Al2O3 crystallizes in the triclinic P1 space group. There are sixteen inequivalent Al sites. In the first Al site, Al(1) is bonded in a 4-coordinate geometry to one O(10), one O(13), one O(22), and one O(6) atom. In the second Al site, Al(2) is bonded to one O(1), one O(10), one O(2), one O(20), one O(4), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(15)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  an edgeedge with one Al(3)O6 octahedra. In the third Al site, Al(3) is bonded to one O(11), one O(14), one O(18), one O(20), one O(8), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(12)O4 tetrahedra and  an edgeedge with one Al(2)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(13), one O(3), and one O(6) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra and corners with two equivalent Al(15)O4 tetrahedra. The corner-sharing octahedral tilt angles are 72°. In the fifth Al site, Al(5) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(8), and one O(9) atom. In the sixth Al site, Al(6) is bonded in a 6-coordinate geometry to one O(1), one O(13), one O(18), one O(2), one O(4), and one O(9) atom. In the seventh Al site, Al(7) is bonded in a 5-coordinate geometry to one O(14), one O(18), one O(20), one O(7), and one O(8) atom. In the eighth Al site, Al(8) is bonded to one O(12), one O(19), one O(21), one O(23), and one O(24) atom to form distorted corner-sharing AlO5 trigonal bipyramids. In the ninth Al site, Al(9) is bonded in a 6-coordinate geometry to one O(11), one O(16), one O(17), one O(24), one O(5), and one O(7) atom. In the tenth Al site, Al(10) is bonded in a 5-coordinate geometry to one O(14), one O(18), one O(20), one O(5), and one O(8) atom. In the eleventh Al site, Al(11) is bonded in a 6-coordinate geometry to one O(16), one O(17), one O(23), one O(24), one O(5), and one O(7) atom. In the twelfth Al site, Al(12) is bonded to one O(11), one O(16), one O(17), and one O(7) atom to form distorted corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 89°. In the thirteenth Al site, Al(13) is bonded to one O(15), one O(21), one O(22), and one O(23) atom to form distorted corner-sharing AlO4 tetrahedra. In the fourteenth Al site, Al(14) is bonded in a 5-coordinate geometry to one O(12), one O(15), one O(16), one O(19), and one O(21) atom. In the fifteenth Al site, Al(15) is bonded to one O(10), one O(12), one O(3), and one O(6) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Al(4)O4 tetrahedra, and  a cornercorner with one Al(8)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 69°. In the sixteenth Al site, Al(16) is bonded in a 4-coordinate geometry to one O(15), one O(19), one O(22), and one O(3) atom. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Al(2), one Al(4), one Al(5), and one Al(6) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Al(2), one Al(5), and one Al(6) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Al(15), one Al(16), and one Al(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Al(2), one Al(5), and one Al(6) atom. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Al(10), one Al(11), and one Al(9) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Al(1), one Al(15), and one Al(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Al(11), one Al(12), one Al(7), and one Al(9) atom. In the eighth O site, O(8) is bonded to one Al(10), one Al(3), one Al(5), and one Al(7) atom to form a mixture of corner and edge-sharing OAl4 trigonal pyramids. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Al(2), one Al(3), one Al(5), and one Al(6) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Al(1), one Al(15), and one Al(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Al(12), one Al(3), and one Al(9) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Al(14), one Al(15), and one Al(8) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Al(1), one Al(4), and one Al(6) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Al(10), one Al(3), and one Al(7) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Al(13), one Al(14), and one Al(16) atom. In the sixteenth O site, O(16) is bonded in a distorted rectangular see-saw-like geometry to one Al(11), one Al(12), one Al(14), and one Al(9) atom. In the seventeenth O site, O(17) is bonded in a distorted trigonal non-coplanar geometry to one Al(11), one Al(12), and one Al(9) atom. In the eighteenth O site, O(18) is bonded to one Al(10), one Al(3), one Al(6), and one Al(7) atom to form a mixture of distorted corner and edge-sharing OAl4 trigonal pyramids. In the