The structure described by NdTa3O9 crystallizes in the triclinic P-1 space group. Nd(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), two equivalent O(7), two equivalent O(9), and three equivalent O(8) atoms to form NdO12 cuboctahedra that share corners with three equivalent Nd(1)O12 cuboctahedra, faces with two equivalent Nd(1)O12 cuboctahedra, faces with two equivalent Ta(1)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Ta(3)O6 octahedra. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), and one O(6) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with two equivalent Nd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(6), one O(7), one O(8), and one O(9) atom to form TaO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Nd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-19°. In the third Ta site, Ta(3) is bonded to one O(10), one O(4), one O(5), one O(7), one O(8), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Nd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-19°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Nd(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(2) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(3) atom. In the fifth O site, O(5) is bonded in a linear geometry to two equivalent Ta(3) atoms. In the sixth O site, O(6) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. In the seventh O site, O(7) is bonded to two equivalent Nd(1), one Ta(2), and one Ta(3) atom to form distorted edge-sharing ONd2Ta2 trigonal pyramids. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to three equivalent Nd(1), one Ta(2), and one Ta(3) atom. In the ninth O site, O(9) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Nd(1), one Ta(2), and one Ta(3) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(3) atom. is represented by the CIF card [CIF]
data_NdTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.580
_cell_length_b   8.826
_cell_length_c   8.884
_cell_angle_alpha   101.507
_cell_angle_beta   108.265
_cell_angle_gamma   108.401
_symmetry_Int_Tables_number   1
_cell_volume   372.049
_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
  Nd  Nd0  1  0.326  0.663  0.002  1.0
  Nd  Nd1  1  0.674  0.337  0.998  1.0
  Ta  Ta2  1  0.334  0.918  0.750  1.0
  Ta  Ta3  1  0.012  0.762  0.264  1.0
  Ta  Ta4  1  0.335  0.413  0.259  1.0
  Ta  Ta5  1  0.666  0.082  0.250  1.0
  Ta  Ta6  1  0.988  0.238  0.736  1.0
  Ta  Ta7  1  0.665  0.587  0.741  1.0
  O  O8  1  0.326  0.905  0.233  1.0
  O  O9  1  0.500  0.000  0.000  1.0
  O  O10  1  0.801  0.900  0.230  1.0
  O  O11  1  0.019  0.751  0.769  1.0
  O  O12  1  0.500  0.500  0.500  1.0
  O  O13  1  0.167  0.834  0.503  1.0
  O  O14  1  0.649  0.574  0.219  1.0
  O  O15  1  0.838  0.651  0.000  1.0
  O  O16  1  0.162  0.349  1.000  1.0
  O  O17  1  0.854  0.426  0.773  1.0
  O  O18  1  0.505  0.254  0.231  1.0
  O  O19  1  0.495  0.746  0.769  1.0
  O  O20  1  0.146  0.574  0.227  1.0
  O  O21  1  0.833  0.166  0.497  1.0
  O  O22  1  0.981  0.249  0.231  1.0
  O  O23  1  0.351  0.426  0.781  1.0
  O  O24  1  0.199  0.100  0.770  1.0
  O  O25  1  0.674  0.095  0.767  1.0
[/CIF]
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The structure described by NdTa3O9 crystallizes in the triclinic P-1 space group. Nd(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), two equivalent O(7), two equivalent O(9), and three equivalent O(8) atoms to form NdO12 cuboctahedra that share corners with three equivalent Nd(1)O12 cuboctahedra, faces with two equivalent Nd(1)O12 cuboctahedra, faces with two equivalent Ta(1)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Ta(3)O6 octahedra. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(4), and one O(6) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with two equivalent Nd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(6), one O(7), one O(8), and one O(9) atom to form TaO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Nd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-19°. In the third Ta site, Ta(3) is bonded to one O(10), one O(4), one O(5), one O(7), one O(8), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Nd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-19°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Nd(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(2) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(3) atom. In the fifth O site, O(5) is bonded in a linear geometry to two equivalent Ta(3) atoms. In the sixth O site, O(6) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. In the seventh O site, O(7) is bonded to two equivalent Nd(1), one Ta(2), and one Ta(3) atom to form distorted edge-sharing ONd2Ta2 trigonal pyramids. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to three equivalent Nd(1), one Ta(2), and one Ta(3) atom. In the ninth O site, O(9) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Nd(1), one Ta(2), and one Ta(3) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Nd(1), one Ta(1), and one Ta(3) atom. is represented by the CIF card [CIF]
data_NdTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.580
_cell_length_b   8.826
_cell_length_c   8.884
_cell_angle_alpha   101.507
_cell_angle_beta   108.265
_cell_angle_gamma   108.401
_symmetry_Int_Tables_number   1
_cell_volume   372.049
_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
  Nd  Nd0  1  0.326  0.663  0.002  1.0
  Nd  Nd1  1  0.674  0.337  0.998  1.0
  Ta  Ta2  1  0.334  0.918  0.750  1.0
  Ta  Ta3  1  0.012  0.762  0.264  1.0
  Ta  Ta4  1  0.335  0.413  0.259  1.0
  Ta  Ta5  1  0.666  0.082  0.250  1.0
  Ta  Ta6  1  0.988  0.238  0.736  1.0
  Ta  Ta7  1  0.665  0.587  0.741  1.0
  O  O8  1  0.326  0.905  0.233  1.0
  O  O9  1  0.500  0.000  0.000  1.0
  O  O10  1  0.801  0.900  0.230  1.0
  O  O11  1  0.019  0.751  0.769  1.0
  O  O12  1  0.500  0.500  0.500  1.0
  O  O13  1  0.167  0.834  0.503  1.0
  O  O14  1  0.649  0.574  0.219  1.0
  O  O15  1  0.838  0.651  0.000  1.0
  O  O16  1  0.162  0.349  1.000  1.0
  O  O17  1  0.854  0.426  0.773  1.0
  O  O18  1  0.505  0.254  0.231  1.0
  O  O19  1  0.495  0.746  0.769  1.0
  O  O20  1  0.146  0.574  0.227  1.0
  O  O21  1  0.833  0.166  0.497  1.0
  O  O22  1  0.981  0.249  0.231  1.0
  O  O23  1  0.351  0.426  0.781  1.0
  O  O24  1  0.199  0.100  0.770  1.0
  O  O25  1  0.674  0.095  0.767  1.0
[/CIF]
.