DOI: 10.17188/1744803
title: Materials Data on CaHfMg6 by Materials Project

description: CaMg6Hf crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Ca is bonded to twelve Mg atoms to form CaMg12 cuboctahedra that share corners with four equivalent CaMg12 cuboctahedra, corners with eight equivalent HfMg12 cuboctahedra, edges with twenty-four MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with four equivalent HfMg12 cuboctahedra, and faces with twelve MgCa2Hf2Mg8 cuboctahedra. There are a spread of Ca–Mg bond distances ranging from 3.21–3.38 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.24–3.27 Å. There are one shorter (3.21 Å) and one longer (3.22 Å) Mg–Hf bond lengths. In the second Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve equivalent MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. There are two shorter (3.03 Å) and two longer (3.40 Å) Mg–Mg bond lengths. Both Mg–Hf bond lengths are 3.16 Å. In the third Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. Both Mg–Hf bond lengths are 3.18 Å. In the fourth Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Hf atoms to form distorted MgCa2Hf2Mg8 cuboctahedra that share corners with twelve MgCa2Hf2Mg8 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with four equivalent HfMg12 cuboctahedra, edges with sixteen MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent CaMg12 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, and faces with fourteen MgCa2Hf2Mg8 cuboctahedra. Both Mg–Hf bond lengths are 3.17 Å. Hf is bonded to twelve Mg atoms to form HfMg12 cuboctahedra that share corners with four equivalent HfMg12 cuboctahedra, corners with eight equivalent CaMg12 cuboctahedra, edges with twenty-four MgCa2Hf2Mg8 cuboctahedra, faces with two equivalent HfMg12 cuboctahedra, faces with four equivalent CaMg12 cuboctahedra, and faces with twelve MgCa2Hf2Mg8 cuboctahedra.