DOI: 10.17188/1666960
title: Materials Data on CaAl2Si6(HO4)4 by Materials Project

description: CaAl2Si6O16(H2)2 crystallizes in the monoclinic Pc space group. The structure is three-dimensional and consists of eight hydrogen molecules and one CaAl2Si6O16 framework. In the CaAl2Si6O16 framework, Ca2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.43 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with four SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.72–1.81 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with four SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.72–1.82 Å. There are six inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- 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 1.62–1.65 Å. In the second Si4+ site, Si4+ is bonded to four O2- 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 1.60–1.64 Å. In the third Si4+ site, Si4+ is bonded to four O2- 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 1.60–1.65 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- 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 1.60–1.65 Å. In the fifth Si4+ site, Si4+ is bonded to four O2- 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 1.62–1.64 Å. In the sixth Si4+ site, Si4+ is bonded to four O2- 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 1.61–1.64 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Al3+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Al3+, and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the thirteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Al3+, and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Al3+, and one Si4+ atom.