data_Ba2NbAl
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.64
_cell_length_b   11.64
_cell_length_c   11.64
_cell_angle_alpha   17.42
_cell_angle_beta   17.42
_cell_angle_gamma   17.42
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ba2NbAl
_chemical_formula_sum   'Ba2 Nb1 Al1'
_cell_volume   123.2
_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  Ba1  1  0.0  0.0  0.83  1.0
  Ba  Ba2  1  0.0  0.0  0.54  1.0
  Nb  Nb3  1  0.0  0.0  0.19  1.0
  Al  Al0  1  0.0  0.0  0.0  1.0

data_Ba2NbAl
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.1
_cell_length_b   3.52
_cell_length_c   11.64
_cell_angle_alpha   90.0
_cell_angle_beta   100.07
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Ba2NbAl
_chemical_formula_sum   'Ba4 Nb2 Al2'
_cell_volume   246.39
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  2  0.0  0.0  0.17  1.0
  Ba  Ba1  2  0.0  0.0  0.46  1.0
  Nb  Nb2  2  0.0  0.0  0.81  1.0
  Al  Al3  2  0.0  0.0  0.0  1.0

Ba Ba Nb Al
Ba2NbAl crystallizes in the monoclinic Cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a single-bond geometry to one Ba(2) and one Al(1) atom. The Ba(1)-Ba(2) bond length is 3.38 Å. The Ba(1)-Al(1) bond length is 1.95 Å. In the second Ba site, Ba(2) is bonded to one Ba(1), six equivalent Ba(2), and one Nb(1) atom to form a mixture of distorted edge and corner-sharing BaBa7Nb hexagonal bipyramids. All Ba(2)-Ba(2) bond lengths are 3.52 Å. The Ba(2)-Nb(1) bond length is 4.13 Å. Nb(1) is bonded in a distorted single-bond geometry to one Ba(2) and one Al(1) atom. The Nb(1)-Al(1) bond length is 2.18 Å. Al(1) is bonded in a distorted single-bond geometry to one Ba(1) and one Nb(1) atom.