The structure described by Na3NiO3 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. In the second Na site, Na(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing NaO4 tetrahedra. Ni(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), four equivalent Na(1), and one Ni(1) atom. is represented by the CIF file [CIF]
data_Na3NiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.186
_cell_length_b   9.186
_cell_length_c   4.455
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   375.911
_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
  Na  Na0  1  0.627  0.129  0.000  1.0
  Na  Na1  1  0.371  0.127  0.500  1.0
  Na  Na2  1  0.851  0.149  0.500  1.0
  Na  Na3  1  0.351  0.351  0.000  1.0
  Na  Na4  1  0.871  0.373  0.000  1.0
  Na  Na5  1  0.127  0.371  0.500  1.0
  Na  Na6  1  0.873  0.629  0.500  1.0
  Na  Na7  1  0.129  0.627  0.000  1.0
  Na  Na8  1  0.649  0.649  0.000  1.0
  Na  Na9  1  0.149  0.851  0.500  1.0
  Na  Na10  1  0.629  0.873  0.500  1.0
  Na  Na11  1  0.373  0.871  0.000  1.0
  Ni  Ni12  1  0.109  0.109  0.000  1.0
  Ni  Ni13  1  0.609  0.391  0.500  1.0
  Ni  Ni14  1  0.391  0.609  0.500  1.0
  Ni  Ni15  1  0.891  0.891  0.000  1.0
  O  O16  1  0.907  0.093  0.000  1.0
  O  O17  1  0.308  0.105  0.000  1.0
  O  O18  1  0.605  0.192  0.500  1.0
  O  O19  1  0.105  0.308  0.000  1.0
  O  O20  1  0.808  0.395  0.500  1.0
  O  O21  1  0.407  0.407  0.500  1.0
  O  O22  1  0.593  0.593  0.500  1.0
  O  O23  1  0.192  0.605  0.500  1.0
  O  O24  1  0.895  0.692  0.000  1.0
  O  O25  1  0.395  0.808  0.500  1.0
  O  O26  1  0.692  0.895  0.000  1.0
  O  O27  1  0.093  0.907  0.000  1.0
[/CIF]
.
The structure described by Na3NiO3 crystallizes in the tetragonal P4_2/mnm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. In the second Na site, Na(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing NaO4 tetrahedra. Ni(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), four equivalent Na(1), and one Ni(1) atom. is represented by the CIF file [CIF]
data_Na3NiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.186
_cell_length_b   9.186
_cell_length_c   4.455
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   375.911
_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
  Na  Na0  1  0.627  0.129  0.000  1.0
  Na  Na1  1  0.371  0.127  0.500  1.0
  Na  Na2  1  0.851  0.149  0.500  1.0
  Na  Na3  1  0.351  0.351  0.000  1.0
  Na  Na4  1  0.871  0.373  0.000  1.0
  Na  Na5  1  0.127  0.371  0.500  1.0
  Na  Na6  1  0.873  0.629  0.500  1.0
  Na  Na7  1  0.129  0.627  0.000  1.0
  Na  Na8  1  0.649  0.649  0.000  1.0
  Na  Na9  1  0.149  0.851  0.500  1.0
  Na  Na10  1  0.629  0.873  0.500  1.0
  Na  Na11  1  0.373  0.871  0.000  1.0
  Ni  Ni12  1  0.109  0.109  0.000  1.0
  Ni  Ni13  1  0.609  0.391  0.500  1.0
  Ni  Ni14  1  0.391  0.609  0.500  1.0
  Ni  Ni15  1  0.891  0.891  0.000  1.0
  O  O16  1  0.907  0.093  0.000  1.0
  O  O17  1  0.308  0.105  0.000  1.0
  O  O18  1  0.605  0.192  0.500  1.0
  O  O19  1  0.105  0.308  0.000  1.0
  O  O20  1  0.808  0.395  0.500  1.0
  O  O21  1  0.407  0.407  0.500  1.0
  O  O22  1  0.593  0.593  0.500  1.0
  O  O23  1  0.192  0.605  0.500  1.0
  O  O24  1  0.895  0.692  0.000  1.0
  O  O25  1  0.395  0.808  0.500  1.0
  O  O26  1  0.692  0.895  0.000  1.0
  O  O27  1  0.093  0.907  0.000  1.0
[/CIF]
.