Materials Data on Na2Co3O4 by Materials Project
Na2Co3O4 is Ilmenite-like structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.43–2.83 Å. There are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to four O2- atoms to form a mixture of edge and corner-sharing CoO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.94–2.02 Å. In the second Co2+ site, Co2+ is bonded in a distorted square co-planar geometry to four equivalent O2- atoms. There are two shorter (2.01 Å) and two longer (2.05 Å) Co–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Na1+ and three Co2+ atoms to form a mixture of distorted face, edge, and corner-sharing ONa3Co3 octahedra. The corner-sharing octahedra tilt angles range from 32–75°. In the second O2- site, O2- is bonded in a 6-coordinate geometry to three equivalent Na1+ and three equivalent Co2+ atoms.