Materials Data on Ca2Sn7S16 by Materials Project
Ca2Sn7S16 crystallizes in the orthorhombic Pba2 space group. The structure is three-dimensional. Ca2+ is bonded in a 6-coordinate geometry to six S2- atoms. There are a spread of Ca–S bond distances ranging from 2.81–2.99 Å. There are four inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to four S2- atoms to form corner-sharing SnS4 tetrahedra. The corner-sharing octahedral tilt angles are 68°. All Sn–S bond lengths are 2.43 Å. In the second Sn4+ site, Sn4+ is bonded to six S2- atoms to form corner-sharing SnS6 octahedra. There are a spread of Sn–S bond distances ranging from 2.55–2.61 Å. In the third Sn4+ site, Sn4+ is bonded to four S2- atoms to form SnS4 tetrahedra that share corners with two equivalent SnS6 octahedra and corners with two equivalent SnS4 tetrahedra. The corner-sharing octahedra tilt angles range from 64–69°. There are a spread of Sn–S bond distances ranging from 2.44–2.47 Å. In the fourth Sn4+ site, Sn4+ is bonded to four S2- atoms to form SnS4 tetrahedra that share corners with two equivalent SnS6 octahedra and corners with two equivalent SnS4 tetrahedra. The corner-sharing octahedra tilt angles range from 64–69°. There are a spread of Sn–S bond distances ranging from 2.44–2.47 Å. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two Sn4+ atoms. In the second S2- site, S2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Sn4+ atoms. In the third S2- site, S2- is bonded in a water-like geometry to two Sn4+ atoms. In the fourth S2- site, S2- is bonded in a water-like geometry to two Sn4+ atoms. In the fifth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two Sn4+ atoms. In the sixth S2- site, S2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Sn4+ atoms. In the seventh S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two Sn4+ atoms. In the eighth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two Sn4+ atoms.