Materials Data on Ca3Co4O9 by Materials Project
Ca3Co4O9 crystallizes in the orthorhombic Cmm2 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 distorted CaO6 pentagonal pyramids that share corners with eight equivalent CoO4 tetrahedra. There are two shorter (2.32 Å) and four longer (2.38 Å) Ca–O bond lengths. 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 2.35–2.95 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 2.28–2.87 Å. In the fourth 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 2.44–2.82 Å. There are four inequivalent Co3+ sites. In the first Co3+ site, Co3+ is bonded to four O2- atoms to form CoO4 tetrahedra that share corners with two equivalent CaO6 pentagonal pyramids and corners with four CoO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.77–1.99 Å. In the second Co3+ site, Co3+ is bonded to four O2- atoms to form corner-sharing CoO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.81–1.92 Å. In the third Co3+ site, Co3+ is bonded to four O2- atoms to form distorted corner-sharing CoO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.77–1.91 Å. In the fourth Co3+ site, Co3+ is bonded to four O2- atoms to form corner-sharing CoO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.78–1.98 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Co3+ atoms to form corner-sharing OCa2Co2 tetrahedra. In the second O2- site, O2- is bonded to three Ca2+ and one Co3+ atom to form a mixture of distorted edge and corner-sharing OCa3Co tetrahedra. In the third O2- site, O2- is bonded to two Ca2+ and two equivalent Co3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Co2 tetrahedra. In the fourth O2- site, O2- is bonded to two Ca2+ and two Co3+ atoms to form distorted OCa2Co2 tetrahedra that share corners with seven OCa2Co2 tetrahedra and edges with two OCa3Co tetrahedra. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ca2+ and three Co3+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and two Co3+ atoms. In the seventh O2- site, O2- is bonded to two equivalent Ca2+ and two equivalent Co3+ atoms to form a mixture of edge and corner-sharing OCa2Co2 tetrahedra. In the eighth O2- site, O2- is bonded to three Ca2+ and one Co3+ atom to form distorted OCa3Co tetrahedra that share corners with eight OCa2Co2 tetrahedra and edges with two OCa3Co tetrahedra. In the ninth O2- site, O2- is bonded to three Ca2+ and one Co3+ atom to form a mixture of distorted edge and corner-sharing OCa3Co tetrahedra. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Co3+ atoms.