The material structure described by Ca(NiO2)2 is Spinel-like structured and crystallizes in the trigonal P3m1 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(9) and three equivalent O(1) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra, and corners with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-70°. In the second Ca site, Ca(2) is bonded to one O(2) and three equivalent O(3) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Ni(1)O6 octahedra, and corners with six equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-74°. In the third Ca site, Ca(3) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form distorted CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Ni(4)O4 tetrahedra, edges with three equivalent Ni(1)O6 octahedra, and edges with three equivalent Ni(2)O6 octahedra. In the fourth Ca site, Ca(4) is bonded to one O(5), three equivalent O(11), and three equivalent O(7) atoms to form distorted CaO7 trigonal pyramids that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ni(2)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra, edges with six equivalent Ni(5)O6 octahedra, and  a faceface with one Ni(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-56°. In the fifth Ca site, Ca(5) is bonded to three equivalent O(1) and three equivalent O(11) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Ni(6)O4 tetrahedra, corners with three equivalent Ca(4)O7 trigonal pyramids, edges with three equivalent Ni(1)O6 octahedra, and edges with three equivalent Ni(5)O6 octahedra. In the sixth Ca site, Ca(6) is bonded to one O(12) and three equivalent O(8) atoms to form CaO4 tetrahedra that share corners with three equivalent Ni(3)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra, and corners with six equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-66°. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form NiO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Ni(6)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Ni(4)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(10), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form NiO6 octahedra that share  a cornercorner with one Ni(4)O4 tetrahedra, corners with two equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(6)O4 tetrahedra,  a cornercorner with one Ca(4)O7 trigonal pyramid,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. In the third Ni site, Ni(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form NiO6 octahedra that share corners with three equivalent Ca(6)O4 tetrahedra, corners with three equivalent Ca(4)O7 trigonal pyramids, edges with three equivalent Ni(2)O6 octahedra, and edges with three equivalent Ni(5)O6 octahedra. In the fourth Ni site, Ni(4) is bonded to one O(10) and three equivalent O(4) atoms to form NiO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Ni(2)O6 octahedra, and corners with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-64°. In the fifth Ni site, Ni(5) is bonded to one O(12), one O(9), two equivalent O(11), and two equivalent O(7) atoms to form NiO6 octahedra that share  a cornercorner with one Ca(1)O4 tetrahedra,  a cornercorner with one Ca(6)O4 tetrahedra, corners with two equivalent Ni(6)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra, edges with four equivalent Ni(5)O6 octahedra, and edges with two equivalent Ca(4)O7 trigonal pyramids. In the sixth Ni site, Ni(6) is bonded to one O(6) and three equivalent O(11) atoms to form NiO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ni(1)O6 octahedra, corners with six equivalent Ni(5)O6 octahedra, and  a faceface with one Ca(4)O7 trigonal pyramid. The corner-sharing octahedral tilt angles range from 52-64°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(5), and two equivalent Ni(1) atoms to form distorted OCa2Ni2 tetrahedra that share  a cornercorner with one O(9)CaNi3 tetrahedra, corners with two equivalent O(1)Ca2Ni2 tetrahedra, corners with four equivalent O(4)CaNi3 trigonal pyramids, and edges with two equivalent O(1)Ca2Ni2 tetrahedra. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2) and three equivalent Ni(1) atoms. In the third O site, O(3) is bonded to one Ca(2), one Ca(3), and two equivalent Ni(2) atoms to form distorted OCa2Ni2 trigonal pyramids that share corners with four equivalent O(8)CaNi3 tetrahedra, corners with two equivalent O(3)Ca2Ni2 trigonal pyramids, corners with three equivalent O(4)CaNi3 trigonal pyramids, and edges with two equivalent O(3)Ca2Ni2 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ca(3), one Ni(4), and two equivalent Ni(1) atoms to form distorted OCaNi3 trigonal pyramids that share corners with four equivalent O(1)Ca2Ni2 tetrahedra, corners with two equivalent O(4)CaNi3 trigonal pyramids, corners with three equivalent O(3)Ca2Ni2 trigonal pyramids, and edges with two equivalent O(4)CaNi3 trigonal pyramids. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Ca(4) and three equivalent Ni(2) atoms. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Ni(6) and three equivalent Ni(1) atoms. In the seventh O site, O(7) is bonded to one Ca(4), one Ni(3), and two equivalent Ni(5) atoms to form a mixture of distorted corner and edge-sharing OCaNi3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Ca(6), one Ni(3), and two equivalent Ni(2) atoms to form OCaNi3 tetrahedra that share  a cornercorner with one O(12)CaNi3 tetrahedra, corners with two equivalent O(8)CaNi3 tetrahedra, corners with three equivalent O(7)CaNi3 trigonal pyramids, corners with four equivalent O(3)Ca2Ni2 trigonal pyramids, and edges with two equivalent O(8)CaNi3 tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1) and three equivalent Ni(5) atoms to form distorted OCaNi3 tetrahedra that share corners with three equivalent O(1)Ca2Ni2 tetrahedra, corners with three equivalent O(12)CaNi3 tetrahedra, and edges with three equivalent O(7)CaNi3 trigonal pyramids. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Ni(4) and three equivalent Ni(2) atoms. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Ca(4), one Ca(5), one Ni(6), and two equivalent Ni(5) atoms. In the twelfth O site, O(12) is bonded to one Ca(6) and three equivalent Ni(5) atoms to form corner-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   6.142
_cell_length_b   6.142
_cell_length_c   14.995
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   489.828
_cell_formula_units_Z   6
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  0.333  0.667  0.047  1.0
  Ca  Ca1  1  0.000  0.000  0.386  1.0
  Ca  Ca2  1  0.667  0.333  0.336  1.0
  Ca  Ca3  1  0.667  0.333  0.745  1.0
  Ca  Ca4  1  0.000  0.000  0.989  1.0
  Ca  Ca5  1  0.000  0.000  0.626  1.0
  Ni  Ni6  1  0.325  0.162  0.166  1.0
  Ni  Ni7  1  0.838  0.675  0.166  1.0
  Ni  Ni8  1  0.996  0.498  0.511  1.0
  Ni  Ni9  1  0.838  0.162  0.166  1.0
  Ni  Ni10  1  0.502  0.004  0.511  1.0
  Ni  Ni11  1  0.333  0.667  0.662  1.0
  Ni  Ni12  1  0.333  0.667  0.277  1.0
  Ni  Ni13  1  0.655  0.827  0.827  1.0
  Ni  Ni14  1  0.502  0.498  0.511  1.0
  Ni  Ni15  1  0.173  0.345  0.827  1.0
  Ni  Ni16  1  0.173  0.827  0.827  1.0
  Ni  Ni17  1  0.667  0.333  0.953  1.0
  O  O18  1  0.712  0.856  0.101  1.0
  O  O19  1  0.000  0.000  0.242  1.0
  O  O20  1  0.144  0.288  0.101  1.0
  O  O21  1  0.144  0.856  0.101  1.0
  O  O22  1  0.370  0.185  0.451  1.0
  O  O23  1  0.511  0.489  0.230  1.0
  O  O24  1  0.667  0.333  0.589  1.0
  O  O25  1  0.511  0.023  0.230  1.0
  O  O26  1  0.667  0.333  0.076  1.0
  O  O27  1  0.815  0.630  0.451  1.0
  O  O28  1  0.815  0.185  0.451  1.0
  O  O29  1  0.977  0.489  0.230  1.0
  O  O30  1  0.067  0.533  0.738  1.0
  O  O31  1  0.198  0.802  0.577  1.0
  O  O32  1  0.198  0.396  0.577  1.0
  O  O33  1  0.333  0.667  0.893  1.0
  O  O34  1  0.333  0.667  0.418  1.0
  O  O35  1  0.467  0.933  0.738  1.0
  O  O36  1  0.467  0.533  0.738  1.0
  O  O37  1  0.604  0.802  0.577  1.0
  O  O38  1  0.825  0.175  0.896  1.0
  O  O39  1  0.825  0.649  0.896  1.0
  O  O40  1  0.000  0.000  0.773  1.0
  O  O41  1  0.351  0.175  0.896  1.0
[/CIF]
.
The material structure described by Ca(NiO2)2 is Spinel-like structured and crystallizes in the trigonal P3m1 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(9) and three equivalent O(1) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra, and corners with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-70°. In the second Ca site, Ca(2) is bonded to one O(2) and three equivalent O(3) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Ni(1)O6 octahedra, and corners with six equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-74°. In the third Ca site, Ca(3) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form distorted CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Ni(4)O4 tetrahedra, edges with three equivalent Ni(1)O6 octahedra, and edges with three equivalent Ni(2)O6 octahedra. In the fourth Ca site, Ca(4) is bonded to one O(5), three equivalent O(11), and three equivalent O(7) atoms to form distorted CaO7 trigonal pyramids that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ni(2)O6 octahedra, corners with three equivalent Ni(3)O6 octahedra, edges with six equivalent Ni(5)O6 octahedra, and  a faceface with one Ni(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-56°. In the fifth Ca site, Ca(5) is bonded to three equivalent O(1) and three equivalent O(11) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Ni(6)O4 tetrahedra, corners with three equivalent Ca(4)O7 trigonal pyramids, edges with three equivalent Ni(1)O6 octahedra, and edges with three equivalent Ni(5)O6 octahedra. In the sixth Ca site, Ca(6) is bonded to one O(12) and three equivalent O(8) atoms to form CaO4 tetrahedra that share corners with three equivalent Ni(3)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra, and corners with six equivalent Ni(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-66°. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form NiO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Ni(6)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Ni(4)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Ni(1)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(10), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form NiO6 octahedra that share  a cornercorner with one Ni(4)O4 tetrahedra, corners with two equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(6)O4 tetrahedra,  a cornercorner with one Ca(4)O7 trigonal pyramid,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra, and edges with four equivalent Ni(2)O6 octahedra. In the third Ni site, Ni(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form NiO6 octahedra that share corners with three equivalent Ca(6)O4 tetrahedra, corners with three equivalent Ca(4)O7 trigonal pyramids, edges with three equivalent Ni(2)O6 octahedra, and edges with three equivalent Ni(5)O6 octahedra. In the fourth Ni site, Ni(4) is bonded to one O(10) and three equivalent O(4) atoms to form NiO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Ni(2)O6 octahedra, and corners with six equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-64°. In the fifth Ni site, Ni(5) is bonded to one O(12), one O(9), two equivalent O(11), and two equivalent O(7) atoms to form NiO6 octahedra that share  a cornercorner with one Ca(1)O4 tetrahedra,  a cornercorner with one Ca(6)O4 tetrahedra, corners with two equivalent Ni(6)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra, edges with four equivalent Ni(5)O6 octahedra, and edges with two equivalent Ca(4)O7 trigonal pyramids. In the sixth Ni site, Ni(6) is bonded to one O(6) and three equivalent O(11) atoms to form NiO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ni(1)O6 octahedra, corners with six equivalent Ni(5)O6 octahedra, and  a faceface with one Ca(4)O7 trigonal pyramid. The corner-sharing octahedral tilt angles range from 52-64°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(5), and two equivalent Ni(1) atoms to form distorted OCa2Ni2 tetrahedra that share  a cornercorner with one O(9)CaNi3 tetrahedra, corners with two equivalent O(1)Ca2Ni2 tetrahedra, corners with four equivalent O(4)CaNi3 trigonal pyramids, and edges with two equivalent O(1)Ca2Ni2 tetrahedra. