The crystal structure described by Li2Fe3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form LiO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one Fe(2)O6 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), and one O(7) atom. In the second Fe site, Fe(2) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form distorted FeO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent Li(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-46°. 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  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Li(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 19°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Fe(1), one P(1), and one P(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Li(1), one Fe(2), and one P(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Fe(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(2), and one P(1) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2Fe3(P2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.743
_cell_length_b   7.663
_cell_length_c   10.958
_cell_angle_alpha   68.931
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   606.787
_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  0.599  0.240  0.237  1.0
  Li  Li1  1  0.401  0.760  0.763  1.0
  Li  Li2  1  0.901  0.240  0.737  1.0
  Li  Li3  1  0.099  0.760  0.263  1.0
  Fe  Fe4  1  0.799  0.494  0.457  1.0
  Fe  Fe5  1  0.201  0.506  0.543  1.0
  Fe  Fe6  1  0.299  0.506  0.043  1.0
  Fe  Fe7  1  0.701  0.494  0.957  1.0
  Fe  Fe8  1  0.000  0.000  0.000  1.0
  Fe  Fe9  1  0.500  0.000  0.500  1.0
  P  P10  1  0.267  0.136  0.715  1.0
  P  P11  1  0.733  0.864  0.285  1.0
  P  P12  1  0.551  0.453  0.699  1.0
  P  P13  1  0.449  0.547  0.301  1.0
  P  P14  1  0.051  0.547  0.801  1.0
  P  P15  1  0.233  0.136  0.215  1.0
  P  P16  1  0.949  0.453  0.199  1.0
  P  P17  1  0.767  0.864  0.785  1.0
  O  O18  1  0.426  0.613  0.153  1.0
  O  O19  1  0.109  0.332  0.174  1.0
  O  O20  1  0.992  0.347  0.868  1.0
  O  O21  1  0.713  0.400  0.636  1.0
  O  O22  1  0.241  0.046  0.860  1.0
  O  O23  1  0.787  0.400  0.136  1.0
  O  O24  1  0.137  0.014  0.153  1.0
  O  O25  1  0.213  0.600  0.864  1.0
  O  O26  1  0.508  0.347  0.368  1.0
  O  O27  1  0.363  0.014  0.653  1.0
  O  O28  1  0.759  0.954  0.140  1.0
  O  O29  1  0.259  0.046  0.360  1.0
  O  O30  1  0.893  0.766  0.366  1.0
  O  O31  1  0.926  0.387  0.347  1.0
  O  O32  1  0.609  0.668  0.326  1.0
  O  O33  1  0.637  0.986  0.347  1.0
  O  O34  1  0.074  0.613  0.653  1.0
  O  O35  1  0.607  0.766  0.866  1.0
  O  O36  1  0.391  0.332  0.674  1.0
  O  O37  1  0.287  0.600  0.364  1.0
  O  O38  1  0.574  0.387  0.847  1.0
  O  O39  1  0.393  0.234  0.134  1.0
  O  O40  1  0.863  0.986  0.847  1.0
  O  O41  1  0.741  0.954  0.640  1.0
  O  O42  1  0.891  0.668  0.826  1.0
  O  O43  1  0.008  0.653  0.132  1.0
  O  O44  1  0.107  0.234  0.634  1.0
  O  O45  1  0.492  0.653  0.632  1.0
[/CIF]
.
The crystal structure described by Li2Fe3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form LiO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one Fe(2)O6 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), and one O(7) atom. In the second Fe site, Fe(2) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form distorted FeO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and edges with two equivalent Li(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and corners with two equivalent Li(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-46°. 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  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and corners with two equivalent Li(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 19°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Fe(1), one P(1), and one P(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Li(1), one Fe(2), and one P(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Li(1), one Fe(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Fe(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Fe(2), and one P(1) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Li(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Li2Fe3(P2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.743
_cell_length_b   7.663
_cell_length_c   10.958
_cell_angle_alpha   68.931
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   606.787
_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  0.599  0.240  0.237  1.0
  Li  Li1  1  0.401  0.760  0.763  1.0
  Li  Li2  1  0.901  0.240  0.737  1.0
  Li  Li3  1  0.099  0.760  0.263  1.0
  Fe  Fe4  1  0.799  0.494  0.457  1.0
  Fe  Fe5  1  0.201  0.506  0.543  1.0
  Fe  Fe6  1  0.299  0.506  0.043  1.0
  Fe  Fe7  1  0.701  0.494  0.957  1.0
  Fe  Fe8  1  0.000  0.000  0.000  1.0
  Fe  Fe9  1  0.500  0.000  0.500  1.0
  P  P10  1  0.267  0.136  0.715  1.0
  P  P11  1  0.733  0.864  0.285  1.0
  P  P12  1  0.551  0.453  0.699  1.0
  P  P13  1  0.449  0.547  0.301  1.0
  P  P14  1  0.051  0.547  0.801  1.0
  P  P15  1  0.233  0.136  0.215  1.0
  P  P16  1  0.949  0.453  0.199  1.0
  P  P17  1  0.767  0.864  0.785  1.0
  O  O18  1  0.426  0.613  0.153  1.0
  O  O19  1  0.109  0.332  0.174  1.0
  O  O20  1  0.992  0.347  0.868  1.0
  O  O21  1  0.713  0.400  0.636  1.0
  O  O22  1  0.241  0.046  0.860  1.0
  O  O23  1  0.787  0.400  0.136  1.0
  O  O24  1  0.137  0.014  0.153  1.0
  O  O25  1  0.213  0.600  0.864  1.0
  O  O26  1  0.508  0.347  0.368  1.0
  O  O27  1  0.363  0.014  0.653  1.0
  O  O28  1  0.759  0.954  0.140  1.0
  O  O29  1  0.259  0.046  0.360  1.0
  O  O30  1  0.893  0.766  0.366  1.0
  O  O31  1  0.926  0.387  0.347  1.0
  O  O32  1  0.609  0.668  0.326  1.0
  O  O33  1  0.637  0.986  0.347  1.0
  O  O34  1  0.074  0.613  0.653  1.0
  O  O35  1  0.607  0.766  0.866  1.0
  O  O36  1  0.391  0.332  0.674  1.0
  O  O37  1  0.287  0.600  0.364  1.0
  O  O38  1  0.574  0.387  0.847  1.0
  O  O39  1  0.393  0.234  0.134  1.0
  O  O40  1  0.863  0.986  0.847  1.0
  O  O41  1  0.741  0.954  0.640  1.0
  O  O42  1  0.891  0.668  0.826  1.0
  O  O43  1  0.008  0.653  0.132  1.0
  O  O44  1  0.107  0.234  0.634  1.0
  O  O45  1  0.492  0.653  0.632  1.0
[/CIF]
.