Materials Data on Fe4SiO9 by Materials Project

Fe4SiO9 crystallizes in the trigonal P3_1 space group. The structure is two-dimensional and consists of three Fe4SiO9 sheets oriented in the (0, 0, 1) direction. there are four inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra, a cornercorner with one SiO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.21 Å. In the second Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra, a cornercorner with one SiO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.89–2.17 Å. In the third Fe site, Fe is bonded to four O atoms to form FeO4 tetrahedra that share corners with three FeO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–59°. There is three shorter (1.83 Å) and one longer (1.99 Å) Fe–O bond length. In the fourth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra, a cornercorner with one SiO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.94–2.18 Å. Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three FeO6 octahedra and corners with three equivalent FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–56°. There is three shorter (1.62 Å) and one longer (1.70 Å) Si–O bond length. There are nine inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Fe and one Si atom. In the second O site, O is bonded in a trigonal non-coplanar geometry to three Fe atoms. In the third O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the fourth O site, O is bonded in a bent 120 degrees geometry to one Fe and one Si atom. In the fifth O site, O is bonded in a rectangular see-saw-like geometry to three Fe and one Si atom. In the sixth O site, O is bonded in a distorted trigonal pyramidal geometry to four Fe atoms. In the seventh O site, O is bonded in a bent 120 degrees geometry to one Fe and one Si atom. In the eighth O site, O is bonded in a trigonal non-coplanar geometry to three Fe atoms. In the ninth O site, O is bonded in a trigonal non-coplanar geometry to three Fe atoms.