DOI: 10.17188/1287085
title: Materials Data on Fe2O3 by Materials Project

description: Fe2O3 crystallizes in the trigonal P3 space group. The structure is three-dimensional. there are eight inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form distorted FeO4 trigonal pyramids that share corners with two FeO6 octahedra, corners with six equivalent FeO4 trigonal pyramids, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 18–49°. There are a spread of Fe–O bond distances ranging from 1.80–2.03 Å. In the second Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with four FeO6 octahedra, corners with six equivalent FeO4 tetrahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 20–63°. There are a spread of Fe–O bond distances ranging from 1.91–2.02 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra, edges with six FeO6 octahedra, and a faceface with one FeO6 octahedra. There are three shorter (2.10 Å) and three longer (2.11 Å) Fe–O bond lengths. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO6 octahedra, corners with three equivalent FeO4 trigonal pyramids, edges with three equivalent FeO4 trigonal pyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–51°. There are three shorter (2.04 Å) and three longer (2.17 Å) Fe–O bond lengths. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra, edges with three equivalent FeO4 tetrahedra, and a faceface with one FeO6 octahedra. There is three shorter (1.80 Å) and three longer (2.10 Å) Fe–O bond length. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO6 octahedra, corners with three equivalent FeO4 tetrahedra, and edges with six FeO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are three shorter (2.05 Å) and three longer (2.10 Å) Fe–O bond lengths. In the seventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO6 octahedra, corners with three equivalent FeO4 tetrahedra, and edges with six FeO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are three shorter (2.08 Å) and three longer (2.09 Å) Fe–O bond lengths. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 trigonal pyramids and a faceface with one FeO6 octahedra. There is three shorter (1.85 Å) and three longer (1.97 Å) Fe–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a see-saw-like geometry to four Fe3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe3+ atoms. In the third O2- site, O2- is bonded to four Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe4 trigonal pyramids. In the fourth O2- site, O2- is bonded in an L-shaped geometry to two Fe3+ atoms. In the fifth O2- site, O2- is bonded in a see-saw-like geometry to four Fe3+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two Fe3+ atoms.