Materials Data on CaAl2(Si8O19)2 by Materials Project

Abstract

CaAl2(Si4O9)4O2 is Low Tridymite-derived structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional and consists of eight water molecules and one CaAl2(Si4O9)4 framework. In the CaAl2(Si4O9)4 framework, Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.63–2.87 Å. Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with four SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.72–1.77 Å. There are five inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one AlO4 tetrahedra and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.66 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one AlO4 tetrahedra and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.57–1.66 Å. In the third Si site, Si is bonded to four O atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.68 Å. In the fourth Si site, Si is bonded to four O atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.67 Å. In the fifth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one AlO4 tetrahedra and corners with three SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.57–1.70 Å. There are thirteen inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the second O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the third O site, O is bonded in a linear geometry to one Al and one Si atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the sixth O site, O is bonded in a linear geometry to two Si atoms. In the seventh O site, O is bonded in a linear geometry to two equivalent Si atoms. In the eighth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the ninth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the tenth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eleventh O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and two equivalent Si atoms. In the twelfth O site, O is bonded in a distorted trigonal planar geometry to one Ca and two Si atoms. In the thirteenth O site, O is bonded in a distorted trigonal planar geometry to one Ca and two equivalent Si atoms.