nineteenth O site, O(19) is bonded in a 3-coordinate geometry to one Al(14), one Al(16), and one Al(8) atom. In the twentieth O site, O(20) is bonded in a distorted see-saw-like geometry to one Al(10), one Al(2), one Al(3), and one Al(7) atom. In the twenty-first O site, O(21) is bonded in a 3-coordinate geometry to one Al(13), one Al(14), and one Al(8) atom. In the twenty-second O site, O(22) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(13), and one Al(16) atom. In the twenty-third O site, O(23) is bonded in a 3-coordinate geometry to one Al(11), one Al(13), and one Al(8) atom. In the twenty-fourth O site, O(24) is bonded in a distorted T-shaped geometry to one Al(11), one Al(8), and one Al(9) atom.
Al2O3 crystallizes in the triclinic P1 space group. There are sixteen inequivalent Al sites. In the first Al site, Al(1) is bonded in a 4-coordinate geometry to one O(10), one O(13), one O(22), and one O(6) atom. The Al(1)-O(10) bond length is 1.96 Å. The Al(1)-O(13) bond length is 1.75 Å. The Al(1)-O(22) bond length is 1.94 Å. The Al(1)-O(6) bond length is 1.74 Å. In the second Al site, Al(2) is bonded to one O(1), one O(10), one O(2), one O(20), one O(4), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(15)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  an edgeedge with one Al(3)O6 octahedra. The Al(2)-O(1) bond length is 2.29 Å. The Al(2)-O(10) bond length is 2.16 Å. The Al(2)-O(2) bond length is 1.82 Å. The Al(2)-O(20) bond length is 2.14 Å. The Al(2)-O(4) bond length is 1.91 Å. The Al(2)-O(9) bond length is 1.87 Å. In the third Al site, Al(3) is bonded to one O(11), one O(14), one O(18), one O(20), one O(8), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(12)O4 tetrahedra and  an edgeedge with one Al(2)O6 octahedra. The Al(3)-O(11) bond length is 2.02 Å. The Al(3)-O(14) bond length is 1.90 Å. The Al(3)-O(18) bond length is 1.91 Å. The Al(3)-O(20) bond length is 1.94 Å. The Al(3)-O(8) bond length is 1.99 Å. The Al(3)-O(9) bond length is 2.13 Å. In the fourth Al site, Al(4) is bonded to one O(1), one O(13), one O(3), and one O(6) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra and corners with two equivalent Al(15)O4 tetrahedra. The corner-sharing octahedral tilt angles are 72°. The Al(4)-O(1) bond length is 2.00 Å. The Al(4)-O(13) bond length is 1.81 Å. The Al(4)-O(3) bond length is 1.45 Å. The Al(4)-O(6) bond length is 1.80 Å. In the fifth Al site, Al(5) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(8), and one O(9) atom. The Al(5)-O(1) bond length is 1.86 Å. The Al(5)-O(2) bond length is 1.91 Å. The Al(5)-O(4) bond length is 1.69 Å. The Al(5)-O(8) bond length is 1.89 Å. The Al(5)-O(9) bond length is 2.02 Å. In the sixth Al site, Al(6) is bonded in a 6-coordinate geometry to one O(1), one O(13), one O(18), one O(2), one O(4), and one O(9) atom. The Al(6)-O(1) bond length is 1.98 Å. The Al(6)-O(13) bond length is 2.13 Å. The Al(6)-O(18) bond length is 2.33 Å. The Al(6)-O(2) bond length is 1.81 Å. The Al(6)-O(4) bond length is 1.92 Å. The Al(6)-O(9) bond length is 1.82 Å. In the seventh Al site, Al(7) is bonded in a 5-coordinate geometry to one O(14), one O(18), one O(20), one O(7), and one O(8) atom. The Al(7)-O(14) bond length is 1.64 Å. The Al(7)-O(18) bond length is 2.10 Å. The Al(7)-O(20) bond length is 2.00 Å. The Al(7)-O(7) bond length is 2.01 Å. The Al(7)-O(8) bond length is 2.06 Å. In the eighth Al site, Al(8) is bonded to one O(12), one O(19), one O(21), one O(23), and one O(24) atom to form distorted corner-sharing AlO5 trigonal bipyramids. The Al(8)-O(12) bond length is 2.06 Å. The Al(8)-O(19) bond length is 2.03 Å. The Al(8)-O(21) bond length is 1.97 Å. The Al(8)-O(23) bond length is 1.57 Å. The Al(8)-O(24) bond length is 1.96 Å. In the ninth Al site, Al(9) is bonded in a 6-coordinate geometry to one O(11), one O(16), one O(17), one O(24), one O(5), and one O(7) atom. The Al(9)-O(11) bond length is 1.99 Å. The Al(9)-O(16) bond length is 2.40 Å. The Al(9)-O(17) bond length is 1.79 Å. The Al(9)-O(24) bond length is 2.13 Å. The Al(9)-O(5) bond length is 2.03 Å. The Al(9)-O(7) bond length is 2.31 Å. In the tenth Al site, Al(10) is bonded in a 5-coordinate geometry to one O(14), one O(18), one O(20), one O(5), and one O(8) atom. The Al(10)-O(14) bond length is 1.98 Å. The Al(10)-O(18) bond length is 1.81 Å. The Al(10)-O(20) bond length is 2.17 Å. The Al(10)-O(5) bond length is 1.96 Å. The Al(10)-O(8) bond length is 1.89 Å. In the eleventh Al site, Al(11) is bonded in a 6-coordinate geometry to one O(16), one O(17), one O(23), one