DOI: 10.17188/1318978
title: Materials Data on CaCoO2 by Materials Project

description: CaCoO2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with two equivalent CoO4 trigonal pyramids, edges with seven CaO6 octahedra, and an edgeedge with one CoO4 trigonal pyramid. The corner-sharing octahedral tilt angles are 1°. There are a spread of Ca–O bond distances ranging from 2.28–2.83 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO6 octahedra, corners with two equivalent CoO4 trigonal pyramids, edges with seven CaO6 octahedra, and edges with three equivalent CoO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 1°. There are a spread of Ca–O bond distances ranging from 2.32–2.46 Å. There are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Co–O bond distances ranging from 1.92–2.02 Å. In the second Co2+ site, Co2+ is bonded to four O2- atoms to form distorted CoO4 trigonal pyramids that share corners with four CaO6 octahedra, corners with two equivalent CoO4 trigonal pyramids, and edges with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 7–85°. There are a spread of Co–O bond distances ranging from 1.96–2.14 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+ and three Co2+ atoms to form distorted OCaCo3 tetrahedra that share corners with two equivalent OCa5Co octahedra, corners with six OCa3Co2 square pyramids, corners with two equivalent OCaCo3 tetrahedra, an edgeedge with one OCa5Co octahedra, and an edgeedge with one OCa3Co2 square pyramid. The corner-sharing octahedra tilt angles range from 13–82°. In the second O2- site, O2- is bonded to three equivalent Ca2+ and two equivalent Co2+ atoms to form OCa3Co2 square pyramids that share corners with two equivalent OCa5Co octahedra, corners with three equivalent OCa3Co2 square pyramids, corners with two equivalent OCaCo3 tetrahedra, edges with three equivalent OCa5Co octahedra, and edges with four equivalent OCa3Co2 square pyramids. The corner-sharing octahedral tilt angles are 13°. In the third O2- site, O2- is bonded to three Ca2+ and two equivalent Co2+ atoms to form distorted OCa3Co2 square pyramids that share corners with two equivalent OCa5Co octahedra, corners with three equivalent OCa3Co2 square pyramids, corners with four equivalent OCaCo3 tetrahedra, edges with three equivalent OCa5Co octahedra, edges with two equivalent OCa3Co2 square pyramids, and an edgeedge with one OCaCo3 tetrahedra. The corner-sharing octahedral tilt angles are 13°. In the fourth O2- site, O2- is bonded to five Ca2+ and one Co2+ atom to form distorted OCa5Co octahedra that share corners with four OCa3Co2 square pyramids, corners with two equivalent OCaCo3 tetrahedra, edges with four equivalent OCa5Co octahedra, edges with six OCa3Co2 square pyramids, and an edgeedge with one OCaCo3 tetrahedra.