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2) and three equivalent Ni(1) atoms. In the third O site, O(3) is bonded to one Ca(2), one Ca(3), and two equivalent Ni(2) atoms to form distorted OCa2Ni2 trigonal pyramids that share corners with four equivalent O(8)CaNi3 tetrahedra, corners with two equivalent O(3)Ca2Ni2 trigonal pyramids, corners with three equivalent O(4)CaNi3 trigonal pyramids, and edges with two equivalent O(3)Ca2Ni2 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ca(3), one Ni(4), and two equivalent Ni(1) atoms to form distorted OCaNi3 trigonal pyramids that share corners with four equivalent O(1)Ca2Ni2 tetrahedra, corners with two equivalent O(4)CaNi3 trigonal pyramids, corners with three equivalent O(3)Ca2Ni2 trigonal pyramids, and edges with two equivalent O(4)CaNi3 trigonal pyramids. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Ca(4) and three equivalent Ni(2) atoms. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Ni(6) and three equivalent Ni(1) atoms. In the seventh O site, O(7) is bonded to one Ca(4), one Ni(3), and two equivalent Ni(5) atoms to form a mixture of distorted corner and edge-sharing OCaNi3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Ca(6), one Ni(3), and two equivalent Ni(2) atoms to form OCaNi3 tetrahedra that share  a cornercorner with one O(12)CaNi3 tetrahedra, corners with two equivalent O(8)CaNi3 tetrahedra, corners with three equivalent O(7)CaNi3 trigonal pyramids, corners with four equivalent O(3)Ca2Ni2 trigonal pyramids, and edges with two equivalent O(8)CaNi3 tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1) and three equivalent Ni(5) atoms to form distorted OCaNi3 tetrahedra that share corners with three equivalent O(1)Ca2Ni2 tetrahedra, corners with three equivalent O(12)CaNi3 tetrahedra, and edges with three equivalent O(7)CaNi3 trigonal pyramids. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Ni(4) and three equivalent Ni(2) atoms. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Ca(4), one Ca(5), one Ni(6), and two equivalent Ni(5) atoms. In the twelfth O site, O(12) is bonded to one Ca(6) and three equivalent Ni(5) atoms to form corner-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   6.142
_cell_length_b   6.142
_cell_length_c   14.995
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   489.828
_cell_formula_units_Z   6
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  0.333  0.667  0.047  1.0
  Ca  Ca1  1  0.000  0.000  0.386  1.0
  Ca  Ca2  1  0.667  0.333  0.336  1.0
  Ca  Ca3  1  0.667  0.333  0.745  1.0
  Ca  Ca4  1  0.000  0.000  0.989  1.0
  Ca  Ca5  1  0.000  0.000  0.626  1.0
  Ni  Ni6  1  0.325  0.162  0.166  1.0
  Ni  Ni7  1  0.838  0.675  0.166  1.0
  Ni  Ni8  1  0.996  0.498  0.511  1.0
  Ni  Ni9  1  0.838  0.162  0.166  1.0
  Ni  Ni10  1  0.502  0.004  0.511  1.0
  Ni  Ni11  1  0.333  0.667  0.662  1.0
  Ni  Ni12  1  0.333  0.667  0.277  1.0
  Ni  Ni13  1  0.655  0.827  0.827  1.0
  Ni  Ni14  1  0.502  0.498  0.511  1.0
  Ni  Ni15  1  0.173  0.345  0.827  1.0
  Ni  Ni16  1  0.173  0.827  0.827  1.0
  Ni  Ni17  1  0.667  0.333  0.953  1.0
  O  O18  1  0.712  0.856  0.101  1.0
  O  O19  1  0.000  0.000  0.242  1.0
  O  O20  1  0.144  0.288  0.101  1.0
  O  O21  1  0.144  0.856  0.101  1.0
  O  O22  1  0.370  0.185  0.451  1.0
  O  O23  1  0.511  0.489  0.230  1.0
  O  O24  1  0.667  0.333  0.589  1.0
  O  O25  1  0.511  0.023  0.230  1.0
  O  O26  1  0.667  0.333  0.076  1.0
  O  O27  1  0.815  0.630  0.451  1.0
  O  O28  1  0.815  0.185  0.451  1.0
  O  O29  1  0.977  0.489  0.230  1.0
  O  O30  1  0.067  0.533  0.738  1.0
  O  O31  1  0.198  0.802  0.577  1.0
  O  O32  1  0.198  0.396  0.577  1.0
  O  O33  1  0.333  0.667  0.893  1.0
  O  O34  1  0.333  0.667  0.418  1.0
  O  O35  1  0.467  0.933  0.738  1.0
  O  O36  1  0.467  0.533  0.738  1.0
  O  O37  1  0.604  0.802  0.577  1.0
  O  O38  1  0.825  0.175  0.896  1.0
  O  O39  1  0.825  0.649  0.896  1.0
  O  O40  1  0.000  0.000  0.773  1.0
  O  O41  1  0.351  0.175  0.896  1.0
[/CIF]
.