Materials Data on Ca(FeO2)4 by Materials Project
Ca(FeO2)4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Ca is bonded in a 4-coordinate geometry to four O atoms. There are two shorter (2.35 Å) and two longer (2.39 Å) Ca–O bond lengths. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Fe–O bond distances ranging from 1.92–2.05 Å. In the second Fe site, Fe is bonded to six O atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–60°. There are a spread of Fe–O bond distances ranging from 1.93–2.23 Å. In the third Fe site, Fe is bonded to six O atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–55°. There are a spread of Fe–O bond distances ranging from 1.90–2.02 Å. In the fourth Fe site, Fe is bonded to six O atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Fe–O bond distances ranging from 1.96–2.15 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 3-coordinate geometry to three Fe atoms. In the third O site, O is bonded in a distorted trigonal planar geometry to three Fe atoms. In the fourth O site, O is bonded in a distorted trigonal planar geometry to three Fe atoms. In the fifth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the sixth O site, O is bonded to two equivalent Ca and three Fe atoms to form a mixture of distorted corner and edge-sharing OCa2Fe3 trigonal bipyramids. In the seventh O site, O is bonded to two equivalent Ca and three Fe atoms to form a mixture of corner and edge-sharing OCa2Fe3 trigonal bipyramids. In the eighth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms.