Materials Data on Na2(CoO2)3 by Materials Project
Na2(CoO2)3 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.41 Å) and three longer (2.48 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.39–2.58 Å. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.30–2.55 Å. There are four inequivalent Co+3.33+ sites. In the first Co+3.33+ site, Co+3.33+ is bonded to six equivalent O2- atoms to form edge-sharing CoO6 octahedra. All Co–O bond lengths are 1.94 Å. In the second Co+3.33+ site, Co+3.33+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. All Co–O bond lengths are 2.02 Å. In the third Co+3.33+ site, Co+3.33+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.88–1.95 Å. In the fourth Co+3.33+ site, Co+3.33+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.97–2.05 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+ and three Co+3.33+ atoms to form distorted ONaCo3 trigonal pyramids that share corners with two equivalent ONa3Co3 octahedra, corners with four ONa2Co3 trigonal bipyramids, corners with four equivalent ONaCo3 trigonal pyramids, edges with three equivalent ONa3Co3 octahedra, and edges with two ONa2Co3 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 36–40°. In the second O2- site, O2- is bonded to three Na1+ and three Co+3.33+ atoms to form distorted ONa3Co3 octahedra that share corners with three equivalent ONa3Co3 octahedra, corners with four ONa2Co3 trigonal bipyramids, corners with two equivalent ONaCo3 trigonal pyramids, edges with two equivalent ONa3Co3 octahedra, edges with four ONa2Co3 trigonal bipyramids, edges with three equivalent ONaCo3 trigonal pyramids, and a faceface with one ONa3Co3 octahedra. The corner-sharing octahedra tilt angles range from 0–53°. In the third O2- site, O2- is bonded to two Na1+ and three Co+3.33+ atoms to form distorted ONa2Co3 trigonal bipyramids that share corners with two equivalent ONa3Co3 octahedra, corners with five ONa2Co3 trigonal bipyramids, corners with two equivalent ONaCo3 trigonal pyramids, edges with three equivalent ONa3Co3 octahedra, edges with four ONa2Co3 trigonal bipyramids, and an edgeedge with one ONaCo3 trigonal pyramid. The corner-sharing octahedra tilt angles range from 5–49°. In the fourth O2- site, O2- is bonded to two Na1+ and three Co+3.33+ atoms to form distorted ONa2Co3 trigonal bipyramids that share corners with two equivalent ONa3Co3 octahedra, corners with five ONa2Co3 trigonal bipyramids, corners with two equivalent ONaCo3 trigonal pyramids, an edgeedge with one ONa3Co3 octahedra, edges with six ONa2Co3 trigonal bipyramids, and an edgeedge with one ONaCo3 trigonal pyramid. The corner-sharing octahedra tilt angles range from 1–51°.