The structure described by Al2Se3 crystallizes in the monoclinic Cc space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form corner-sharing AlSe4 tetrahedra. In the second Al site, Al(2) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form corner-sharing AlSe4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one Al(2) and two equivalent Al(1) atoms. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one Al(1) and two equivalent Al(2) atoms. is represented by the CIF file [CIF]
data_Al2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.776
_cell_length_b   6.797
_cell_length_c   7.381
_cell_angle_alpha   116.526
_cell_angle_beta   90.000
_cell_angle_gamma   119.900
_symmetry_Int_Tables_number   1
_cell_volume   252.553
_cell_formula_units_Z   2
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  0.637  0.084  0.129  1.0
  Al  Al1  1  0.446  0.084  0.629  1.0
  Al  Al2  1  0.266  0.401  0.117  1.0
  Al  Al3  1  0.135  0.401  0.617  1.0
  Se  Se4  1  0.908  0.996  0.989  1.0
  Se  Se5  1  0.088  0.996  0.489  1.0
  Se  Se6  1  0.586  0.344  0.013  1.0
  Se  Se7  1  0.758  0.344  0.513  1.0
  Se  Se8  1  0.247  0.676  0.002  1.0
  Se  Se9  1  0.428  0.676  0.502  1.0
[/CIF]
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The structure described by Al2Se3 crystallizes in the monoclinic Cc space group. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one Se(1), one Se(3), and two equivalent Se(2) atoms to form corner-sharing AlSe4 tetrahedra. In the second Al site, Al(2) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form corner-sharing AlSe4 tetrahedra. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the second Se site, Se(2) is bonded in a trigonal non-coplanar geometry to one Al(2) and two equivalent Al(1) atoms. In the third Se site, Se(3) is bonded in a trigonal non-coplanar geometry to one Al(1) and two equivalent Al(2) atoms. is represented by the CIF file [CIF]
data_Al2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.776
_cell_length_b   6.797
_cell_length_c   7.381
_cell_angle_alpha   116.526
_cell_angle_beta   90.000
_cell_angle_gamma   119.900
_symmetry_Int_Tables_number   1
_cell_volume   252.553
_cell_formula_units_Z   2
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  0.637  0.084  0.129  1.0
  Al  Al1  1  0.446  0.084  0.629  1.0
  Al  Al2  1  0.266  0.401  0.117  1.0
  Al  Al3  1  0.135  0.401  0.617  1.0
  Se  Se4  1  0.908  0.996  0.989  1.0
  Se  Se5  1  0.088  0.996  0.489  1.0
  Se  Se6  1  0.586  0.344  0.013  1.0
  Se  Se7  1  0.758  0.344  0.513  1.0
  Se  Se8  1  0.247  0.676  0.002  1.0
  Se  Se9  1  0.428  0.676  0.502  1.0
[/CIF]
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