DOE OSTI2020
CaSnS3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six S2- atoms to form distorted CaS6 octahedra that share a cornercorner with one SnS4 tetrahedra, a cornercorner with one SnS5 trigonal bipyramid, a cornercorner with one SnS4 trigonal pyramid, an edgeedge with one CaS5 square pyramid, an edgeedge with one SnS4 tetrahedra, and an edgeedge with one SnS4 trigonal pyramid. There are a spread of Ca–S bond distances ranging from 2.88–2.95 Å. In the second Ca2+ site, Ca2+ is bonded to five S2- atoms to form distorted CaS5 square pyramids that share corners with three SnS4 tetrahedra, corners with two equivalent CaS5 trigonal bipyramids, an edgeedge with one CaS6 octahedra, and an edgeedge with one SnS5 trigonal bipyramid. There are a spread of Ca–S bond distances ranging from 2.67–2.88 Å. In the third Ca2+ site, Ca2+ is bonded to five S2- atoms to form distorted CaS5 trigonal bipyramids that share corners with two equivalent CaS5 square pyramids, a cornercorner with one SnS4 tetrahedra, and edges with two equivalent SnS5 trigonal bipyramids. There are a spread of Ca–S bond distances ranging from 2.73–2.86 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Ca–S bond distances ranging from 2.74–3.33 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Ca–S bond distances ranging from 2.79–3.19 Å. In the sixth Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six S2- atoms. There are a spread of Ca–S bond distances ranging from 2.83–3.07 Å. There are six inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to four S2- atoms to form SnS4 tetrahedra that share a cornercorner with one CaS5 square pyramid. There are a spread of Sn–S bond distances ranging from 2.37–2.64 Å. In the second Sn4+ site, Sn4+ is bonded in a distorted T-shaped geometry to three S2- atoms. There are a spread of Sn–S bond distances ranging from 2.61–2.78 Å. In the third Sn4+ site, Sn4+ is bonded in a trigonal non-coplanar geometry to three S2- atoms. There are a spread of Sn–S bond distances ranging from 2.50–2.68 Å. In the fourth Sn4+ site, Sn4+ is bonded to four S2- atoms to form SnS4 tetrahedra that share a cornercorner with one CaS6 octahedra, corners with two equivalent CaS5 square pyramids, a cornercorner with one CaS5 trigonal bipyramid, and an edgeedge with one CaS6 octahedra. The corner-sharing octahedral tilt angles are 28°. There are a spread of Sn–S bond distances ranging from 2.38–2.46 Å. In the fifth Sn4+ site, Sn4+ is bonded to five S2- atoms to form distorted SnS5 trigonal bipyramids that share a cornercorner with one CaS6 octahedra, a cornercorner with one SnS4 trigonal pyramid, an edgeedge with one CaS5 square pyramid, and edges with two equivalent CaS5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. There are a spread of Sn–S bond distances ranging from 2.46–2.75 Å. In the sixth Sn4+ site, Sn4+ is bonded to four S2- atoms to form distorted SnS4 trigonal pyramids that share a cornercorner with one CaS6 octahedra, a cornercorner with one SnS5 trigonal bipyramid, and an edgeedge with one CaS6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of Sn–S bond distances ranging from 2.38–2.57 Å. There are eighteen inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to one Ca2+ and two S2- atoms. There are one shorter (2.05 Å) and one longer (2.11 Å) S–S bond lengths. In the second S2- site, S2- is bonded in a 4-coordinate geometry to two Ca2+, one Sn4+, and one S2- atom. In the third S2- site, S2- is bonded in a 3-coordinate geometry to two Ca2+ and one Sn4+ atom. In the fourth S2- site, S2- is bonded to two Ca2+ and two Sn4+ atoms to form distorted SCa2Sn2 trigonal pyramids that share a cornercorner with one SCa2Sn2 trigonal pyramid and an edgeedge with one SCa3Sn trigonal pyramid. In the fifth S2- site, S2- is bonded in a 3-coordinate geometry to one Ca2+ and two Sn4+ atoms. In the sixth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to two Ca2+ and two Sn4+ atoms. In the seventh S2- site, S2- is bonded in a trigonal non-coplanar geometry to one Ca2+ and two Sn4+ atoms. In the eighth S2- site, S2- is bonded in a distorted T-shaped geometry to one Ca2+ and two Sn4+ atoms. In the ninth S2- site, S2- is bonded in a bent 120 degrees geometry to two Sn4+ atoms. In the tenth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to two Ca2+ and one Sn4+ atom. In the eleventh S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Ca2+ and one Sn4+ atom. In the twelfth S2- site, S2- is bonded in a rectangular see-saw-like geometry to three Ca2+ and one Sn4+ atom. In the thirteenth S2- site, S2- is bonded in a rectangular see-saw-like geometry to three Ca2+ and one Sn4+ atom. In the fourteenth S2- site, S2- is bonded to two Ca2+ and two Sn4+ atoms to form distorted SCa2Sn2 trigonal pyramids that share corners with three SCa2Sn2 trigonal pyramids and an edgeedge with one SCa3Sn trigonal pyramid. In the fifteenth S2- site, S2- is bonded to three Ca2+ and one Sn4+ atom to form a mixture of distorted corner and edge-sharing SCa3Sn trigonal pyramids. In the sixteenth S2- site, S2- is bonded in a distorted L-shaped geometry to one Ca2+ and one S2- atom. In the seventeenth S2- site, S2- is bonded to three Ca2+ and one Sn4+ atom to form distorted SCa3Sn trigonal pyramids that share a cornercorner with one SCa3Sn trigonal pyramid and an edgeedge with one SCa2Sn2 trigonal pyramid. In the eighteenth S2- site, S2- is bonded in a distorted T-shaped geometry to two Ca2+ and one Sn4+ atom.