The crystal 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 to one O(3), one O(5), and two equivalent O(6) atoms to form distorted LiO4 trigonal pyramids that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three 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(1)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 65-75°. In the second Li site, Li(2) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form distorted LiO4 trigonal pyramids that share corners with four equivalent Ni(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  a cornercorner with one Li(1)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 55-74°. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, corners with four equivalent Li(2)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent Li(2)O4 trigonal pyramids, and corners with three equivalent Li(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 30-60°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one Li(1)O4 trigonal pyramid, and corners with two equivalent Li(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 48-56°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(2), one Ni(1), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(2), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Ni(1), and one P(1) atom to form a mixture of distorted edge and corner-sharing OLi2NiP tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Li(1), one Ni(1), and one P(1) atom to form a mixture of distorted edge and corner-sharing OLi2NiP trigonal pyramids. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Li(2), one Ni(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2NiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.032
_cell_length_b   6.877
_cell_length_c   8.248
_cell_angle_alpha   66.945
_cell_angle_beta   89.022
_cell_angle_gamma   89.986
_symmetry_Int_Tables_number   1
_cell_volume   262.611
_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  0.711  0.160  0.003  1.0
  Li  Li1  1  0.289  0.840  0.997  1.0
  Li  Li2  1  0.237  0.814  0.566  1.0
  Li  Li3  1  0.763  0.186  0.434  1.0
  Ni  Ni4  1  0.227  0.231  0.721  1.0
  Ni  Ni5  1  0.773  0.769  0.279  1.0
  O  O6  1  0.722  0.637  0.846  1.0
  O  O7  1  0.278  0.363  0.154  1.0
  O  O8  1  0.579  0.482  0.336  1.0
  O  O9  1  0.421  0.518  0.664  1.0
  O  O10  1  0.136  0.666  0.223  1.0
  O  O11  1  0.864  0.334  0.777  1.0
  O  O12  1  0.863  0.709  0.533  1.0
  O  O13  1  0.137  0.291  0.467  1.0
  O  O14  1  0.072  0.922  0.782  1.0
  O  O15  1  0.928  0.078  0.218  1.0
  O  O16  1  0.692  0.869  0.007  1.0
  O  O17  1  0.308  0.131  0.993  1.0
  O  O18  1  0.593  0.025  0.679  1.0
  O  O19  1  0.407  0.975  0.321  1.0
  P  P20  1  0.772  0.878  0.824  1.0
  P  P21  1  0.228  0.122  0.176  1.0
  P  P22  1  0.282  0.456  0.308  1.0
  P  P23  1  0.718  0.544  0.692  1.0
[/CIF]
.
The crystal 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 to one O(3), one O(5), and two equivalent O(6) atoms to form distorted LiO4 trigonal pyramids that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three 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(1)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 65-75°. In the second Li site, Li(2) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form distorted LiO4 trigonal pyramids that share corners with four equivalent Ni(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  a cornercorner with one Li(1)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 55-74°. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, corners with four equivalent Li(2)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with two equivalent Li(2)O4 trigonal pyramids, and corners with three equivalent Li(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 30-60°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one Li(1)O4 trigonal pyramid, and corners with two equivalent Li(2)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 48-56°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Li(2), one Ni(1), and one P(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(2), one Ni(1), and one P(2) atom. In the fifth O site, O(5) is bonded to one Li(1), one Li(2), one Ni(1), and one P(1) atom to form a mixture of distorted edge and corner-sharing OLi2NiP tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Li(1), one Ni(1), and one P(1) atom to form a mixture of distorted edge and corner-sharing OLi2NiP trigonal pyramids. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Li(2), one Ni(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2NiP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.032
_cell_length_b   6.877
_cell_length_c   8.248
_cell_angle_alpha   66.945
_cell_angle_beta   89.022
_cell_angle_gamma   89.986
_symmetry_Int_Tables_number   1
_cell_volume   262.611
_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  0.711  0.160  0.003  1.0
  Li  Li1  1  0.289  0.840  0.997  1.0
  Li  Li2  1  0.237  0.814  0.566  1.0
  Li  Li3  1  0.763  0.186  0.434  1.0
  Ni  Ni4  1  0.227  0.231  0.721  1.0
  Ni  Ni5  1  0.773  0.769  0.279  1.0
  O  O6  1  0.722  0.637  0.846  1.0
  O  O7  1  0.278  0.363  0.154  1.0
  O  O8  1  0.579  0.482  0.336  1.0
  O  O9  1  0.421  0.518  0.664  1.0
  O  O10  1  0.136  0.666  0.223  1.0
  O  O11  1  0.864  0.334  0.777  1.0
  O  O12  1  0.863  0.709  0.533  1.0
  O  O13  1  0.137  0.291  0.467  1.0
  O  O14  1  0.072  0.922  0.782  1.0
  O  O15  1  0.928  0.078  0.218  1.0
  O  O16  1  0.692  0.869  0.007  1.0
  O  O17  1  0.308  0.131  0.993  1.0
  O  O18  1  0.593  0.025  0.679  1.0
  O  O19  1  0.407  0.975  0.321  1.0
  P  P20  1  0.772  0.878  0.824  1.0
  P  P21  1  0.228  0.122  0.176  1.0
  P  P22  1  0.282  0.456  0.308  1.0
  P  P23  1  0.718  0.544  0.692  1.0
[/CIF]
.