The crystal structure described by CaFe2O4 is Spinel structured and crystallizes in the triclinic P-1 space group. Ca(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form CaO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(3)O6 octahedra, and corners with three equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-64°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of corner and edge-sharing OCaFe3 tetrahedra. In the second O site, O(2) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Fe(4) atom to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the third O site, O(3) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Fe(3) atom to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the fourth O site, O(4) is bonded to one Ca(1), one Fe(2), one Fe(3), and one Fe(4) atom to form a mixture of corner and edge-sharing OCaFe3 tetrahedra. is represented by the CIF card [CIF]
data_Ca(FeO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.233
_cell_length_b   6.227
_cell_length_c   6.192
_cell_angle_alpha   90.944
_cell_angle_beta   118.952
_cell_angle_gamma   119.231
_symmetry_Int_Tables_number   1
_cell_volume   173.162
_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  0.246  0.122  0.877  1.0
  Ca  Ca1  1  0.754  0.878  0.123  1.0
  Fe  Fe2  1  0.500  0.000  0.500  1.0
  Fe  Fe3  1  0.500  0.500  0.500  1.0
  Fe  Fe4  1  1.000  0.500  1.000  1.0
  Fe  Fe5  1  0.000  0.500  0.500  1.0
  O  O6  1  0.038  0.730  0.262  1.0
  O  O7  1  0.453  0.729  0.697  1.0
  O  O8  1  0.483  0.741  0.281  1.0
  O  O9  1  0.960  0.693  0.741  1.0
  O  O10  1  0.517  0.259  0.719  1.0
  O  O11  1  0.547  0.271  0.303  1.0
  O  O12  1  0.040  0.307  0.260  1.0
  O  O13  1  0.962  0.270  0.738  1.0
[/CIF]
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The crystal structure described by CaFe2O4 is Spinel structured and crystallizes in the triclinic P-1 space group. Ca(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form CaO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(3)O6 octahedra, and corners with three equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-64°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Ca(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(1), one Fe(3), and one Fe(4) atom to form a mixture of corner and edge-sharing OCaFe3 tetrahedra. In the second O site, O(2) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Fe(4) atom to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the third O site, O(3) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Fe(3) atom to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the fourth O site, O(4) is bonded to one Ca(1), one Fe(2), one Fe(3), and one Fe(4) atom to form a mixture of corner and edge-sharing OCaFe3 tetrahedra. is represented by the CIF card [CIF]
data_Ca(FeO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.233
_cell_length_b   6.227
_cell_length_c   6.192
_cell_angle_alpha   90.944
_cell_angle_beta   118.952
_cell_angle_gamma   119.231
_symmetry_Int_Tables_number   1
_cell_volume   173.162
_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  0.246  0.122  0.877  1.0
  Ca  Ca1  1  0.754  0.878  0.123  1.0
  Fe  Fe2  1  0.500  0.000  0.500  1.0
  Fe  Fe3  1  0.500  0.500  0.500  1.0
  Fe  Fe4  1  1.000  0.500  1.000  1.0
  Fe  Fe5  1  0.000  0.500  0.500  1.0
  O  O6  1  0.038  0.730  0.262  1.0
  O  O7  1  0.453  0.729  0.697  1.0
  O  O8  1  0.483  0.741  0.281  1.0
  O  O9  1  0.960  0.693  0.741  1.0
  O  O10  1  0.517  0.259  0.719  1.0
  O  O11  1  0.547  0.271  0.303  1.0
  O  O12  1  0.040  0.307  0.260  1.0
  O  O13  1  0.962  0.270  0.738  1.0
[/CIF]
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