The material described by Li2NiP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(7), and two equivalent O(4) atoms. In the second Li site, Li(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form distorted LiO4 trigonal pyramids that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 78°. Ni(1) is bonded to one O(1), one O(3), one O(4), one O(6), and two equivalent O(2) atoms to form NiO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra,  a cornercorner with one Li(2)O4 trigonal pyramid,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Li(2)O4 trigonal pyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with four equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 23-55°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Li(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 17-59°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Li(2), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Li(1), one Li(2), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Li(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Li(1), one Li(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Li(2), one Ni(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one P(1), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2NiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.218
_cell_length_b   6.548
_cell_length_c   8.702
_cell_angle_alpha   111.112
_cell_angle_beta   97.342
_cell_angle_gamma   104.530
_symmetry_Int_Tables_number   1
_cell_volume   260.557
_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
  Li  Li0  1  0.188  0.712  0.034  1.0
  Li  Li1  1  0.321  0.207  0.724  1.0
  Li  Li2  1  0.679  0.792  0.276  1.0
  Li  Li3  1  0.812  0.289  0.967  1.0
  Ni  Ni4  1  0.094  0.598  0.369  1.0
  Ni  Ni5  1  0.907  0.402  0.631  1.0
  P  P6  1  0.235  0.144  0.375  1.0
  P  P7  1  0.596  0.684  0.885  1.0
  P  P8  1  0.404  0.316  0.115  1.0
  P  P9  1  0.765  0.855  0.625  1.0
  O  O10  1  0.077  0.891  0.329  1.0
  O  O11  1  0.050  0.300  0.412  1.0
  O  O12  1  0.307  0.529  0.785  1.0
  O  O13  1  0.196  0.454  0.133  1.0
  O  O14  1  0.399  0.175  0.934  1.0
  O  O15  1  0.507  0.764  0.486  1.0
  O  O16  1  0.699  0.872  0.806  1.0
  O  O17  1  0.301  0.128  0.194  1.0
  O  O18  1  0.494  0.236  0.514  1.0
  O  O19  1  0.600  0.825  0.066  1.0
  O  O20  1  0.804  0.547  0.868  1.0
  O  O21  1  0.693  0.471  0.215  1.0
  O  O22  1  0.950  0.701  0.589  1.0
  O  O23  1  0.923  0.109  0.671  1.0
[/CIF]
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The material described by Li2NiP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(7), and two equivalent O(4) atoms. In the second Li site, Li(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form distorted LiO4 trigonal pyramids that share  a cornercorner with one Ni(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 78°. Ni(1) is bonded to one O(1), one O(3), one O(4), one O(6), and two equivalent O(2) atoms to form NiO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra,  a cornercorner with one Li(2)O4 trigonal pyramid,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Li(2)O4 trigonal pyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with four equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 23-55°. In the second P site, P(2) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Li(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 17-59°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Li(2), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to one Li(1), one Li(2), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Li(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Li(1), one Li(2), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Li(2), one Ni(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one P(1), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2NiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.218
_cell_length_b   6.548
_cell_length_c   8.702
_cell_angle_alpha   111.112
_cell_angle_beta   97.342
_cell_angle_gamma   104.530
_symmetry_Int_Tables_number   1
_cell_volume   260.557
_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
  Li  Li0  1  0.188  0.712  0.034  1.0
  Li  Li1  1  0.321  0.207  0.724  1.0
  Li  Li2  1  0.679  0.792  0.276  1.0
  Li  Li3  1  0.812  0.289  0.967  1.0
  Ni  Ni4  1  0.094  0.598  0.369  1.0
  Ni  Ni5  1  0.907  0.402  0.631  1.0
  P  P6  1  0.235  0.144  0.375  1.0
  P  P7  1  0.596  0.684  0.885  1.0
  P  P8  1  0.404  0.316  0.115  1.0
  P  P9  1  0.765  0.855  0.625  1.0
  O  O10  1  0.077  0.891  0.329  1.0
  O  O11  1  0.050  0.300  0.412  1.0
  O  O12  1  0.307  0.529  0.785  1.0
  O  O13  1  0.196  0.454  0.133  1.0
  O  O14  1  0.399  0.175  0.934  1.0
  O  O15  1  0.507  0.764  0.486  1.0
  O  O16  1  0.699  0.872  0.806  1.0
  O  O17  1  0.301  0.128  0.194  1.0
  O  O18  1  0.494  0.236  0.514  1.0
  O  O19  1  0.600  0.825  0.066  1.0
  O  O20  1  0.804  0.547  0.868  1.0
  O  O21  1  0.693  0.471  0.215  1.0
  O  O22  1  0.950  0.701  0.589  1.0
  O  O23  1  0.923  0.109  0.671  1.0
[/CIF]
.