Materials Data on Mg3(SiO3)4 by Materials Project

Mg3Si4O12 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Mg3Si4O12 sheet oriented in the (0, 0, 1) direction. 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 equivalent SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.14 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four equivalent 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. 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 three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. 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 bent 150 degrees geometry to two equivalent Si atoms. In the third O site, O is bonded in a rectangular see-saw-like geometry to three Mg and one Si atom. In the fourth O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. The O–Si bond length is 1.65 Å. In the fifth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the sixth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms.