The crystal structure described by NdNb3O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(14), one O(15), two equivalent O(18), and two equivalent O(6) atoms. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to one O(16), one O(17), one O(4), one O(5), two equivalent O(12), and two equivalent O(13) atoms. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(11), one O(15), one O(18), one O(6), and one O(7) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 7-32°. In the second Nb site, Nb(2) is bonded to one O(12), one O(13), one O(17), one O(2), one O(4), and one O(8) atom to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 3-31°. In the third Nb site, Nb(3) is bonded to one O(10), one O(14), one O(16), one O(3), one O(5), and one O(9) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 12-28°. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(10), one O(15), one O(17), one O(4), and one O(7) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 7-31°. In the fifth Nb site, Nb(5) is bonded to one O(12), one O(13), one O(16), one O(2), one O(5), and one O(9) atom to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 3-28°. In the sixth Nb site, Nb(6) is bonded to one O(11), one O(14), one O(18), one O(3), one O(6), and one O(8) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 14-32°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(1) and one Nb(4) atom. In the second O site, O(2) is bonded in a linear geometry to one Nb(2) and one Nb(5) atom. In the third O site, O(3) is bonded in a distorted linear geometry to one Nb(3) and one Nb(6) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Nd(2), one Nb(2), and one Nb(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Nd(2), one Nb(3), and one Nb(5) atom. In the sixth O site, O(6) is bonded to two equivalent Nd(1), one Nb(1), and one Nb(6) atom to form distorted edge-sharing ONd2Nb2 tetrahedra. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(6) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Nb(3) and one Nb(5) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Nd(1), one Nb(3), and one Nb(4) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Nd(1), one Nb(1), and one Nb(6) atom. In the twelfth O site, O(12) is bonded to two equivalent Nd(2), one Nb(2), and one Nb(5) atom to form a mixture of distorted corner and edge-sharing ONd2Nb2 trigonal pyramids. In the thirteenth O site, O(13) is bonded to two equivalent Nd(2), one Nb(2), and one Nb(5) atom to form a mixture of distorted corner and edge-sharing ONd2Nb2 trigonal pyramids. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Nd(1), one Nb(3), and one Nb(6) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Nd(1), one Nb(1), and one Nb(4) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one Nd(2), one Nb(3), and one Nb(5) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Nd(2), one Nb(2), and one Nb(4) atom. In the eighteenth O site, O(18) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Nd(1), one Nb(1), and one Nb(6) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NdNb3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.591
_cell_length_b   9.732
_cell_length_c   13.739
_cell_angle_alpha   90.216
_cell_angle_beta   90.528
_cell_angle_gamma   90.315
_symmetry_Int_Tables_number   1
_cell_volume   747.497
_cell_formula_units_Z   4
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  0.747  0.583  0.581  1.0
  Nd  Nd1  1  0.739  0.923  0.923  1.0
  Nd  Nd2  1  0.261  0.077  0.077  1.0
  Nd  Nd3  1  0.253  0.417  0.419  1.0
  Nb  Nb4  1  0.252  0.762  0.499  1.0
  Nb  Nb5  1  0.252  0.088  0.824  1.0
  Nb  Nb6  1  0.248  0.410  0.166  1.0
  Nb  Nb7  1  0.756  0.922  0.666  1.0
  Nb  Nb8  1  0.750  0.265  0.996  1.0
  Nb  Nb9  1  0.748  0.581  0.325  1.0
  Nb  Nb10  1  0.244  0.078  0.334  1.0
  Nb  Nb11  1  0.252  0.419  0.675  1.0
  Nb  Nb12  1  0.250  0.735  0.004  1.0
  Nb  Nb13  1  0.748  0.238  0.501  1.0
  Nb  Nb14  1  0.752  0.590  0.834  1.0
  Nb  Nb15  1  0.748  0.912  0.176  1.0
  O  O16  1  0.501  0.849  0.575  1.0
  O  O17  1  0.499  0.182  0.908  1.0
  O  O18  1  0.498  0.522  0.241  1.0
  O  O19  1  0.499  0.151  0.425  1.0
  O  O20  1  0.502  0.478  0.759  1.0
  O  O21  1  0.501  0.818  0.092  1.0
  O  O22  1  0.985  0.968  0.773  1.0
  O  O23  1  0.013  0.293  0.095  1.0
  O  O24  1  0.002  0.625  0.439  1.0
  O  O25  1  0.998  0.375  0.561  1.0
  O  O26  1  0.987  0.707  0.905  1.0
  O  O27  1  0.015  0.032  0.227  1.0
  O  O28  1  0.209  0.907  0.403  1.0
  O  O29  1  0.212  0.234  0.735  1.0
  O  O30  1  0.207  0.571  0.074  1.0
  O  O31  1  0.791  0.093  0.597  1.0
  O  O32  1  0.793  0.429  0.926  1.0
  O  O33  1  0.788  0.766  0.265  1.0
  O  O34  1  0.285  0.271  0.268  1.0
  O  O35  1  0.304  0.589  0.592  1.0
  O  O36  1  0.312  0.935  0.935  1.0
  O  O37  1  0.696  0.411  0.408  1.0
  O  O38  1  0.715  0.729  0.732  1.0
  O  O39  1  0.688  0.065  0.065  1.0
  O  O40  1  1.000  0.140  0.930  1.0
  O  O41  1  0.016  0.496  0.262  1.0
  O  O42  1  0.984  0.814  0.585  1.0
  O  O43  1  0.506  0.681  0.914  1.0
  O  O44  1  0.492  0.013  0.240  1.0
  O  O45  1  0.502  0.347  0.575  1.0
  O  O46  1  0.984  0.504  0.738  1.0
  O  O47  1  0.000  0.860  0.070  1.0
  O  O48  1  0.016  0.186  0.415  1.0
  O  O49  1  0.494  0.319  0.086  1.0
  O  O50  1  0.498  0.653  0.425  1.0
  O  O51  1  0.508  0.987  0.760  1.0
[/CIF]
.
The crystal structure described by NdNb3O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(14), one O(15), two equivalent O(18), and two equivalent O(6) atoms. In the second Nd site, Nd(2) is bonded in a 8-coordinate geometry to one O(16), one O(17), one O(4), one O(5), two equivalent O(12), and two equivalent O(13) atoms. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(11), one O(15), one O(18), one O(6), and one O(7) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 7-32°. In the second Nb site, Nb(2) is bonded to one O(12), one O(13), one O(17), one O(2), one O(4), and one O(8) atom to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 3-31°. In the third Nb site, Nb(3) is bonded to one O(10), one O(14), one O(16), one O(3), one O(5), and one O(9) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 12-28°. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(10), one O(15), one O(17), one O(4), and one O(7) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 7-31°. In the fifth Nb site, Nb(5) is bonded to one O(12), one O(13), one O(16), one O(2), one O(5), and one O(9) atom to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 3-28°. In the sixth Nb site, Nb(6) is bonded to one O(11), one O(14), one O(18), one O(3), one O(6), and one O(8) atom to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 14-32°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(1) and one Nb(4) atom. In the second O site, O(2) is bonded in a linear geometry to one Nb(2) and one Nb(5) atom. In the third O site, O(3) is bonded in a distorted linear geometry to one Nb(3) and one Nb(6) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Nd(2), one Nb(2), and one Nb(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Nd(2), one Nb(3), and one Nb(5) atom. In the sixth O site, O(6) is bonded to two equivalent Nd(1), one Nb(1), and one Nb(6) atom to form distorted edge-sharing ONd2Nb2 tetrahedra. