DOI: 10.17188/1677239
title: Materials Data on HfMg14AlO16 by Materials Project

description: Mg14HfAlO16 is Molybdenum Carbide MAX Phase-derived structured and crystallizes in the orthorhombic Pmmm 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 2.12–2.27 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with two equivalent HfO6 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 2.04–2.20 Å. 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 HfO6 octahedra, edges with two equivalent AlO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–12°. There are a spread of Mg–O bond distances ranging from 2.11–2.20 Å. 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 octahedra tilt angles range from 0–2°. There are two shorter (2.15 Å) and four longer (2.16 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, edges with two equivalent AlO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–7°. There are a spread of Mg–O bond distances ranging from 2.14–2.18 Å. In the sixth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent HfO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.10–2.23 Å. In the seventh Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, edges with two equivalent HfO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Mg–O bond distances ranging from 2.10–2.23 Å. In the eighth 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 HfO6 octahedra, an edgeedge with one AlO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–14°. There are a spread of Mg–O bond distances ranging from 2.14–2.21 Å. Hf is bonded to six O atoms to form HfO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent HfO6 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 Hf–O bond distances ranging from 2.15–2.43 Å. Al is bonded to six O atoms to form AlO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with two equivalent HfO6 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 Al–O bond distances ranging from 1.88–2.15 Å. There are eleven 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 0–7°. In the second O site, O is bonded to five Mg and one Hf atom to form OHfMg5 octahedra that share corners with six OMg5Al octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–3°. In the third O site, O is bonded to five Mg and one Hf atom to form OHfMg5 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 2.16 Å. 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 0–3°. In the fifth O site, O is bonded to four 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 four Mg and two equivalent Hf atoms to form OHf2Mg4 octahedra that share corners with six OMg4Al2 octahedra and edges with twelve OHfMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the seventh O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg4Al2 octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedral tilt angles are 0°. In the eighth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OHf2Mg4 octahedra and edges with twelve OHfMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the ninth O site, O is bonded to four Mg, one Hf, and one Al atom to form distorted OHfMg4Al octahedra that share corners with six OHfMg4Al octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedra tilt angles range from 0–12°. In the tenth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OHfMg4Al octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedra tilt angles range from 0–8°. In the eleventh O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OHfMg4Al octahedra and edges with twelve OMg5Al octahedra. The corner-sharing octahedra tilt angles range from 0–8°. There are two shorter (2.14 Å) and two longer (2.15 Å) O–Mg bond lengths.