Materials Data on CaMg by Materials Project

Abstract

MgCa crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded to four equivalent Ca and eight Mg atoms to form distorted CaCa4Mg8 cuboctahedra that share corners with six equivalent CaCa4Mg8 cuboctahedra, edges with fourteen CaCa4Mg8 cuboctahedra, and faces with eight equivalent CaCa5Mg7 cuboctahedra. There are two shorter (3.62 Å) and two longer (3.69 Å) Ca–Ca bond lengths. There are a spread of Ca–Mg bond distances ranging from 3.42–3.70 Å. In the second Ca site, Ca is bonded to five Ca and seven Mg atoms to form distorted CaCa5Mg7 cuboctahedra that share corners with twelve equivalent CaCa5Mg7 cuboctahedra, edges with ten CaCa4Mg8 cuboctahedra, and faces with eight CaCa4Mg8 cuboctahedra. There are one shorter (3.49 Å) and two longer (3.58 Å) Ca–Ca bond lengths. There are a spread of Ca–Mg bond distances ranging from 3.45–3.64 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded in a 7-coordinate geometry to seven Ca atoms. In the second Mg site, Mg is bonded in a 8-coordinate geometry to eight Ca atoms.