The structure described by NaNiO2 is Caswellsilverite-like structured and crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NaO6 pentagonal pyramids that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with three equivalent Ni(1)O6 octahedra, and edges with two equivalent Na(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 11-16°. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form NiO6 octahedra that share corners with three equivalent Na(1)O6 pentagonal pyramids, edges with six equivalent Ni(1)O6 octahedra, and edges with three equivalent Na(1)O6 pentagonal pyramids. In the second Ni site, Ni(2) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form NiO6 octahedra that share edges with two equivalent Ni(2)O6 octahedra, edges with four equivalent Ni(3)O6 octahedra, and edges with four equivalent Na(1)O6 pentagonal pyramids. In the third Ni site, Ni(3) is bonded to two equivalent O(4) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Na(1)O6 pentagonal pyramids, edges with two equivalent Ni(3)O6 octahedra, edges with four equivalent Ni(2)O6 octahedra, and edges with two equivalent Na(1)O6 pentagonal pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), and three equivalent Ni(1) atoms to form a mixture of edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-50°. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), and three equivalent Ni(1) atoms to form a mixture of edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-47°. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Ni(2), and two equivalent Ni(3) atoms to form a mixture of edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-47°. In the fourth O site, O(4) is bonded to one Na(1), two equivalent Na(2), one Ni(3), and two equivalent Ni(2) atoms to form a mixture of distorted edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-50°. is represented by the Crystallographic Information File (CIF) [CIF]
data_NaNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.996
_cell_length_b   10.886
_cell_length_c   4.990
_cell_angle_alpha   76.801
_cell_angle_beta   92.095
_cell_angle_gamma   81.458
_symmetry_Int_Tables_number   1
_cell_volume   156.254
_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  0.881  0.250  0.219  1.0
  Na  Na1  1  0.347  0.250  0.719  1.0
  Na  Na2  1  0.119  0.750  0.781  1.0
  Na  Na3  1  0.653  0.750  0.281  1.0
  Ni  Ni4  1  0.250  0.500  0.250  1.0
  Ni  Ni5  1  0.500  1.000  0.500  1.0
  Ni  Ni6  1  0.750  0.500  0.750  1.0
  Ni  Ni7  1  1.000  1.000  1.000  1.0
  O  O8  1  0.272  0.403  0.978  1.0
  O  O9  1  0.768  0.402  0.479  1.0
  O  O10  1  0.728  0.597  0.022  1.0
  O  O11  1  0.232  0.598  0.522  1.0
  O  O12  1  0.509  0.903  0.871  1.0
  O  O13  1  0.102  0.903  0.370  1.0
  O  O14  1  0.491  0.097  0.129  1.0
  O  O15  1  0.897  0.097  0.630  1.0
[/CIF]
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The structure described by NaNiO2 is Caswellsilverite-like structured and crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NaO6 pentagonal pyramids that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with three equivalent Ni(1)O6 octahedra, and edges with two equivalent Na(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 11-16°. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form NiO6 octahedra that share corners with three equivalent Na(1)O6 pentagonal pyramids, edges with six equivalent Ni(1)O6 octahedra, and edges with three equivalent Na(1)O6 pentagonal pyramids. In the second Ni site, Ni(2) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form NiO6 octahedra that share edges with two equivalent Ni(2)O6 octahedra, edges with four equivalent Ni(3)O6 octahedra, and edges with four equivalent Na(1)O6 pentagonal pyramids. In the third Ni site, Ni(3) is bonded to two equivalent O(4) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Na(1)O6 pentagonal pyramids, edges with two equivalent Ni(3)O6 octahedra, edges with four equivalent Ni(2)O6 octahedra, and edges with two equivalent Na(1)O6 pentagonal pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(2), two equivalent Na(1), and three equivalent Ni(1) atoms to form a mixture of edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-50°. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), and three equivalent Ni(1) atoms to form a mixture of edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-47°. In the third O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Ni(2), and two equivalent Ni(3) atoms to form a mixture of edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-47°. In the fourth O site, O(4) is bonded to one Na(1), two equivalent Na(2), one Ni(3), and two equivalent Ni(2) atoms to form a mixture of distorted edge, corner, and face-sharing ONa3Ni3 octahedra. The corner-sharing octahedral tilt angles range from 0-50°. is represented by the Crystallographic Information File (CIF) [CIF]
data_NaNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.996
_cell_length_b   10.886
_cell_length_c   4.990
_cell_angle_alpha   76.801
_cell_angle_beta   92.095
_cell_angle_gamma   81.458
_symmetry_Int_Tables_number   1
_cell_volume   156.254
_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  0.881  0.250  0.219  1.0
  Na  Na1  1  0.347  0.250  0.719  1.0
  Na  Na2  1  0.119  0.750  0.781  1.0
  Na  Na3  1  0.653  0.750  0.281  1.0
  Ni  Ni4  1  0.250  0.500  0.250  1.0
  Ni  Ni5  1  0.500  1.000  0.500  1.0
  Ni  Ni6  1  0.750  0.500  0.750  1.0
  Ni  Ni7  1  1.000  1.000  1.000  1.0
  O  O8  1  0.272  0.403  0.978  1.0
  O  O9  1  0.768  0.402  0.479  1.0
  O  O10  1  0.728  0.597  0.022  1.0
  O  O11  1  0.232  0.598  0.522  1.0
  O  O12  1  0.509  0.903  0.871  1.0
  O  O13  1  0.102  0.903  0.370  1.0
  O  O14  1  0.491  0.097  0.129  1.0
  O  O15  1  0.897  0.097  0.630  1.0
[/CIF]
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