Materials Data on CaMg5 by Materials Project

Abstract

CaMg5 crystallizes in the trigonal R32 space group. The structure is three-dimensional. Ca is bonded to twelve Mg atoms to form CaMg12 cuboctahedra that share corners with six equivalent CaMg12 cuboctahedra, corners with twelve equivalent MgCa3Mg9 cuboctahedra, edges with six equivalent CaMg12 cuboctahedra, edges with twelve equivalent MgCa2Mg10 cuboctahedra, and faces with twenty MgCa2Mg10 cuboctahedra. There are six shorter (3.27 Å) and six longer (3.39 Å) Ca–Mg bond lengths. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded to two equivalent Ca and ten Mg atoms to form distorted MgCa2Mg10 cuboctahedra that share corners with eighteen equivalent MgCa2Mg10 cuboctahedra, edges with four equivalent CaMg12 cuboctahedra, edges with fourteen MgCa2Mg10 cuboctahedra, faces with four equivalent CaMg12 cuboctahedra, and faces with sixteen MgCa2Mg10 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.22–3.40 Å. In the second Mg site, Mg is bonded to three equivalent Ca and nine Mg atoms to form distorted MgCa3Mg9 cuboctahedra that share corners with six equivalent CaMg12 cuboctahedra, corners with twelve equivalent MgCa3Mg9 cuboctahedra, edges with eighteen MgCa2Mg10 cuboctahedra, faces with four equivalent CaMg12 cuboctahedra, and faces with sixteen MgCa2Mg10 cuboctahedra. All Mg–Mg bond lengths are 3.27 Å.