The structure described by Na8NbO6 crystallizes in the hexagonal P6_3cm space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent Nb(1)O4 tetrahedra, corners with four equivalent Na(2)O4 tetrahedra, corners with six equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(3)O4 tetrahedra, and edges with three equivalent Na(2)O4 tetrahedra. In the second Na site, Na(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra, corners with four equivalent Na(3)O4 tetrahedra, corners with six equivalent Na(2)O4 tetrahedra,  an edgeedge with one Nb(1)O4 tetrahedra, and edges with three equivalent Na(1)O4 tetrahedra. In the third Na site, Na(3) is bonded to one O(2) and three equivalent O(1) atoms to form NaO4 tetrahedra that share corners with three equivalent Na(3)O4 tetrahedra, corners with three equivalent Nb(1)O4 tetrahedra, corners with six equivalent Na(2)O4 tetrahedra, and edges with three equivalent Na(1)O4 tetrahedra. Nb(1) is bonded to one O(3) and three equivalent O(1) atoms to form NbO4 tetrahedra that share corners with six equivalent Na(1)O4 tetrahedra, corners with six equivalent Na(3)O4 tetrahedra, and edges with three equivalent Na(2)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), two equivalent Na(3), and one Nb(1) atom to form ONa4Nb trigonal bipyramids that share corners with two equivalent O(2)Na7 pentagonal bipyramids, corners with six equivalent O(1)Na4Nb trigonal bipyramids, and edges with two equivalent O(2)Na7 pentagonal bipyramids. In the second O site, O(2) is bonded to one Na(3), three equivalent Na(1), and three equivalent Na(2) atoms to form distorted ONa7 pentagonal bipyramids that share corners with three equivalent O(1)Na4Nb trigonal bipyramids, edges with three equivalent O(2)Na7 pentagonal bipyramids, and edges with three equivalent O(1)Na4Nb trigonal bipyramids. In the third O site, O(3) is bonded in a 7-coordinate geometry to three equivalent Na(1), three equivalent Na(2), and one Nb(1) atom. is represented by the CIF file [CIF]
data_Na8NbO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.527
_cell_length_b   6.527
_cell_length_c   13.254
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   488.999
_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  0.000  0.697  0.769  1.0
  Na  Na1  1  0.000  0.602  0.128  1.0
  Na  Na2  1  0.000  0.398  0.628  1.0
  Na  Na3  1  0.000  0.303  0.269  1.0
  Na  Na4  1  0.333  0.667  0.409  1.0
  Na  Na5  1  0.333  0.667  0.909  1.0
  Na  Na6  1  0.303  0.303  0.769  1.0
  Na  Na7  1  0.398  0.398  0.128  1.0
  Na  Na8  1  0.602  0.602  0.628  1.0
  Na  Na9  1  0.303  0.000  0.269  1.0
  Na  Na10  1  0.697  0.697  0.269  1.0
  Na  Na11  1  0.398  0.000  0.628  1.0
  Na  Na12  1  0.667  0.333  0.909  1.0
  Na  Na13  1  0.667  0.333  0.409  1.0
  Na  Na14  1  0.602  0.000  0.128  1.0
  Na  Na15  1  0.697  0.000  0.769  1.0
  Nb  Nb16  1  0.000  0.000  0.991  1.0
  Nb  Nb17  1  0.000  0.000  0.491  1.0
  O  O18  1  0.000  0.720  0.953  1.0
  O  O19  1  0.000  0.280  0.453  1.0
  O  O20  1  0.333  0.667  0.223  1.0
  O  O21  1  0.000  0.000  0.134  1.0
  O  O22  1  0.000  0.000  0.634  1.0
  O  O23  1  0.333  0.667  0.723  1.0
  O  O24  1  0.280  0.280  0.953  1.0
  O  O25  1  0.280  0.000  0.453  1.0
  O  O26  1  0.720  0.720  0.453  1.0
  O  O27  1  0.667  0.333  0.723  1.0
  O  O28  1  0.667  0.333  0.223  1.0
  O  O29  1  0.720  0.000  0.953  1.0
[/CIF]
