The crystal structure described by Nb9PO25 crystallizes in the tetragonal I-4 space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(3), one O(5), one O(7), and two equivalent O(1) atoms to form distorted NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-32°. In the second Nb site, Nb(2) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(5) atoms to form a mixture of distorted edge and corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 2-32°. In the third Nb site, Nb(3) is bonded to two equivalent O(4) and four equivalent O(6) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. P(1) is bonded to four equivalent O(2) atoms to form PO4 tetrahedra that share corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a linear geometry to one Nb(2) and one Nb(3) atom. In the second O site, O(7) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Nb(1) atoms. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the fifth O site, O(3) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the sixth O site, O(4) is bonded in a linear geometry to two equivalent Nb(3) atoms. In the seventh O site, O(5) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Nb(2) atoms. is represented by the CIF file [CIF]
data_Nb9PO25
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.335
_cell_length_b   11.335
_cell_length_c   11.335
_cell_angle_alpha   91.661
_cell_angle_beta   91.661
_cell_angle_gamma   160.393
_symmetry_Int_Tables_number   1
_cell_volume   481.507
_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
  Nb  Nb0  1  0.890  0.673  0.557  1.0
  Nb  Nb1  1  0.116  0.333  0.443  1.0
  Nb  Nb2  1  0.667  0.110  0.783  1.0
  Nb  Nb3  1  0.117  0.789  0.891  1.0
  Nb  Nb4  1  0.774  0.883  0.672  1.0
  Nb  Nb5  1  0.211  0.102  0.328  1.0
  Nb  Nb6  1  0.898  0.226  0.109  1.0
  Nb  Nb7  1  1.000  1.000  0.000  1.0
  Nb  Nb8  1  0.327  0.884  0.217  1.0
  P  P9  1  0.750  0.250  0.500  1.0
  O  O10  1  0.346  0.145  0.510  1.0
  O  O11  1  0.164  0.654  0.799  1.0
  O  O12  1  0.855  0.365  0.201  1.0
  O  O13  1  0.635  0.836  0.490  1.0
  O  O14  1  0.482  0.968  0.386  1.0
  O  O15  1  0.904  0.518  0.486  1.0
  O  O16  1  0.032  0.418  0.514  1.0
  O  O17  1  0.582  0.096  0.614  1.0
  O  O18  1  0.270  0.980  0.270  1.0
  O  O19  1  1.000  0.730  0.710  1.0
  O  O20  1  0.500  0.500  1.000  1.0
  O  O21  1  0.622  0.257  0.860  1.0
  O  O22  1  0.238  0.378  0.634  1.0
  O  O23  1  0.743  0.604  0.366  1.0
  O  O24  1  0.396  0.762  0.140  1.0
  O  O25  1  0.949  0.118  0.062  1.0
  O  O26  1  0.114  0.051  0.169  1.0
  O  O27  1  0.882  0.944  0.831  1.0
  O  O28  1  0.056  0.886  0.938  1.0
  O  O29  1  0.798  0.194  0.955  1.0
  O  O30  1  0.157  0.202  0.396  1.0
  O  O31  1  0.806  0.761  0.604  1.0
  O  O32  1  0.239  0.843  0.045  1.0
  O  O33  1  0.710  0.000  0.730  1.0
  O  O34  1  0.020  0.290  0.290  1.0
[/CIF]
.
The crystal structure described by Nb9PO25 crystallizes in the tetragonal I-4 space group. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(3), one O(5), one O(7), and two equivalent O(1) atoms to form distorted NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-32°. In the second Nb site, Nb(2) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(5) atoms to form a mixture of distorted edge and corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 2-32°. In the third Nb site, Nb(3) is bonded to two equivalent O(4) and four equivalent O(6) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-4°. P(1) is bonded to four equivalent O(2) atoms to form PO4 tetrahedra that share corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a linear geometry to one Nb(2) and one Nb(3) atom. In the second O site, O(7) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Nb(1) atoms. In the fourth O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the fifth O site, O(3) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the sixth O site, O(4) is bonded in a linear geometry to two equivalent Nb(3) atoms. In the seventh O site, O(5) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Nb(2) atoms. is represented by the CIF file [CIF]
data_Nb9PO25
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.335
_cell_length_b   11.335
_cell_length_c   11.335
_cell_angle_alpha   91.661
_cell_angle_beta   91.661
_cell_angle_gamma   160.393
_symmetry_Int_Tables_number   1
_cell_volume   481.507
_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
  Nb  Nb0  1  0.890  0.673  0.557  1.0
  Nb  Nb1  1  0.116  0.333  0.443  1.0
  Nb  Nb2  1  0.667  0.110  0.783  1.0
  Nb  Nb3  1  0.117  0.789  0.891  1.0
  Nb  Nb4  1  0.774  0.883  0.672  1.0
  Nb  Nb5  1  0.211  0.102  0.328  1.0
  Nb  Nb6  1  0.898  0.226  0.109  1.0
  Nb  Nb7  1  1.000  1.000  0.000  1.0
  Nb  Nb8  1  0.327  0.884  0.217  1.0
  P  P9  1  0.750  0.250  0.500  1.0
  O  O10  1  0.346  0.145  0.510  1.0
  O  O11  1  0.164  0.654  0.799  1.0
  O  O12  1  0.855  0.365  0.201  1.0
  O  O13  1  0.635  0.836  0.490  1.0
  O  O14  1  0.482  0.968  0.386  1.0
  O  O15  1  0.904  0.518  0.486  1.0
  O  O16  1  0.032  0.418  0.514  1.0
  O  O17  1  0.582  0.096  0.614  1.0
  O  O18  1  0.270  0.980  0.270  1.0
  O  O19  1  1.000  0.730  0.710  1.0
  O  O20  1  0.500  0.500  1.000  1.0
  O  O21  1  0.622  0.257  0.860  1.0
  O  O22  1  0.238  0.378  0.634  1.0
  O  O23  1  0.743  0.604  0.366  1.0
  O  O24  1  0.396  0.762  0.140  1.0
  O  O25  1  0.949  0.118  0.062  1.0
  O  O26  1  0.114  0.051  0.169  1.0
  O  O27  1  0.882  0.944  0.831  1.0
  O  O28  1  0.056  0.886  0.938  1.0
  O  O29  1  0.798  0.194  0.955  1.0
  O  O30  1  0.157  0.202  0.396  1.0
  O  O31  1  0.806  0.761  0.604  1.0
  O  O32  1  0.239  0.843  0.045  1.0
  O  O33  1  0.710  0.000  0.730  1.0
  O  O34  1  0.020  0.290  0.290  1.0
[/CIF]
.