DOE OSTI2020
Al14Ca13 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are five 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 3.19–3.56 Å. In the second Ca site, Ca is bonded in a 5-coordinate geometry to seven Al atoms. There are a spread of Ca–Al bond distances ranging from 3.11–3.50 Å. In the third Ca site, Ca is bonded in a 5-coordinate geometry to nine Al atoms. There are a spread of Ca–Al bond distances ranging from 3.22–3.63 Å. In the fourth Ca site, Ca is bonded in a 9-coordinate geometry to nine Al atoms. There are a spread of Ca–Al bond distances ranging from 3.23–3.47 Å. In the fifth Ca site, Ca is bonded in a distorted square co-planar geometry to four Al atoms. There are two shorter (3.32 Å) and two longer (3.48 Å) Ca–Al bond lengths. There are six inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to seven Ca and three Al atoms. There are two shorter (2.78 Å) and one longer (2.82 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to seven Ca and three Al atoms. Both Al–Al bond lengths are 2.76 Å. In the third Al site, Al is bonded in a 10-coordinate geometry to seven Ca and three Al atoms. The Al–Al bond length is 2.88 Å. In the fourth Al site, Al is bonded to eight Ca and four Al atoms to form a mixture of distorted edge and face-sharing AlCa8Al4 cuboctahedra. There are two shorter (2.69 Å) and two longer (2.70 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a 10-coordinate geometry to seven Ca and three Al atoms. The Al–Al bond length is 2.68 Å. In the sixth Al site, Al is bonded in a 9-coordinate geometry to seven Ca and two equivalent Al atoms.