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(6) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Nb(3) and one Nb(5) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Nd(1), one Nb(3), and one Nb(4) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Nd(1), one Nb(1), and one Nb(6) atom. In the twelfth O site, O(12) is bonded to two equivalent Nd(2), one Nb(2), and one Nb(5) atom to form a mixture of distorted corner and edge-sharing ONd2Nb2 trigonal pyramids. In the thirteenth O site, O(13) is bonded to two equivalent Nd(2), one Nb(2), and one Nb(5) atom to form a mixture of distorted corner and edge-sharing ONd2Nb2 trigonal pyramids. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Nd(1), one Nb(3), and one Nb(6) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Nd(1), one Nb(1), and one Nb(4) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one Nd(2), one Nb(3), and one Nb(5) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Nd(2), one Nb(2), and one Nb(4) atom. In the eighteenth O site, O(18) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Nd(1), one Nb(1), and one Nb(6) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NdNb3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.591
_cell_length_b   9.732
_cell_length_c   13.739
_cell_angle_alpha   90.216
_cell_angle_beta   90.528
_cell_angle_gamma   90.315
_symmetry_Int_Tables_number   1
_cell_volume   747.497
_cell_formula_units_Z   4
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  0.747  0.583  0.581  1.0
  Nd  Nd1  1  0.739  0.923  0.923  1.0
  Nd  Nd2  1  0.261  0.077  0.077  1.0
  Nd  Nd3  1  0.253  0.417  0.419  1.0
  Nb  Nb4  1  0.252  0.762  0.499  1.0
  Nb  Nb5  1  0.252  0.088  0.824  1.0
  Nb  Nb6  1  0.248  0.410  0.166  1.0
  Nb  Nb7  1  0.756  0.922  0.666  1.0
  Nb  Nb8  1  0.750  0.265  0.996  1.0
  Nb  Nb9  1  0.748  0.581  0.325  1.0
  Nb  Nb10  1  0.244  0.078  0.334  1.0
  Nb  Nb11  1  0.252  0.419  0.675  1.0
  Nb  Nb12  1  0.250  0.735  0.004  1.0
  Nb  Nb13  1  0.748  0.238  0.501  1.0
  Nb  Nb14  1  0.752  0.590  0.834  1.0
  Nb  Nb15  1  0.748  0.912  0.176  1.0
  O  O16  1  0.501  0.849  0.575  1.0
  O  O17  1  0.499  0.182  0.908  1.0
  O  O18  1  0.498  0.522  0.241  1.0
  O  O19  1  0.499  0.151  0.425  1.0
  O  O20  1  0.502  0.478  0.759  1.0
  O  O21  1  0.501  0.818  0.092  1.0
  O  O22  1  0.985  0.968  0.773  1.0
  O  O23  1  0.013  0.293  0.095  1.0
  O  O24  1  0.002  0.625  0.439  1.0
  O  O25  1  0.998  0.375  0.561  1.0
  O  O26  1  0.987  0.707  0.905  1.0
  O  O27  1  0.015  0.032  0.227  1.0
  O  O28  1  0.209  0.907  0.403  1.0
  O  O29  1  0.212  0.234  0.735  1.0
  O  O30  1  0.207  0.571  0.074  1.0
  O  O31  1  0.791  0.093  0.597  1.0
  O  O32  1  0.793  0.429  0.926  1.0
  O  O33  1  0.788  0.766  0.265  1.0
  O  O34  1  0.285  0.271  0.268  1.0
  O  O35  1  0.304  0.589  0.592  1.0
  O  O36  1  0.312  0.935  0.935  1.0
  O  O37  1  0.696  0.411  0.408  1.0
  O  O38  1  0.715  0.729  0.732  1.0
  O  O39  1  0.688  0.065  0.065  1.0
  O  O40  1  1.000  0.140  0.930  1.0
  O  O41  1  0.016  0.496  0.262  1.0
  O  O42  1  0.984  0.814  0.585  1.0
  O  O43  1  0.506  0.681  0.914  1.0
  O  O44  1  0.492  0.013  0.240  1.0
  O  O45  1  0.502  0.347  0.575  1.0
  O  O46  1  0.984  0.504  0.738  1.0
  O  O47  1  0.000  0.860  0.070  1.0
  O  O48  1  0.016  0.186  0.415  1.0
  O  O49  1  0.494  0.319  0.086  1.0
  O  O50  1  0.498  0.653  0.425  1.0
  O  O51  1  0.508  0.987  0.760  1.0
[/CIF]
.