DOI: 10.17188/1691086
title: Materials Data on Mg14AlCrO16 by Materials Project

description: Mg14CrAlO16 is Molybdenum Carbide MAX Phase-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are four 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 MgO6 octahedra, corners with two equivalent CrO6 octahedra, corners with two equivalent AlO6 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 1.99–2.34 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent AlO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–11°. There are three shorter (2.14 Å) and three longer (2.15 Å) Mg–O bond lengths. In the third Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent CrO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–9°. There are a spread of Mg–O bond distances ranging from 2.14–2.16 Å. In the fourth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six equivalent 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 2–11°. There are a spread of Mg–O bond distances ranging from 2.13–2.18 Å. Cr is bonded to six O atoms to form CrO6 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 (2.14 Å) and four longer (2.31 Å) Cr–O bond lengths. Al is bonded to six O atoms to form AlO6 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 (1.95 Å) and two longer (2.14 Å) Al–O bond lengths. There are ten 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 0–11°. There are two shorter (2.15 Å) and one longer (2.34 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 OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. Both O–Mg bond lengths are 2.14 Å. In the third 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 OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are two shorter (2.13 Å) and two longer (2.14 Å) O–Mg bond lengths. In the fourth 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 1–2°. In the fifth O site, O is bonded to four equivalent Mg and two equivalent Al atoms to form OMg4Al2 octahedra that share corners with six OMg4Al2 octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedral tilt angles are 0°. In the sixth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg4Al2 octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh O site, O is bonded to four equivalent Mg and two equivalent Cr atoms to form OMg4Cr2 octahedra that share corners with six OMg6 octahedra and edges with twelve OMg5Cr octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth 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 0–11°. In the ninth O site, O is bonded to five Mg and one Cr atom to form a mixture of edge and corner-sharing OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–10°. The O–Mg bond length is 1.99 Å. In the tenth O site, O is bonded to five Mg and one Cr atom to form a mixture of edge and corner-sharing OMg5Cr octahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are a spread of O–Mg bond distances ranging from 1.99–2.14 Å.