DOI: 10.17188/1655879
title: Materials Data on KMg6CoO8 by Materials Project

description: KMg6CoO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. K1+ is bonded to six O2- atoms to form KO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent KO6 octahedra, edges with four equivalent CoO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.18 Å) and two longer (2.44 Å) K–O bond lengths. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CoO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.18 Å) and two longer (2.24 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent KO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.00 Å) and four longer (2.18 Å) Mg–O bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MgO6 octahedra, edges with two equivalent KO6 octahedra, edges with two equivalent CoO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–7°. There are a spread of Mg–O bond distances ranging from 2.13–2.30 Å. Co3+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent CoO6 octahedra, edges with four equivalent KO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.18 Å) and two longer (2.20 Å) Co–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Co3+ atom to form OMg5Co octahedra that share corners with six equivalent OMg5Co octahedra and edges with twelve OKMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the second O2- site, O2- is bonded to one K1+ and five Mg2+ atoms to form OKMg5 octahedra that share corners with six equivalent OKMg5 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedra tilt angles range from 0–7°. In the third O2- site, O2- is bonded to two equivalent K1+, two equivalent Mg2+, and two equivalent Co3+ atoms to form OK2Mg2Co2 octahedra that share corners with six OK2Mg2Co2 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OK2Mg2Co2 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to two equivalent K1+, two equivalent Mg2+, and two equivalent Co3+ atoms to form OK2Mg2Co2 octahedra that share corners with six OK2Mg2Co2 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.30 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OK2Mg2Co2 octahedra and edges with twelve OMg5Co octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.13 Å.