DOI: 10.17188/1708376
title: Materials Data on K8Sn8Se20O9 by Materials Project

description: K8Sn8Se20O9 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 3-coordinate geometry to three equivalent Se+1.10- and three equivalent O2- atoms. All K–Se bond lengths are 3.63 Å. All K–O bond lengths are 2.91 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to three equivalent Se+1.10- and three equivalent O2- atoms. All K–Se bond lengths are 3.75 Å. All K–O bond lengths are 3.41 Å. In the third K1+ site, K1+ is bonded in a 2-coordinate geometry to three Se+1.10- and two O2- atoms. There are two shorter (3.33 Å) and one longer (3.69 Å) K–Se bond lengths. There are one shorter (2.65 Å) and one longer (2.79 Å) K–O bond lengths. In the fourth K1+ site, K1+ is bonded in a 1-coordinate geometry to four Se+1.10- and two O2- atoms. There are a spread of K–Se bond distances ranging from 3.30–3.70 Å. There are one shorter (2.61 Å) and one longer (3.21 Å) K–O bond lengths. There are four inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to four Se+1.10- atoms to form a mixture of edge and corner-sharing SnSe4 tetrahedra. There are a spread of Sn–Se bond distances ranging from 2.62–2.93 Å. In the second Sn4+ site, Sn4+ is bonded to four Se+1.10- atoms to form a mixture of edge and corner-sharing SnSe4 tetrahedra. There are a spread of Sn–Se bond distances ranging from 2.63–2.67 Å. In the third Sn4+ site, Sn4+ is bonded to four Se+1.10- atoms to form corner-sharing SnSe4 tetrahedra. There are one shorter (2.46 Å) and three longer (2.62 Å) Sn–Se bond lengths. In the fourth Sn4+ site, Sn4+ is bonded to four Se+1.10- atoms to form corner-sharing SnSe4 tetrahedra. There are one shorter (2.46 Å) and three longer (2.63 Å) Sn–Se bond lengths. There are eight inequivalent Se+1.10- sites. In the first Se+1.10- site, Se+1.10- is bonded in a 4-coordinate geometry to three equivalent K1+, one Sn4+, and one Se+1.10- atom. The Se–Se bond length is 2.90 Å. In the second Se+1.10- site, Se+1.10- is bonded in a 4-coordinate geometry to three equivalent K1+, one Sn4+, one Se+1.10-, and three equivalent O2- atoms. All Se–O bond lengths are 3.53 Å. In the third Se+1.10- site, Se+1.10- is bonded in a 2-coordinate geometry to one K1+ and two Sn4+ atoms. In the fourth Se+1.10- site, Se+1.10- is bonded in a 4-coordinate geometry to two K1+ and two Sn4+ atoms. In the fifth Se+1.10- site, Se+1.10- is bonded in a 4-coordinate geometry to two K1+ and two Sn4+ atoms. In the sixth Se+1.10- site, Se+1.10- is bonded in a 4-coordinate geometry to two K1+ and two Sn4+ atoms. In the seventh Se+1.10- site, Se+1.10- is bonded in a distorted water-like geometry to one Sn4+ and two O2- atoms. Both Se–O bond lengths are 1.69 Å. In the eighth Se+1.10- site, Se+1.10- is bonded in a 1-coordinate geometry to one Sn4+ and two O2- atoms. There are one shorter (1.74 Å) and one longer (3.12 Å) Se–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and two Se+1.10- atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and one Se+1.10- atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two K1+ and two Se+1.10- atoms.