DOE OSTI2020
Ca2FeNbO6 is Orthorhombic Perovskite-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.78 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 30°. There are four shorter (2.02 Å) and two longer (2.03 Å) Nb–O bond lengths. Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent NbO6 octahedra. The corner-sharing octahedral tilt angles are 30°. There are two shorter (2.04 Å) and four longer (2.05 Å) Fe–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ca2+, one Nb5+, and one Fe3+ atom to form distorted corner-sharing OCa2NbFe tetrahedra. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent Ca2+, one Nb5+, and one Fe3+ atom. In the third O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent Ca2+, one Nb5+, and one Fe3+ atom.