Materials Data on Na4(CoO2)7 by Materials Project

Abstract

Na4(CoO2)7 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Na–O bond lengths are 2.43 Å. 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 2.31–2.62 Å. There are two inequivalent Co+3.43+ sites. In the first Co+3.43+ site, Co+3.43+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.89–1.93 Å. In the second Co+3.43+ site, Co+3.43+ is bonded to six equivalent O2- atoms to form edge-sharing CoO6 octahedra. All Co–O bond lengths are 1.92 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two Na1+ and three Co+3.43+ atoms to form distorted ONa2Co3 trigonal bipyramids that share corners with two equivalent ONa3Co3 octahedra, corners with three equivalent ONa2Co3 trigonal bipyramids, corners with four equivalent ONaCo3 trigonal pyramids, an edgeedge with one ONa3Co3 octahedra, edges with five equivalent ONa2Co3 trigonal bipyramids, and edges with two equivalent ONaCo3 trigonal pyramids. The corner-sharing octahedra tilt angles range from 0–52°. In the second O2- site, O2- is bonded to three equivalent Na1+ and three equivalent Co+3.43+ atoms to form distorted ONa3Co3 octahedra that share corners with six equivalent ONa2Co3 trigonal bipyramids, corners with three equivalent ONaCo3 trigonal pyramids, edges with three equivalent ONa2Co3 trigonal bipyramids, edges with six equivalent ONaCo3 trigonal pyramids, and a faceface with one ONa3Co3 octahedra. In the third O2- site, O2- is bonded to one Na1+ and three equivalent Co+3.43+ atoms to form distorted ONaCo3 trigonal pyramids that share a cornercorner with one ONa3Co3 octahedra, corners with four equivalent ONa2Co3 trigonal bipyramids, corners with five equivalent ONaCo3 trigonal pyramids, edges with two equivalent ONa3Co3 octahedra, edges with two equivalent ONa2Co3 trigonal bipyramids, and an edgeedge with one ONaCo3 trigonal pyramid. The corner-sharing octahedral tilt angles are 44°.