DOI: 10.17188/1672086
title: Materials Data on CaMg6Cr by Materials Project

description: CaMg6Cr is beta Cu3Ti-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Ca is bonded to ten Mg and two equivalent Cr atoms to form CaMg10Cr2 cuboctahedra that share corners with six equivalent CaMg10Cr2 cuboctahedra, corners with twelve MgCa2Mg8Cr2 cuboctahedra, edges with four equivalent CrCa2Mg10 cuboctahedra, edges with fourteen MgCa2Mg8Cr2 cuboctahedra, faces with two equivalent CaMg10Cr2 cuboctahedra, faces with two equivalent CrCa2Mg10 cuboctahedra, and faces with sixteen MgCa2Mg8Cr2 cuboctahedra. There are a spread of Ca–Mg bond distances ranging from 3.20–3.32 Å. Both Ca–Cr bond lengths are 3.20 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Cr atoms to form distorted MgCa2Mg8Cr2 cuboctahedra that share corners with four equivalent CaMg10Cr2 cuboctahedra, corners with fourteen MgCa2Mg8Cr2 cuboctahedra, edges with two equivalent CaMg10Cr2 cuboctahedra, edges with four equivalent CrCa2Mg10 cuboctahedra, edges with twelve MgCa2Mg8Cr2 cuboctahedra, faces with two equivalent CaMg10Cr2 cuboctahedra, faces with two equivalent CrCa2Mg10 cuboctahedra, and faces with sixteen MgCa2Mg8Cr2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.16–3.37 Å. Both Mg–Cr bond lengths are 3.16 Å. In the second Mg site, Mg is bonded to two equivalent Ca and ten Mg atoms to form distorted MgCa2Mg10 cuboctahedra that share corners with four equivalent CaMg10Cr2 cuboctahedra, corners with fourteen MgCa2Mg8Cr2 cuboctahedra, edges with two equivalent CaMg10Cr2 cuboctahedra, edges with sixteen MgCa2Mg8Cr2 cuboctahedra, faces with two equivalent CaMg10Cr2 cuboctahedra, faces with six equivalent CrCa2Mg10 cuboctahedra, and faces with twelve MgCa2Mg8Cr2 cuboctahedra. There are four shorter (3.18 Å) and two longer (3.22 Å) Mg–Mg bond lengths. In the third Mg site, Mg is bonded to two equivalent Ca, eight Mg, and two equivalent Cr atoms to form distorted MgCa2Mg8Cr2 cuboctahedra that share corners with four equivalent CrCa2Mg10 cuboctahedra, corners with fourteen MgCa2Mg8Cr2 cuboctahedra, edges with two equivalent CrCa2Mg10 cuboctahedra, edges with four equivalent CaMg10Cr2 cuboctahedra, edges with twelve MgCa2Mg8Cr2 cuboctahedra, faces with two equivalent CaMg10Cr2 cuboctahedra, faces with two equivalent CrCa2Mg10 cuboctahedra, and faces with sixteen MgCa2Mg8Cr2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.19–3.34 Å. There are one shorter (3.18 Å) and one longer (3.34 Å) Mg–Cr bond lengths. In the fourth Mg site, Mg is bonded to ten Mg and two equivalent Cr atoms to form distorted MgMg10Cr2 cuboctahedra that share corners with four equivalent CrCa2Mg10 cuboctahedra, corners with fourteen MgCa2Mg8Cr2 cuboctahedra, edges with two equivalent CrCa2Mg10 cuboctahedra, edges with sixteen MgCa2Mg8Cr2 cuboctahedra, faces with two equivalent CrCa2Mg10 cuboctahedra, faces with six equivalent CaMg10Cr2 cuboctahedra, and faces with twelve MgCa2Mg8Cr2 cuboctahedra. Both Mg–Cr bond lengths are 3.26 Å. Cr is bonded to two equivalent Ca and ten Mg atoms to form CrCa2Mg10 cuboctahedra that share corners with six equivalent CrCa2Mg10 cuboctahedra, corners with twelve MgCa2Mg8Cr2 cuboctahedra, edges with four equivalent CaMg10Cr2 cuboctahedra, edges with fourteen MgCa2Mg8Cr2 cuboctahedra, faces with two equivalent CaMg10Cr2 cuboctahedra, faces with two equivalent CrCa2Mg10 cuboctahedra, and faces with sixteen MgCa2Mg8Cr2 cuboctahedra.