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The structure described by Na8NbO6 crystallizes in the hexagonal P6_3cm space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent Nb(1)O4 tetrahedra, corners with four equivalent Na(2)O4 tetrahedra, corners with six equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(3)O4 tetrahedra, and edges with three equivalent Na(2)O4 tetrahedra. In the second Na site, Na(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra, corners with four equivalent Na(3)O4 tetrahedra, corners with six equivalent Na(2)O4 tetrahedra,  an edgeedge with one Nb(1)O4 tetrahedra, and edges with three equivalent Na(1)O4 tetrahedra. In the third Na site, Na(3) is bonded to one O(2) and three equivalent O(1) atoms to form NaO4 tetrahedra that share corners with three equivalent Na(3)O4 tetrahedra, corners with three equivalent Nb(1)O4 tetrahedra, corners with six equivalent Na(2)O4 tetrahedra, and edges with three equivalent Na(1)O4 tetrahedra. Nb(1) is bonded to one O(3) and three equivalent O(1) atoms to form NbO4 tetrahedra that share corners with six equivalent Na(1)O4 tetrahedra, corners with six equivalent Na(3)O4 tetrahedra, and edges with three equivalent Na(2)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), two equivalent Na(3), and one Nb(1) atom to form ONa4Nb trigonal bipyramids that share corners with two equivalent O(2)Na7 pentagonal bipyramids, corners with six equivalent O(1)Na4Nb trigonal bipyramids, and edges with two equivalent O(2)Na7 pentagonal bipyramids. In the second O site, O(2) is bonded to one Na(3), three equivalent Na(1), and three equivalent Na(2) atoms to form distorted ONa7 pentagonal bipyramids that share corners with three equivalent O(1)Na4Nb trigonal bipyramids, edges with three equivalent O(2)Na7 pentagonal bipyramids, and edges with three equivalent O(1)Na4Nb trigonal bipyramids. In the third O site, O(3) is bonded in a 7-coordinate geometry to three equivalent Na(1), three equivalent Na(2), and one Nb(1) atom. is represented by the CIF file [CIF]
data_Na8NbO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.527
_cell_length_b   6.527
_cell_length_c   13.254
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   488.999
_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  0.000  0.697  0.769  1.0
  Na  Na1  1  0.000  0.602  0.128  1.0
  Na  Na2  1  0.000  0.398  0.628  1.0
  Na  Na3  1  0.000  0.303  0.269  1.0
  Na  Na4  1  0.333  0.667  0.409  1.0
  Na  Na5  1  0.333  0.667  0.909  1.0
  Na  Na6  1  0.303  0.303  0.769  1.0
  Na  Na7  1  0.398  0.398  0.128  1.0
  Na  Na8  1  0.602  0.602  0.628  1.0
  Na  Na9  1  0.303  0.000  0.269  1.0
  Na  Na10  1  0.697  0.697  0.269  1.0
  Na  Na11  1  0.398  0.000  0.628  1.0
  Na  Na12  1  0.667  0.333  0.909  1.0
  Na  Na13  1  0.667  0.333  0.409  1.0
  Na  Na14  1  0.602  0.000  0.128  1.0
  Na  Na15  1  0.697  0.000  0.769  1.0
  Nb  Nb16  1  0.000  0.000  0.991  1.0
  Nb  Nb17  1  0.000  0.000  0.491  1.0
  O  O18  1  0.000  0.720  0.953  1.0
  O  O19  1  0.000  0.280  0.453  1.0
  O  O20  1  0.333  0.667  0.223  1.0
  O  O21  1  0.000  0.000  0.134  1.0
  O  O22  1  0.000  0.000  0.634  1.0
  O  O23  1  0.333  0.667  0.723  1.0
  O  O24  1  0.280  0.280  0.953  1.0
  O  O25  1  0.280  0.000  0.453  1.0
  O  O26  1  0.720  0.720  0.453  1.0
  O  O27  1  0.667  0.333  0.723  1.0
  O  O28  1  0.667  0.333  0.223  1.0
  O  O29  1  0.720  0.000  0.953  1.0
[/CIF]
.