The material structure described by CaCr3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and  an edgeedge with one Cr(2)O6 octahedra. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra, corners with three equivalent Cr(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-60°. In the second P site, P(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with three equivalent Cr(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-63°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one Ca(1), one Cr(1), and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one P(2) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Cr(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cr(2), and one P(2) atom. In the fifth O site, O(2) is bonded to one Ca(1), one Cr(1), one Cr(2), and one P(1) atom to form distorted corner-sharing OCaCr2P tetrahedra. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Cr(1), and one P(1) atom. In the seventh O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. is represented by the CIF file [CIF]
data_CaCr3(P2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.995
_cell_length_b   7.550
_cell_length_c   9.562
_cell_angle_alpha   69.966
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   542.289
_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
  Ca  Ca0  1  0.000  0.500  0.000  1.0
  Ca  Ca1  1  0.500  0.500  0.500  1.0
  Cr  Cr2  1  0.130  0.810  0.523  1.0
  Cr  Cr3  1  0.630  0.190  0.977  1.0
  Cr  Cr4  1  0.870  0.190  0.477  1.0
  Cr  Cr5  1  0.370  0.810  0.023  1.0
  Cr  Cr6  1  0.000  0.000  0.000  1.0
  Cr  Cr7  1  0.500  0.000  0.500  1.0
  P  P8  1  0.943  0.405  0.703  1.0
  P  P9  1  0.443  0.595  0.797  1.0
  P  P10  1  0.057  0.595  0.297  1.0
  P  P11  1  0.557  0.405  0.203  1.0
  P  P12  1  0.205  0.117  0.693  1.0
  P  P13  1  0.705  0.883  0.807  1.0
  P  P14  1  0.795  0.883  0.307  1.0
  P  P15  1  0.295  0.117  0.193  1.0
  O  O16  1  0.373  0.170  0.613  1.0
  O  O17  1  0.873  0.830  0.887  1.0
  O  O18  1  0.627  0.830  0.387  1.0
  O  O19  1  0.127  0.170  0.113  1.0
  O  O20  1  0.395  0.703  0.633  1.0
  O  O21  1  0.895  0.297  0.867  1.0
  O  O22  1  0.605  0.297  0.367  1.0
  O  O23  1  0.105  0.703  0.133  1.0
  O  O24  1  0.817  0.377  0.592  1.0
  O  O25  1  0.317  0.623  0.908  1.0
  O  O26  1  0.183  0.623  0.408  1.0
  O  O27  1  0.683  0.377  0.092  1.0
  O  O28  1  0.120  0.318  0.674  1.0
  O  O29  1  0.620  0.682  0.826  1.0
  O  O30  1  0.880  0.682  0.326  1.0
  O  O31  1  0.380  0.318  0.174  1.0
  O  O32  1  0.513  0.607  0.188  1.0
  O  O33  1  0.013  0.393  0.312  1.0
  O  O34  1  0.487  0.393  0.812  1.0
  O  O35  1  0.987  0.607  0.688  1.0
  O  O36  1  0.788  0.986  0.136  1.0
  O  O37  1  0.288  0.014  0.364  1.0
  O  O38  1  0.212  0.014  0.864  1.0
  O  O39  1  0.712  0.986  0.636  1.0
  O  O40  1  0.410  0.015  0.119  1.0
  O  O41  1  0.910  0.985  0.381  1.0
  O  O42  1  0.590  0.985  0.881  1.0
  O  O43  1  0.090  0.015  0.619  1.0
[/CIF]
.
The material structure described by CaCr3(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Cr(1)O6 octahedra, and  an edgeedge with one Cr(2)O6 octahedra. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Cr(2)O6 octahedra, corners with three equivalent Cr(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-60°. In the second P site, P(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with three equivalent Cr(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-63°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one Ca(1), one Cr(1), and one P(1) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Cr(1), one Cr(2), and one P(2) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Cr(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Cr(2), and one P(2) atom. In the fifth O site, O(2) is bonded to one Ca(1), one Cr(1), one Cr(2), and one P(1) atom to form distorted corner-sharing OCaCr2P tetrahedra. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one Cr(1), and one P(1) atom. In the seventh O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. is represented by the CIF file [CIF]
data_CaCr3(P2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.995
_cell_length_b   7.550
_cell_length_c   9.562
_cell_angle_alpha   69.966
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   542.289
_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
  Ca  Ca0  1  0.000  0.500  0.000  1.0
  Ca  Ca1  1  0.500  0.500  0.500  1.0
  Cr  Cr2  1  0.130  0.810  0.523  1.0
  Cr  Cr3  1  0.630  0.190  0.977  1.0
  Cr  Cr4  1  0.870  0.190  0.477  1.0
  Cr  Cr5  1  0.370  0.810  0.023  1.0
  Cr  Cr6  1  0.000  0.000  0.000  1.0
  Cr  Cr7  1  0.500  0.000  0.500  1.0
  P  P8  1  0.943  0.405  0.703  1.0
  P  P9  1  0.443  0.595  0.797  1.0
  P  P10  1  0.057  0.595  0.297  1.0
  P  P11  1  0.557  0.405  0.203  1.0
  P  P12  1  0.205  0.117  0.693  1.0
  P  P13  1  0.705  0.883  0.807  1.0
  P  P14  1  0.795  0.883  0.307  1.0
  P  P15  1  0.295  0.117  0.193  1.0
  O  O16  1  0.373  0.170  0.613  1.0
  O  O17  1  0.873  0.830  0.887  1.0
  O  O18  1  0.627  0.830  0.387  1.0
  O  O19  1  0.127  0.170  0.113  1.0
  O  O20  1  0.395  0.703  0.633  1.0
  O  O21  1  0.895  0.297  0.867  1.0
  O  O22  1  0.605  0.297  0.367  1.0
  O  O23  1  0.105  0.703  0.133  1.0
  O  O24  1  0.817  0.377  0.592  1.0
  O  O25  1  0.317  0.623  0.908  1.0
  O  O26  1  0.183  0.623  0.408  1.0
  O  O27  1  0.683  0.377  0.092  1.0
  O  O28  1  0.120  0.318  0.674  1.0
  O  O29  1  0.620  0.682  0.826  1.0
  O  O30  1  0.880  0.682  0.326  1.0
  O  O31  1  0.380  0.318  0.174  1.0
  O  O32  1  0.513  0.607  0.188  1.0
  O  O33  1  0.013  0.393  0.312  1.0
  O  O34  1  0.487  0.393  0.812  1.0
  O  O35  1  0.987  0.607  0.688  1.0
  O  O36  1  0.788  0.986  0.136  1.0
  O  O37  1  0.288  0.014  0.364  1.0
  O  O38  1  0.212  0.014  0.864  1.0
  O  O39  1  0.712  0.986  0.636  1.0
  O  O40  1  0.410  0.015  0.119  1.0
  O  O41  1  0.910  0.985  0.381  1.0
  O  O42  1  0.590  0.985  0.881  1.0
  O  O43  1  0.090  0.015  0.619  1.0
[/CIF]
.