Materials Data on Al(CoO2)2 by Materials Project

Co2AlO4 is Spinel structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Co+2.50+ sites. In the first Co+2.50+ site, Co+2.50+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent AlO4 tetrahedra and edges with six CoO6 octahedra. There are two shorter (2.05 Å) and four longer (2.07 Å) Co–O bond lengths. In the second Co+2.50+ site, Co+2.50+ is bonded to six equivalent O2- atoms to form CoO6 octahedra that share corners with six equivalent AlO4 tetrahedra and edges with six equivalent CoO6 octahedra. All Co–O bond lengths are 2.05 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with twelve CoO6 octahedra. The corner-sharing octahedral tilt angles are 55°. There is one shorter (1.79 Å) and three longer (1.81 Å) Al–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Co+2.50+ and one Al3+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Co+2.50+ and one Al3+ atom.