DOI: 10.17188/1713400
title: Materials Data on Mg30AlCrO32 by Materials Project

description: Mg30CrAlO32 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are eight inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.10–2.22 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with four MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.02–2.18 Å. In the third Mg site, Mg is bonded to six O atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.12 Å) and four longer (2.15 Å) Mg–O bond lengths. In the fourth Mg site, Mg is bonded to six O atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.15 Å) Mg–O bond lengths. In the fifth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CrO6 octahedra, an edgeedge with one AlO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–15°. There are four shorter (2.13 Å) and two longer (2.15 Å) Mg–O bond lengths. In the sixth Mg site, Mg is bonded to six O atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–3°. There are a spread of Mg–O bond distances ranging from 2.13–2.15 Å. In the seventh Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one AlO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. There are four shorter (2.13 Å) and two longer (2.14 Å) Mg–O bond lengths. In the eighth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CrO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are two shorter (2.13 Å) and four longer (2.14 Å) Mg–O bond lengths. Cr is bonded to six O atoms to form CrO6 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 (2.25 Å) and two longer (2.41 Å) Cr–O bond lengths. Al is bonded to six O atoms to form AlO6 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 is two shorter (1.86 Å) and four longer (2.04 Å) Al–O bond length. There are fifteen inequivalent O sites. In the first O site, O is bonded to five Mg and one Al atom to form OMg5Al octahedra that share corners with six OMg5Al octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are two shorter (2.15 Å) and one longer (2.22 Å) O–Mg bond lengths. In the second O site, O is bonded to five Mg and one Cr atom to form OMg5Cr octahedra that share corners with six OMg5Al octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the third O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg5Al octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. Both O–Mg bond lengths are 2.15 Å. In the fourth O site, O is bonded to six Mg atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the fifth O site, O is bonded to five Mg and one Cr atom to form OMg5Cr octahedra that share corners with six OMg5Al octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–4°. All O–Mg bond lengths are 2.13 Å. In the sixth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg5Al octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are two shorter (2.13 Å) and two longer (2.15 Å) O–Mg bond lengths. In the seventh O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are two shorter (2.13 Å) and two longer (2.14 Å) O–Mg bond lengths. In the eighth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the ninth O site, O is bonded to four equivalent Mg, one Cr, and one Al atom to form distorted OMg4AlCr octahedra that share corners with six OMg4AlCr octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedra tilt angles range from 0–9°. In the tenth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg4AlCr octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–9°. In the eleventh O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg4AlCr octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–9°. All O–Mg bond lengths are 2.13 Å. In the twelfth O site, O is bonded to six Mg atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. In the thirteenth O site, O is bonded to five Mg and one Al atom to form a mixture of edge and corner-sharing OMg5Al octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the fourteenth O site, O is bonded to six Mg atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. The O–Mg bond length is 2.12 Å. In the fifteenth O site, O is bonded to six Mg atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of O–Mg bond distances ranging from 2.12–2.15 Å.