Materials Data on Mg3(SiO3)4 by Materials Project

Mg3Si4O12 crystallizes in the monoclinic Cc space group. The structure is two-dimensional and consists of two Mg3Si4O12 sheets oriented in the (0, 0, 1) direction. 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 2.02–2.14 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four 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 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 two shorter (2.06 Å) and four longer (2.11 Å) Mg–O bond lengths. 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 56–58°. There is three shorter (1.64 Å) and one 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 56–59°. There is three shorter (1.64 Å) and one longer (1.65 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 56–58°. There is three shorter (1.64 Å) and one longer (1.65 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 56–59°. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the third O site, O is bonded in a distorted 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. 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 bent 150 degrees geometry to two Si atoms. In the seventh O site, O is bonded in a bent 150 degrees geometry to two Si atoms. 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 in a trigonal non-coplanar geometry to three Mg atoms. In the twelfth O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms.