Materials Data on Fe3Si2O9 by Materials Project

Abstract

(FeO2)3Fe3(SiO3)4 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Fe3(SiO3)4 sheet oriented in the (0, 0, 1) direction and one FeO2 sheet oriented in the (0, 0, 1) direction. In the Fe3(SiO3)4 sheet, there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with four equivalent SiO4 tetrahedra and edges with six equivalent FeO6 octahedra. There are two shorter (1.96 Å) and four longer (2.10 Å) Fe–O bond lengths. In the second Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with four equivalent SiO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.18 Å. Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three FeO6 octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There is three shorter (1.62 Å) and one longer (1.69 Å) Si–O bond length. There are four inequivalent O sites. In the first O site, O is bonded in a rectangular see-saw-like geometry to three Fe and one Si atom. In the second O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the third O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the fourth O site, O is bonded in a bent 150 degrees geometry to two equivalent Si atoms. In the FeO2 sheet, there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There are four shorter (1.95 Å) and two longer (2.11 Å) Fe–O bond lengths. In the second Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.10 Å. There are two inequivalent O sites. In the first O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the second O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms.