The structure described by Na3CoO2 is Pb(Zr_(1-x)Ti_x)O3-like structured and 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 linear geometry to two equivalent O(1) atoms. In the second Na site, Na(2) is bonded in a distorted see-saw-like geometry to four equivalent O(1) atoms. Co(1) is bonded in a linear geometry to two equivalent O(1) atoms. O(1) is bonded to one Na(1), four equivalent Na(2), and one Co(1) atom to form a mixture of distorted corner and edge-sharing ONa5Co octahedra. The corner-sharing octahedral tilt angles range from 4-18°. is represented by the CIF card [CIF]
data_Na3CoO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.679
_cell_length_b   9.447
_cell_length_c   9.447
_cell_angle_alpha   90.002
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   417.609
_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  0.500  0.141  0.141  1.0
  Na  Na1  1  0.500  0.859  0.859  1.0
  Na  Na2  1  0.000  0.359  0.641  1.0
  Na  Na3  1  0.000  0.641  0.359  1.0
  Na  Na4  1  0.000  0.026  0.658  1.0
  Na  Na5  1  0.000  0.974  0.342  1.0
  Na  Na6  1  0.500  0.842  0.526  1.0
  Na  Na7  1  0.500  0.158  0.474  1.0
  Na  Na8  1  0.000  0.658  0.026  1.0
  Na  Na9  1  0.500  0.474  0.158  1.0
  Na  Na10  1  0.000  0.342  0.974  1.0
  Na  Na11  1  0.500  0.526  0.842  1.0
  Co  Co12  1  0.000  0.323  0.323  1.0
  Co  Co13  1  0.500  0.823  0.177  1.0
  Co  Co14  1  0.500  0.177  0.823  1.0
  Co  Co15  1  0.000  0.677  0.677  1.0
  O  O16  1  0.500  0.040  0.695  1.0
  O  O17  1  0.000  0.805  0.540  1.0
  O  O18  1  0.500  0.695  0.040  1.0
  O  O19  1  0.000  0.460  0.195  1.0
  O  O20  1  0.500  0.305  0.960  1.0
  O  O21  1  0.000  0.540  0.805  1.0
  O  O22  1  0.500  0.960  0.305  1.0
  O  O23  1  0.000  0.195  0.460  1.0
[/CIF]
.
The structure described by Na3CoO2 is Pb(Zr_(1-x)Ti_x)O3-like structured and 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 linear geometry to two equivalent O(1) atoms. In the second Na site, Na(2) is bonded in a distorted see-saw-like geometry to four equivalent O(1) atoms. Co(1) is bonded in a linear geometry to two equivalent O(1) atoms. O(1) is bonded to one Na(1), four equivalent Na(2), and one Co(1) atom to form a mixture of distorted corner and edge-sharing ONa5Co octahedra. The corner-sharing octahedral tilt angles range from 4-18°. is represented by the CIF card [CIF]
data_Na3CoO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.679
_cell_length_b   9.447
_cell_length_c   9.447
_cell_angle_alpha   90.002
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   417.609
_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  0.500  0.141  0.141  1.0
  Na  Na1  1  0.500  0.859  0.859  1.0
  Na  Na2  1  0.000  0.359  0.641  1.0
  Na  Na3  1  0.000  0.641  0.359  1.0
  Na  Na4  1  0.000  0.026  0.658  1.0
  Na  Na5  1  0.000  0.974  0.342  1.0
  Na  Na6  1  0.500  0.842  0.526  1.0
  Na  Na7  1  0.500  0.158  0.474  1.0
  Na  Na8  1  0.000  0.658  0.026  1.0
  Na  Na9  1  0.500  0.474  0.158  1.0
  Na  Na10  1  0.000  0.342  0.974  1.0
  Na  Na11  1  0.500  0.526  0.842  1.0
  Co  Co12  1  0.000  0.323  0.323  1.0
  Co  Co13  1  0.500  0.823  0.177  1.0
  Co  Co14  1  0.500  0.177  0.823  1.0
  Co  Co15  1  0.000  0.677  0.677  1.0
  O  O16  1  0.500  0.040  0.695  1.0
  O  O17  1  0.000  0.805  0.540  1.0
  O  O18  1  0.500  0.695  0.040  1.0
  O  O19  1  0.000  0.460  0.195  1.0
  O  O20  1  0.500  0.305  0.960  1.0
  O  O21  1  0.000  0.540  0.805  1.0
  O  O22  1  0.500  0.960  0.305  1.0
  O  O23  1  0.000  0.195  0.460  1.0
[/CIF]
.