The compound described by Al2Se3 is beta indium sulfide structured and crystallizes in the tetragonal I4_1/amd space group. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form corner-sharing AlSe4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-64°. In the second Al site, Al(2) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form AlSe6 octahedra that share corners with four equivalent Al(1)Se4 tetrahedra, edges with two equivalent Al(3)Se6 octahedra, and edges with four equivalent Al(2)Se6 octahedra. In the third Al site, Al(3) is bonded to two equivalent Se(3) and four equivalent Se(1) atoms to form AlSe6 octahedra that share corners with four equivalent Al(1)Se4 tetrahedra, edges with two equivalent Al(3)Se6 octahedra, and edges with four equivalent Al(2)Se6 octahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), and two equivalent Al(3) atoms. In the second Se site, Se(2) is bonded to one Al(1) and three equivalent Al(2) atoms to form a mixture of distorted corner and edge-sharing SeAl4 tetrahedra. In the third Se site, Se(3) is bonded in a distorted T-shaped geometry to one Al(3) and two equivalent Al(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Al2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   16.810
_cell_length_b   16.810
_cell_length_c   16.810
_cell_angle_alpha   154.138
_cell_angle_beta   154.138
_cell_angle_gamma   36.898
_symmetry_Int_Tables_number   1
_cell_volume   902.544
_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  0.671  0.671  0.000  1.0
  Al  Al1  1  0.329  0.329  0.000  1.0
  Al  Al2  1  0.421  0.921  0.500  1.0
  Al  Al3  1  0.021  0.794  0.227  1.0
  Al  Al4  1  0.544  0.271  0.727  1.0
  Al  Al5  1  0.079  0.579  0.500  1.0
  Al  Al6  1  0.729  0.456  0.273  1.0
  Al  Al7  1  0.206  0.979  0.773  1.0
  Al  Al8  1  0.544  0.816  0.273  1.0
  Al  Al9  1  0.875  0.125  0.750  1.0
  Al  Al10  1  0.375  0.125  0.250  1.0
  Al  Al11  1  0.206  0.434  0.227  1.0
  Al  Al12  1  0.875  0.625  0.750  1.0
  Al  Al13  1  0.566  0.794  0.773  1.0
  Al  Al14  1  0.875  0.125  0.250  1.0
  Al  Al15  1  0.184  0.456  0.727  1.0
  Se  Se16  1  0.116  0.875  0.241  1.0
  Se  Se17  1  0.463  0.232  0.769  1.0
  Se  Se18  1  0.768  0.537  0.231  1.0
  Se  Se19  1  0.116  0.375  0.741  1.0
  Se  Se20  1  0.463  0.694  0.231  1.0
  Se  Se21  1  0.625  0.884  0.259  1.0
  Se  Se22  1  0.125  0.884  0.759  1.0
  Se  Se23  1  0.448  0.204  0.244  1.0
  Se  Se24  1  0.789  0.046  0.744  1.0
  Se  Se25  1  0.961  0.204  0.756  1.0
  Se  Se26  1  0.625  0.366  0.741  1.0
  Se  Se27  1  0.125  0.366  0.241  1.0
  Se  Se28  1  0.287  0.556  0.269  1.0
  Se  Se29  1  0.796  0.552  0.756  1.0
  Se  Se30  1  0.444  0.713  0.731  1.0
  Se  Se31  1  0.634  0.875  0.759  1.0
  Se  Se32  1  0.982  0.713  0.269  1.0
  Se  Se33  1  0.287  0.018  0.731  1.0
  Se  Se34  1  0.796  0.039  0.244  1.0
  Se  Se35  1  0.954  0.211  0.256  1.0
  Se  Se36  1  0.306  0.537  0.769  1.0
  Se  Se37  1  0.634  0.375  0.259  1.0
  Se  Se38  1  0.954  0.698  0.744  1.0
  Se  Se39  1  0.302  0.046  0.256  1.0
[/CIF]
