The material described by Na2CaNb(PO4)3 crystallizes in the monoclinic Cc space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(10), one O(7), and one O(9) atom. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom to form CaO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(3)O4 tetrahedra. Nb(1) is bonded to one O(10), one O(11), one O(12), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(3)O4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(10), one O(5), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 18-45°. In the second P site, P(2) is bonded to one O(11), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-37°. In the third P site, P(3) is bonded to one O(12), one O(3), one O(6), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 21-42°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Ca(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Nb(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(3) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ca(1), and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(2), one Ca(1), and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Ca(1), and one P(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal pyramidal geometry to one Na(1), one Na(2), one Nb(1), and one P(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(2), one Nb(1), and one P(2) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Na(2), one Nb(1), and one P(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2CaNb(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.119
_cell_length_b   9.131
_cell_length_c   9.212
_cell_angle_alpha   119.709
_cell_angle_beta   90.000
_cell_angle_gamma   119.955
_symmetry_Int_Tables_number   1
_cell_volume   545.146
_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
  Ca  Ca0  1  0.367  0.715  0.060  1.0
  Ca  Ca1  1  0.848  0.715  0.560  1.0
  Na  Na2  1  0.903  0.510  0.739  1.0
  Na  Na3  1  0.107  0.510  0.239  1.0
  Na  Na4  1  0.499  0.990  0.477  1.0
  Na  Na5  1  0.991  0.990  0.977  1.0
  Nb  Nb6  1  0.639  0.292  0.946  1.0
  Nb  Nb7  1  0.154  0.292  0.446  1.0
  O  O8  1  0.097  0.413  0.936  1.0
  O  O9  1  0.285  0.794  0.907  1.0
  O  O10  1  0.523  0.620  0.918  1.0
  O  O11  1  0.815  0.413  0.436  1.0
  O  O12  1  0.597  0.620  0.418  1.0
  O  O13  1  0.009  0.794  0.407  1.0
  O  O14  1  0.862  0.591  0.077  1.0
  O  O15  1  0.730  0.239  0.102  1.0
  O  O16  1  0.491  0.361  0.085  1.0
  O  O17  1  0.229  0.591  0.577  1.0
  O  O18  1  0.370  0.361  0.585  1.0
  O  O19  1  0.009  0.239  0.602  1.0
  O  O20  1  0.206  0.812  0.225  1.0
  O  O21  1  0.620  0.028  0.241  1.0
  O  O22  1  0.389  0.607  0.230  1.0
  O  O23  1  0.106  0.812  0.725  1.0
  O  O24  1  0.718  0.607  0.730  1.0
  O  O25  1  0.908  0.028  0.741  1.0
  O  O26  1  0.777  0.223  0.760  1.0
  O  O27  1  0.440  0.989  0.770  1.0
  O  O28  1  0.541  0.314  0.761  1.0
  O  O29  1  0.946  0.223  0.260  1.0
  O  O30  1  0.273  0.314  0.261  1.0
  O  O31  1  0.048  0.989  0.270  1.0
  P  P32  1  0.951  0.221  0.764  1.0
  P  P33  1  0.262  0.798  0.748  1.0
  P  P34  1  0.543  0.485  0.754  1.0
  P  P35  1  0.770  0.221  0.264  1.0
  P  P36  1  0.442  0.485  0.254  1.0
  P  P37  1  0.036  0.798  0.248  1.0
[/CIF]
.
The material described by Na2CaNb(PO4)3 crystallizes in the monoclinic Cc space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(10), one O(7), and one O(9) atom. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom to form CaO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(3)O4 tetrahedra. Nb(1) is bonded to one O(10), one O(11), one O(12), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(3)O4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(10), one O(5), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 18-45°. In the second P site, P(2) is bonded to one O(11), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-37°. In the third P site, P(3) is bonded to one O(12), one O(3), one O(6), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 21-42°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Ca(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Nb(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(3) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ca(1), and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(2), one Ca(1), and one P(1) atom. In the ninth O site, O(9) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Ca(1), and one P(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal pyramidal geometry to one Na(1), one Na(2), one Nb(1), and one P(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(2), one Nb(1), and one P(2) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Na(2), one Nb(1), and one P(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2CaNb(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.119
_cell_length_b   9.131
_cell_length_c   9.212
_cell_angle_alpha   119.709
_cell_angle_beta   90.000
_cell_angle_gamma   119.955
_symmetry_Int_Tables_number   1
_cell_volume   545.146
_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
  Ca  Ca0  1  0.367  0.715  0.060  1.0
  Ca  Ca1  1  0.848  0.715  0.560  1.0
  Na  Na2  1  0.903  0.510  0.739  1.0
  Na  Na3  1  0.107  0.510  0.239  1.0
  Na  Na4  1  0.499  0.990  0.477  1.0
  Na  Na5  1  0.991  0.990  0.977  1.0
  Nb  Nb6  1  0.639  0.292  0.946  1.0
  Nb  Nb7  1  0.154  0.292  0.446  1.0
  O  O8  1  0.097  0.413  0.936  1.0
  O  O9  1  0.285  0.794  0.907  1.0
  O  O10  1  0.523  0.620  0.918  1.0
  O  O11  1  0.815  0.413  0.436  1.0
  O  O12  1  0.597  0.620  0.418  1.0
  O  O13  1  0.009  0.794  0.407  1.0
  O  O14  1  0.862  0.591  0.077  1.0
  O  O15  1  0.730  0.239  0.102  1.0
  O  O16  1  0.491  0.361  0.085  1.0
  O  O17  1  0.229  0.591  0.577  1.0
  O  O18  1  0.370  0.361  0.585  1.0
  O  O19  1  0.009  0.239  0.602  1.0
  O  O20  1  0.206  0.812  0.225  1.0
  O  O21  1  0.620  0.028  0.241  1.0
  O  O22  1  0.389  0.607  0.230  1.0
  O  O23  1  0.106  0.812  0.725  1.0
  O  O24  1  0.718  0.607  0.730  1.0
  O  O25  1  0.908  0.028  0.741  1.0
  O  O26  1  0.777  0.223  0.760  1.0
  O  O27  1  0.440  0.989  0.770  1.0
  O  O28  1  0.541  0.314  0.761  1.0
  O  O29  1  0.946  0.223  0.260  1.0
  O  O30  1  0.273  0.314  0.261  1.0
  O  O31  1  0.048  0.989  0.270  1.0
  P  P32  1  0.951  0.221  0.764  1.0
  P  P33  1  0.262  0.798  0.748  1.0
  P  P34  1  0.543  0.485  0.754  1.0
  P  P35  1  0.770  0.221  0.264  1.0
  P  P36  1  0.442  0.485  0.254  1.0
  P  P37  1  0.036  0.798  0.248  1.0
[/CIF]
.