The material structure described by Ca2Ni3O8 is Pyrite-derived structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with three equivalent Ni(1)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 21-56°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Ca(1)O6 pentagonal pyramids, edges with four equivalent Ni(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. 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 corners with four equivalent Ca(1)O6 pentagonal pyramids, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ca(1) and two equivalent Ni(2) atoms. In the second O site, O(2) is bonded to one Ca(1), one Ni(1), and two equivalent Ni(2) atoms to form distorted OCaNi3 trigonal pyramids that share  a cornercorner with one O(2)CaNi3 trigonal pyramid, corners with four equivalent O(3)Ca2Ni2 trigonal pyramids,  an edgeedge with one O(2)CaNi3 trigonal pyramid, and edges with four equivalent O(3)Ca2Ni2 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Ca(1), one Ni(1), and one Ni(2) atom to form distorted OCa2Ni2 trigonal pyramids that share corners with two equivalent O(2)CaNi3 trigonal pyramids, corners with six equivalent O(3)Ca2Ni2 trigonal pyramids, edges with two equivalent O(3)Ca2Ni2 trigonal pyramids, and edges with two equivalent O(2)CaNi3 trigonal pyramids. is represented by the CIF card [CIF]
data_Ca2Ni3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.200
_cell_length_b   6.200
_cell_length_c   4.932
_cell_angle_alpha   72.896
_cell_angle_beta   72.896
_cell_angle_gamma   56.034
_symmetry_Int_Tables_number   1
_cell_volume   148.253
_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
  Ca  Ca0  1  0.722  0.722  0.337  1.0
  Ca  Ca1  1  0.278  0.278  0.663  1.0
  Ni  Ni2  1  0.000  0.000  0.500  1.0
  Ni  Ni3  1  0.747  0.253  0.000  1.0
  Ni  Ni4  1  0.253  0.747  0.000  1.0
  O  O5  1  0.399  0.399  0.962  1.0
  O  O6  1  0.601  0.601  0.038  1.0
  O  O7  1  0.906  0.906  0.900  1.0
  O  O8  1  0.094  0.094  0.100  1.0
  O  O9  1  0.320  0.879  0.612  1.0
  O  O10  1  0.879  0.320  0.612  1.0
  O  O11  1  0.121  0.680  0.388  1.0
  O  O12  1  0.680  0.121  0.388  1.0
[/CIF]
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The material structure described by Ca2Ni3O8 is Pyrite-derived structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with three equivalent Ni(1)O6 octahedra, corners with four equivalent Ni(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 21-56°. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Ca(1)O6 pentagonal pyramids, edges with four equivalent Ni(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. 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 corners with four equivalent Ca(1)O6 pentagonal pyramids, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ca(1) and two equivalent Ni(2) atoms. In the second O site, O(2) is bonded to one Ca(1), one Ni(1), and two equivalent Ni(2) atoms to form distorted OCaNi3 trigonal pyramids that share  a cornercorner with one O(2)CaNi3 trigonal pyramid, corners with four equivalent O(3)Ca2Ni2 trigonal pyramids,  an edgeedge with one O(2)CaNi3 trigonal pyramid, and edges with four equivalent O(3)Ca2Ni2 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Ca(1), one Ni(1), and one Ni(2) atom to form distorted OCa2Ni2 trigonal pyramids that share corners with two equivalent O(2)CaNi3 trigonal pyramids, corners with six equivalent O(3)Ca2Ni2 trigonal pyramids, edges with two equivalent O(3)Ca2Ni2 trigonal pyramids, and edges with two equivalent O(2)CaNi3 trigonal pyramids. is represented by the CIF card [CIF]
data_Ca2Ni3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.200
_cell_length_b   6.200
_cell_length_c   4.932
_cell_angle_alpha   72.896
_cell_angle_beta   72.896
_cell_angle_gamma   56.034
_symmetry_Int_Tables_number   1
_cell_volume   148.253
_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
  Ca  Ca0  1  0.722  0.722  0.337  1.0
  Ca  Ca1  1  0.278  0.278  0.663  1.0
  Ni  Ni2  1  0.000  0.000  0.500  1.0
  Ni  Ni3  1  0.747  0.253  0.000  1.0
  Ni  Ni4  1  0.253  0.747  0.000  1.0
  O  O5  1  0.399  0.399  0.962  1.0
  O  O6  1  0.601  0.601  0.038  1.0
  O  O7  1  0.906  0.906  0.900  1.0
  O  O8  1  0.094  0.094  0.100  1.0
  O  O9  1  0.320  0.879  0.612  1.0
  O  O10  1  0.879  0.320  0.612  1.0
  O  O11  1  0.121  0.680  0.388  1.0
  O  O12  1  0.680  0.121  0.388  1.0
[/CIF]
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