DOI: 10.17188/1737150
title: Materials Data on Ca2Al4Si8O31 by Materials Project

description: (CaAl2(Si2O7)2)4(O2)3 crystallizes in the monoclinic C2 space group. The structure is three-dimensional and consists of two trioxidane molecules and one CaAl2(Si2O7)2 framework. In the CaAl2(Si2O7)2 framework, Ca is bonded in a 5-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.95 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 (1.73 Å) and two longer (1.80 Å) Al–O bond length. In the second Al site, 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 1.73–1.81 Å. There are four 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 SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the second 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 SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two AlO4 tetrahedra and corners with two SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.61–1.65 Å. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two AlO4 tetrahedra and corners with two SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.61–1.65 Å. There are fourteen inequivalent O sites. In the first O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Al, and one Si atom. In the second O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Al, and one Si atom. In the third O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the fourth O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. 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 bent 150 degrees geometry to two Si atoms. In the seventh O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eighth O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the ninth O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the tenth O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Al, and one Si atom. In the eleventh O site, O is bonded in a distorted trigonal planar geometry to one Ca, one Al, and one Si atom. In the twelfth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the thirteenth O site, O is bonded in an L-shaped geometry to one Ca and one O atom. The O–O bond length is 1.24 Å. In the fourteenth O site, O is bonded in a distorted single-bond geometry to one Ca and two O atoms. The O–O bond length is 1.94 Å.