Materials Data on Ca2Al2(SiO4)3 by Materials Project

Abstract

Ca2Al2(SiO4)3 crystallizes in the orthorhombic Pma2 space group. The structure is three-dimensional. Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.79 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with four SiO4 tetrahedra. There is two shorter (1.75 Å) and two longer (1.76 Å) Al–O bond length. In the second Al site, Al is bonded to six O atoms to form AlO6 octahedra that share corners with four equivalent SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.89–1.94 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent AlO4 tetrahedra and corners with two equivalent SiO4 tetrahedra. There is two shorter (1.62 Å) and two longer (1.65 Å) Si–O bond length. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one AlO4 tetrahedra, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–52°. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. There are seven inequivalent O sites. In the first O site, O is bonded in a trigonal non-coplanar geometry to two equivalent Ca and one Al atom. In the second O site, O is bonded in a trigonal non-coplanar geometry to two equivalent Ca and one Al atom. In the third O site, O is bonded in a 3-coordinate geometry to one Ca, one Al, and one Si atom. In the fourth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and two Si atoms. In the fifth O site, O is bonded in a 3-coordinate geometry to one Ca, one Al, and one Si atom. In the sixth O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Al, and one Si atom. In the seventh O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Al, and one Si atom.