The material structure described by Na2Nb4O11 crystallizes in the trigonal R-3c space group. Na(1) is bonded in a 7-coordinate geometry to one O(3) and six equivalent O(1) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(1), two equivalent O(3), and three equivalent O(2) atoms to form distorted NbO7 pentagonal bipyramids that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(1)O7 pentagonal bipyramids, and edges with four equivalent Nb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. In the second Nb site, Nb(2) is bonded to six equivalent O(1) atoms to form corner-sharing NbO6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Nb(1) atoms. In the third O site, O(3) is bonded to one Na(1) and three equivalent Nb(1) atoms to form distorted corner-sharing ONaNb3 tetrahedra. is represented by the CIF file [CIF]
data_Na2Nb4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.942
_cell_length_b   12.942
_cell_length_c   12.942
_cell_angle_alpha   28.209
_cell_angle_beta   28.209
_cell_angle_gamma   28.209
_symmetry_Int_Tables_number   1
_cell_volume   427.976
_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
  Na  Na0  1  0.832  0.832  0.832  1.0
  Na  Na1  1  0.668  0.668  0.668  1.0
  Na  Na2  1  0.168  0.168  0.168  1.0
  Na  Na3  1  0.332  0.332  0.332  1.0
  Nb  Nb4  1  0.250  0.613  0.887  1.0
  Nb  Nb5  1  0.887  0.250  0.613  1.0
  Nb  Nb6  1  0.750  0.387  0.113  1.0
  Nb  Nb7  1  0.113  0.750  0.387  1.0
  Nb  Nb8  1  0.613  0.887  0.250  1.0
  Nb  Nb9  1  0.387  0.113  0.750  1.0
  Nb  Nb10  1  0.000  0.000  0.000  1.0
  Nb  Nb11  1  0.500  0.500  0.500  1.0
  O  O12  1  0.245  0.723  0.937  1.0
  O  O13  1  0.777  0.255  0.563  1.0
  O  O14  1  0.755  0.277  0.063  1.0
  O  O15  1  0.223  0.745  0.437  1.0
  O  O16  1  0.255  0.563  0.777  1.0
  O  O17  1  0.937  0.245  0.723  1.0
  O  O18  1  0.745  0.437  0.223  1.0
  O  O19  1  0.063  0.755  0.277  1.0
  O  O20  1  0.723  0.937  0.245  1.0
  O  O21  1  0.563  0.777  0.255  1.0
  O  O22  1  0.277  0.063  0.755  1.0
  O  O23  1  0.437  0.223  0.745  1.0
  O  O24  1  0.497  0.250  0.003  1.0
  O  O25  1  0.250  0.003  0.497  1.0
  O  O26  1  0.503  0.750  0.997  1.0
  O  O27  1  0.750  0.997  0.503  1.0
  O  O28  1  0.905  0.905  0.905  1.0
  O  O29  1  0.595  0.595  0.595  1.0
  O  O30  1  0.095  0.095  0.095  1.0
  O  O31  1  0.405  0.405  0.405  1.0
  O  O32  1  0.003  0.497  0.250  1.0
  O  O33  1  0.997  0.503  0.750  1.0
[/CIF]
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The material structure described by Na2Nb4O11 crystallizes in the trigonal R-3c space group. Na(1) is bonded in a 7-coordinate geometry to one O(3) and six equivalent O(1) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(1), two equivalent O(3), and three equivalent O(2) atoms to form distorted NbO7 pentagonal bipyramids that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(1)O7 pentagonal bipyramids, and edges with four equivalent Nb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. In the second Nb site, Nb(2) is bonded to six equivalent O(1) atoms to form corner-sharing NbO6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Nb(1) atoms. In the third O site, O(3) is bonded to one Na(1) and three equivalent Nb(1) atoms to form distorted corner-sharing ONaNb3 tetrahedra. is represented by the CIF file [CIF]
data_Na2Nb4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.942
_cell_length_b   12.942
_cell_length_c   12.942
_cell_angle_alpha   28.209
_cell_angle_beta   28.209
_cell_angle_gamma   28.209
_symmetry_Int_Tables_number   1
_cell_volume   427.976
_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
  Na  Na0  1  0.832  0.832  0.832  1.0
  Na  Na1  1  0.668  0.668  0.668  1.0
  Na  Na2  1  0.168  0.168  0.168  1.0
  Na  Na3  1  0.332  0.332  0.332  1.0
  Nb  Nb4  1  0.250  0.613  0.887  1.0
  Nb  Nb5  1  0.887  0.250  0.613  1.0
  Nb  Nb6  1  0.750  0.387  0.113  1.0
  Nb  Nb7  1  0.113  0.750  0.387  1.0
  Nb  Nb8  1  0.613  0.887  0.250  1.0
  Nb  Nb9  1  0.387  0.113  0.750  1.0
  Nb  Nb10  1  0.000  0.000  0.000  1.0
  Nb  Nb11  1  0.500  0.500  0.500  1.0
  O  O12  1  0.245  0.723  0.937  1.0
  O  O13  1  0.777  0.255  0.563  1.0
  O  O14  1  0.755  0.277  0.063  1.0
  O  O15  1  0.223  0.745  0.437  1.0
  O  O16  1  0.255  0.563  0.777  1.0
  O  O17  1  0.937  0.245  0.723  1.0
  O  O18  1  0.745  0.437  0.223  1.0
  O  O19  1  0.063  0.755  0.277  1.0
  O  O20  1  0.723  0.937  0.245  1.0
  O  O21  1  0.563  0.777  0.255  1.0
  O  O22  1  0.277  0.063  0.755  1.0
  O  O23  1  0.437  0.223  0.745  1.0
  O  O24  1  0.497  0.250  0.003  1.0
  O  O25  1  0.250  0.003  0.497  1.0
  O  O26  1  0.503  0.750  0.997  1.0
  O  O27  1  0.750  0.997  0.503  1.0
  O  O28  1  0.905  0.905  0.905  1.0
  O  O29  1  0.595  0.595  0.595  1.0
  O  O30  1  0.095  0.095  0.095  1.0
  O  O31  1  0.405  0.405  0.405  1.0
  O  O32  1  0.003  0.497  0.250  1.0
  O  O33  1  0.997  0.503  0.750  1.0
[/CIF]
.