Materials Data on BaCaFe4O7 by Materials Project
CaBaFe4O7 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Ba2+ is bonded in a 3-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.66–3.35 Å. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with twelve FeO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.35–2.42 Å. There are four inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with six FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Fe–O bond distances ranging from 1.98–2.13 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with six FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–65°. There are a spread of Fe–O bond distances ranging from 1.89–1.96 Å. In the third Fe+2.50+ site, Fe+2.50+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with six FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–70°. There are a spread of Fe–O bond distances ranging from 1.96–2.26 Å. In the fourth Fe+2.50+ site, Fe+2.50+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with six FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–61°. There are a spread of Fe–O bond distances ranging from 1.90–1.99 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ba2+, one Ca2+, and two Fe+2.50+ atoms to form distorted corner-sharing OBaCaFe2 tetrahedra. In the second O2- site, O2- is bonded to four Fe+2.50+ atoms to form corner-sharing OFe4 tetrahedra. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ba2+, one Ca2+, and two Fe+2.50+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ba2+, one Ca2+, and two Fe+2.50+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ba2+, one Ca2+, and two Fe+2.50+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, one Ca2+, and two Fe+2.50+ atoms. In the seventh O2- site, O2- is bonded to one Ba2+, one Ca2+, and two Fe+2.50+ atoms to form distorted corner-sharing OBaCaFe2 tetrahedra.