DOI: 10.17188/1652879
title: Materials Data on HfMg6CdO8 by Materials Project

description: Mg6HfCdO8 is Caswellsilverite-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 six MgO6 octahedra, edges with four equivalent CdO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.23 Å) and two longer (2.25 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 six MgO6 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 (2.23 Å) and two longer (2.29 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 CdO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. There are a spread of Mg–O bond distances ranging from 2.18–2.36 Å. Hf is bonded to six O atoms to form HfO6 octahedra that share corners with two equivalent CdO6 octahedra, corners with four equivalent HfO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.05 Å) and four longer (2.23 Å) Hf–O bond lengths. Cd is bonded to six O atoms to form CdO6 octahedra that share corners with two equivalent HfO6 octahedra, corners with four equivalent CdO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.23 Å) and two longer (2.49 Å) Cd–O bond lengths. There are five inequivalent O sites. In the first O site, O is bonded to four equivalent Mg, one Hf, and one Cd atom to form distorted OHfMg4Cd octahedra that share corners with six equivalent OHfMg4Cd octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. In the second 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 OHfMg4Cd octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the third O site, O is bonded to four Mg and two equivalent Cd atoms to form OMg4Cd2 octahedra that share corners with six OMg4Cd2 octahedra and edges with twelve OHfMg4Cd octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O site, O is bonded to four Mg and two equivalent Hf atoms to form OHf2Mg4 octahedra that share corners with six OMg4Cd2 octahedra and edges with twelve OHfMg4Cd octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O site, O is bonded to four Mg and two equivalent Cd atoms to form OMg4Cd2 octahedra that share corners with six OHf2Mg4 octahedra and edges with twelve OHfMg4Cd octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.18 Å.