Materials Data on Ba3Nb2CoO9 by Materials Project
Ba3CoNb2O9 is (Cubic) Perovskite-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, faces with three equivalent CoO6 octahedra, and faces with five equivalent NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.88–2.99 Å. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, faces with two equivalent CoO6 octahedra, and faces with six equivalent NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.91–2.94 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three equivalent NbO6 octahedra, corners with three equivalent CoO6 octahedra, and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Nb–O bond distances ranging from 1.95–2.13 Å. Co2+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent NbO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–4°. There are four shorter (2.10 Å) and two longer (2.24 Å) Co–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+, one Nb5+, and one Co2+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to four Ba2+, one Nb5+, and one Co2+ atom. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Nb5+ atoms.