The structure described by Ta3AlB8 is hexagonal omega structure-derived structured and crystallizes in the hexagonal P6/mmm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent B(1) and six equivalent B(2) atoms to form TaB12 cuboctahedra that share edges with six equivalent Ta(2)B12 cuboctahedra, edges with six equivalent Al(1)B12 cuboctahedra,  a faceface with one Ta(2)B12 cuboctahedra,  a faceface with one Al(1)B12 cuboctahedra, and faces with six equivalent Ta(1)B12 cuboctahedra. In the second Ta site, Ta(2) is bonded to twelve equivalent B(2) atoms to form a mixture of face and edge-sharing TaB12 cuboctahedra. Al(1) is bonded to twelve equivalent B(1) atoms to form AlB12 cuboctahedra that share edges with twelve equivalent Ta(1)B12 cuboctahedra, faces with two equivalent Ta(1)B12 cuboctahedra, and faces with six equivalent Al(1)B12 cuboctahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to three equivalent Ta(1), three equivalent Al(1), and three equivalent B(1) atoms. In the second B site, B(2) is bonded in a 9-coordinate geometry to three equivalent Ta(1), three equivalent Ta(2), and three equivalent B(2) atoms. is represented by the CIF file [CIF]
data_Ta3AlB8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.048
_cell_length_b   3.048
_cell_length_c   13.452
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   108.245
_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
  Ta  Ta0  1  0.000  0.000  0.745  1.0
  Ta  Ta1  1  0.000  0.000  0.500  1.0
  Ta  Ta2  1  0.000  0.000  0.255  1.0
  Al  Al3  1  0.000  0.000  0.000  1.0
  B  B4  1  0.667  0.333  0.879  1.0
  B  B5  1  0.667  0.333  0.624  1.0
  B  B6  1  0.667  0.333  0.376  1.0
  B  B7  1  0.667  0.333  0.121  1.0
  B  B8  1  0.333  0.667  0.879  1.0
  B  B9  1  0.333  0.667  0.624  1.0
  B  B10  1  0.333  0.667  0.376  1.0
  B  B11  1  0.333  0.667  0.121  1.0
[/CIF]
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The structure described by Ta3AlB8 is hexagonal omega structure-derived structured and crystallizes in the hexagonal P6/mmm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent B(1) and six equivalent B(2) atoms to form TaB12 cuboctahedra that share edges with six equivalent Ta(2)B12 cuboctahedra, edges with six equivalent Al(1)B12 cuboctahedra,  a faceface with one Ta(2)B12 cuboctahedra,  a faceface with one Al(1)B12 cuboctahedra, and faces with six equivalent Ta(1)B12 cuboctahedra. In the second Ta site, Ta(2) is bonded to twelve equivalent B(2) atoms to form a mixture of face and edge-sharing TaB12 cuboctahedra. Al(1) is bonded to twelve equivalent B(1) atoms to form AlB12 cuboctahedra that share edges with twelve equivalent Ta(1)B12 cuboctahedra, faces with two equivalent Ta(1)B12 cuboctahedra, and faces with six equivalent Al(1)B12 cuboctahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to three equivalent Ta(1), three equivalent Al(1), and three equivalent B(1) atoms. In the second B site, B(2) is bonded in a 9-coordinate geometry to three equivalent Ta(1), three equivalent Ta(2), and three equivalent B(2) atoms. is represented by the CIF file [CIF]
data_Ta3AlB8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.048
_cell_length_b   3.048
_cell_length_c   13.452
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   108.245
_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
  Ta  Ta0  1  0.000  0.000  0.745  1.0
  Ta  Ta1  1  0.000  0.000  0.500  1.0
  Ta  Ta2  1  0.000  0.000  0.255  1.0
  Al  Al3  1  0.000  0.000  0.000  1.0
  B  B4  1  0.667  0.333  0.879  1.0
  B  B5  1  0.667  0.333  0.624  1.0
  B  B6  1  0.667  0.333  0.376  1.0
  B  B7  1  0.667  0.333  0.121  1.0
  B  B8  1  0.333  0.667  0.879  1.0
  B  B9  1  0.333  0.667  0.624  1.0
  B  B10  1  0.333  0.667  0.376  1.0
  B  B11  1  0.333  0.667  0.121  1.0
[/CIF]
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