DOI: 10.17188/1318608
title: Materials Data on Mg(FeO2)4 by Materials Project

description: Mg(FeO2)4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Mg is bonded to five O atoms to form MgO5 square pyramids that share corners with six FeO6 octahedra, edges with three FeO6 octahedra, edges with two equivalent MgO5 square pyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 5–55°. There are a spread of Mg–O bond distances ranging from 2.05–2.15 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form distorted FeO6 octahedra that share corners with four FeO6 octahedra, edges with four FeO6 octahedra, and edges with two equivalent MgO5 square pyramids. The corner-sharing octahedra tilt angles range from 48–53°. There are a spread of Fe–O bond distances ranging from 1.92–2.24 Å. In the second Fe site, Fe is bonded to six O atoms to form distorted FeO6 octahedra that share corners with four FeO6 octahedra, corners with two equivalent MgO5 square pyramids, edges with four FeO6 octahedra, and a faceface with one MgO5 square pyramid. The corner-sharing octahedra tilt angles range from 48–54°. There are a spread of Fe–O bond distances ranging from 1.88–2.19 Å. In the third Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, corners with two equivalent MgO5 square pyramids, and edges with four FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–53°. There are a spread of Fe–O bond distances ranging from 1.95–2.13 Å. In the fourth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, corners with two equivalent MgO5 square pyramids, edges with four FeO6 octahedra, and an edgeedge with one MgO5 square pyramid. The corner-sharing octahedra tilt angles range from 51–54°. There are a spread of Fe–O bond distances ranging from 1.93–2.16 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the second O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the third O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the fourth O site, O is bonded to one Mg and three Fe atoms to form OMgFe3 trigonal pyramids that share corners with two equivalent OMgFe3 trigonal pyramids, edges with two equivalent OMg2Fe3 square pyramids, and edges with two equivalent OMg2Fe3 trigonal bipyramids. In the fifth O site, O is bonded in a trigonal non-coplanar geometry to three Fe atoms. In the sixth O site, O is bonded to two equivalent Mg and three Fe atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with two equivalent OMg2Fe3 square pyramids, an edgeedge with one OMg2Fe3 square pyramid, edges with two equivalent OMg2Fe3 trigonal bipyramids, and edges with two equivalent OMgFe3 trigonal pyramids. In the seventh O site, O is bonded to two equivalent Mg and three Fe atoms to form OMg2Fe3 square pyramids that share corners with two equivalent OMg2Fe3 trigonal bipyramids, edges with two equivalent OMg2Fe3 square pyramids, an edgeedge with one OMg2Fe3 trigonal bipyramid, and edges with two equivalent OMgFe3 trigonal pyramids. In the eighth O site, O is bonded in a trigonal non-coplanar geometry to three Fe atoms.