Materials Data on CaMg3 by Materials Project

Abstract

Mg3Ca crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. Ca is bonded to two equivalent Ca and ten Mg atoms to form CaCa2Mg10 cuboctahedra that share corners with four equivalent MgCa4Mg8 cuboctahedra, corners with fourteen equivalent CaCa2Mg10 cuboctahedra, edges with two equivalent CaCa2Mg10 cuboctahedra, edges with sixteen MgCa4Mg8 cuboctahedra, faces with two equivalent CaCa2Mg10 cuboctahedra, and faces with eighteen MgCa4Mg8 cuboctahedra. Both Ca–Ca bond lengths are 3.37 Å. There are a spread of Ca–Mg bond distances ranging from 3.34–3.41 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded to four equivalent Ca and eight Mg atoms to form distorted MgCa4Mg8 cuboctahedra that share corners with four equivalent CaCa2Mg10 cuboctahedra, corners with fourteen equivalent MgCa4Mg8 cuboctahedra, edges with four equivalent CaCa2Mg10 cuboctahedra, edges with fourteen MgCa4Mg8 cuboctahedra, faces with six equivalent CaCa2Mg10 cuboctahedra, and faces with fourteen MgCa4Mg8 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.33–3.41 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 eighteen equivalent MgCa3Mg9 cuboctahedra, edges with six equivalent CaCa2Mg10 cuboctahedra, edges with twelve MgCa4Mg8 cuboctahedra, faces with six equivalent CaCa2Mg10 cuboctahedra, and faces with fourteen MgCa4Mg8 cuboctahedra. All Mg–Mg bond lengths are 3.37 Å.