Materials Data on Ca2Mg by Materials Project

Abstract

Ca2Mg crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. there are three inequivalent Ca sites. In the first Ca site, Ca is bonded to twelve Ca atoms to form a mixture of corner, edge, and face-sharing CaCa12 cuboctahedra. There are six shorter (3.79 Å) and six longer (3.88 Å) Ca–Ca bond lengths. In the second Ca site, Ca is bonded to three equivalent Ca and three equivalent Mg atoms to form distorted CaCa3Mg3 cuboctahedra that share corners with eighteen CaCa12 cuboctahedra, edges with twelve CaCa12 cuboctahedra, and faces with two CaCa3Mg3 cuboctahedra. All Ca–Mg bond lengths are 3.50 Å. In the third Ca site, Ca is bonded to six equivalent Mg atoms to form distorted CaMg6 cuboctahedra that share corners with twelve equivalent CaCa3Mg3 cuboctahedra, edges with six equivalent CaMg6 cuboctahedra, and faces with two equivalent CaCa3Mg3 cuboctahedra. All Ca–Mg bond lengths are 3.56 Å. Mg is bonded in a 6-coordinate geometry to six Ca atoms.