DOI: 10.17188/1740122
title: Materials Data on Mg2Fe5(SiO3)8 by Materials Project

description: Mg2Fe5(SiO3)8 crystallizes in the monoclinic C2 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 four SiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five FeO6 octahedra. There are two shorter (2.05 Å) and four longer (2.14 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six SiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with two equivalent FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.17 Å. There are five inequivalent Fe+2.40+ sites. In the first Fe+2.40+ site, Fe+2.40+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Fe–O bond distances ranging from 2.03–2.68 Å. In the second Fe+2.40+ site, Fe+2.40+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.02 Å) and two longer (2.18 Å) Fe–O bond lengths. In the third Fe+2.40+ site, Fe+2.40+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six SiO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with two equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.09–2.21 Å. In the fourth Fe+2.40+ site, Fe+2.40+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four SiO4 tetrahedra, an edgeedge with one FeO6 octahedra, and edges with four MgO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.25 Å. In the fifth Fe+2.40+ site, Fe+2.40+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four SiO4 tetrahedra, edges with two equivalent MgO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.23 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra, corners with two MgO6 octahedra, and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–63°. There are a spread of Si–O bond distances ranging from 1.62–1.64 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with two FeO6 octahedra, and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–62°. There is one shorter (1.62 Å) and three longer (1.64 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with two FeO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–61°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with two FeO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–59°. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Fe+2.40+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Mg2+, one Fe+2.40+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Fe+2.40+ and two Si4+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Mg2+ and two Fe+2.40+ atoms. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mg2+, one Fe+2.40+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+, two Fe+2.40+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the tenth O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to one Mg2+, two Fe+2.40+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe+2.40+ and one Si4+ atom.