Materials Data on Na2CoO3 by Materials Project
Na2CoO3 is High Pressure (4-7GPa) Tellurium-derived structured and crystallizes in the monoclinic C2/c 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 a spread of Na–O bond distances ranging from 2.24–2.60 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with four CoO6 octahedra, edges with two equivalent NaO6 octahedra, and edges with four CoO6 octahedra. The corner-sharing octahedra tilt angles range from 16–18°. There are two shorter (2.24 Å) and four longer (2.48 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra, edges with two equivalent NaO6 octahedra, and edges with six CoO6 octahedra. The corner-sharing octahedral tilt angles are 18°. There are a spread of Na–O bond distances ranging from 2.29–2.33 Å. There are two inequivalent Co4+ sites. In the first Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent NaO6 octahedra, edges with three equivalent CoO6 octahedra, and edges with five NaO6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are a spread of Co–O bond distances ranging from 1.89–2.05 Å. In the second Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent NaO6 octahedra, edges with three equivalent CoO6 octahedra, and edges with five NaO6 octahedra. The corner-sharing octahedral tilt angles are 18°. There are a spread of Co–O bond distances ranging from 1.94–2.06 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Na1+ and two Co4+ atoms to form a mixture of distorted corner and edge-sharing ONa4Co2 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. In the second O2- site, O2- is bonded in a 6-coordinate geometry to four Na1+ and two Co4+ atoms. In the third O2- site, O2- is bonded to four Na1+ and two Co4+ atoms to form a mixture of distorted corner and edge-sharing ONa4Co2 octahedra. The corner-sharing octahedra tilt angles range from 0–17°.