The crystal structure described by KNb(PO4)2 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(5), one O(8), two equivalent O(7), and three equivalent O(4) atoms. Nb(1) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 23-30°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 29-31°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a 1-coordinate geometry to one K(1), one Nb(1), and one P(1) atom. In the second O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the third O site, O(7) is bonded in a distorted single-bond geometry to two equivalent K(1) and one Nb(1) atom. In the fourth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one K(1), one Nb(1), and one P(2) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the sixth O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one P(1), and one P(2) atom. In the seventh O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Nb(1), and one P(2) atom. In the eighth O site, O(4) is bonded in a 1-coordinate geometry to three equivalent K(1) and one P(2) atom. is represented by the CIF file [CIF]
data_KNb(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.006
_cell_length_b   5.259
_cell_length_c   13.057
_cell_angle_alpha   67.482
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   761.526
_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
  K  K0  1  0.366  0.685  0.053  1.0
  K  K1  1  0.634  0.315  0.947  1.0
  K  K2  1  0.134  0.685  0.553  1.0
  K  K3  1  0.866  0.315  0.447  1.0
  Nb  Nb4  1  0.377  0.912  0.331  1.0
  Nb  Nb5  1  0.877  0.088  0.169  1.0
  Nb  Nb6  1  0.623  0.088  0.669  1.0
  Nb  Nb7  1  0.123  0.912  0.831  1.0
  P  P8  1  0.564  0.385  0.365  1.0
  P  P9  1  0.936  0.385  0.865  1.0
  P  P10  1  0.436  0.615  0.635  1.0
  P  P11  1  0.064  0.615  0.135  1.0
  P  P12  1  0.189  0.395  0.348  1.0
  P  P13  1  0.311  0.395  0.848  1.0
  P  P14  1  0.811  0.605  0.652  1.0
  P  P15  1  0.689  0.605  0.152  1.0
  O  O16  1  0.513  0.667  0.348  1.0
  O  O17  1  0.013  0.333  0.152  1.0
  O  O18  1  0.487  0.333  0.652  1.0
  O  O19  1  0.987  0.667  0.848  1.0
  O  O20  1  0.672  0.445  0.286  1.0
  O  O21  1  0.172  0.555  0.214  1.0
  O  O22  1  0.328  0.555  0.714  1.0
  O  O23  1  0.828  0.445  0.786  1.0
  O  O24  1  0.277  0.575  0.376  1.0
  O  O25  1  0.777  0.425  0.124  1.0
  O  O26  1  0.723  0.425  0.624  1.0
  O  O27  1  0.223  0.575  0.876  1.0
  O  O28  1  0.083  0.364  0.411  1.0
  O  O29  1  0.583  0.636  0.089  1.0
  O  O30  1  0.917  0.636  0.589  1.0
  O  O31  1  0.417  0.364  0.911  1.0
  O  O32  1  0.891  0.229  0.979  1.0
  O  O33  1  0.391  0.771  0.521  1.0
  O  O34  1  0.109  0.771  0.021  1.0
  O  O35  1  0.609  0.229  0.479  1.0
  O  O36  1  0.019  0.224  0.823  1.0
  O  O37  1  0.519  0.776  0.677  1.0
  O  O38  1  0.981  0.776  0.177  1.0
  O  O39  1  0.481  0.224  0.323  1.0
  O  O40  1  0.641  0.982  0.813  1.0
  O  O41  1  0.141  0.018  0.687  1.0
  O  O42  1  0.359  0.018  0.187  1.0
  O  O43  1  0.859  0.982  0.313  1.0
  O  O44  1  0.256  0.119  0.861  1.0
  O  O45  1  0.756  0.881  0.639  1.0
  O  O46  1  0.744  0.881  0.139  1.0
  O  O47  1  0.244  0.119  0.361  1.0
[/CIF]
.
