data_Nb3Tl
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.34
_cell_length_b   5.34
_cell_length_c   5.34
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb3Tl
_chemical_formula_sum   'Nb6 Tl2'
_cell_volume   152.6
_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
  Nb  Nb0  1  0.67  0.34  0.0  1.0
  Nb  Nb1  1  0.67  0.01  0.0  1.0
  Nb  Nb2  1  0.0  0.67  0.34  1.0
  Nb  Nb3  1  0.34  0.0  0.67  1.0
  Nb  Nb4  1  0.01  0.0  0.67  1.0
  Nb  Nb5  1  0.0  0.67  0.01  1.0
  Tl  Tl6  1  0.0  0.0  0.0  1.0
  Tl  Tl7  1  0.67  0.67  0.67  1.0

data_Nb3Tl
_symmetry_space_group_name_H-M   R3
_cell_length_a   7.56
_cell_length_b   7.56
_cell_length_c   9.26
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Nb3Tl
_chemical_formula_sum   'Nb18 Tl6'
_cell_volume   457.8
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+1/3, z+1/3'
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
  Nb  Nb0  9  0.0  0.66  0.34  1.0
  Nb  Nb1  9  0.11  0.89  0.89  1.0
  Tl  Tl2  3  0.0  0.0  0.0  1.0
  Tl  Tl3  3  0.0  0.0  0.67  1.0

Nb Nb Nb Nb Nb Nb Tl Tl
Nb3Tl crystallizes in the trigonal R3 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 1-coordinate geometry to one Nb(2) and one Tl(2) atom. The Nb(1)-Nb(2) bond length is 1.75 Å. The Nb(1)-Tl(2) bond length is 2.51 Å. In the second Nb site, Nb(2) is bonded in a 2-coordinate geometry to one Nb(1), one Tl(1), and one Tl(2) atom. The Nb(2)-Tl(1) bond length is 1.75 Å. The Nb(2)-Tl(2) bond length is 2.51 Å. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 3-coordinate geometry to three equivalent Nb(2) atoms. In the second Tl site, Tl(2) is bonded in a distorted hexagonal planar geometry to three equivalent Nb(1) and three equivalent Nb(2) atoms.