The structure described by Ba2Cu3AlO8 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 12-coordinate geometry to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted CuO5 trigonal bipyramids that share  a cornercorner with one Cu(2)O6 octahedra and corners with four equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. In the second Cu site, Cu(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form CuO6 octahedra that share corners with four equivalent Cu(2)O6 octahedra and corners with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. Al(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Cu(1), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ba(1) and two equivalent Cu(2) atoms. In the third O site, O(3) is bonded to four equivalent Ba(1), one Cu(1), and one Cu(2) atom to form a mixture of corner and edge-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2AlCu3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.810
_cell_length_b   3.810
_cell_length_c   11.576
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   168.081
_cell_formula_units_Z   1
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  0.500  0.500  0.171  1.0
  Ba  Ba1  1  0.500  0.500  0.829  1.0
  Al  Al2  1  0.500  0.500  0.500  1.0
  Cu  Cu3  1  0.000  0.000  0.356  1.0
  Cu  Cu4  1  0.000  0.000  0.000  1.0
  Cu  Cu5  1  0.000  0.000  0.644  1.0
  O  O6  1  0.000  0.500  0.398  1.0
  O  O7  1  0.500  0.000  0.398  1.0
  O  O8  1  0.500  0.000  0.000  1.0
  O  O9  1  0.000  0.000  0.183  1.0
  O  O10  1  0.000  0.500  0.602  1.0
  O  O11  1  0.500  0.000  0.602  1.0
  O  O12  1  0.000  0.000  0.817  1.0
  O  O13  1  0.000  0.500  0.000  1.0
[/CIF]
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The structure described by Ba2Cu3AlO8 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 12-coordinate geometry to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(3) and four equivalent O(1) atoms to form distorted CuO5 trigonal bipyramids that share  a cornercorner with one Cu(2)O6 octahedra and corners with four equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. In the second Cu site, Cu(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form CuO6 octahedra that share corners with four equivalent Cu(2)O6 octahedra and corners with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedra are not tilted. Al(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Cu(1), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ba(1) and two equivalent Cu(2) atoms. In the third O site, O(3) is bonded to four equivalent Ba(1), one Cu(1), and one Cu(2) atom to form a mixture of corner and edge-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2AlCu3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.810
_cell_length_b   3.810
_cell_length_c   11.576
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   168.081
_cell_formula_units_Z   1
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  0.500  0.500  0.171  1.0
  Ba  Ba1  1  0.500  0.500  0.829  1.0
  Al  Al2  1  0.500  0.500  0.500  1.0
  Cu  Cu3  1  0.000  0.000  0.356  1.0
  Cu  Cu4  1  0.000  0.000  0.000  1.0
  Cu  Cu5  1  0.000  0.000  0.644  1.0
  O  O6  1  0.000  0.500  0.398  1.0
  O  O7  1  0.500  0.000  0.398  1.0
  O  O8  1  0.500  0.000  0.000  1.0
  O  O9  1  0.000  0.000  0.183  1.0
  O  O10  1  0.000  0.500  0.602  1.0
  O  O11  1  0.500  0.000  0.602  1.0
  O  O12  1  0.000  0.000  0.817  1.0
  O  O13  1  0.000  0.500  0.000  1.0
[/CIF]
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