DOI: 10.17188/1692971
title: Materials Data on Fe7(SiO4)4 by Materials Project

description: Fe7(SiO4)4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four 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 four equivalent FeO6 octahedra, corners with two equivalent SiO4 tetrahedra, edges with four FeO6 octahedra, and edges with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–66°. There are a spread of Fe–O bond distances ranging from 2.16–2.25 Å. In the second Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, corners with two SiO4 tetrahedra, edges with three FeO6 octahedra, and edges with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–66°. There are a spread of Fe–O bond distances ranging from 2.09–2.25 Å. In the third Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight FeO6 octahedra, corners with four SiO4 tetrahedra, edges with two FeO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–66°. There are a spread of Fe–O bond distances ranging from 2.12–2.33 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 six FeO6 octahedra, corners with four SiO4 tetrahedra, an edgeedge with one FeO6 octahedra, and an edgeedge with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–66°. There are a spread of Fe–O bond distances ranging from 1.99–2.15 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six FeO6 octahedra and edges with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–62°. There are a spread of Si–O bond distances ranging from 1.64–1.67 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with five FeO6 octahedra and edges with two FeO6 octahedra. The corner-sharing octahedra tilt angles range from 45–60°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Fe+2.29+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Fe+2.29+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted 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 distorted rectangular see-saw-like geometry to three Fe+2.29+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Fe+2.29+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Fe+2.29+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Fe+2.29+ and one Si4+ atom.