Materials Data on Ca2Nb2CoO9 by Materials Project
Ca2Nb2CoO9 is Orthorhombic Perovskite-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.77 Å. In the second Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.64 Å. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three NbO6 octahedra and corners with three CoO6 octahedra. The corner-sharing octahedra tilt angles range from 19–33°. There are a spread of Nb–O bond distances ranging from 1.94–2.13 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three NbO6 octahedra and corners with three CoO6 octahedra. The corner-sharing octahedra tilt angles range from 21–29°. There are a spread of Nb–O bond distances ranging from 1.93–2.10 Å. There are two inequivalent Co4+ sites. In the first Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six NbO6 octahedra. The corner-sharing octahedra tilt angles range from 21–29°. There is two shorter (1.90 Å) and four longer (1.91 Å) Co–O bond length. In the second Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six NbO6 octahedra. The corner-sharing octahedra tilt angles range from 19–24°. There are a spread of Co–O bond distances ranging from 1.90–1.92 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+ and two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+, one Nb5+, and one Co4+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Nb5+, and one Co4+ atom. In the fifth O2- site, O2- is bonded to two Ca2+, one Nb5+, and one Co4+ atom to form distorted corner-sharing OCa2NbCo trigonal pyramids. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+, one Nb5+, and one Co4+ atom. In the seventh O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+ and two Nb5+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Nb5+, and one Co4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Nb5+, and one Co4+ atom.