The structure described by BaAl2O4 crystallizes in the monoclinic C2 space group. Ba(1) is bonded in a 9-coordinate geometry to one O(3), one O(5), two equivalent O(2), two equivalent O(4), and three equivalent O(1) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(1), one O(5), and two equivalent O(4) atoms to form corner-sharing AlO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Ba(1), one Al(1), and one Al(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Al(1) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Al(1) atoms. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Al(2) atoms. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1) and two equivalent Al(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaAl2O4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.267
_cell_length_b   5.267
_cell_length_c   8.970
_cell_angle_alpha   89.439
_cell_angle_beta   89.439
_cell_angle_gamma   60.273
_symmetry_Int_Tables_number   1
_cell_volume   216.090
_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
  Ba  Ba0  1  1.000  0.001  0.750  1.0
  Ba  Ba1  1  0.999  0.000  0.250  1.0
  Al  Al2  1  0.661  0.674  0.554  1.0
  Al  Al3  1  0.326  0.339  0.446  1.0
  Al  Al4  1  0.324  0.341  0.054  1.0
  Al  Al5  1  0.659  0.676  0.946  1.0
  O  O6  1  0.641  0.703  0.750  1.0
  O  O7  1  0.297  0.359  0.250  1.0
  O  O8  1  0.641  0.002  0.487  1.0
  O  O9  1  0.355  0.645  0.500  1.0
  O  O10  1  0.998  0.359  0.513  1.0
  O  O11  1  0.353  0.002  0.009  1.0
  O  O12  1  0.637  0.363  0.000  1.0
  O  O13  1  0.998  0.647  0.991  1.0
[/CIF]
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The structure described by BaAl2O4 crystallizes in the monoclinic C2 space group. Ba(1) is bonded in a 9-coordinate geometry to one O(3), one O(5), two equivalent O(2), two equivalent O(4), and three equivalent O(1) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(1), one O(5), and two equivalent O(4) atoms to form corner-sharing AlO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Ba(1), one Al(1), and one Al(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Al(1) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Al(1) atoms. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Al(2) atoms. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1) and two equivalent Al(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaAl2O4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.267
_cell_length_b   5.267
_cell_length_c   8.970
_cell_angle_alpha   89.439
_cell_angle_beta   89.439
_cell_angle_gamma   60.273
_symmetry_Int_Tables_number   1
_cell_volume   216.090
_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
  Ba  Ba0  1  1.000  0.001  0.750  1.0
  Ba  Ba1  1  0.999  0.000  0.250  1.0
  Al  Al2  1  0.661  0.674  0.554  1.0
  Al  Al3  1  0.326  0.339  0.446  1.0
  Al  Al4  1  0.324  0.341  0.054  1.0
  Al  Al5  1  0.659  0.676  0.946  1.0
  O  O6  1  0.641  0.703  0.750  1.0
  O  O7  1  0.297  0.359  0.250  1.0
  O  O8  1  0.641  0.002  0.487  1.0
  O  O9  1  0.355  0.645  0.500  1.0
  O  O10  1  0.998  0.359  0.513  1.0
  O  O11  1  0.353  0.002  0.009  1.0
  O  O12  1  0.637  0.363  0.000  1.0
  O  O13  1  0.998  0.647  0.991  1.0
[/CIF]
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