The structure described by Li2FeP2O7 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 4-coordinate geometry to one O(3), one O(6), and two equivalent O(5) atoms. In the second Li site, Li(2) is bonded to one O(1), one O(7), and two equivalent O(2) atoms to form distorted LiO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent P(2)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Li(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 73-78°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with four equivalent Li(2)O4 tetrahedra, corners with six equivalent P(2)O4 tetrahedra, and edges with two equivalent Li(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-55°. In the second P site, P(2) 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 Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with four equivalent Li(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-56°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(2), and one P(2) atom. In the second O site, O(2) is bonded to two equivalent Li(2), one Fe(2), and one P(2) atom to form a mixture of distorted corner and edge-sharing OLi2FeP tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded to two equivalent Li(1), one Fe(1), and one P(1) atom to form a mixture of distorted corner and edge-sharing OLi2FeP tetrahedra. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(2), and one P(2) atom. is represented by the CIF card [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.041
_cell_length_b   5.139
_cell_length_c   13.319
_cell_angle_alpha   88.476
_cell_angle_beta   100.797
_cell_angle_gamma   60.613
_symmetry_Int_Tables_number   1
_cell_volume   292.498
_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  0.208  0.872  0.408  1.0
  Li  Li1  1  0.669  0.627  0.092  1.0
  Li  Li2  1  0.331  0.373  0.908  1.0
  Li  Li3  1  0.792  0.128  0.592  1.0
  Fe  Fe4  1  0.000  0.500  0.500  1.0
  Fe  Fe5  1  1.000  1.000  0.000  1.0
  P  P6  1  0.467  0.780  0.632  1.0
  P  P7  1  0.618  0.721  0.868  1.0
  P  P8  1  0.382  0.279  0.132  1.0
  P  P9  1  0.533  0.221  0.368  1.0
  O  O10  1  0.669  0.991  0.880  1.0
  O  O11  1  0.377  0.735  0.927  1.0
  O  O12  1  0.562  0.916  0.397  1.0
  O  O13  1  0.447  0.749  0.750  1.0
  O  O14  1  0.181  0.767  0.574  1.0
  O  O15  1  0.776  0.510  0.619  1.0
  O  O16  1  0.078  0.584  0.103  1.0
  O  O17  1  0.922  0.416  0.897  1.0
  O  O18  1  0.224  0.490  0.381  1.0
  O  O19  1  0.819  0.233  0.426  1.0
  O  O20  1  0.553  0.251  0.250  1.0
  O  O21  1  0.438  0.084  0.603  1.0
  O  O22  1  0.623  0.265  0.073  1.0
  O  O23  1  0.331  0.009  0.120  1.0
[/CIF]
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The structure described by Li2FeP2O7 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 4-coordinate geometry to one O(3), one O(6), and two equivalent O(5) atoms. In the second Li site, Li(2) is bonded to one O(1), one O(7), and two equivalent O(2) atoms to form distorted LiO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent P(2)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Li(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 73-78°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with four equivalent Li(2)O4 tetrahedra, corners with six equivalent P(2)O4 tetrahedra, and edges with two equivalent Li(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-55°. In the second P site, P(2) 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 Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with four equivalent Li(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-56°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(2), and one P(2) atom. In the second O site, O(2) is bonded to two equivalent Li(2), one Fe(2), and one P(2) atom to form a mixture of distorted corner and edge-sharing OLi2FeP tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded to two equivalent Li(1), one Fe(1), and one P(1) atom to form a mixture of distorted corner and edge-sharing OLi2FeP tetrahedra. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(2), one Fe(2), and one P(2) atom. is represented by the CIF card [CIF]
data_Li2FeP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.041
_cell_length_b   5.139
_cell_length_c   13.319
_cell_angle_alpha   88.476
_cell_angle_beta   100.797
_cell_angle_gamma   60.613
_symmetry_Int_Tables_number   1
_cell_volume   292.498
_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  0.208  0.872  0.408  1.0
  Li  Li1  1  0.669  0.627  0.092  1.0
  Li  Li2  1  0.331  0.373  0.908  1.0
  Li  Li3  1  0.792  0.128  0.592  1.0
  Fe  Fe4  1  0.000  0.500  0.500  1.0
  Fe  Fe5  1  1.000  1.000  0.000  1.0
  P  P6  1  0.467  0.780  0.632  1.0
  P  P7  1  0.618  0.721  0.868  1.0
  P  P8  1  0.382  0.279  0.132  1.0
  P  P9  1  0.533  0.221  0.368  1.0
  O  O10  1  0.669  0.991  0.880  1.0
  O  O11  1  0.377  0.735  0.927  1.0
  O  O12  1  0.562  0.916  0.397  1.0
  O  O13  1  0.447  0.749  0.750  1.0
  O  O14  1  0.181  0.767  0.574  1.0
  O  O15  1  0.776  0.510  0.619  1.0
  O  O16  1  0.078  0.584  0.103  1.0
  O  O17  1  0.922  0.416  0.897  1.0
  O  O18  1  0.224  0.490  0.381  1.0
  O  O19  1  0.819  0.233  0.426  1.0
  O  O20  1  0.553  0.251  0.250  1.0
  O  O21  1  0.438  0.084  0.603  1.0
  O  O22  1  0.623  0.265  0.073  1.0
  O  O23  1  0.331  0.009  0.120  1.0
[/CIF]
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