The crystal structure described by CaNiP2O7 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(5), one O(6), one O(7), and two equivalent O(2) atoms. Ni(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-60°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-48°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ca(1), one P(1), and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ni(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(1) atom. is represented by the CIF file [CIF]
data_CaNiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.763
_cell_length_b   7.298
_cell_length_c   9.129
_cell_angle_alpha   63.374
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   521.938
_cell_formula_units_Z   4
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  0.954  0.729  0.119  1.0
  Ca  Ca1  1  0.454  0.271  0.381  1.0
  Ca  Ca2  1  0.546  0.729  0.619  1.0
  Ca  Ca3  1  0.046  0.271  0.881  1.0
  Ni  Ni4  1  0.075  0.224  0.385  1.0
  Ni  Ni5  1  0.925  0.776  0.615  1.0
  Ni  Ni6  1  0.575  0.776  0.115  1.0
  Ni  Ni7  1  0.425  0.224  0.885  1.0
  P  P8  1  0.723  0.048  0.764  1.0
  P  P9  1  0.250  0.524  0.036  1.0
  P  P10  1  0.777  0.048  0.264  1.0
  P  P11  1  0.250  0.524  0.536  1.0
  P  P12  1  0.223  0.952  0.736  1.0
  P  P13  1  0.750  0.476  0.464  1.0
  P  P14  1  0.750  0.476  0.964  1.0
  P  P15  1  0.277  0.952  0.236  1.0
  O  O16  1  0.183  0.739  0.895  1.0
  O  O17  1  0.632  0.064  0.349  1.0
  O  O18  1  0.868  0.064  0.849  1.0
  O  O19  1  0.394  0.561  0.112  1.0
  O  O20  1  0.817  0.261  0.105  1.0
  O  O21  1  0.079  0.985  0.628  1.0
  O  O22  1  0.606  0.439  0.888  1.0
  O  O23  1  0.108  0.458  0.150  1.0
  O  O24  1  0.230  0.384  0.454  1.0
  O  O25  1  0.921  0.015  0.372  1.0
  O  O26  1  0.421  0.985  0.128  1.0
  O  O27  1  0.766  0.894  0.193  1.0
  O  O28  1  0.266  0.106  0.307  1.0
  O  O29  1  0.317  0.739  0.395  1.0
  O  O30  1  0.579  0.015  0.872  1.0
  O  O31  1  0.132  0.936  0.151  1.0
  O  O32  1  0.234  0.106  0.807  1.0
  O  O33  1  0.892  0.542  0.850  1.0
  O  O34  1  0.270  0.384  0.954  1.0
  O  O35  1  0.730  0.616  0.046  1.0
  O  O36  1  0.894  0.439  0.388  1.0
  O  O37  1  0.392  0.458  0.650  1.0
  O  O38  1  0.608  0.542  0.350  1.0
  O  O39  1  0.368  0.936  0.651  1.0
  O  O40  1  0.734  0.894  0.693  1.0
  O  O41  1  0.106  0.561  0.612  1.0
  O  O42  1  0.770  0.616  0.546  1.0
  O  O43  1  0.683  0.261  0.605  1.0
[/CIF]
.
The crystal structure described by CaNiP2O7 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(5), one O(6), one O(7), and two equivalent O(2) atoms. Ni(1) is bonded to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-60°. In the second P site, P(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-48°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ca(1), one P(1), and one P(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ni(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ca(1), one Ni(1), and one P(1) atom. is represented by the CIF file [CIF]
data_CaNiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.763
_cell_length_b   7.298
_cell_length_c   9.129
_cell_angle_alpha   63.374
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   521.938
_cell_formula_units_Z   4
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  0.954  0.729  0.119  1.0
  Ca  Ca1  1  0.454  0.271  0.381  1.0
  Ca  Ca2  1  0.546  0.729  0.619  1.0
  Ca  Ca3  1  0.046  0.271  0.881  1.0
  Ni  Ni4  1  0.075  0.224  0.385  1.0
  Ni  Ni5  1  0.925  0.776  0.615  1.0
  Ni  Ni6  1  0.575  0.776  0.115  1.0
  Ni  Ni7  1  0.425  0.224  0.885  1.0
  P  P8  1  0.723  0.048  0.764  1.0
  P  P9  1  0.250  0.524  0.036  1.0
  P  P10  1  0.777  0.048  0.264  1.0
  P  P11  1  0.250  0.524  0.536  1.0
  P  P12  1  0.223  0.952  0.736  1.0
  P  P13  1  0.750  0.476  0.464  1.0
  P  P14  1  0.750  0.476  0.964  1.0
  P  P15  1  0.277  0.952  0.236  1.0
  O  O16  1  0.183  0.739  0.895  1.0
  O  O17  1  0.632  0.064  0.349  1.0
  O  O18  1  0.868  0.064  0.849  1.0
  O  O19  1  0.394  0.561  0.112  1.0
  O  O20  1  0.817  0.261  0.105  1.0
  O  O21  1  0.079  0.985  0.628  1.0
  O  O22  1  0.606  0.439  0.888  1.0
  O  O23  1  0.108  0.458  0.150  1.0
  O  O24  1  0.230  0.384  0.454  1.0
  O  O25  1  0.921  0.015  0.372  1.0
  O  O26  1  0.421  0.985  0.128  1.0
  O  O27  1  0.766  0.894  0.193  1.0
  O  O28  1  0.266  0.106  0.307  1.0
  O  O29  1  0.317  0.739  0.395  1.0
  O  O30  1  0.579  0.015  0.872  1.0
  O  O31  1  0.132  0.936  0.151  1.0
  O  O32  1  0.234  0.106  0.807  1.0
  O  O33  1  0.892  0.542  0.850  1.0
  O  O34  1  0.270  0.384  0.954  1.0
  O  O35  1  0.730  0.616  0.046  1.0
  O  O36  1  0.894  0.439  0.388  1.0
  O  O37  1  0.392  0.458  0.650  1.0
  O  O38  1  0.608  0.542  0.350  1.0
  O  O39  1  0.368  0.936  0.651  1.0
  O  O40  1  0.734  0.894  0.693  1.0
  O  O41  1  0.106  0.561  0.612  1.0
  O  O42  1  0.770  0.616  0.546  1.0
  O  O43  1  0.683  0.261  0.605  1.0
[/CIF]
.