Materials Data on Mg2Al3(SiO3)6 by Materials Project

Abstract

(MgAl(SiO3)3)2Al crystallizes in the orthorhombic Cccm space group. The structure is three-dimensional and consists of four aluminum molecules and one MgAl(SiO3)3 framework. In the MgAl(SiO3)3 framework, Mg is bonded to six O atoms to form distorted MgO6 pentagonal pyramids that share corners with four SiO4 tetrahedra and faces with two equivalent AlO6 pentagonal pyramids. There are two shorter (1.89 Å) and four longer (2.13 Å) Mg–O bond lengths. Al is bonded to six O atoms to form distorted AlO6 pentagonal pyramids that share corners with four SiO4 tetrahedra and faces with two equivalent MgO6 pentagonal pyramids. There are a spread of Al–O bond distances ranging from 1.91–2.01 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 pentagonal pyramids, corners with two equivalent AlO6 pentagonal pyramids, and a cornercorner with one SiO4 tetrahedra. There is three shorter (1.64 Å) and one longer (1.78 Å) Si–O bond length. In the second Si site, Si is bonded in a water-like geometry to two O atoms. Both Si–O bond lengths are 1.64 Å. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent MgO6 pentagonal pyramids, corners with two equivalent AlO6 pentagonal pyramids, and a cornercorner with one SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.64–1.77 Å. There are six inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to one Mg, one Al, and one Si atom. In the second O site, O is bonded in a distorted linear geometry to two Si atoms. In the third O site, O is bonded in a 2-coordinate geometry to one Mg and one Al atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. 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 distorted trigonal planar geometry to one Mg, one Al, and one Si atom.