Materials Data on CaAl4 by Materials Project
Al4Ca crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to sixteen Al atoms. There are eight shorter (3.33 Å) and eight longer (3.55 Å) Ca–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Ca and eight Al atoms to form a mixture of distorted corner, edge, and face-sharing AlCa4Al8 cuboctahedra. There are four shorter (2.66 Å) and four longer (3.08 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 9-coordinate geometry to four equivalent Ca and five Al atoms. The Al–Al bond length is 2.55 Å.
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