Materials Data on Na7(CoO3)2 by Materials Project

Abstract

Na7(CoO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to four O2- atoms to form a mixture of distorted edge and corner-sharing NaO4 trigonal pyramids. There are a spread of Na–O bond distances ranging from 2.30–2.37 Å. In the second Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.45–2.70 Å. In the third Na1+ site, Na1+ is bonded to four O2- atoms to form a mixture of edge and corner-sharing NaO4 trigonal pyramids. There are a spread of Na–O bond distances ranging from 2.29–2.44 Å. In the fourth Na1+ site, Na1+ is bonded to four O2- atoms to form a mixture of distorted edge and corner-sharing NaO4 trigonal pyramids. There are two shorter (2.36 Å) and two longer (2.44 Å) Na–O bond lengths. Co+2.50+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of Co–O bond distances ranging from 1.81–1.84 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to five Na1+ and one Co+2.50+ atom to form a mixture of distorted edge and corner-sharing ONa5Co octahedra. The corner-sharing octahedra tilt angles range from 40–60°. In the second O2- site, O2- is bonded to five Na1+ and one Co+2.50+ atom to form a mixture of distorted edge, face, and corner-sharing ONa5Co octahedra. The corner-sharing octahedra tilt angles range from 50–58°. In the third O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Co+2.50+ atom.