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The compound described by Al2Se3 is beta indium sulfide structured and crystallizes in the tetragonal I4_1/amd space group. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form corner-sharing AlSe4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-64°. In the second Al site, Al(2) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form AlSe6 octahedra that share corners with four equivalent Al(1)Se4 tetrahedra, edges with two equivalent Al(3)Se6 octahedra, and edges with four equivalent Al(2)Se6 octahedra. In the third Al site, Al(3) is bonded to two equivalent Se(3) and four equivalent Se(1) atoms to form AlSe6 octahedra that share corners with four equivalent Al(1)Se4 tetrahedra, edges with two equivalent Al(3)Se6 octahedra, and edges with four equivalent Al(2)Se6 octahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), and two equivalent Al(3) atoms. In the second Se site, Se(2) is bonded to one Al(1) and three equivalent Al(2) atoms to form a mixture of distorted corner and edge-sharing SeAl4 tetrahedra. In the third Se site, Se(3) is bonded in a distorted T-shaped geometry to one Al(3) and two equivalent Al(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Al2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   16.810
_cell_length_b   16.810
_cell_length_c   16.810
_cell_angle_alpha   154.138
_cell_angle_beta   154.138
_cell_angle_gamma   36.898
_symmetry_Int_Tables_number   1
_cell_volume   902.544
_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  0.671  0.671  0.000  1.0
  Al  Al1  1  0.329  0.329  0.000  1.0
  Al  Al2  1  0.421  0.921  0.500  1.0
  Al  Al3  1  0.021  0.794  0.227  1.0
  Al  Al4  1  0.544  0.271  0.727  1.0
  Al  Al5  1  0.079  0.579  0.500  1.0
  Al  Al6  1  0.729  0.456  0.273  1.0
  Al  Al7  1  0.206  0.979  0.773  1.0
  Al  Al8  1  0.544  0.816  0.273  1.0
  Al  Al9  1  0.875  0.125  0.750  1.0
  Al  Al10  1  0.375  0.125  0.250  1.0
  Al  Al11  1  0.206  0.434  0.227  1.0
  Al  Al12  1  0.875  0.625  0.750  1.0
  Al  Al13  1  0.566  0.794  0.773  1.0
  Al  Al14  1  0.875  0.125  0.250  1.0
  Al  Al15  1  0.184  0.456  0.727  1.0
  Se  Se16  1  0.116  0.875  0.241  1.0
  Se  Se17  1  0.463  0.232  0.769  1.0
  Se  Se18  1  0.768  0.537  0.231  1.0
  Se  Se19  1  0.116  0.375  0.741  1.0
  Se  Se20  1  0.463  0.694  0.231  1.0
  Se  Se21  1  0.625  0.884  0.259  1.0
  Se  Se22  1  0.125  0.884  0.759  1.0
  Se  Se23  1  0.448  0.204  0.244  1.0
  Se  Se24  1  0.789  0.046  0.744  1.0
  Se  Se25  1  0.961  0.204  0.756  1.0
  Se  Se26  1  0.625  0.366  0.741  1.0
  Se  Se27  1  0.125  0.366  0.241  1.0
  Se  Se28  1  0.287  0.556  0.269  1.0
  Se  Se29  1  0.796  0.552  0.756  1.0
  Se  Se30  1  0.444  0.713  0.731  1.0
  Se  Se31  1  0.634  0.875  0.759  1.0
  Se  Se32  1  0.982  0.713  0.269  1.0
  Se  Se33  1  0.287  0.018  0.731  1.0
  Se  Se34  1  0.796  0.039  0.244  1.0
  Se  Se35  1  0.954  0.211  0.256  1.0
  Se  Se36  1  0.306  0.537  0.769  1.0
  Se  Se37  1  0.634  0.375  0.259  1.0
  Se  Se38  1  0.954  0.698  0.744  1.0
  Se  Se39  1  0.302  0.046  0.256  1.0
[/CIF]
.