data_Zr3TaNb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.0
_cell_length_b   5.0
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Zr3TaNb
_chemical_formula_sum   'Zr3 Ta1 Nb1'
_cell_volume   124.97
_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
  Zr  Zr1  1  0.0  0.5  0.0  1.0
  Zr  Zr2  1  0.0  0.0  0.5  1.0
  Zr  Zr3  1  0.5  0.0  0.0  1.0
  Ta  Ta4  1  0.5  0.5  0.5  1.0
  Nb  Nb0  1  0.0  0.0  0.0  1.0

data_Zr3TaNb
_symmetry_space_group_name_H-M   Pm-3m
_cell_length_a   5.0
_cell_length_b   5.0
_cell_length_c   5.0
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   221
_chemical_formula_structural   Zr3TaNb
_chemical_formula_sum   'Zr3 Ta1 Nb1'
_cell_volume   124.97
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-x, -y, -z'
  3  '-y, x, z'
  4  'y, -x, -z'
  5  '-x, -y, z'
  6  'x, y, -z'
  7  'y, -x, z'
  8  '-y, x, -z'
  9  'x, -y, -z'
  10  '-x, y, z'
  11  '-y, -x, -z'
  12  'y, x, z'
  13  '-x, y, -z'
  14  'x, -y, z'
  15  'y, x, -z'
  16  '-y, -x, z'
  17  'z, x, y'
  18  '-z, -x, -y'
  19  'z, -y, x'
  20  '-z, y, -x'
  21  'z, -x, -y'
  22  '-z, x, y'
  23  'z, y, -x'
  24  '-z, -y, x'
  25  '-z, x, -y'
  26  'z, -x, y'
  27  '-z, -y, -x'
  28  'z, y, x'
  29  '-z, -x, y'
  30  'z, x, -y'
  31  '-z, y, x'
  32  'z, -y, -x'
  33  'y, z, x'
  34  '-y, -z, -x'
  35  'x, z, -y'
  36  '-x, -z, y'
  37  '-y, z, -x'
  38  'y, -z, x'
  39  '-x, z, y'
  40  'x, -z, -y'
  41  '-y, -z, x'
  42  'y, z, -x'
  43  '-x, -z, -y'
  44  'x, z, y'
  45  'y, -z, -x'
  46  '-y, z, x'
  47  'x, -z, y'
  48  '-x, z, -y'
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
  Zr  Zr0  3  0.0  0.5  0.5  1.0
  Ta  Ta1  1  0.0  0.0  0.0  1.0
  Nb  Nb2  1  0.5  0.5  0.5  1.0

Zr Zr Zr Ta Nb
Zr3TaNb is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. Zr(1) is bonded in a distorted linear geometry to four equivalent Ta(1) and two equivalent Nb(1) atoms. All Zr(1)-Ta(1) bond lengths are 3.54 Å. Both Zr(1)-Nb(1) bond lengths are 2.50 Å. Ta(1) is bonded to twelve equivalent Zr(1) atoms to form TaZr12 cuboctahedra that share corners with twelve equivalent Ta(1)Zr12 cuboctahedra, faces with six equivalent Ta(1)Zr12 cuboctahedra, and faces with eight equivalent Nb(1)Zr6 octahedra. Nb(1) is bonded to six equivalent Zr(1) atoms to form NbZr6 octahedra that share corners with six equivalent Nb(1)Zr6 octahedra and faces with eight equivalent Ta(1)Zr12 cuboctahedra. The corner-sharing octahedra are not tilted.