DOI: 10.17188/1709512
title: Materials Data on Mg3Si2O9 by Materials Project

description: (MgO2)3Mg3Si4O12 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of two Mg3Si4O12 sheets oriented in the (0, 0, 1) direction and two MgO2 sheets oriented in the (0, 0, 1) direction. In each Mg3Si4O12 sheet, there are three inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.09–2.13 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.01–2.20 Å. In the third Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.22 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 three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is one shorter (1.65 Å) and three longer (1.66 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 three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is one shorter (1.65 Å) and three longer (1.66 Å) Si–O bond length. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is one shorter (1.65 Å) and three longer (1.66 Å) Si–O bond length. In the fourth Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–60°. There is one shorter (1.65 Å) and three longer (1.66 Å) Si–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the second O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. 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 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 to three Mg and one Si atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the seventh O site, O is bonded to three Mg and one Si atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the eighth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the ninth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the tenth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the eleventh O site, O is bonded to three Mg and one Si atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In the twelfth O site, O is bonded to three Mg and one Si atom to form a mixture of distorted corner and edge-sharing OMg3Si trigonal pyramids. In each MgO2 sheet, there are three inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form distorted edge-sharing MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.94–2.08 Å. In the second Mg site, Mg is bonded to six O atoms to form distorted edge-sharing MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.94–2.08 Å. In the third Mg site, Mg is bonded to six O atoms to form distorted edge-sharing MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.93–2.09 Å. There are six inequivalent O sites. In the first O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the second O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the third O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the fourth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the fifth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the sixth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms.