share a cornercorner with one SeK5Sn octahedra, a cornercorner with one SeK6Sn pentagonal bipyramid, an edgeedge with one SeK5Sn octahedra, edges with two SeK6Sn pentagonal bipyramids, and a faceface with one SeK6Sn pentagonal bipyramid. The corner-sharing octahedral tilt angles are 56°. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to three K1+ and two Sn4+ atoms. In the third Se2- site, Se2- is bonded to five K1+ and one Sn4+ atom to form distorted SeK5Sn octahedra that share a cornercorner with one SeK5Sn octahedra, a cornercorner with one SeK6Sn pentagonal bipyramid, edges with two equivalent SeK5Sn octahedra, and an edgeedge with one SeK6Sn pentagonal bipyramid. The corner-sharing octahedral tilt angles are 56°. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to four K1+ and two Sn4+ atoms. In the fifth Se2- site, Se2- is bonded in a 6-coordinate geometry to five K1+ and one Sn4+ atom. In the sixth Se2- site, Se2- is bonded to six K1+ and one Sn4+ atom to form distorted SeK6Sn pentagonal bipyramids that share a cornercorner with one SeK5Sn octahedra, edges with three SeK5Sn octahedra, an edgeedge with one SeK6Sn pentagonal bipyramid, and a faceface with one SeK6Sn pentagonal bipyramid. The corner-sharing octahedral tilt angles are 43°. In the seventh Se2- site, Se2- is bonded in a 6-coordinate geometry to five K1+ and one Sn4+ atom. In the eighth Se2- site, Se2- is bonded in a 6-coordinate geometry to five K1+ and one Sn4+ atom. In the ninth Se2- site, Se2- is bonded to six K1+ and one Sn4+ atom to form distorted SeK6Sn pentagonal bipyramids that share a cornercorner with one SeK5Sn octahedra, an edgeedge with one SeK5Sn octahedra, edges with two SeK6Sn pentagonal bipyramids, a faceface with one SeK5Sn octahedra, and a faceface with one SeK6Sn pentagonal bipyramid. The corner-sharing octahedral tilt angles are 35°. In the tenth Se2- site, Se2- is bonded to five K1+ and one Sn4+ atom to form distorted SeK5Sn octahedra that share edges with two equivalent SeK5Sn octahedra and an edgeedge with one SeK6Sn pentagonal bipyramid. In the eleventh Se2- site, Se2- is bonded in a 6-coordinate geometry to five K1+ and one Sn4+ atom. In the twelfth Se2- site, Se2- is bonded in a 6-coordinate geometry to five K1+ and one Sn4+ atom. In the thirteenth Se2- site, Se2- is bonded in a 6-coordinate geometry to five K1+ and one Sn4+ atom. In the fourteenth Se2- site, Se2- is bonded in a 5-coordinate geometry to four K1+ and one Sn4+ atom.