The material structure described by Ba4Sb2O9 crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to three equivalent O(2) and six equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. In the third Ba site, Ba(3) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(3)O12 cuboctahedra and faces with six equivalent Sb(1)O6 octahedra. Sb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted SbO6 octahedra that share faces with three equivalent Ba(3)O12 cuboctahedra and  a faceface with one Sb(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), and one Sb(1) atom. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(3), and two equivalent Sb(1) atoms to form a mixture of distorted face and corner-sharing OBa4Sb2 octahedra. The corner-sharing octahedral tilt angles range from 8-60°. is represented by the CIF card [CIF]
data_Ba4Sb2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.045
_cell_length_b   6.045
_cell_length_c   16.925
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   535.575
_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  0.667  0.333  0.871  1.0
  Ba  Ba1  1  0.333  0.667  0.129  1.0
  Ba  Ba2  1  0.333  0.667  0.371  1.0
  Ba  Ba3  1  0.667  0.333  0.629  1.0
  Ba  Ba4  1  0.000  1.000  0.500  1.0
  Ba  Ba5  1  0.000  1.000  0.000  1.0
  Ba  Ba6  1  0.000  1.000  0.750  1.0
  Ba  Ba7  1  1.000  0.000  0.250  1.0
  Sb  Sb8  1  0.333  0.667  0.664  1.0
  Sb  Sb9  1  0.667  0.333  0.336  1.0
  Sb  Sb10  1  0.667  0.333  0.164  1.0
  Sb  Sb11  1  0.333  0.667  0.836  1.0
  O  O12  1  0.172  0.343  0.889  1.0
  O  O13  1  0.828  0.657  0.111  1.0
  O  O14  1  0.657  0.828  0.889  1.0
  O  O15  1  0.343  0.172  0.111  1.0
  O  O16  1  0.172  0.828  0.889  1.0
  O  O17  1  0.828  0.172  0.111  1.0
  O  O18  1  0.828  0.657  0.389  1.0
  O  O19  1  0.172  0.343  0.611  1.0
  O  O20  1  0.343  0.172  0.389  1.0
  O  O21  1  0.657  0.828  0.611  1.0
  O  O22  1  0.828  0.172  0.389  1.0
  O  O23  1  0.172  0.828  0.611  1.0
  O  O24  1  0.521  0.042  0.250  1.0
  O  O25  1  0.479  0.958  0.750  1.0
  O  O26  1  0.958  0.479  0.250  1.0
  O  O27  1  0.042  0.521  0.750  1.0
  O  O28  1  0.521  0.479  0.250  1.0
  O  O29  1  0.479  0.521  0.750  1.0
[/CIF]
.
The material structure described by Ba4Sb2O9 crystallizes in the hexagonal P6_3/mmc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to three equivalent O(2) and six equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. In the third Ba site, Ba(3) is bonded to six equivalent O(1) and six equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(3)O12 cuboctahedra and faces with six equivalent Sb(1)O6 octahedra. Sb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted SbO6 octahedra that share faces with three equivalent Ba(3)O12 cuboctahedra and  a faceface with one Sb(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), and one Sb(1) atom. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(3), and two equivalent Sb(1) atoms to form a mixture of distorted face and corner-sharing OBa4Sb2 octahedra. The corner-sharing octahedral tilt angles range from 8-60°. is represented by the CIF card [CIF]
data_Ba4Sb2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.045
_cell_length_b   6.045
_cell_length_c   16.925
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   535.575
_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  0.667  0.333  0.871  1.0
  Ba  Ba1  1  0.333  0.667  0.129  1.0
  Ba  Ba2  1  0.333  0.667  0.371  1.0
  Ba  Ba3  1  0.667  0.333  0.629  1.0
  Ba  Ba4  1  0.000  1.000  0.500  1.0
  Ba  Ba5  1  0.000  1.000  0.000  1.0
  Ba  Ba6  1  0.000  1.000  0.750  1.0
  Ba  Ba7  1  1.000  0.000  0.250  1.0
  Sb  Sb8  1  0.333  0.667  0.664  1.0
  Sb  Sb9  1  0.667  0.333  0.336  1.0
  Sb  Sb10  1  0.667  0.333  0.164  1.0
  Sb  Sb11  1  0.333  0.667  0.836  1.0
  O  O12  1  0.172  0.343  0.889  1.0
  O  O13  1  0.828  0.657  0.111  1.0
  O  O14  1  0.657  0.828  0.889  1.0
  O  O15  1  0.343  0.172  0.111  1.0
  O  O16  1  0.172  0.828  0.889  1.0
  O  O17  1  0.828  0.172  0.111  1.0
  O  O18  1  0.828  0.657  0.389  1.0
  O  O19  1  0.172  0.343  0.611  1.0
  O  O20  1  0.343  0.172  0.389  1.0
  O  O21  1  0.657  0.828  0.611  1.0
  O  O22  1  0.828  0.172  0.389  1.0
  O  O23  1  0.172  0.828  0.611  1.0
  O  O24  1  0.521  0.042  0.250  1.0
  O  O25  1  0.479  0.958  0.750  1.0
  O  O26  1  0.958  0.479  0.250  1.0
  O  O27  1  0.042  0.521  0.750  1.0
  O  O28  1  0.521  0.479  0.250  1.0
  O  O29  1  0.479  0.521  0.750  1.0
[/CIF]
.