The material described by RbNb(PO4)2 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to one O(1), one O(5), one O(7), one O(8), two equivalent O(2), and three equivalent O(3) atoms. Nb(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) 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(4), one O(5), one O(6), and one O(8) 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 18-28°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(7), 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 23-28°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one Rb(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 bent 150 degrees geometry to one Rb(1), one Nb(1), and one P(2) atom. In the fourth O site, O(8) is bonded in a 2-coordinate geometry to one Rb(1), one P(1), and one P(2) atom. In the fifth O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Nb(1), and one P(2) atom. In the sixth O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one Nb(1) atom. In the seventh O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one P(2) atom. In the eighth O site, O(4) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_RbNb(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.214
_cell_length_b   5.286
_cell_length_c   13.262
_cell_angle_alpha   67.017
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   788.329
_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
  Rb  Rb0  1  0.372  0.299  0.957  1.0
  Rb  Rb1  1  0.872  0.701  0.543  1.0
  Rb  Rb2  1  0.628  0.701  0.043  1.0
  Rb  Rb3  1  0.128  0.299  0.457  1.0
  Nb  Nb4  1  0.113  0.082  0.174  1.0
  Nb  Nb5  1  0.613  0.918  0.326  1.0
  Nb  Nb6  1  0.887  0.918  0.826  1.0
  Nb  Nb7  1  0.387  0.082  0.674  1.0
  P  P8  1  0.431  0.381  0.371  1.0
  P  P9  1  0.931  0.619  0.129  1.0
  P  P10  1  0.569  0.619  0.629  1.0
  P  P11  1  0.069  0.381  0.871  1.0
  P  P12  1  0.301  0.594  0.163  1.0
  P  P13  1  0.801  0.406  0.337  1.0
  P  P14  1  0.699  0.406  0.837  1.0
  P  P15  1  0.199  0.594  0.663  1.0
  O  O16  1  0.284  0.408  0.639  1.0
  O  O17  1  0.784  0.592  0.861  1.0
  O  O18  1  0.716  0.592  0.361  1.0
  O  O19  1  0.216  0.408  0.139  1.0
  O  O20  1  0.379  0.961  0.817  1.0
  O  O21  1  0.879  0.039  0.683  1.0
  O  O22  1  0.621  0.039  0.183  1.0
  O  O23  1  0.121  0.961  0.317  1.0
  O  O24  1  0.403  0.636  0.098  1.0
  O  O25  1  0.903  0.364  0.402  1.0
  O  O26  1  0.597  0.364  0.902  1.0
  O  O27  1  0.097  0.636  0.598  1.0
  O  O28  1  0.518  0.335  0.653  1.0
  O  O29  1  0.018  0.665  0.847  1.0
  O  O30  1  0.482  0.665  0.347  1.0
  O  O31  1  0.982  0.335  0.153  1.0
  O  O32  1  0.111  0.234  0.985  1.0
  O  O33  1  0.611  0.766  0.515  1.0
  O  O34  1  0.889  0.766  0.015  1.0
  O  O35  1  0.389  0.234  0.485  1.0
  O  O36  1  0.490  0.785  0.670  1.0
  O  O37  1  0.990  0.215  0.830  1.0
  O  O38  1  0.510  0.215  0.330  1.0
  O  O39  1  0.010  0.785  0.170  1.0
  O  O40  1  0.256  0.865  0.652  1.0
  O  O41  1  0.756  0.135  0.848  1.0
  O  O42  1  0.744  0.135  0.348  1.0
  O  O43  1  0.244  0.865  0.152  1.0
  O  O44  1  0.322  0.435  0.295  1.0
  O  O45  1  0.822  0.565  0.205  1.0
  O  O46  1  0.678  0.565  0.705  1.0
  O  O47  1  0.178  0.435  0.795  1.0
[/CIF]
.
