Materials Data on Al2O3 by Materials Project

Al2O3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Al3+ is bonded to five O2- atoms to form a mixture of edge and corner-sharing AlO5 trigonal bipyramids. There are a spread of Al–O bond distances ranging from 1.78–2.02 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a T-shaped geometry to three equivalent Al3+ atoms. In the second O2- site, O2- is bonded in a see-saw-like geometry to four equivalent Al3+ atoms.