The structure described by Ca2V2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(3), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded to one O(1), one O(4), one O(5), one O(6), one O(7), and two equivalent O(2) atoms to form distorted CaO7 pentagonal bipyramids that share corners with four equivalent V(2)O4 tetrahedra, corners with three equivalent V(1)O5 trigonal bipyramids,  an edgeedge with one Ca(2)O7 pentagonal bipyramid, and  an edgeedge with one V(1)O5 trigonal bipyramid. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(4), one O(5), and two equivalent O(6) atoms to form distorted VO5 trigonal bipyramids that share corners with three equivalent Ca(2)O7 pentagonal bipyramids,  a cornercorner with one V(2)O4 tetrahedra,  an edgeedge with one Ca(2)O7 pentagonal bipyramid, and  an edgeedge with one V(1)O5 trigonal bipyramid. In the second V site, V(2) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form VO4 tetrahedra that share corners with four equivalent Ca(2)O7 pentagonal bipyramids and  a cornercorner with one V(1)O5 trigonal bipyramid. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one V(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one V(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one V(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one V(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(2), one V(1), and one V(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(2) and two equivalent V(1) atoms. In the seventh O site, O(7) is bonded to one Ca(2), two equivalent Ca(1), and one V(2) atom to form distorted edge-sharing OCa3V tetrahedra. is represented by the CIF file [CIF]
data_Ca2V2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.677
_cell_length_b   6.960
_cell_length_c   7.036
_cell_angle_alpha   85.816
_cell_angle_beta   63.848
_cell_angle_gamma   82.725
_symmetry_Int_Tables_number   1
_cell_volume   291.092
_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  0.264  0.552  0.262  1.0
  Ca  Ca1  1  0.736  0.448  0.738  1.0
  Ca  Ca2  1  0.744  0.841  0.330  1.0
  Ca  Ca3  1  0.256  0.159  0.670  1.0
  V  V4  1  0.725  0.949  0.845  1.0
  V  V5  1  0.275  0.051  0.155  1.0
  V  V6  1  0.198  0.667  0.766  1.0
  V  V7  1  0.802  0.333  0.234  1.0
  O  O8  1  0.754  0.785  0.671  1.0
  O  O9  1  0.246  0.215  0.329  1.0
  O  O10  1  0.360  0.820  0.578  1.0
  O  O11  1  0.640  0.180  0.422  1.0
  O  O12  1  0.345  0.554  0.897  1.0
  O  O13  1  0.655  0.446  0.103  1.0
  O  O14  1  0.889  0.130  0.738  1.0
  O  O15  1  0.111  0.870  0.262  1.0
  O  O16  1  0.049  0.200  0.063  1.0
  O  O17  1  0.951  0.800  0.937  1.0
  O  O18  1  0.462  0.097  0.870  1.0
  O  O19  1  0.136  0.494  0.639  1.0
  O  O20  1  0.864  0.506  0.361  1.0
  O  O21  1  0.538  0.903  0.130  1.0
[/CIF]
.
The structure described by Ca2V2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(3), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded to one O(1), one O(4), one O(5), one O(6), one O(7), and two equivalent O(2) atoms to form distorted CaO7 pentagonal bipyramids that share corners with four equivalent V(2)O4 tetrahedra, corners with three equivalent V(1)O5 trigonal bipyramids,  an edgeedge with one Ca(2)O7 pentagonal bipyramid, and  an edgeedge with one V(1)O5 trigonal bipyramid. There are two inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(4), one O(5), and two equivalent O(6) atoms to form distorted VO5 trigonal bipyramids that share corners with three equivalent Ca(2)O7 pentagonal bipyramids,  a cornercorner with one V(2)O4 tetrahedra,  an edgeedge with one Ca(2)O7 pentagonal bipyramid, and  an edgeedge with one V(1)O5 trigonal bipyramid. In the second V site, V(2) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form VO4 tetrahedra that share corners with four equivalent Ca(2)O7 pentagonal bipyramids and  a cornercorner with one V(1)O5 trigonal bipyramid. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one V(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one V(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one V(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one V(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(2), one V(1), and one V(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(2) and two equivalent V(1) atoms. In the seventh O site, O(7) is bonded to one Ca(2), two equivalent Ca(1), and one V(2) atom to form distorted edge-sharing OCa3V tetrahedra. is represented by the CIF file [CIF]
data_Ca2V2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.677
_cell_length_b   6.960
_cell_length_c   7.036
_cell_angle_alpha   85.816
_cell_angle_beta   63.848
_cell_angle_gamma   82.725
_symmetry_Int_Tables_number   1
_cell_volume   291.092
_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  0.264  0.552  0.262  1.0
  Ca  Ca1  1  0.736  0.448  0.738  1.0
  Ca  Ca2  1  0.744  0.841  0.330  1.0
  Ca  Ca3  1  0.256  0.159  0.670  1.0
  V  V4  1  0.725  0.949  0.845  1.0
  V  V5  1  0.275  0.051  0.155  1.0
  V  V6  1  0.198  0.667  0.766  1.0
  V  V7  1  0.802  0.333  0.234  1.0
  O  O8  1  0.754  0.785  0.671  1.0
  O  O9  1  0.246  0.215  0.329  1.0
  O  O10  1  0.360  0.820  0.578  1.0
  O  O11  1  0.640  0.180  0.422  1.0
  O  O12  1  0.345  0.554  0.897  1.0
  O  O13  1  0.655  0.446  0.103  1.0
  O  O14  1  0.889  0.130  0.738  1.0
  O  O15  1  0.111  0.870  0.262  1.0
  O  O16  1  0.049  0.200  0.063  1.0
  O  O17  1  0.951  0.800  0.937  1.0
  O  O18  1  0.462  0.097  0.870  1.0
  O  O19  1  0.136  0.494  0.639  1.0
  O  O20  1  0.864  0.506  0.361  1.0
  O  O21  1  0.538  0.903  0.130  1.0
[/CIF]
.