The material structure described by Al2O3 is beta indium sulfide-like structured and crystallizes in the monoclinic C2/c space group. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(2) and two equivalent O(5) atoms to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-61°. In the second Al site, Al(2) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(1) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent Al(4)O4 tetrahedra,  an edgeedge with one Al(2)O6 octahedra,  an edgeedge with one Al(5)O6 octahedra, and edges with three equivalent Al(3)O6 octahedra. In the third Al site, Al(3) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(3) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent Al(4)O4 tetrahedra,  an edgeedge with one Al(3)O6 octahedra,  an edgeedge with one Al(5)O6 octahedra, and edges with three equivalent Al(2)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-61°. In the fifth Al site, Al(5) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent Al(4)O4 tetrahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Al(3), one Al(4), and two equivalent Al(2) atoms to form distorted edge-sharing OAl4 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Al(2), one Al(4), and two equivalent Al(3) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Al(3), one Al(4), and one Al(5) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), one Al(3), and one Al(5) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Al(2), one Al(4), and one Al(5) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Al2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   16.665
_cell_length_b   5.599
_cell_length_c   5.599
_cell_angle_alpha   90.057
_cell_angle_beta   60.427
_cell_angle_gamma   59.113
_symmetry_Int_Tables_number   1
_cell_volume   366.550
_cell_formula_units_Z   8
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Al  Al0  1  1.000  1.000  1.000  1.0
  Al  Al1  1  0.092  0.344  0.105  1.0
  Al  Al2  1  0.090  0.347  0.615  1.0
  Al  Al3  1  0.333  0.017  0.005  1.0
  Al  Al4  1  0.167  0.733  0.245  1.0
  Al  Al5  1  0.250  0.375  0.625  1.0
  Al  Al6  1  0.408  0.406  0.145  1.0
  Al  Al7  1  0.410  0.403  0.635  1.0
  Al  Al8  1  0.667  0.003  0.015  1.0
  Al  Al9  1  0.500  0.750  0.250  1.0
  Al  Al10  1  0.592  0.369  0.631  1.0
  Al  Al11  1  0.750  0.375  0.125  1.0
  Al  Al12  1  0.590  0.864  0.633  1.0
  Al  Al13  1  0.833  0.747  0.235  1.0
  Al  Al14  1  0.908  0.381  0.619  1.0
  Al  Al15  1  0.910  0.886  0.617  1.0
  O  O16  1  0.080  0.137  0.376  1.0
  O  O17  1  0.074  0.159  0.886  1.0
  O  O18  1  0.075  0.610  0.384  1.0
  O  O19  1  0.245  0.151  0.387  1.0
  O  O20  1  0.086  0.599  0.867  1.0
  O  O21  1  0.254  0.598  0.371  1.0
  O  O22  1  0.246  0.152  0.879  1.0
  O  O23  1  0.414  0.151  0.383  1.0
  O  O24  1  0.255  0.599  0.863  1.0
  O  O25  1  0.425  0.140  0.866  1.0
  O  O26  1  0.426  0.591  0.364  1.0
  O  O27  1  0.575  0.140  0.415  1.0
  O  O28  1  0.420  0.613  0.874  1.0
  O  O29  1  0.586  0.624  0.392  1.0
  O  O30  1  0.580  0.132  0.871  1.0
  O  O31  1  0.746  0.134  0.361  1.0
  O  O32  1  0.574  0.643  0.870  1.0
  O  O33  1  0.755  0.123  0.887  1.0
  O  O34  1  0.745  0.627  0.363  1.0
  O  O35  1  0.926  0.107  0.380  1.0
  O  O36  1  0.754  0.616  0.889  1.0
  O  O37  1  0.920  0.618  0.379  1.0
  O  O38  1  0.914  0.126  0.858  1.0
  O  O39  1  0.925  0.610  0.835  1.0
[/CIF]
.
The material structure described by Al2O3 is beta indium sulfide-like structured and crystallizes in the monoclinic C2/c space group. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(2) and two equivalent O(5) atoms to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-61°. In the second Al site, Al(2) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(1) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent Al(4)O4 tetrahedra,  an edgeedge with one Al(2)O6 octahedra,  an edgeedge with one Al(5)O6 octahedra, and edges with three equivalent Al(3)O6 octahedra. In the third Al site, Al(3) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(3) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent Al(4)O4 tetrahedra,  an edgeedge with one Al(3)O6 octahedra,  an edgeedge with one Al(5)O6 octahedra, and edges with three equivalent Al(2)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-61°. In the fifth Al site, Al(5) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent Al(4)O4 tetrahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Al(3), one Al(4), and two equivalent Al(2) atoms to form distorted edge-sharing OAl4 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Al(2), one Al(4), and two equivalent Al(3) atoms. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Al(3), one Al(4), and one Al(5) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), one Al(3), and one Al(5) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Al(2), one Al(4), and one Al(5) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Al2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   16.665
_cell_length_b   5.599
_cell_length_c   5.599
_cell_angle_alpha   90.057
_cell_angle_beta   60.427
_cell_angle_gamma   59.113
_symmetry_Int_Tables_number   1
_cell_volume   366.550
_cell_formula_units_Z   8
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Al  Al0  1  1.000  1.000  1.000  1.0
  Al  Al1  1  0.092  0.344  0.105  1.0
  Al  Al2  1  0.090  0.347  0.615  1.0
  Al  Al3  1  0.333  0.017  0.005  1.0
  Al  Al4  1  0.167  0.733  0.245  1.0
  Al  Al5  1  0.250  0.375  0.625  1.0
  Al  Al6  1  0.408  0.406  0.145  1.0
  Al  Al7  1  0.410  0.403  0.635  1.0
  Al  Al8  1  0.667  0.003  0.015  1.0
  Al  Al9  1  0.500  0.750  0.250  1.0
  Al  Al10  1  0.592  0.369  0.631  1.0
  Al  Al11  1  0.750  0.375  0.125  1.0
  Al  Al12  1  0.590  0.864  0.633  1.0
  Al  Al13  1  0.833  0.747  0.235  1.0
  Al  Al14  1  0.908  0.381  0.619  1.0
  Al  Al15  1  0.910  0.886  0.617  1.0
  O  O16  1  0.080  0.137  0.376  1.0
  O  O17  1  0.074  0.159  0.886  1.0
  O  O18  1  0.075  0.610  0.384  1.0
  O  O19  1  0.245  0.151  0.387  1.0
  O  O20  1  0.086  0.599  0.867  1.0
  O  O21  1  0.254  0.598  0.371  1.0
  O  O22  1  0.246  0.152  0.879  1.0
  O  O23  1  0.414  0.151  0.383  1.0
  O  O24  1  0.255  0.599  0.863  1.0
  O  O25  1  0.425  0.140  0.866  1.0
  O  O26  1  0.426  0.591  0.364  1.0
  O  O27  1  0.575  0.140  0.415  1.0
  O  O28  1  0.420  0.613  0.874  1.0
  O  O29  1  0.586  0.624  0.392  1.0
  O  O30  1  0.580  0.132  0.871  1.0
  O  O31  1  0.746  0.134  0.361  1.0
  O  O32  1  0.574  0.643  0.870  1.0
  O  O33  1  0.755  0.123  0.887  1.0
  O  O34  1  0.745  0.627  0.363  1.0
  O  O35  1  0.926  0.107  0.380  1.0
  O  O36  1  0.754  0.616  0.889  1.0
  O  O37  1  0.920  0.618  0.379  1.0
  O  O38  1  0.914  0.126  0.858  1.0
  O  O39  1  0.925  0.610  0.835  1.0
[/CIF]
.