The material described by RbNb(PO4)2 crystallizes in the monoclinic P2_1/c space group. Rb(1) is bonded in a 9-coordinate geometry to one O(1), one O(5), one O(7), one O(8), two equivalent O(2), and three equivalent O(3) atoms. Nb(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) 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(4), one O(5), one O(6), and one O(8) 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 18-28°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(7), 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 23-28°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one Rb(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 bent 150 degrees geometry to one Rb(1), one Nb(1), and one P(2) atom. In the fourth O site, O(8) is bonded in a 2-coordinate geometry to one Rb(1), one P(1), and one P(2) atom. In the fifth O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Nb(1), and one P(2) atom. In the sixth O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one Nb(1) atom. In the seventh O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one P(2) atom. In the eighth O site, O(4) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_RbNb(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.214
_cell_length_b   5.286
_cell_length_c   13.262
_cell_angle_alpha   67.017
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   788.329
_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
  Rb  Rb0  1  0.372  0.299  0.957  1.0
  Rb  Rb1  1  0.872  0.701  0.543  1.0
  Rb  Rb2  1  0.628  0.701  0.043  1.0
  Rb  Rb3  1  0.128  0.299  0.457  1.0
  Nb  Nb4  1  0.113  0.082  0.174  1.0
  Nb  Nb5  1  0.613  0.918  0.326  1.0
  Nb  Nb6  1  0.887  0.918  0.826  1.0
  Nb  Nb7  1  0.387  0.082  0.674  1.0
  P  P8  1  0.431  0.381  0.371  1.0
  P  P9  1  0.931  0.619  0.129  1.0
  P  P10  1  0.569  0.619  0.629  1.0
  P  P11  1  0.069  0.381  0.871  1.0
  P  P12  1  0.301  0.594  0.163  1.0
  P  P13  1  0.801  0.406  0.337  1.0
  P  P14  1  0.699  0.406  0.837  1.0
  P  P15  1  0.199  0.594  0.663  1.0
  O  O16  1  0.284  0.408  0.639  1.0
  O  O17  1  0.784  0.592  0.861  1.0
  O  O18  1  0.716  0.592  0.361  1.0
  O  O19  1  0.216  0.408  0.139  1.0
  O  O20  1  0.379  0.961  0.817  1.0
  O  O21  1  0.879  0.039  0.683  1.0
  O  O22  1  0.621  0.039  0.183  1.0
  O  O23  1  0.121  0.961  0.317  1.0
  O  O24  1  0.403  0.636  0.098  1.0
  O  O25  1  0.903  0.364  0.402  1.0
  O  O26  1  0.597  0.364  0.902  1.0
  O  O27  1  0.097  0.636  0.598  1.0
  O  O28  1  0.518  0.335  0.653  1.0
  O  O29  1  0.018  0.665  0.847  1.0
  O  O30  1  0.482  0.665  0.347  1.0
  O  O31  1  0.982  0.335  0.153  1.0
  O  O32  1  0.111  0.234  0.985  1.0
  O  O33  1  0.611  0.766  0.515  1.0
  O  O34  1  0.889  0.766  0.015  1.0
  O  O35  1  0.389  0.234  0.485  1.0
  O  O36  1  0.490  0.785  0.670  1.0
  O  O37  1  0.990  0.215  0.830  1.0
  O  O38  1  0.510  0.215  0.330  1.0
  O  O39  1  0.010  0.785  0.170  1.0
  O  O40  1  0.256  0.865  0.652  1.0
  O  O41  1  0.756  0.135  0.848  1.0
  O  O42  1  0.744  0.135  0.348  1.0
  O  O43  1  0.244  0.865  0.152  1.0
  O  O44  1  0.322  0.435  0.295  1.0
  O  O45  1  0.822  0.565  0.205  1.0
  O  O46  1  0.678  0.565  0.705  1.0
  O  O47  1  0.178  0.435  0.795  1.0
[/CIF]
.