Materials Data on CaAl2Si3O13 by Materials Project

CaAl2Si3O13 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Ca is bonded to seven O atoms to form CaO7 pentagonal bipyramids that share corners with two AlO4 tetrahedra, corners with two equivalent SiO4 tetrahedra, an edgeedge with one AlO4 tetrahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.36–2.64 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 a cornercorner with one CaO7 pentagonal bipyramid and corners with four SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.74–1.78 Å. In the second Al site, Al is bonded to four O atoms to form AlO4 tetrahedra that share a cornercorner with one CaO7 pentagonal bipyramid, corners with four SiO4 tetrahedra, and an edgeedge with one CaO7 pentagonal bipyramid. There are a spread of Al–O bond distances ranging from 1.76–1.79 Å. There are three inequivalent Si sites. In the first 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 is three shorter (1.63 Å) and one longer (1.64 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 CaO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, and corners with three AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra, corners with three AlO4 tetrahedra, and an edgeedge with one CaO7 pentagonal bipyramid. There are a spread of Si–O bond distances ranging from 1.61–1.65 Å. There are thirteen 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 3-coordinate 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 two Si atoms. In the sixth O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom. In the seventh O site, O is bonded in a single-bond geometry to one Ca atom. In the eighth O site, O is bonded in a single-bond geometry to one Ca atom. In the ninth O site, O is bonded in a single-bond geometry to one Ca atom. In the tenth O site, O is bonded in a bent 120 degrees geometry to 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 3-coordinate geometry to one Ca, one Al, and one Si atom. In the thirteenth O site, O is bonded in a bent 150 degrees geometry to one Al and one Si atom.