DOI: 10.17188/1322675
title: Materials Data on CaCoNi2O7 by Materials Project

description: CaCoNi2O7 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 2.33–2.92 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 2.31–2.98 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 three NiO4 tetrahedra, corners with three NiO5 trigonal bipyramids, an edgeedge with one CoO6 octahedra, and an edgeedge with one NiO5 trigonal bipyramid. There are a spread of Co–O bond distances ranging from 1.76–1.97 Å. In the second Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with four NiO4 tetrahedra, corners with two equivalent NiO5 trigonal bipyramids, and an edgeedge with one CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.84–1.91 Å. There are four inequivalent Ni4+ sites. In the first Ni4+ site, Ni4+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with three CoO6 octahedra and a cornercorner with one NiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 49–58°. There are a spread of Ni–O bond distances ranging from 1.78–1.84 Å. In the second Ni4+ site, Ni4+ is bonded to five O2- atoms to form NiO5 trigonal bipyramids that share corners with two equivalent CoO6 octahedra, a cornercorner with one NiO4 tetrahedra, and an edgeedge with one NiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 33–46°. There are a spread of Ni–O bond distances ranging from 1.79–1.97 Å. In the third Ni4+ site, Ni4+ is bonded to five O2- atoms to form distorted NiO5 trigonal bipyramids that share corners with three CoO6 octahedra, a cornercorner with one NiO4 tetrahedra, an edgeedge with one CoO6 octahedra, and an edgeedge with one NiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 42–63°. There are a spread of Ni–O bond distances ranging from 1.82–2.04 Å. In the fourth Ni4+ site, Ni4+ is bonded to four O2- atoms to form NiO4 tetrahedra that share corners with four CoO6 octahedra and a cornercorner with one NiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 43–67°. There are a spread of Ni–O bond distances ranging from 1.80–1.87 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one Ni4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Co4+, and one Ni4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ca2+, one Co4+, and one Ni4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Co4+, and one Ni4+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Co4+, and one Ni4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, two Co4+, and one Ni4+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Co4+, and one Ni4+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one Ni4+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two Ni4+ atoms. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ca2+ and two Ni4+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Co4+ and one Ni4+ atom. In the twelfth O2- site, O2- is bonded in a distorted tetrahedral geometry to one Ca2+, one Co4+, and two Ni4+ atoms. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one Co4+, and one Ni4+ atom. In the fourteenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Co4+ and two Ni4+ atoms.