Materials Data on Mg3Si4O13 by Materials Project

(Mg3Si4O12)2O2 crystallizes in the monoclinic Cm space group. The structure is two-dimensional and consists of two water molecules and one Mg3Si4O12 sheet oriented in the (0, 0, 1) direction. In the Mg3Si4O12 sheet, there are two 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 2.02–2.15 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 equivalent MgO6 octahedra. There are two shorter (2.06 Å) and four longer (2.11 Å) Mg–O bond lengths. There are two 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 56–58°. There is two shorter (1.64 Å) and two longer (1.65 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 56–58°. All Si–O bond lengths are 1.64 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the second O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the third O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the fourth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the fifth O site, O is bonded in a rectangular see-saw-like geometry to three Mg and one Si atom. In the sixth O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the seventh O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. In the eighth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms.