The material described by Y2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, edges with two equivalent Y(4)O8 hexagonal bipyramids, edges with two equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, edges with two equivalent Y(4)O8 hexagonal bipyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. In the third Y site, Y(3) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(4)O8 hexagonal bipyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. In the fourth Y site, Y(4) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Cr(3)O6 octahedra. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, and edges with two equivalent Y(4)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. In the second Cr site, Cr(2) is bonded to two equivalent O(2), two equivalent O(6), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, and edges with two equivalent Y(4)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-49°. In the third Cr site, Cr(3) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, and edges with two equivalent Y(4)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-49°. In the fourth Cr site, Cr(4) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, and edges with two equivalent Y(3)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-49°. There are seven inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), one Y(3), and one Y(4) atom to form OY4 tetrahedra that share corners with two equivalent O(4)Y2Cr2 tetrahedra, corners with two equivalent O(5)Y2Cr2 tetrahedra, corners with two equivalent O(7)Y2Cr2 tetrahedra, corners with four equivalent O(1)Y4 tetrahedra,  an edgeedge with one O(4)Y2Cr2 tetrahedra,  an edgeedge with one O(5)Y2Cr2 tetrahedra, and  an edgeedge with one O(7)Y2Cr2 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(1), one Y(3), one Cr(2), and one Cr(4) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Y(2), one Y(4), one Cr(1), and one Cr(3) atom. In the fourth O site, O(4) is bonded to one Y(2), one Y(3), one Cr(1), and one Cr(4) atom to form distorted OY2Cr2 tetrahedra that share corners with two equivalent O(5)Y2Cr2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(4)Y2Cr2 tetrahedra,  an edgeedge with one O(5)Y2Cr2 tetrahedra, and  an edgeedge with one O(1)Y4 tetrahedra. In the fifth O site, O(5) is bonded to one Y(1), one Y(2), one Cr(3), and one Cr(4) atom to form distorted OY2Cr2 tetrahedra that share corners with two equivalent O(4)Y2Cr2 tetrahedra, corners with two equivalent O(7)Y2Cr2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(5)Y2Cr2 tetrahedra,  an edgeedge with one O(4)Y2Cr2 tetrahedra,  an edgeedge with one O(7)Y2Cr2 tetrahedra, and  an edgeedge with one O(1)Y4 tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Y(3), one Y(4), one Cr(1), and one Cr(2) atom. In the seventh O site, O(7) is bonded to one Y(1), one Y(4), one Cr(2), and one Cr(3) atom to form distorted OY2Cr2 tetrahedra that share corners with two equivalent O(5)Y2Cr2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(7)Y2Cr2 tetrahedra,  an edgeedge with one O(5)Y2Cr2 tetrahedra, and  an edgeedge with one O(1)Y4 tetrahedra. is represented by the CIF file [CIF]
data_Y2Cr2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.114
_cell_length_b   7.118
_cell_length_c   7.145
_cell_angle_alpha   60.111
_cell_angle_beta   60.228
_cell_angle_gamma   60.020
_symmetry_Int_Tables_number   1
_cell_volume   256.533
_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
  Y  Y0  1  0.500  1.000  0.500  1.0
  Y  Y1  1  1.000  0.500  0.500  1.0
  Y  Y2  1  0.500  0.500  0.000  1.0
  Y  Y3  1  0.500  0.500  0.500  1.0
  Cr  Cr4  1  0.000  0.500  0.000  1.0
  Cr  Cr5  1  0.500  0.000  0.000  1.0
  Cr  Cr6  1  1.000  0.000  0.500  1.0
  Cr  Cr7  1  1.000  0.000  0.000  1.0
  O  O8  1  0.625  0.624  0.627  1.0
  O  O9  1  0.375  0.376  0.373  1.0
  O  O10  1  0.326  0.929  0.914  1.0
  O  O11  1  0.082  0.665  0.678  1.0
  O  O12  1  0.918  0.328  0.924  1.0
  O  O13  1  0.926  0.913  0.334  1.0
  O  O14  1  0.334  0.323  0.923  1.0
  O  O15  1  0.327  0.918  0.333  1.0
  O  O16  1  0.918  0.335  0.322  1.0
  O  O17  1  0.665  0.677  0.077  1.0
  O  O18  1  0.074  0.087  0.666  1.0
  O  O19  1  0.674  0.071  0.086  1.0
  O  O20  1  0.673  0.082  0.667  1.0
  O  O21  1  0.082  0.672  0.076  1.0
[/CIF]
.
The material described by Y2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, edges with two equivalent Y(4)O8 hexagonal bipyramids, edges with two equivalent Cr(2)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, edges with two equivalent Y(4)O8 hexagonal bipyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. In the third Y site, Y(3) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(4)O8 hexagonal bipyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. In the fourth Y site, Y(4) is bonded to two equivalent O(1), two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Cr(3)O6 octahedra. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, edges with two equivalent Y(2)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, and edges with two equivalent Y(4)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. In the second Cr site, Cr(2) is bonded to two equivalent O(2), two equivalent O(6), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(3)O8 hexagonal bipyramids, and edges with two equivalent Y(4)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-49°. In the third Cr site, Cr(3) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(4)O6 octahedra, edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, and edges with two equivalent Y(4)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-49°. In the fourth Cr site, Cr(4) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form CrO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, corners with two equivalent Cr(3)O6 octahedra, edges with two equivalent Y(1)O8 hexagonal bipyramids, edges with two equivalent Y(2)O8 hexagonal bipyramids, and edges with two equivalent Y(3)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 48-49°. There are seven inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), one Y(3), and one Y(4) atom to form OY4 tetrahedra that share corners with two equivalent O(4)Y2Cr2 tetrahedra, corners with two equivalent O(5)Y2Cr2 tetrahedra, corners with two equivalent O(7)Y2Cr2 tetrahedra, corners with four equivalent O(1)Y4 tetrahedra,  an edgeedge with one O(4)Y2Cr2 tetrahedra,  an edgeedge with one O(5)Y2Cr2 tetrahedra, and  an edgeedge with one O(7)Y2Cr2 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(1), one Y(3), one Cr(2), and one Cr(4) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Y(2), one Y(4), one Cr(1), and one Cr(3) atom. In the fourth O site, O(4) is bonded to one Y(2), one Y(3), one Cr(1), and one Cr(4) atom to form distorted OY2Cr2 tetrahedra that share corners with two equivalent O(5)Y2Cr2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(4)Y2Cr2 tetrahedra,  an edgeedge with one O(5)Y2Cr2 tetrahedra, and  an edgeedge with one O(1)Y4 tetrahedra. In the fifth O site, O(5) is bonded to one Y(1), one Y(2), one Cr(3), and one Cr(4) atom to form distorted OY2Cr2 tetrahedra that share corners with two equivalent O(4)Y2Cr2 tetrahedra, corners with two equivalent O(7)Y2Cr2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(5)Y2Cr2 tetrahedra,  an edgeedge with one O(4)Y2Cr2 tetrahedra,  an edgeedge with one O(7)Y2Cr2 tetrahedra, and  an edgeedge with one O(1)Y4 tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Y(3), one Y(4), one Cr(1), and one Cr(2) atom. In the seventh O site, O(7) is bonded to one Y(1), one Y(4), one Cr(2), and one Cr(3) atom to form distorted OY2Cr2 tetrahedra that share corners with two equivalent O(5)Y2Cr2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(7)Y2Cr2 tetrahedra,  an edgeedge with one O(5)Y2Cr2 tetrahedra, and  an edgeedge with one O(1)Y4 tetrahedra. is represented by the CIF file [CIF]
data_Y2Cr2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.114
_cell_length_b   7.118
_cell_length_c   7.145
_cell_angle_alpha   60.111
_cell_angle_beta   60.228
_cell_angle_gamma   60.020
_symmetry_Int_Tables_number   1
_cell_volume   256.533
_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
  Y  Y0  1  0.500  1.000  0.500  1.0
  Y  Y1  1  1.000  0.500  0.500  1.0
  Y  Y2  1  0.500  0.500  0.000  1.0
  Y  Y3  1  0.500  0.500  0.500  1.0
  Cr  Cr4  1  0.000  0.500  0.000  1.0
  Cr  Cr5  1  0.500  0.000  0.000  1.0
  Cr  Cr6  1  1.000  0.000  0.500  1.0
  Cr  Cr7  1  1.000  0.000  0.000  1.0
  O  O8  1  0.625  0.624  0.627  1.0
  O  O9  1  0.375  0.376  0.373  1.0
  O  O10  1  0.326  0.929  0.914  1.0
  O  O11  1  0.082  0.665  0.678  1.0
  O  O12  1  0.918  0.328  0.924  1.0
  O  O13  1  0.926  0.913  0.334  1.0
  O  O14  1  0.334  0.323  0.923  1.0
  O  O15  1  0.327  0.918  0.333  1.0
  O  O16  1  0.918  0.335  0.322  1.0
  O  O17  1  0.665  0.677  0.077  1.0
  O  O18  1  0.074  0.087  0.666  1.0
  O  O19  1  0.674  0.071  0.086  1.0
  O  O20  1  0.673  0.082  0.667  1.0
  O  O21  1  0.082  0.672  0.076  1.0
[/CIF]
.