Materials Data on Mg2SiO4 by Materials Project

Abstract

Mg2SiO4 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent SiO6 octahedra, edges with two equivalent MgO6 octahedra, and edges with three equivalent SiO6 octahedra. The corner-sharing octahedra tilt angles range from 7–53°. There are a spread of Mg–O bond distances ranging from 2.02–2.12 Å. In the second Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.03–2.59 Å. Si4+ is bonded to six O2- atoms to form SiO6 octahedra that share corners with three equivalent MgO6 octahedra, edges with two equivalent SiO6 octahedra, and edges with three equivalent MgO6 octahedra. The corner-sharing octahedra tilt angles range from 7–53°. There are a spread of Si–O bond distances ranging from 1.73–1.90 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Mg2+ and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded to three Mg2+ and two equivalent Si4+ atoms to form distorted OMg3Si2 square pyramids that share corners with five equivalent OMg3Si tetrahedra, corners with two equivalent OMg4Si trigonal bipyramids, edges with two equivalent OMg3Si2 square pyramids, an edgeedge with one OMg3Si tetrahedra, and edges with three equivalent OMg4Si trigonal bipyramids. In the third O2- site, O2- is bonded to four Mg2+ and one Si4+ atom to form distorted OMg4Si trigonal bipyramids that share corners with two equivalent OMg3Si2 square pyramids, corners with five equivalent OMg3Si tetrahedra, edges with three equivalent OMg3Si2 square pyramids, an edgeedge with one OMg3Si tetrahedra, and edges with two equivalent OMg4Si trigonal bipyramids. In the fourth O2- site, O2- is bonded to three Mg2+ and one Si4+ atom to form distorted OMg3Si tetrahedra that share corners with five equivalent OMg3Si2 square pyramids, corners with two equivalent OMg3Si tetrahedra, corners with five equivalent OMg4Si trigonal bipyramids, an edgeedge with one OMg3Si2 square pyramid, and an edgeedge with one OMg4Si trigonal bipyramid.