Materials Data on CaMg by Materials Project

Abstract

MgCa crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are three inequivalent Ca sites. In the first Ca site, Ca is bonded to six Ca and six Mg atoms to form distorted CaCa6Mg6 cuboctahedra that share corners with twelve CaCa6Mg6 cuboctahedra, edges with nine CaCa5Mg7 cuboctahedra, and faces with eight CaCa6Mg6 cuboctahedra. There are a spread of Ca–Ca bond distances ranging from 3.64–3.75 Å. There are a spread of Ca–Mg bond distances ranging from 3.42–3.80 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 six equivalent CaCa5Mg7 cuboctahedra, edges with ten CaCa6Mg6 cuboctahedra, and faces with nine CaCa6Mg6 cuboctahedra. There are one shorter (3.50 Å) and two longer (3.64 Å) Ca–Ca bond lengths. There are a spread of Ca–Mg bond distances ranging from 3.49–3.64 Å. In the third Ca site, Ca is bonded to five Ca and seven Mg atoms to form a mixture of distorted corner, edge, and face-sharing CaCa5Mg7 cuboctahedra. Both Ca–Ca bond lengths are 3.64 Å. There are a spread of Ca–Mg bond distances ranging from 3.43–3.71 Å. There are three inequivalent Mg sites. In the first Mg site, Mg is bonded in a 9-coordinate geometry to seven Ca and two equivalent Mg atoms. Both Mg–Mg bond lengths are 3.42 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to six Ca and two equivalent Mg atoms. In the third Mg site, Mg is bonded in a 9-coordinate geometry to seven Ca atoms.