The compound described by CaFe2O4 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms to form OCaFe3 trigonal pyramids that share  a cornercorner with one O(4)Ca2Fe3 square pyramid, corners with two equivalent O(3)Ca2Fe3 square pyramids, corners with two equivalent O(1)CaFe3 trigonal pyramids, edges with two equivalent O(4)Ca2Fe3 square pyramids, and edges with three equivalent O(3)Ca2Fe3 square pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Fe(1) atoms to form OCa2Fe3 square pyramids that share corners with two equivalent O(4)Ca2Fe3 square pyramids, corners with two equivalent O(1)CaFe3 trigonal pyramids,  an edgeedge with one O(4)Ca2Fe3 square pyramid, edges with four equivalent O(3)Ca2Fe3 square pyramids, and edges with three equivalent O(1)CaFe3 trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and three equivalent Fe(2) atoms to form distorted OCa2Fe3 square pyramids that share corners with two equivalent O(3)Ca2Fe3 square pyramids,  a cornercorner with one O(1)CaFe3 trigonal pyramid,  an edgeedge with one O(3)Ca2Fe3 square pyramid, edges with four equivalent O(4)Ca2Fe3 square pyramids, and edges with two equivalent O(1)CaFe3 trigonal pyramids. is represented by the CIF card [CIF]
data_Ca(FeO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.162
_cell_length_b   7.162
_cell_length_c   9.436
_cell_angle_alpha   55.750
_cell_angle_beta   55.750
_cell_angle_gamma   25.138
_symmetry_Int_Tables_number   1
_cell_volume   168.009
_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  0.655  0.655  0.829  1.0
  Ca  Ca1  1  0.345  0.345  0.171  1.0
  Fe  Fe2  1  0.370  0.370  0.818  1.0
  Fe  Fe3  1  0.863  0.863  0.469  1.0
  Fe  Fe4  1  0.137  0.137  0.531  1.0
  Fe  Fe5  1  0.630  0.630  0.182  1.0
  O  O6  1  0.134  0.134  0.314  1.0
  O  O7  1  0.544  0.544  0.693  1.0
  O  O8  1  0.456  0.456  0.307  1.0
  O  O9  1  0.866  0.866  0.686  1.0
  O  O10  1  0.843  0.843  0.992  1.0
  O  O11  1  0.239  0.239  0.619  1.0
  O  O12  1  0.157  0.157  0.008  1.0
  O  O13  1  0.761  0.761  0.381  1.0
[/CIF]
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The compound described by CaFe2O4 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles range from 51-62°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms to form OCaFe3 trigonal pyramids that share  a cornercorner with one O(4)Ca2Fe3 square pyramid, corners with two equivalent O(3)Ca2Fe3 square pyramids, corners with two equivalent O(1)CaFe3 trigonal pyramids, edges with two equivalent O(4)Ca2Fe3 square pyramids, and edges with three equivalent O(3)Ca2Fe3 square pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Fe(1), and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Fe(1) atoms to form OCa2Fe3 square pyramids that share corners with two equivalent O(4)Ca2Fe3 square pyramids, corners with two equivalent O(1)CaFe3 trigonal pyramids,  an edgeedge with one O(4)Ca2Fe3 square pyramid, edges with four equivalent O(3)Ca2Fe3 square pyramids, and edges with three equivalent O(1)CaFe3 trigonal pyramids. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and three equivalent Fe(2) atoms to form distorted OCa2Fe3 square pyramids that share corners with two equivalent O(3)Ca2Fe3 square pyramids,  a cornercorner with one O(1)CaFe3 trigonal pyramid,  an edgeedge with one O(3)Ca2Fe3 square pyramid, edges with four equivalent O(4)Ca2Fe3 square pyramids, and edges with two equivalent O(1)CaFe3 trigonal pyramids. is represented by the CIF card [CIF]
data_Ca(FeO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.162
_cell_length_b   7.162
_cell_length_c   9.436
_cell_angle_alpha   55.750
_cell_angle_beta   55.750
_cell_angle_gamma   25.138
_symmetry_Int_Tables_number   1
_cell_volume   168.009
_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  0.655  0.655  0.829  1.0
  Ca  Ca1  1  0.345  0.345  0.171  1.0
  Fe  Fe2  1  0.370  0.370  0.818  1.0
  Fe  Fe3  1  0.863  0.863  0.469  1.0
  Fe  Fe4  1  0.137  0.137  0.531  1.0
  Fe  Fe5  1  0.630  0.630  0.182  1.0
  O  O6  1  0.134  0.134  0.314  1.0
  O  O7  1  0.544  0.544  0.693  1.0
  O  O8  1  0.456  0.456  0.307  1.0
  O  O9  1  0.866  0.866  0.686  1.0
  O  O10  1  0.843  0.843  0.992  1.0
  O  O11  1  0.239  0.239  0.619  1.0
  O  O12  1  0.157  0.157  0.008  1.0
  O  O13  1  0.761  0.761  0.381  1.0
[/CIF]
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