Materials Data on Al2O3 by Materials Project

Abstract

Al2O3 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form distorted AlO4 tetrahedra that share corners with two equivalent AlO4 tetrahedra, corners with four equivalent AlO5 trigonal bipyramids, and an edgeedge with one AlO4 tetrahedra. There is three shorter (1.80 Å) and one longer (1.83 Å) Al–O bond length. In the second Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 trigonal bipyramids that share corners with four equivalent AlO4 tetrahedra, corners with two equivalent AlO5 trigonal bipyramids, and edges with two equivalent AlO5 trigonal bipyramids. There are a spread of Al–O bond distances ranging from 1.79–1.96 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three equivalent Al3+ atoms.