DOI: 10.17188/1652479
title: Materials Data on Mg6CrNiO8 by Materials Project

description: Mg6CrNiO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. 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 NiO6 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 (2.09 Å) and four longer (2.15 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 CrO6 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 (2.11 Å) and four longer (2.15 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 CrO6 octahedra, edges with two equivalent NiO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Mg–O bond distances ranging from 2.10–2.15 Å. Cr2+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent CrO6 octahedra, edges with four equivalent NiO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.11 Å) and four longer (2.15 Å) Cr–O bond lengths. Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent NiO6 octahedra, edges with four equivalent CrO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.13 Å) and four longer (2.15 Å) Ni–O bond lengths. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Ni2+ atom to form OMg5Ni octahedra that share corners with six equivalent OMg5Ni octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the second O2- site, O2- is bonded to five Mg2+ and one Cr2+ atom to form OMg5Cr octahedra that share corners with six equivalent OMg5Cr octahedra and edges with twelve OMg5Ni octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the third O2- site, O2- is bonded to two equivalent Mg2+, two equivalent Cr2+, and two equivalent Ni2+ atoms to form OMg2Cr2Ni2 octahedra that share corners with six OMg2Cr2Ni2 octahedra and edges with twelve OMg5Ni 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 OMg2Cr2Ni2 octahedra and edges with twelve OMg5Ni octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to two equivalent Mg2+, two equivalent Cr2+, and two equivalent Ni2+ atoms to form OMg2Cr2Ni2 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Ni octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.10 Å.