Materials Data on Ca5Mg by Materials Project
Ca5Mg crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are five inequivalent Ca sites. In the first Ca site, Ca is bonded to twelve Ca atoms to form CaCa12 cuboctahedra that share corners with eighteen CaCa12 cuboctahedra, edges with six CaCa8Mg4 cuboctahedra, and faces with eight CaCa12 cuboctahedra. There are a spread of Ca–Ca bond distances ranging from 3.84–3.88 Å. In the second Ca site, Ca is bonded to eight Ca and four equivalent Mg atoms to form a mixture of distorted edge, corner, and face-sharing CaCa8Mg4 cuboctahedra. There are a spread of Ca–Ca bond distances ranging from 3.66–3.84 Å. All Ca–Mg bond lengths are 3.76 Å. In the third Ca site, Ca is bonded to ten Ca and two equivalent Mg atoms to form a mixture of distorted edge, corner, and face-sharing CaCa10Mg2 cuboctahedra. There are four shorter (3.75 Å) and two longer (3.84 Å) Ca–Ca bond lengths. Both Ca–Mg bond lengths are 3.73 Å. In the fourth Ca site, Ca is bonded in a 12-coordinate geometry to six Ca and two equivalent Mg atoms. Both Ca–Mg bond lengths are 3.62 Å. In the fifth Ca site, Ca is bonded in a 12-coordinate geometry to six Ca and two equivalent Mg atoms. Both Ca–Mg bond lengths are 3.63 Å. Mg is bonded in a distorted q6 geometry to ten Ca atoms.