The material described by BaMg(NiO2)4 crystallizes in the monoclinic C2/m space group. Ba(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted BaO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Mg(1) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(1) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ba(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share edges with two equivalent Ba(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. In the third Ni site, Ni(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form NiO6 octahedra that share edges with two equivalent Ba(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), one Mg(1), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of edge and corner-sharing OBaMgNi3 square pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Ba(1), one Ni(1), and two equivalent Ni(2) atoms. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(3), and two equivalent Ni(2) atoms. is represented by the CIF card [CIF]
data_BaMg(NiO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.509
_cell_length_b   6.509
_cell_length_c   6.420
_cell_angle_alpha   53.873
_cell_angle_beta   53.873
_cell_angle_gamma   57.140
_symmetry_Int_Tables_number   1
_cell_volume   169.358
_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
  Ba  Ba0  1  0.500  0.500  0.500  1.0
  Mg  Mg1  1  0.000  0.000  0.500  1.0
  Ni  Ni2  1  0.000  0.000  0.000  1.0
  Ni  Ni3  1  0.500  0.000  0.500  1.0
  Ni  Ni4  1  0.500  0.500  0.000  1.0
  Ni  Ni5  1  0.000  0.500  0.500  1.0
  O  O6  1  0.799  0.247  0.756  1.0
  O  O7  1  0.216  0.216  0.745  1.0
  O  O8  1  0.201  0.753  0.244  1.0
  O  O9  1  0.753  0.201  0.244  1.0
  O  O10  1  0.258  0.258  0.289  1.0
  O  O11  1  0.742  0.742  0.711  1.0
  O  O12  1  0.784  0.784  0.255  1.0
  O  O13  1  0.247  0.799  0.756  1.0
[/CIF]
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The material described by BaMg(NiO2)4 crystallizes in the monoclinic C2/m space group. Ba(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted BaO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. Mg(1) is bonded in a 6-coordinate geometry to two equivalent O(3) and four equivalent O(1) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ba(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-14°. In the second Ni site, Ni(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share edges with two equivalent Ba(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(3)O6 octahedra. In the third Ni site, Ni(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form NiO6 octahedra that share edges with two equivalent Ba(1)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ba(1), one Mg(1), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of edge and corner-sharing OBaMgNi3 square pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Ba(1), one Ni(1), and two equivalent Ni(2) atoms. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ni(3), and two equivalent Ni(2) atoms. is represented by the CIF card [CIF]
data_BaMg(NiO2)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.509
_cell_length_b   6.509
_cell_length_c   6.420
_cell_angle_alpha   53.873
_cell_angle_beta   53.873
_cell_angle_gamma   57.140
_symmetry_Int_Tables_number   1
_cell_volume   169.358
_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
  Ba  Ba0  1  0.500  0.500  0.500  1.0
  Mg  Mg1  1  0.000  0.000  0.500  1.0
  Ni  Ni2  1  0.000  0.000  0.000  1.0
  Ni  Ni3  1  0.500  0.000  0.500  1.0
  Ni  Ni4  1  0.500  0.500  0.000  1.0
  Ni  Ni5  1  0.000  0.500  0.500  1.0
  O  O6  1  0.799  0.247  0.756  1.0
  O  O7  1  0.216  0.216  0.745  1.0
  O  O8  1  0.201  0.753  0.244  1.0
  O  O9  1  0.753  0.201  0.244  1.0
  O  O10  1  0.258  0.258  0.289  1.0
  O  O11  1  0.742  0.742  0.711  1.0
  O  O12  1  0.784  0.784  0.255  1.0
  O  O13  1  0.247  0.799  0.756  1.0
[/CIF]
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