Materials Data on BaErFe4O7 by Materials Project
BaErFe4O7 crystallizes in the cubic F-43m space group. The structure is three-dimensional. Ba2+ is bonded to twelve equivalent O2- atoms to form BaO12 cuboctahedra that share corners with twelve equivalent BaO12 cuboctahedra, edges with twelve equivalent FeO4 tetrahedra, and faces with four equivalent ErO6 octahedra. All Ba–O bond lengths are 3.24 Å. Er3+ is bonded to six equivalent O2- atoms to form ErO6 octahedra that share corners with twelve equivalent FeO4 tetrahedra and faces with four equivalent BaO12 cuboctahedra. All Er–O bond lengths are 2.25 Å. Fe+2.25+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent ErO6 octahedra, corners with six equivalent FeO4 tetrahedra, and edges with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 51°. There are three shorter (1.98 Å) and one longer (2.09 Å) Fe–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ba2+, one Er3+, and two equivalent Fe+2.25+ atoms. In the second O2- site, O2- is bonded in a tetrahedral geometry to four equivalent Fe+2.25+ atoms.