Materials Data on Ca6Si6O19 by Materials Project

Abstract

(CaSiO3)12O2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional and consists of four water molecules and one CaSiO3 framework. In the CaSiO3 framework, there are three inequivalent Ca sites. In the first Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with four SiO4 tetrahedra and edges with two equivalent CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.29–2.39 Å. In the second Ca site, Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.81 Å. In the third Ca site, Ca is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.80 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded in a trigonal non-coplanar geometry to three O atoms. There is one shorter (1.62 Å) and two longer (1.67 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 CaO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–65°. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent CaO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–65°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and two Si atoms. In the second O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the third O site, O is bonded in a 4-coordinate geometry to three Ca and one Si atom. In the fourth O site, O is bonded to three Ca and one Si atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the fifth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the sixth O site, O is bonded in a trigonal non-coplanar geometry to three Ca atoms. In the seventh O site, O is bonded to three Ca and one Si atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the eighth O site, O is bonded to three Ca and one Si atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the ninth O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and two Si atoms.