DOI: 10.17188/1720721
title: Materials Data on Ca2MgAl2Si3O14 by Materials Project

description: Ca2MgAl2Si3O14 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.59 Å. In the second Ca site, Ca is bonded to seven O atoms to form distorted CaO7 pentagonal bipyramids that share corners with five SiO4 tetrahedra, edges with two equivalent MgO6 octahedra, edges with two equivalent AlO6 octahedra, and an edgeedge with one SiO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.51 Å. Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra, edges with two equivalent MgO6 octahedra, and edges with two equivalent CaO7 pentagonal bipyramids. There are a spread of Mg–O bond distances ranging from 1.98–2.16 Å. Al is bonded to six O atoms to form AlO6 octahedra that share corners with four SiO4 tetrahedra, edges with two equivalent AlO6 octahedra, and an edgeedge with one CaO7 pentagonal bipyramid. There are a spread of Al–O bond distances ranging from 1.86–2.08 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 equivalent MgO6 octahedra, corners with four equivalent AlO6 octahedra, and corners with two equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 48–55°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with four equivalent AlO6 octahedra, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent MgO6 octahedra, corners with three equivalent CaO7 pentagonal bipyramids, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Si–O bond distances ranging from 1.62–1.70 Å. There are eleven 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 rectangular see-saw-like geometry to one Ca, two equivalent Mg, and one Si atom. In the third O site, O is bonded in a trigonal non-coplanar geometry to one Ca and two equivalent Mg atoms. In the fourth O site, O is bonded in a water-like geometry to two equivalent Al atoms. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Ca and one Si atom. In the sixth O site, O is bonded in a 4-coordinate geometry to two Ca, one Mg, and one Si atom. In the seventh O site, O is bonded in a water-like geometry to two equivalent Al atoms. In the eighth O site, O is bonded in a trigonal planar geometry to one Ca, one Al, and one Si atom. In the ninth O site, O is bonded in a distorted trigonal pyramidal geometry to one Ca, two equivalent Al, and one Si atom. In the tenth O site, O is bonded in a 3-coordinate geometry to one Ca and two Si atoms. In the eleventh O site, O is bonded in a 3-coordinate geometry to two equivalent Al and one Si atom.