Materials Data on Ca4MgAl3 by Materials Project
Ca4Al3Mg crystallizes in the orthorhombic Pbcm space group. The structure is three-dimensional. there are four inequivalent Ca sites. In the first Ca site, Ca is bonded in a 6-coordinate geometry to eight Al atoms. There are a spread of Ca–Al bond distances ranging from 3.22–3.63 Å. In the second Ca site, Ca is bonded in a 6-coordinate geometry to six Al atoms. There are a spread of Ca–Al bond distances ranging from 3.25–3.44 Å. In the third Ca site, Ca is bonded in a 2-coordinate geometry to six Al atoms. There are a spread of Ca–Al bond distances ranging from 3.17–3.50 Å. In the fourth Ca site, Ca is bonded in a 4-coordinate geometry to four Al atoms. There are a spread of Ca–Al bond distances ranging from 3.21–3.39 Å. Mg is bonded in a distorted linear geometry to two equivalent Al atoms. Both Mg–Al bond lengths are 2.82 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded to eight Ca and four Al atoms to form a mixture of distorted corner, edge, and face-sharing AlCa8Al4 cuboctahedra. There are two shorter (2.75 Å) and two longer (2.93 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 10-coordinate geometry to eight Ca and two equivalent Mg atoms. In the third Al site, Al is bonded in a 10-coordinate geometry to eight Ca and two equivalent Al atoms.