DOI: 10.17188/1656275
title: Materials Data on HfMg6WO8 by Materials Project

description: Mg6HfWO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are three 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 WO6 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 (2.20 Å) Mg–O bond lengths. 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 equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.13 Å) and four longer (2.20 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 equivalent MgO6 octahedra, edges with two equivalent HfO6 octahedra, edges with two equivalent WO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are a spread of Mg–O bond distances ranging from 2.10–2.32 Å. Hf is bonded to six O atoms to form HfO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent HfO6 octahedra, edges with four equivalent WO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.20 Å) and two longer (2.30 Å) Hf–O bond lengths. W is bonded to six O atoms to form WO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent WO6 octahedra, edges with four equivalent HfO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.20 Å) and two longer (2.31 Å) W–O bond lengths. There are five inequivalent O sites. In the first O site, O is bonded to five Mg and one W atom to form OMg5W octahedra that share corners with six equivalent OMg5W octahedra and edges with twelve OHfMg5 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O site, O is bonded to five Mg and one Hf atom to form OHfMg5 octahedra that share corners with six equivalent OHfMg5 octahedra and edges with twelve OMg5W octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the third O site, O is bonded to two equivalent Mg, two equivalent Hf, and two equivalent W atoms to form OHf2Mg2W2 octahedra that share corners with six OHf2Mg2W2 octahedra and edges with twelve OMg5W octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OHf2Mg2W2 octahedra and edges with twelve OMg5W octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OHf2Mg2W2 octahedra and edges with twelve OMg5W octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.10 Å.