DOI: 10.17188/1319486
title: Materials Data on CaCoO2 by Materials Project

description: CaCoO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CoO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with two equivalent CoO5 square pyramids. There are a spread of Ca–O bond distances ranging from 2.24–2.70 Å. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.66 Å. In the third Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.18–3.02 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.54 Å. There are four inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Co–O bond distances ranging from 1.93–2.04 Å. In the second Co2+ site, Co2+ is bonded to five O2- atoms to form CoO5 square pyramids that share corners with two equivalent CoO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with two equivalent CoO5 square pyramids. There are a spread of Co–O bond distances ranging from 1.98–2.11 Å. In the third Co2+ site, Co2+ is bonded to four O2- atoms to form CoO4 tetrahedra that share a cornercorner with one CaO6 octahedra, corners with two equivalent CoO5 square pyramids, and corners with two equivalent CoO4 tetrahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Co–O bond distances ranging from 1.87–2.04 Å. In the fourth Co2+ site, Co2+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of Co–O bond distances ranging from 1.93–1.96 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to four Ca2+ and one Co2+ atom to form distorted OCa4Co trigonal bipyramids that share a cornercorner with one OCaCo3 tetrahedra, corners with two equivalent OCa5 trigonal bipyramids, edges with two equivalent OCa4Co trigonal bipyramids, and edges with two equivalent OCa2Co2 trigonal pyramids. In the second O2- site, O2- is bonded to five Ca2+ atoms to form distorted OCa5 trigonal bipyramids that share corners with two equivalent OCa2Co3 square pyramids, corners with two equivalent OCaCo3 tetrahedra, corners with two equivalent OCa4Co trigonal bipyramids, corners with two equivalent OCa2Co2 trigonal pyramids, an edgeedge with one OCa2Co3 square pyramid, and edges with two equivalent OCa5 trigonal bipyramids. In the third O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Ca2+ and three Co2+ atoms. In the fourth O2- site, O2- is bonded to two equivalent Ca2+ and three Co2+ atoms to form distorted OCa2Co3 square pyramids that share corners with two equivalent OCa5 trigonal bipyramids, edges with two equivalent OCa2Co3 square pyramids, edges with two equivalent OCaCo3 tetrahedra, and an edgeedge with one OCa5 trigonal bipyramid. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to four Ca2+ and two equivalent Co2+ atoms. In the sixth O2- site, O2- is bonded to one Ca2+ and three Co2+ atoms to form OCaCo3 tetrahedra that share corners with two equivalent OCaCo3 tetrahedra, corners with three OCa4Co trigonal bipyramids, corners with two equivalent OCa2Co2 trigonal pyramids, and edges with two equivalent OCa2Co3 square pyramids. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to three Ca2+ and two equivalent Co2+ atoms. In the eighth O2- site, O2- is bonded to two Ca2+ and two equivalent Co2+ atoms to form OCa2Co2 trigonal pyramids that share corners with two equivalent OCaCo3 tetrahedra, corners with two equivalent OCa5 trigonal bipyramids, corners with two equivalent OCa2Co2 trigonal pyramids, and edges with two equivalent OCa4Co trigonal bipyramids.