O(24), one O(5), and one O(7) atom. The Al(11)-O(16) bond length is 2.14 Å. The Al(11)-O(17) bond length is 2.21 Å. The Al(11)-O(23) bond length is 2.09 Å. The Al(11)-O(24) bond length is 1.82 Å. The Al(11)-O(5) bond length is 1.64 Å. The Al(11)-O(7) bond length is 2.05 Å. In the twelfth Al site, Al(12) is bonded to one O(11), one O(16), one O(17), and one O(7) atom to form distorted corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 89°. The Al(12)-O(11) bond length is 1.57 Å. The Al(12)-O(16) bond length is 1.91 Å. The Al(12)-O(17) bond length is 1.75 Å. The Al(12)-O(7) bond length is 2.01 Å. In the thirteenth Al site, Al(13) is bonded to one O(15), one O(21), one O(22), and one O(23) atom to form distorted corner-sharing AlO4 tetrahedra. The Al(13)-O(15) bond length is 1.89 Å. The Al(13)-O(21) bond length is 1.50 Å. The Al(13)-O(22) bond length is 1.85 Å. The Al(13)-O(23) bond length is 2.16 Å. In the fourteenth Al site, Al(14) is bonded in a 5-coordinate geometry to one O(12), one O(15), one O(16), one O(19), and one O(21) atom. The Al(14)-O(12) bond length is 2.12 Å. The Al(14)-O(15) bond length is 2.21 Å. The Al(14)-O(16) bond length is 1.78 Å. The Al(14)-O(19) bond length is 1.62 Å. The Al(14)-O(21) bond length is 2.06 Å. In the fifteenth Al site, Al(15) is bonded to one O(10), one O(12), one O(3), and one O(6) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Al(4)O4 tetrahedra, and  a cornercorner with one Al(8)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 69°. The Al(15)-O(10) bond length is 1.47 Å. The Al(15)-O(12) bond length is 1.80 Å. The Al(15)-O(3) bond length is 1.89 Å. The Al(15)-O(6) bond length is 2.09 Å. In the sixteenth Al site, Al(16) is bonded in a 4-coordinate geometry to one O(15), one O(19), one O(22), and one O(3) atom. The Al(16)-O(15) bond length is 2.04 Å. The Al(16)-O(19) bond length is 1.53 Å. The Al(16)-O(22) bond length is 1.80 Å. The Al(16)-O(3) bond length is 1.96 Å. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Al(2), one Al(4), one Al(5), and one Al(6) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Al(2), one Al(5), and one Al(6) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Al(15), one Al(16), and one Al(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Al(2), one Al(5), and one Al(6) atom. In the fifth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Al(10), one Al(11), and one Al(9) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Al(1), one Al(15), and one Al(4) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Al(11), one Al(12), one Al(7), and one Al(9) atom. In the eighth O site, O(8) is bonded to one Al(10), one Al(3), one Al(5), and one Al(7) atom to form a mixture of corner and edge-sharing OAl4 trigonal pyramids. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Al(2), one Al(3), one Al(5), and one Al(6) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Al(1), one Al(15), and one Al(2) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Al(12), one Al(3), and one Al(9) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Al(14), one Al(15), and one Al(8) atom. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Al(1), one Al(4), and one Al(6) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Al(10), one Al(3), and one Al(7) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Al(13), one Al(14), and one Al(16) atom. In the sixteenth O site, O(16) is bonded in a distorted rectangular see-saw-like geometry to one Al(11), one Al(12), one Al(14), and one Al(9) atom. In the seventeenth O site, O(17) is bonded in a distorted trigonal non-coplanar geometry to one Al(11), one Al(12), and one Al(9) atom. In the eighteenth O site, O(18) is bonded to one Al(10), one Al(3), one Al(6), and one Al(7) atom to form a mixture of distorted corner and edge-sharing OAl4 trigonal pyramids. In the nineteenth O site, O(19) is bonded in a 3-coordinate geometry to one Al(14), one Al(16), and one Al(8) atom. In the twentieth O site, O(20) is bonded in a distorted see-saw-like geometry to one Al(10), one Al(2), one Al(3), and one Al(7) atom. In the twenty-first O site, O(21) is bonded in a 3-coordinate geometry to one Al(13), one Al(14), and one Al(8) atom. In the twenty-second O site, O(22) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(13), and one Al(16) atom. In the twenty-third O site, O(23) is bonded in a 3-coordinate geometry to one Al(11), one Al(13), and one Al(8) atom. In the twenty-fourth O site, O(24) is bonded in a distorted T-shaped geometry to one Al(11), one Al(8), and one Al(9) atom.