Materials Data on Al2O3 by Materials Project

Abstract

Al2O3 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with eight AlO6 octahedra and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–67°. There are a spread of Al–O bond distances ranging from 1.76–1.80 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with three equivalent AlO4 tetrahedra, and edges with seven AlO6 octahedra. The corner-sharing octahedra tilt angles range from 15–50°. There are a spread of Al–O bond distances ranging from 1.82–1.97 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form distorted AlO6 octahedra that share corners with four equivalent AlO6 octahedra, corners with four equivalent AlO4 tetrahedra, and edges with four AlO6 octahedra. The corner-sharing octahedra tilt angles range from 13–57°. There are a spread of Al–O bond distances ranging from 1.82–2.22 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form distorted AlO6 octahedra that share corners with six AlO6 octahedra, a cornercorner with one AlO4 tetrahedra, and edges with five AlO6 octahedra. The corner-sharing octahedra tilt angles range from 13–57°. There are a spread of Al–O bond distances ranging from 1.83–2.27 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to four Al3+ atoms to form OAl4 tetrahedra that share a cornercorner with one OAl5 square pyramid, corners with two equivalent OAl4 tetrahedra, edges with two equivalent OAl5 square pyramids, and an edgeedge with one OAl4 tetrahedra. In the second O2- site, O2- is bonded to four Al3+ atoms to form distorted OAl4 tetrahedra that share a cornercorner with one OAl5 square pyramid, corners with four OAl4 tetrahedra, edges with two equivalent OAl5 square pyramids, and an edgeedge with one OAl4 tetrahedra. In the third O2- site, O2- is bonded to five Al3+ atoms to form distorted OAl5 square pyramids that share corners with two OAl4 tetrahedra, edges with two equivalent OAl5 square pyramids, and edges with four OAl4 tetrahedra. In the fourth O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms.