Materials Data on K5Ag2(AsSe3)3 by Materials Project

Abstract

K5Ag2As3Se9 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to seven Se2- atoms to form distorted KSe7 pentagonal bipyramids that share corners with four KSe7 pentagonal bipyramids, a cornercorner with one AgSe4 tetrahedra, edges with six KSe7 pentagonal bipyramids, edges with two equivalent AgSe4 tetrahedra, and edges with two equivalent AsSe4 tetrahedra. There are a spread of K–Se bond distances ranging from 3.32–3.72 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of K–Se bond distances ranging from 3.41–3.81 Å. In the third K1+ site, K1+ is bonded to seven Se2- atoms to form distorted KSe7 pentagonal bipyramids that share corners with two equivalent KSe7 pentagonal bipyramids, a cornercorner with one AsSe4 tetrahedra, corners with two equivalent AgSe4 tetrahedra, edges with five KSe7 pentagonal bipyramids, an edgeedge with one AsSe4 tetrahedra, edges with two equivalent AgSe4 tetrahedra, and a faceface with one KSe7 pentagonal bipyramid. There are a spread of K–Se bond distances ranging from 3.37–3.68 Å. Ag1+ is bonded to four Se2- atoms to form AgSe4 tetrahedra that share corners with three KSe7 pentagonal bipyramids, a cornercorner with one AgSe4 tetrahedra, a cornercorner with one AsSe4 tetrahedra, and edges with four KSe7 pentagonal bipyramids. There are a spread of Ag–Se bond distances ranging from 2.67–2.75 Å. There are three inequivalent As+3.67+ sites. In the first As+3.67+ site, As+3.67+ is bonded in a distorted trigonal non-coplanar geometry to three Se2- atoms. There are two shorter (2.36 Å) and one longer (3.13 Å) As–Se bond lengths. In the second As+3.67+ site, As+3.67+ is bonded in a trigonal non-coplanar geometry to three Se2- atoms. There are two shorter (2.39 Å) and one longer (2.41 Å) As–Se bond lengths. In the third As+3.67+ site, As+3.67+ is bonded to four Se2- atoms to form AsSe4 tetrahedra that share corners with two equivalent KSe7 pentagonal bipyramids, corners with two equivalent AgSe4 tetrahedra, and edges with six KSe7 pentagonal bipyramids. There are a spread of As–Se bond distances ranging from 2.34–2.39 Å. There are six inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent K1+, two equivalent Ag1+, and one As+3.67+ atom to form SeK2Ag2As square pyramids that share corners with four equivalent SeK4AgAs octahedra and an edgeedge with one SeK4As2 octahedra. The corner-sharing octahedra tilt angles range from 58–75°. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to four K1+, one Ag1+, and one As+3.67+ atom. In the third Se2- site, Se2- is bonded to four K1+, one Ag1+, and one As+3.67+ atom to form distorted SeK4AgAs octahedra that share corners with two equivalent SeK2Ag2As square pyramids and edges with four SeK4As2 octahedra. In the fourth Se2- site, Se2- is bonded in a 6-coordinate geometry to five K1+ and one As+3.67+ atom. In the fifth Se2- site, Se2- is bonded in a 6-coordinate geometry to four K1+, one Ag1+, and one As+3.67+ atom. In the sixth Se2- site, Se2- is bonded to four K1+ and two As+3.67+ atoms to form distorted SeK4As2 octahedra that share edges with four equivalent SeK4AgAs octahedra and an edgeedge with one SeK2Ag2As square pyramid.