Materials Data on Mg(CoO2)4 by Materials Project

Abstract

Mg(CoO2)4 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent O2- atoms to form MgO6 octahedra that share corners with six equivalent CoO6 octahedra and edges with six equivalent CoO6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Mg–O bond lengths are 2.14 Å. There are two inequivalent Co+3.50+ sites. In the first Co+3.50+ site, Co+3.50+ is bonded to six O2- atoms to form CoO6 octahedra that share edges with two equivalent MgO6 octahedra and edges with six CoO6 octahedra. There is two shorter (1.86 Å) and four longer (1.89 Å) Co–O bond length. In the second Co+3.50+ site, Co+3.50+ is bonded to six equivalent O2- atoms to form CoO6 octahedra that share corners with six equivalent MgO6 octahedra and edges with six equivalent CoO6 octahedra. The corner-sharing octahedral tilt angles are 11°. All Co–O bond lengths are 1.94 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Co+3.50+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Co+3.50+ atoms.