DOI: 10.17188/1674298
title: Materials Data on Mg6AlNiO8 by Materials Project

description: Mg6NiAlO8 is Caswellsilverite-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 AlO6 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 (2.09 Å) and two longer (2.46 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 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 (2.01 Å) and four longer (2.09 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 NiO6 octahedra, edges with two equivalent AlO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–13°. There are a spread of Mg–O bond distances ranging from 2.10–2.25 Å. Ni1+ 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 AlO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.09 Å) and two longer (2.38 Å) Ni–O bond lengths. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent AlO6 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 (1.93 Å) and four longer (2.09 Å) Al–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Al3+ atom to form distorted OMg5Al octahedra that share corners with six equivalent OMg5Al octahedra and edges with twelve OMg5Ni octahedra. The corner-sharing octahedra tilt angles range from 0–12°. In the second O2- site, O2- is bonded to five Mg2+ and one Ni1+ atom to form distorted OMg5Ni octahedra that share corners with six equivalent OMg5Ni octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedra tilt angles range from 0–13°. In the third O2- site, O2- is bonded to two equivalent Mg2+, two equivalent Ni1+, and two equivalent Al3+ atoms to form OMg2Al2Ni2 octahedra that share corners with six OMg2Al2Ni2 octahedra and edges with twelve OMg5Al 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 OMg2Al2Ni2 octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to two equivalent Mg2+, two equivalent Ni1+, and two equivalent Al3+ atoms to form OMg2Al2Ni2 octahedra that share corners with six OMg2Al2Ni2 octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.15 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg2Al2Ni2 octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.25 Å.