The crystal structure described by Na3Cu2O4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2) and three equivalent O(1) atoms to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with two equivalent Na(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 29°. In the second Na site, Na(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with four equivalent Na(1)O4 tetrahedra. Cu(1) is bonded in a square co-planar 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 one Na(2), three equivalent Na(1), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), and two equivalent Cu(1) atoms to form a mixture of edge and corner-sharing ONa3Cu2 square pyramids. is represented by the CIF file [CIF]
data_Na3(CuO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.624
_cell_length_b   5.624
_cell_length_c   8.167
_cell_angle_alpha   66.708
_cell_angle_beta   66.708
_cell_angle_gamma   29.771
_symmetry_Int_Tables_number   1
_cell_volume   117.049
_cell_formula_units_Z   1
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  0.622  0.622  0.116  1.0
  Na  Na1  1  0.000  0.000  0.500  1.0
  Na  Na2  1  0.378  0.378  0.884  1.0
  Cu  Cu3  1  0.829  0.829  0.279  1.0
  Cu  Cu4  1  0.171  0.171  0.721  1.0
  O  O5  1  0.748  0.748  0.804  1.0
  O  O6  1  0.585  0.585  0.655  1.0
  O  O7  1  0.415  0.415  0.345  1.0
  O  O8  1  0.252  0.252  0.196  1.0
[/CIF]
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The crystal structure described by Na3Cu2O4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2) and three equivalent O(1) atoms to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with two equivalent Na(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 29°. In the second Na site, Na(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted NaO6 octahedra that share corners with two equivalent Na(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with four equivalent Na(1)O4 tetrahedra. Cu(1) is bonded in a square co-planar 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 one Na(2), three equivalent Na(1), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), and two equivalent Cu(1) atoms to form a mixture of edge and corner-sharing ONa3Cu2 square pyramids. is represented by the CIF file [CIF]
data_Na3(CuO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.624
_cell_length_b   5.624
_cell_length_c   8.167
_cell_angle_alpha   66.708
_cell_angle_beta   66.708
_cell_angle_gamma   29.771
_symmetry_Int_Tables_number   1
_cell_volume   117.049
_cell_formula_units_Z   1
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  0.622  0.622  0.116  1.0
  Na  Na1  1  0.000  0.000  0.500  1.0
  Na  Na2  1  0.378  0.378  0.884  1.0
  Cu  Cu3  1  0.829  0.829  0.279  1.0
  Cu  Cu4  1  0.171  0.171  0.721  1.0
  O  O5  1  0.748  0.748  0.804  1.0
  O  O6  1  0.585  0.585  0.655  1.0
  O  O7  1  0.415  0.415  0.345  1.0
  O  O8  1  0.252  0.252  0.196  1.0
[/CIF]
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