The structure described by Ca3Bi2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent O(4) and four equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), and three equivalent O(1) atoms. Bi(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 38-46°. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ca(2) and one Bi(1) atom to form distorted OCa3Bi tetrahedra that share corners with six equivalent O(1)Ca3Bi tetrahedra,  a cornercorner with one O(3)Ca3Bi2 trigonal bipyramid,  a cornercorner with one O(4)Ca2Bi2 trigonal pyramid, and edges with two equivalent O(3)Ca3Bi2 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(2) and two equivalent Bi(1) atoms. In the third O site, O(3) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Bi(1) atoms to form distorted OCa3Bi2 trigonal bipyramids that share  a cornercorner with one O(1)Ca3Bi tetrahedra, corners with two equivalent O(3)Ca3Bi2 trigonal bipyramids, corners with four equivalent O(4)Ca2Bi2 trigonal pyramids, edges with two equivalent O(1)Ca3Bi tetrahedra, edges with three equivalent O(3)Ca3Bi2 trigonal bipyramids, and  an edgeedge with one O(4)Ca2Bi2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form distorted OCa2Bi2 trigonal pyramids that share corners with two equivalent O(1)Ca3Bi tetrahedra, corners with eight equivalent O(3)Ca3Bi2 trigonal bipyramids, corners with two equivalent O(4)Ca2Bi2 trigonal pyramids, and edges with two equivalent O(3)Ca3Bi2 trigonal bipyramids. is represented by the CIF file [CIF]
data_Ca3Bi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.501
_cell_length_b   10.501
_cell_length_c   6.066
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   147.820
_symmetry_Int_Tables_number   1
_cell_volume   356.269
_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  0.230  0.230  0.306  1.0
  Ca  Ca1  1  0.770  0.770  0.806  1.0
  Ca  Ca2  1  0.045  0.436  0.182  1.0
  Ca  Ca3  1  0.955  0.564  0.682  1.0
  Ca  Ca4  1  0.436  0.045  0.182  1.0
  Ca  Ca5  1  0.564  0.955  0.682  1.0
  Bi  Bi6  1  0.849  0.642  0.249  1.0
  Bi  Bi7  1  0.151  0.358  0.749  1.0
  Bi  Bi8  1  0.358  0.151  0.749  1.0
  Bi  Bi9  1  0.642  0.849  0.249  1.0
  O  O10  1  0.665  0.074  0.306  1.0
  O  O11  1  0.335  0.926  0.806  1.0
  O  O12  1  0.926  0.335  0.806  1.0
  O  O13  1  0.074  0.665  0.306  1.0
  O  O14  1  0.420  0.691  0.952  1.0
  O  O15  1  0.580  0.309  0.452  1.0
  O  O16  1  0.309  0.580  0.452  1.0
  O  O17  1  0.691  0.420  0.952  1.0
  O  O18  1  0.983  0.137  0.059  1.0
  O  O19  1  0.017  0.863  0.559  1.0
  O  O20  1  0.611  0.611  0.177  1.0
  O  O21  1  0.389  0.389  0.677  1.0
  O  O22  1  0.137  0.983  0.059  1.0
  O  O23  1  0.863  0.017  0.559  1.0
[/CIF]
.
The structure described by Ca3Bi2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent O(4) and four equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), and three equivalent O(1) atoms. Bi(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles range from 38-46°. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ca(2) and one Bi(1) atom to form distorted OCa3Bi tetrahedra that share corners with six equivalent O(1)Ca3Bi tetrahedra,  a cornercorner with one O(3)Ca3Bi2 trigonal bipyramid,  a cornercorner with one O(4)Ca2Bi2 trigonal pyramid, and edges with two equivalent O(3)Ca3Bi2 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(2) and two equivalent Bi(1) atoms. In the third O site, O(3) is bonded to one Ca(2), two equivalent Ca(1), and two equivalent Bi(1) atoms to form distorted OCa3Bi2 trigonal bipyramids that share  a cornercorner with one O(1)Ca3Bi tetrahedra, corners with two equivalent O(3)Ca3Bi2 trigonal bipyramids, corners with four equivalent O(4)Ca2Bi2 trigonal pyramids, edges with two equivalent O(1)Ca3Bi tetrahedra, edges with three equivalent O(3)Ca3Bi2 trigonal bipyramids, and  an edgeedge with one O(4)Ca2Bi2 trigonal pyramid. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Bi(1) atoms to form distorted OCa2Bi2 trigonal pyramids that share corners with two equivalent O(1)Ca3Bi tetrahedra, corners with eight equivalent O(3)Ca3Bi2 trigonal bipyramids, corners with two equivalent O(4)Ca2Bi2 trigonal pyramids, and edges with two equivalent O(3)Ca3Bi2 trigonal bipyramids. is represented by the CIF file [CIF]
data_Ca3Bi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.501
_cell_length_b   10.501
_cell_length_c   6.066
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   147.820
_symmetry_Int_Tables_number   1
_cell_volume   356.269
_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  0.230  0.230  0.306  1.0
  Ca  Ca1  1  0.770  0.770  0.806  1.0
  Ca  Ca2  1  0.045  0.436  0.182  1.0
  Ca  Ca3  1  0.955  0.564  0.682  1.0
  Ca  Ca4  1  0.436  0.045  0.182  1.0
  Ca  Ca5  1  0.564  0.955  0.682  1.0
  Bi  Bi6  1  0.849  0.642  0.249  1.0
  Bi  Bi7  1  0.151  0.358  0.749  1.0
  Bi  Bi8  1  0.358  0.151  0.749  1.0
  Bi  Bi9  1  0.642  0.849  0.249  1.0
  O  O10  1  0.665  0.074  0.306  1.0
  O  O11  1  0.335  0.926  0.806  1.0
  O  O12  1  0.926  0.335  0.806  1.0
  O  O13  1  0.074  0.665  0.306  1.0
  O  O14  1  0.420  0.691  0.952  1.0
  O  O15  1  0.580  0.309  0.452  1.0
  O  O16  1  0.309  0.580  0.452  1.0
  O  O17  1  0.691  0.420  0.952  1.0
  O  O18  1  0.983  0.137  0.059  1.0
  O  O19  1  0.017  0.863  0.559  1.0
  O  O20  1  0.611  0.611  0.177  1.0
  O  O21  1  0.389  0.389  0.677  1.0
  O  O22  1  0.137  0.983  0.059  1.0
  O  O23  1  0.863  0.017  0.559  1.0
[/CIF]
.