DOE OSTI2020
Ca(Sn2O3)2 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.39–2.72 Å. There are two inequivalent Sn+2.50+ sites. In the first Sn+2.50+ site, Sn+2.50+ is bonded to five O2- atoms to form SnO5 square pyramids that share corners with four equivalent SnO6 octahedra, corners with two equivalent SnO5 square pyramids, edges with three equivalent SnO6 octahedra, and edges with three equivalent SnO5 square pyramids. The corner-sharing octahedra tilt angles range from 25–84°. There are a spread of Sn–O bond distances ranging from 2.21–2.54 Å. In the second Sn+2.50+ site, Sn+2.50+ is bonded to six O2- atoms to form distorted SnO6 octahedra that share corners with two equivalent SnO6 octahedra, corners with four equivalent SnO5 square pyramids, edges with two equivalent SnO6 octahedra, and edges with three equivalent SnO5 square pyramids. The corner-sharing octahedra tilt angles range from 0–43°. There are a spread of Sn–O bond distances ranging from 2.09–2.69 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to six Sn+2.50+ atoms to form OSn6 octahedra that share corners with eight equivalent OCaSn4 square pyramids, corners with two equivalent OCa2Sn2 trigonal pyramids, edges with two equivalent OSn6 octahedra, edges with two equivalent OCaSn4 square pyramids, and edges with four equivalent OCa2Sn3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Ca2+ and three Sn+2.50+ atoms to form distorted OCa2Sn3 trigonal bipyramids that share corners with four equivalent OCaSn4 square pyramids, corners with two equivalent OCa2Sn3 trigonal bipyramids, corners with four equivalent OCa2Sn2 trigonal pyramids, edges with two equivalent OSn6 octahedra, edges with three equivalent OCaSn4 square pyramids, edges with three equivalent OCa2Sn3 trigonal bipyramids, and an edgeedge with one OCa2Sn2 trigonal pyramid. In the third O2- site, O2- is bonded to one Ca2+ and four Sn+2.50+ atoms to form distorted OCaSn4 square pyramids that share corners with four equivalent OSn6 octahedra, a cornercorner with one OCaSn4 square pyramid, corners with four equivalent OCa2Sn3 trigonal bipyramids, an edgeedge with one OSn6 octahedra, edges with two equivalent OCaSn4 square pyramids, edges with three equivalent OCa2Sn3 trigonal bipyramids, and edges with two equivalent OCa2Sn2 trigonal pyramids. The corner-sharing octahedra tilt angles range from 9–81°. In the fourth O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Sn+2.50+ atoms to form distorted OCa2Sn2 trigonal pyramids that share corners with two equivalent OSn6 octahedra, corners with eight equivalent OCa2Sn3 trigonal bipyramids, corners with two equivalent OCa2Sn2 trigonal pyramids, edges with four equivalent OCaSn4 square pyramids, and edges with two equivalent OCa2Sn3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 1°.