Al2O3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. In the second Al site, Al(2) is bonded to one O(1), one O(2), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the third O site, O(3) is bonded to one Al(1) and three equivalent Al(2) atoms to form a mixture of corner and edge-sharing OAl4 trigonal pyramids.
Al2O3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. The Al(1)-O(3) bond length is 2.05 Å. There is one shorter (1.80 Å) and one longer (1.83 Å) Al(1)-O(1) bond length. There is one shorter (1.83 Å) and one longer (1.86 Å) Al(1)-O(2) bond length. In the second Al site, Al(2) is bonded to one O(1), one O(2), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. The Al(2)-O(1) bond length is 1.80 Å. The Al(2)-O(2) bond length is 1.82 Å. There are a spread of Al(2)-O(3) bond distances ranging from 1.81-1.98 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the third O site, O(3) is bonded to one Al(1) and three equivalent Al(2) atoms to form a mixture of corner and edge-sharing OAl4 trigonal pyramids.