Materials Data on Ca2Al2Sn2O9 by Materials Project

Abstract

Ca2Sn2Al2O9 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.32–2.65 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent SnO6 octahedra and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–58°. There are a spread of Al–O bond distances ranging from 1.76–1.79 Å. Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share a cornercorner with one SnO6 octahedra, corners with three equivalent AlO4 tetrahedra, and edges with two equivalent SnO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of Sn–O bond distances ranging from 2.04–2.24 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+ and two equivalent Al3+ atoms. In the second O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Sn4+ atoms to form distorted OCa2Sn2 trigonal pyramids that share corners with two equivalent OCaAlSn2 tetrahedra, corners with four OCa2Sn2 trigonal pyramids, edges with two equivalent OCaAlSn2 tetrahedra, and edges with two OCa2Sn2 trigonal pyramids. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Al3+, and one Sn4+ atom. In the fourth O2- site, O2- is bonded to one Ca2+, one Al3+, and two equivalent Sn4+ atoms to form distorted OCaAlSn2 tetrahedra that share corners with two equivalent OCaAlSn2 tetrahedra, corners with three OCa2Sn2 trigonal pyramids, and edges with three OCa2Sn2 trigonal pyramids. In the fifth O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Sn4+ atoms to form distorted OCa2Sn2 trigonal pyramids that share corners with two equivalent OCaAlSn2 tetrahedra, corners with four equivalent OCa2Sn2 trigonal pyramids, edges with two equivalent OCaAlSn2 tetrahedra, and edges with two equivalent OCa2Sn2 trigonal pyramids.