The crystal structure described by Ca(NiO2)2 is Spinel structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form CaO4 tetrahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra, and corners with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-66°. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, 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 second Ni site, Ni(2) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form distorted NiO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the third Ni site, Ni(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of corner and edge-sharing OCaNi3 tetrahedra. In the second O site, O(2) is bonded to one Ca(1), one Ni(3), and two equivalent Ni(1) atoms to form a mixture of corner and edge-sharing OCaNi3 tetrahedra. In the third O site, O(3) is bonded to one Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing OCaNi3 tetrahedra. is represented by the CIF file [CIF]
data_Ca(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.119
_cell_length_b   6.119
_cell_length_c   6.067
_cell_angle_alpha   60.411
_cell_angle_beta   60.411
_cell_angle_gamma   59.580
_symmetry_Int_Tables_number   1
_cell_volume   161.125
_cell_formula_units_Z   2
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
  Ca  Ca0  1  0.876  0.876  0.876  1.0
  Ca  Ca1  1  0.124  0.124  0.124  1.0
  Ni  Ni2  1  0.000  0.500  0.500  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  0.500  0.500  0.500  1.0
  O  O6  1  0.271  0.686  0.261  1.0
  O  O7  1  0.281  0.281  0.692  1.0
  O  O8  1  0.256  0.256  0.293  1.0
  O  O9  1  0.314  0.729  0.739  1.0
  O  O10  1  0.744  0.744  0.707  1.0
  O  O11  1  0.719  0.719  0.308  1.0
  O  O12  1  0.686  0.271  0.261  1.0
  O  O13  1  0.729  0.314  0.739  1.0
[/CIF]
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The crystal structure described by Ca(NiO2)2 is Spinel structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form CaO4 tetrahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra, and corners with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-66°. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, 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 second Ni site, Ni(2) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form distorted NiO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the third Ni site, Ni(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ni(1), one Ni(2), and one Ni(3) atom to form a mixture of corner and edge-sharing OCaNi3 tetrahedra. In the second O site, O(2) is bonded to one Ca(1), one Ni(3), and two equivalent Ni(1) atoms to form a mixture of corner and edge-sharing OCaNi3 tetrahedra. In the third O site, O(3) is bonded to one Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted corner and edge-sharing OCaNi3 tetrahedra. is represented by the CIF file [CIF]
data_Ca(NiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.119
_cell_length_b   6.119
_cell_length_c   6.067
_cell_angle_alpha   60.411
_cell_angle_beta   60.411
_cell_angle_gamma   59.580
_symmetry_Int_Tables_number   1
_cell_volume   161.125
_cell_formula_units_Z   2
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
  Ca  Ca0  1  0.876  0.876  0.876  1.0
  Ca  Ca1  1  0.124  0.124  0.124  1.0
  Ni  Ni2  1  0.000  0.500  0.500  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  0.500  0.500  0.500  1.0
  O  O6  1  0.271  0.686  0.261  1.0
  O  O7  1  0.281  0.281  0.692  1.0
  O  O8  1  0.256  0.256  0.293  1.0
  O  O9  1  0.314  0.729  0.739  1.0
  O  O10  1  0.744  0.744  0.707  1.0
  O  O11  1  0.719  0.719  0.308  1.0
  O  O12  1  0.686  0.271  0.261  1.0
  O  O13  1  0.729  0.314  0.739  1.0
[/CIF]
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