The structure described by CaBi2O4 is Spinel-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(3) and three equivalent O(4) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. In the second Ca site, Ca(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, and edges with six equivalent Bi(2)O6 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2) and three equivalent O(1) atoms to form BiO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-58°. In the second Bi site, Bi(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with four equivalent Bi(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Ca(2), one Bi(1), and two equivalent Bi(2) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Bi(1) and three equivalent Bi(2) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1) and three equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), and two equivalent Bi(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca(BiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.055
_cell_length_b   7.055
_cell_length_c   7.055
_cell_angle_alpha   59.921
_cell_angle_beta   59.921
_cell_angle_gamma   59.921
_symmetry_Int_Tables_number   1
_cell_volume   247.886
_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  0.002  0.002  0.002  1.0
  Ca  Ca1  1  0.625  0.625  0.625  1.0
  Bi  Bi2  1  0.248  0.248  0.248  1.0
  Bi  Bi3  1  0.626  0.118  0.626  1.0
  Bi  Bi4  1  0.626  0.626  0.118  1.0
  Bi  Bi5  1  0.118  0.626  0.626  1.0
  O  O6  1  0.854  0.383  0.383  1.0
  O  O7  1  0.383  0.383  0.854  1.0
  O  O8  1  0.383  0.854  0.383  1.0
  O  O9  1  0.379  0.379  0.379  1.0
  O  O10  1  0.866  0.866  0.866  1.0
  O  O11  1  0.866  0.407  0.866  1.0
  O  O12  1  0.866  0.866  0.407  1.0
  O  O13  1  0.407  0.866  0.866  1.0
[/CIF]
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The structure described by CaBi2O4 is Spinel-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(3) and three equivalent O(4) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. In the second Ca site, Ca(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, and edges with six equivalent Bi(2)O6 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2) and three equivalent O(1) atoms to form BiO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-58°. In the second Bi site, Bi(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, edges with two equivalent Ca(2)O6 octahedra, and edges with four equivalent Bi(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Ca(2), one Bi(1), and two equivalent Bi(2) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Bi(1) and three equivalent Bi(2) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1) and three equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), and two equivalent Bi(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Bi2 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca(BiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.055
_cell_length_b   7.055
_cell_length_c   7.055
_cell_angle_alpha   59.921
_cell_angle_beta   59.921
_cell_angle_gamma   59.921
_symmetry_Int_Tables_number   1
_cell_volume   247.886
_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  0.002  0.002  0.002  1.0
  Ca  Ca1  1  0.625  0.625  0.625  1.0
  Bi  Bi2  1  0.248  0.248  0.248  1.0
  Bi  Bi3  1  0.626  0.118  0.626  1.0
  Bi  Bi4  1  0.626  0.626  0.118  1.0
  Bi  Bi5  1  0.118  0.626  0.626  1.0
  O  O6  1  0.854  0.383  0.383  1.0
  O  O7  1  0.383  0.383  0.854  1.0
  O  O8  1  0.383  0.854  0.383  1.0
  O  O9  1  0.379  0.379  0.379  1.0
  O  O10  1  0.866  0.866  0.866  1.0
  O  O11  1  0.866  0.407  0.866  1.0
  O  O12  1  0.866  0.866  0.407  1.0
  O  O13  1  0.407  0.866  0.866  1.0
[/CIF]
.