Materials Data on Mg2SiO4 by Materials Project

Abstract

Mg2SiO4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share a cornercorner with one MgO6 octahedra, corners with five equivalent SiO4 tetrahedra, an edgeedge with one SiO6 octahedra, and edges with four MgO6 octahedra. The corner-sharing octahedral tilt angles are 18°. There are a spread of Mg–O bond distances ranging from 2.00–2.38 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with five MgO6 octahedra, a cornercorner with one SiO4 tetrahedra, edges with three equivalent SiO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 9–28°. There are a spread of Mg–O bond distances ranging from 1.97–2.25 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent SiO6 octahedra, edges with two equivalent SiO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–18°. There are a spread of Mg–O bond distances ranging from 2.10–2.27 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with three equivalent MgO6 octahedra, corners with three equivalent SiO4 tetrahedra, edges with two equivalent SiO6 octahedra, and edges with five MgO6 octahedra. The corner-sharing octahedra tilt angles range from 11–28°. There are a spread of Mg–O bond distances ranging from 1.99–2.34 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four equivalent MgO6 octahedra, edges with four equivalent SiO6 octahedra, and edges with six MgO6 octahedra. The corner-sharing octahedra tilt angles range from 9–15°. There are four shorter (2.03 Å) and two longer (2.13 Å) Mg–O bond lengths. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to six O2- atoms to form SiO6 octahedra that share corners with two equivalent MgO6 octahedra, a cornercorner with one SiO4 tetrahedra, an edgeedge with one SiO6 octahedra, and edges with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–12°. There are a spread of Si–O bond distances ranging from 1.73–1.92 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO6 octahedra and corners with nine MgO6 octahedra. The corner-sharing octahedra tilt angles range from 49–69°. There are a spread of Si–O bond distances ranging from 1.63–1.75 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Mg2+ and one Si4+ atom. In the second O2- site, O2- is bonded to four Mg2+ and one Si4+ atom to form distorted OMg4Si square pyramids that share corners with four OMg4Si square pyramids, corners with two OMg2Si2 trigonal pyramids, edges with three equivalent OMg5Si octahedra, an edgeedge with one OMg3Si2 square pyramid, and edges with two OMg2Si2 trigonal pyramids. In the third O2- site, O2- is bonded to two Mg2+ and two Si4+ atoms to form distorted OMg2Si2 trigonal pyramids that share corners with three OMg4Si square pyramids, corners with two equivalent OMg3Si trigonal pyramids, an edgeedge with one OMg5Si octahedra, and an edgeedge with one OMg4Si square pyramid. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded to three Mg2+ and one Si4+ atom to form distorted OMg3Si trigonal pyramids that share corners with two equivalent OMg5Si octahedra, corners with two OMg4Si square pyramids, corners with three OMg2Si2 trigonal pyramids, edges with two equivalent OMg5Si octahedra, and edges with three OMg3Si2 square pyramids. The corner-sharing octahedra tilt angles range from 4–13°. In the sixth O2- site, O2- is bonded to three Mg2+ and two equivalent Si4+ atoms to form OMg3Si2 square pyramids that share corners with five OMg4Si square pyramids, corners with three OMg2Si2 trigonal pyramids, edges with four equivalent OMg5Si octahedra, edges with two OMg3Si2 square pyramids, and edges with two equivalent OMg3Si trigonal pyramids. In the seventh O2- site, O2- is bonded to five Mg2+ and one Si4+ atom to form OMg5Si octahedra that share corners with two equivalent OMg5Si octahedra, corners with two equivalent OMg3Si trigonal pyramids, an edgeedge with one OMg5Si octahedra, edges with seven OMg4Si square pyramids, and edges with three OMg2Si2 trigonal pyramids. The corner-sharing octahedral tilt angles are 0°. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Mg2+ and one Si4+ atom.