The crystal structure described by KNb(PO4)2 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 9-coordinate geometry to one O(2), one O(3), one O(5), one O(8), two equivalent O(7), and three equivalent O(4) atoms. Nb(1) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with three equivalent P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 23-30°. In the second P site, P(2) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 29-31°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a 1-coordinate geometry to one K(1), one Nb(1), and one P(1) atom. In the second O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the third O site, O(7) is bonded in a distorted single-bond geometry to two equivalent K(1) and one Nb(1) atom. In the fourth O site, O(8) is bonded in a distorted bent 150 degrees geometry to one K(1), one Nb(1), and one P(2) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the sixth O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one P(1), and one P(2) atom. In the seventh O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Nb(1), and one P(2) atom. In the eighth O site, O(4) is bonded in a 1-coordinate geometry to three equivalent K(1) and one P(2) atom. is represented by the CIF file [CIF]
data_KNb(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.006
_cell_length_b   5.259
_cell_length_c   13.057
_cell_angle_alpha   67.482
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   761.526
_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
  K  K0  1  0.366  0.685  0.053  1.0
  K  K1  1  0.634  0.315  0.947  1.0
  K  K2  1  0.134  0.685  0.553  1.0
  K  K3  1  0.866  0.315  0.447  1.0
  Nb  Nb4  1  0.377  0.912  0.331  1.0
  Nb  Nb5  1  0.877  0.088  0.169  1.0
  Nb  Nb6  1  0.623  0.088  0.669  1.0
  Nb  Nb7  1  0.123  0.912  0.831  1.0
  P  P8  1  0.564  0.385  0.365  1.0
  P  P9  1  0.936  0.385  0.865  1.0
  P  P10  1  0.436  0.615  0.635  1.0
  P  P11  1  0.064  0.615  0.135  1.0
  P  P12  1  0.189  0.395  0.348  1.0
  P  P13  1  0.311  0.395  0.848  1.0
  P  P14  1  0.811  0.605  0.652  1.0
  P  P15  1  0.689  0.605  0.152  1.0
  O  O16  1  0.513  0.667  0.348  1.0
  O  O17  1  0.013  0.333  0.152  1.0
  O  O18  1  0.487  0.333  0.652  1.0
  O  O19  1  0.987  0.667  0.848  1.0
  O  O20  1  0.672  0.445  0.286  1.0
  O  O21  1  0.172  0.555  0.214  1.0
  O  O22  1  0.328  0.555  0.714  1.0
  O  O23  1  0.828  0.445  0.786  1.0
  O  O24  1  0.277  0.575  0.376  1.0
  O  O25  1  0.777  0.425  0.124  1.0
  O  O26  1  0.723  0.425  0.624  1.0
  O  O27  1  0.223  0.575  0.876  1.0
  O  O28  1  0.083  0.364  0.411  1.0
  O  O29  1  0.583  0.636  0.089  1.0
  O  O30  1  0.917  0.636  0.589  1.0
  O  O31  1  0.417  0.364  0.911  1.0
  O  O32  1  0.891  0.229  0.979  1.0
  O  O33  1  0.391  0.771  0.521  1.0
  O  O34  1  0.109  0.771  0.021  1.0
  O  O35  1  0.609  0.229  0.479  1.0
  O  O36  1  0.019  0.224  0.823  1.0
  O  O37  1  0.519  0.776  0.677  1.0
  O  O38  1  0.981  0.776  0.177  1.0
  O  O39  1  0.481  0.224  0.323  1.0
  O  O40  1  0.641  0.982  0.813  1.0
  O  O41  1  0.141  0.018  0.687  1.0
  O  O42  1  0.359  0.018  0.187  1.0
  O  O43  1  0.859  0.982  0.313  1.0
  O  O44  1  0.256  0.119  0.861  1.0
  O  O45  1  0.756  0.881  0.639  1.0
  O  O46  1  0.744  0.881  0.139  1.0
  O  O47  1  0.244  0.119  0.361  1.0
[/CIF]
.