Materials Data on Fe7(SiO6)2 by Materials Project
Fe7(SiO6)2 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are five inequivalent Fe+2.29+ sites. In the first Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with six FeO6 octahedra. There are two shorter (2.04 Å) and four longer (2.22 Å) Fe–O bond lengths. In the second Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with six FeO6 octahedra. There are two shorter (1.98 Å) and four longer (2.15 Å) Fe–O bond lengths. In the third Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.08–2.24 Å. In the fourth Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four equivalent SiO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.08–2.22 Å. In the fifth Fe+2.29+ site, Fe+2.29+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 53–59°. There is two shorter (1.90 Å) and two longer (1.94 Å) Fe–O bond length. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–53°. There are a spread of Si–O bond distances ranging from 1.67–1.69 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe+2.29+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe+2.29+ and one Si4+ atom. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe+2.29+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe+2.29+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.29+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.29+ atoms.