Al2O3 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of corner and edge-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the second Al site, Al(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted square co-planar geometry to two equivalent Al(1) and two equivalent Al(2) atoms. In the second O site, O(2) is bonded to two equivalent Al(1) and two equivalent Al(2) atoms to form corner-sharing OAl4 tetrahedra.
Al2O3 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of corner and edge-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 57°. Both Al(1)-O(2) bond lengths are 2.01 Å. All Al(1)-O(1) bond lengths are 1.88 Å. In the second Al site, Al(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both Al(2)-O(2) bond lengths are 1.87 Å. All Al(2)-O(1) bond lengths are 2.06 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted square co-planar geometry to two equivalent Al(1) and two equivalent Al(2) atoms. In the second O site, O(2) is bonded to two equivalent Al(1) and two equivalent Al(2) atoms to form corner-sharing OAl4 tetrahedra.