Materials Data on Sr4Sn2Se9 by Materials Project
Sr4Sn2Se9 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight Se+1.33- atoms. There are a spread of Sr–Se bond distances ranging from 3.17–3.36 Å. In the second Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight Se+1.33- atoms. There are a spread of Sr–Se bond distances ranging from 3.19–3.35 Å. There are two inequivalent Sn2+ sites. In the first Sn2+ site, Sn2+ is bonded in a distorted tetrahedral geometry to four Se+1.33- atoms. There are a spread of Sn–Se bond distances ranging from 2.57–2.59 Å. In the second Sn2+ site, Sn2+ is bonded in a 6-coordinate geometry to six Se+1.33- atoms. There are a spread of Sn–Se bond distances ranging from 2.57–3.34 Å. There are eight inequivalent Se+1.33- sites. In the first Se+1.33- site, Se+1.33- is bonded in a 5-coordinate geometry to four Sr2+ and one Se+1.33- atom. The Se–Se bond length is 2.46 Å. In the second Se+1.33- site, Se+1.33- is bonded in a 5-coordinate geometry to four Sr2+ and one Sn2+ atom. In the third Se+1.33- site, Se+1.33- is bonded in a 5-coordinate geometry to four Sr2+ and one Se+1.33- atom. The Se–Se bond length is 2.45 Å. In the fourth Se+1.33- site, Se+1.33- is bonded to four Sr2+ and one Sn2+ atom to form distorted edge-sharing SeSr4Sn trigonal bipyramids. In the fifth Se+1.33- site, Se+1.33- is bonded in a 5-coordinate geometry to four Sr2+ and one Sn2+ atom. In the sixth Se+1.33- site, Se+1.33- is bonded in a 5-coordinate geometry to three Sr2+ and two Sn2+ atoms. In the seventh Se+1.33- site, Se+1.33- is bonded to four Sr2+ and one Sn2+ atom to form distorted edge-sharing SeSr4Sn trigonal bipyramids. In the eighth Se+1.33- site, Se+1.33- is bonded in a rectangular see-saw-like geometry to two equivalent Sr2+ and two equivalent Sn2+ atoms.