The structure 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 5-coordinate geometry to one O(3), one O(4), one O(7), and two equivalent O(5) atoms. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form distorted LiO5 trigonal bipyramids that share corners with two equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Ni(1)O5 square pyramid, and  an edgeedge with one P(1)O4 tetrahedra. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(7) atom to form NiO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Li(2)O5 trigonal bipyramids, and  an edgeedge with one Li(2)O5 trigonal bipyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Li(2)O5 trigonal bipyramid, and  an edgeedge with one Li(2)O5 trigonal bipyramid. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Li(2)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Li(2), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(2), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Ni(1), and one P(1) atom to form a mixture of corner and edge-sharing OLi2NiP trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded to one Li(2), two equivalent Li(1), and one P(2) atom to form OLi3P trigonal pyramids that share  a cornercorner with one O(3)Li2NiP trigonal pyramid,  an edgeedge with one O(3)Li2NiP trigonal pyramid, and  an edgeedge with one O(5)Li3P trigonal pyramid. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Ni(1), and one P(2) atom. is represented by the CIF card [CIF]
data_Li2NiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.114
_cell_length_b   7.024
_cell_length_c   8.701
_cell_angle_alpha   101.481
_cell_angle_beta   106.718
_cell_angle_gamma   109.759
_symmetry_Int_Tables_number   1
_cell_volume   266.027
_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  0.914  0.689  0.008  1.0
  Li  Li1  1  0.085  0.311  0.992  1.0
  Li  Li2  1  0.439  0.115  0.755  1.0
  Li  Li3  1  0.561  0.885  0.245  1.0
  Ni  Ni4  1  0.186  0.175  0.333  1.0
  Ni  Ni5  1  0.814  0.825  0.667  1.0
  O  O6  1  0.463  0.735  0.443  1.0
  O  O7  1  0.537  0.265  0.557  1.0
  O  O8  1  0.107  0.853  0.547  1.0
  O  O9  1  0.893  0.147  0.453  1.0
  O  O10  1  0.118  0.857  0.257  1.0
  O  O11  1  0.882  0.143  0.743  1.0
  O  O12  1  0.628  0.752  0.839  1.0
  O  O13  1  0.372  0.248  0.161  1.0
  O  O14  1  0.687  0.375  0.988  1.0
  O  O15  1  0.314  0.625  0.012  1.0
  O  O16  1  0.905  0.507  0.315  1.0
  O  O17  1  0.095  0.493  0.685  1.0
  O  O18  1  0.203  0.867  0.854  1.0
  O  O19  1  0.797  0.133  0.146  1.0
  P  P20  1  0.158  0.748  0.397  1.0
  P  P21  1  0.842  0.252  0.603  1.0
  P  P22  1  0.676  0.305  0.143  1.0
  P  P23  1  0.324  0.695  0.857  1.0
[/CIF]
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The structure 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 5-coordinate geometry to one O(3), one O(4), one O(7), and two equivalent O(5) atoms. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form distorted LiO5 trigonal bipyramids that share corners with two equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Ni(1)O5 square pyramid, and  an edgeedge with one P(1)O4 tetrahedra. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(7) atom to form NiO5 square pyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Li(2)O5 trigonal bipyramids, and  an edgeedge with one Li(2)O5 trigonal bipyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one Li(2)O5 trigonal bipyramid, and  an edgeedge with one Li(2)O5 trigonal bipyramid. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Li(2)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Li(2), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(2), one Ni(1), and one P(1) atom. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Ni(1), and one P(1) atom to form a mixture of corner and edge-sharing OLi2NiP trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded to one Li(2), two equivalent Li(1), and one P(2) atom to form OLi3P trigonal pyramids that share  a cornercorner with one O(3)Li2NiP trigonal pyramid,  an edgeedge with one O(3)Li2NiP trigonal pyramid, and  an edgeedge with one O(5)Li3P trigonal pyramid. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Li(1), one Li(2), one Ni(1), and one P(2) atom. is represented by the CIF card [CIF]
data_Li2NiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.114
_cell_length_b   7.024
_cell_length_c   8.701
_cell_angle_alpha   101.481
_cell_angle_beta   106.718
_cell_angle_gamma   109.759
_symmetry_Int_Tables_number   1
_cell_volume   266.027
_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  0.914  0.689  0.008  1.0
  Li  Li1  1  0.085  0.311  0.992  1.0
  Li  Li2  1  0.439  0.115  0.755  1.0
  Li  Li3  1  0.561  0.885  0.245  1.0
  Ni  Ni4  1  0.186  0.175  0.333  1.0
  Ni  Ni5  1  0.814  0.825  0.667  1.0
  O  O6  1  0.463  0.735  0.443  1.0
  O  O7  1  0.537  0.265  0.557  1.0
  O  O8  1  0.107  0.853  0.547  1.0
  O  O9  1  0.893  0.147  0.453  1.0
  O  O10  1  0.118  0.857  0.257  1.0
  O  O11  1  0.882  0.143  0.743  1.0
  O  O12  1  0.628  0.752  0.839  1.0
  O  O13  1  0.372  0.248  0.161  1.0
  O  O14  1  0.687  0.375  0.988  1.0
  O  O15  1  0.314  0.625  0.012  1.0
  O  O16  1  0.905  0.507  0.315  1.0
  O  O17  1  0.095  0.493  0.685  1.0
  O  O18  1  0.203  0.867  0.854  1.0
  O  O19  1  0.797  0.133  0.146  1.0
  P  P20  1  0.158  0.748  0.397  1.0
  P  P21  1  0.842  0.252  0.603  1.0
  P  P22  1  0.676  0.305  0.143  1.0
  P  P23  1  0.324  0.695  0.857  1.0
[/CIF]
.