Materials Data on BaCo4O7 by Materials Project
BaCo4O7 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form distorted BaO12 cuboctahedra that share corners with twelve equivalent BaO12 cuboctahedra and edges with twelve CoO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.95–3.31 Å. There are two inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six CoO4 tetrahedra and edges with three equivalent BaO12 cuboctahedra. There are a spread of Co–O bond distances ranging from 1.78–2.01 Å. In the second Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with six equivalent CoO4 tetrahedra and edges with three equivalent BaO12 cuboctahedra. There is three shorter (1.82 Å) and one longer (1.90 Å) Co–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Ba2+ and two Co3+ atoms. In the second O2- site, O2- is bonded in a tetrahedral geometry to four Co3+ atoms. In the third O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Ba2+ and two equivalent Co3+ atoms.