Materials Data on Ca3Sn2S7 by Materials Project

Ca3Sn2S7 is beta indium sulfide-derived structured and crystallizes in the orthorhombic Ima2 space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Ca–S bond distances ranging from 2.82–3.31 Å. In the second Ca2+ site, Ca2+ is bonded to six S2- atoms to form CaS6 octahedra that share corners with eight CaS6 octahedra, corners with two equivalent SnS4 tetrahedra, corners with two equivalent SnS4 trigonal pyramids, edges with two equivalent CaS6 octahedra, and an edgeedge with one SnS4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of Ca–S bond distances ranging from 2.85–2.93 Å. In the third Ca2+ site, Ca2+ is bonded to six S2- atoms to form CaS6 octahedra that share corners with four CaS6 octahedra, a cornercorner with one SnS4 tetrahedra, a cornercorner with one SnS4 trigonal pyramid, edges with three CaS6 octahedra, an edgeedge with one SnS4 tetrahedra, and an edgeedge with one SnS4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 54–62°. There are a spread of Ca–S bond distances ranging from 2.84–2.96 Å. In the fourth Ca2+ site, Ca2+ is bonded to six S2- atoms to form CaS6 octahedra that share corners with four CaS6 octahedra, corners with three SnS4 tetrahedra, corners with two equivalent SnS4 trigonal pyramids, an edgeedge with one CaS6 octahedra, and an edgeedge with one SnS4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Ca–S bond distances ranging from 2.78–2.96 Å. There are three inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to four S2- atoms to form SnS4 tetrahedra that share corners with six CaS6 octahedra and edges with three CaS6 octahedra. The corner-sharing octahedra tilt angles range from 59–63°. There are a spread of Sn–S bond distances ranging from 2.39–2.44 Å. In the second Sn4+ site, Sn4+ is bonded to four S2- atoms to form SnS4 trigonal pyramids that share corners with four CaS6 octahedra, a cornercorner with one SnS4 tetrahedra, and edges with two CaS6 octahedra. The corner-sharing octahedra tilt angles range from 60–72°. There are a spread of Sn–S bond distances ranging from 2.37–2.50 Å. In the third Sn4+ site, Sn4+ is bonded to four S2- atoms to form SnS4 tetrahedra that share corners with four equivalent CaS6 octahedra and corners with two equivalent SnS4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 63–71°. There are two shorter (2.36 Å) and two longer (2.46 Å) Sn–S bond lengths. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to two Ca2+ and one Sn4+ atom. In the second S2- site, S2- is bonded to two Ca2+ and two Sn4+ atoms to form distorted SCa2Sn2 trigonal pyramids that share corners with two equivalent SCa3Sn tetrahedra, corners with two equivalent SCa2Sn2 trigonal pyramids, and an edgeedge with one SCa3Sn tetrahedra. In the third S2- site, S2- is bonded in a rectangular see-saw-like geometry to three Ca2+ and one Sn4+ atom. In the fourth S2- site, S2- is bonded in a rectangular see-saw-like geometry to three Ca2+ and one Sn4+ atom. In the fifth S2- site, S2- is bonded to three Ca2+ and one Sn4+ atom to form distorted corner-sharing SCa3Sn tetrahedra. In the sixth S2- site, S2- is bonded in a rectangular see-saw-like geometry to three Ca2+ and one Sn4+ atom. In the seventh S2- site, S2- is bonded in a 4-coordinate geometry to three Ca2+ and one Sn4+ atom. In the eighth S2- site, S2- is bonded to three Ca2+ and one Sn4+ atom to form distorted SCa3Sn tetrahedra that share corners with two SCa3Sn tetrahedra, corners with two equivalent SCa2Sn2 trigonal pyramids, and an edgeedge with one SCa2Sn2 trigonal pyramid.