The material described by Na2Mg(CoO2)2 crystallizes in the triclinic P1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent Mg(1)O5 square pyramids, corners with two equivalent Na(1)O4 tetrahedra, and  an edgeedge with one Co(2)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. Mg(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO5 square pyramids that share corners with two equivalent Co(2)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent Mg(1)O5 square pyramids, and edges with two equivalent Co(2)O4 tetrahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a distorted see-saw-like geometry to one O(1), one O(3), and two equivalent O(4) atoms. In the second Co site, Co(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted CoO4 tetrahedra that share corners with two equivalent Mg(1)O5 square pyramids, corners with two equivalent Co(2)O4 tetrahedra, edges with two equivalent Mg(1)O5 square pyramids, and  an edgeedge with one Na(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Na(2), one Mg(1), one Co(1), and two equivalent Co(2) atoms. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), two equivalent Mg(1), and one Co(2) atom. In the third O site, O(3) is bonded to one Na(1), two equivalent Mg(1), one Co(1), and one Co(2) atom to form distorted ONaMg2Co2 trigonal bipyramids that share corners with four equivalent O(4)Na4Co2 octahedra and corners with two equivalent O(3)NaMg2Co2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-81°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Na(2), and two equivalent Co(1) atoms to form distorted ONa4Co2 octahedra that share corners with two equivalent O(4)Na4Co2 octahedra, corners with four equivalent O(3)NaMg2Co2 trigonal bipyramids, and edges with two equivalent O(4)Na4Co2 octahedra. The corner-sharing octahedral tilt angles are 12°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Mg(CoO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.114
_cell_length_b   7.139
_cell_length_c   5.275
_cell_angle_alpha   92.912
_cell_angle_beta   92.065
_cell_angle_gamma   108.106
_symmetry_Int_Tables_number   1
_cell_volume   111.172
_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  0.442  0.063  0.377  1.0
  Na  Na1  1  0.814  0.872  0.788  1.0
  Mg  Mg2  1  0.078  0.301  0.989  1.0
  Co  Co3  1  0.141  0.661  0.192  1.0
  Co  Co4  1  0.631  0.444  0.616  1.0
  O  O5  1  0.224  0.569  0.811  1.0
  O  O6  1  0.465  0.171  0.792  1.0
  O  O7  1  0.688  0.389  0.255  1.0
  O  O8  1  0.766  0.830  0.277  1.0
[/CIF]
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The material described by Na2Mg(CoO2)2 crystallizes in the triclinic P1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent Mg(1)O5 square pyramids, corners with two equivalent Na(1)O4 tetrahedra, and  an edgeedge with one Co(2)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. Mg(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form MgO5 square pyramids that share corners with two equivalent Co(2)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent Mg(1)O5 square pyramids, and edges with two equivalent Co(2)O4 tetrahedra. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a distorted see-saw-like geometry to one O(1), one O(3), and two equivalent O(4) atoms. In the second Co site, Co(2) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted CoO4 tetrahedra that share corners with two equivalent Mg(1)O5 square pyramids, corners with two equivalent Co(2)O4 tetrahedra, edges with two equivalent Mg(1)O5 square pyramids, and  an edgeedge with one Na(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Na(2), one Mg(1), one Co(1), and two equivalent Co(2) atoms. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), two equivalent Mg(1), and one Co(2) atom. In the third O site, O(3) is bonded to one Na(1), two equivalent Mg(1), one Co(1), and one Co(2) atom to form distorted ONaMg2Co2 trigonal bipyramids that share corners with four equivalent O(4)Na4Co2 octahedra and corners with two equivalent O(3)NaMg2Co2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 38-81°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Na(2), and two equivalent Co(1) atoms to form distorted ONa4Co2 octahedra that share corners with two equivalent O(4)Na4Co2 octahedra, corners with four equivalent O(3)NaMg2Co2 trigonal bipyramids, and edges with two equivalent O(4)Na4Co2 octahedra. The corner-sharing octahedral tilt angles are 12°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Mg(CoO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.114
_cell_length_b   7.139
_cell_length_c   5.275
_cell_angle_alpha   92.912
_cell_angle_beta   92.065
_cell_angle_gamma   108.106
_symmetry_Int_Tables_number   1
_cell_volume   111.172
_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  0.442  0.063  0.377  1.0
  Na  Na1  1  0.814  0.872  0.788  1.0
  Mg  Mg2  1  0.078  0.301  0.989  1.0
  Co  Co3  1  0.141  0.661  0.192  1.0
  Co  Co4  1  0.631  0.444  0.616  1.0
  O  O5  1  0.224  0.569  0.811  1.0
  O  O6  1  0.465  0.171  0.792  1.0
  O  O7  1  0.688  0.389  0.255  1.0
  O  O8  1  0.766  0.830  0.277  1.0
[/CIF]
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