The material structure described by CaFe2O4 crystallizes in the monoclinic Cm 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(2), one O(4), two equivalent O(6), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(5), and two equivalent O(8) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 52-56°. In the second Fe site, Fe(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(3), two equivalent O(1), and two equivalent O(7) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O5 square pyramids. The corner-sharing octahedral tilt angles range from 51-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Fe(3), and two equivalent Fe(4) atoms. 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(3) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Fe(4), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Fe(1) atoms. In the sixth O site, O(6) is bonded to two equivalent Ca(1), one Fe(3), and two equivalent Fe(2) atoms to form distorted edge-sharing OCa2Fe3 trigonal bipyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Fe(4) atoms. In the eighth O site, O(8) is bonded to two equivalent Ca(2), one Fe(2), and two equivalent Fe(3) atoms to form edge-sharing OCa2Fe3 square pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca(FeO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.469
_cell_length_b   7.469
_cell_length_c   9.204
_cell_angle_alpha   61.439
_cell_angle_beta   61.439
_cell_angle_gamma   23.554
_symmetry_Int_Tables_number   1
_cell_volume   179.044
_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  0.659  0.659  0.845  1.0
  Ca  Ca1  1  0.353  0.353  0.176  1.0
  Fe  Fe2  1  0.415  0.415  0.798  1.0
  Fe  Fe3  1  0.850  0.850  0.504  1.0
  Fe  Fe4  1  0.153  0.153  0.518  1.0
  Fe  Fe5  1  0.590  0.590  0.226  1.0
  O  O6  1  0.126  0.126  0.327  1.0
  O  O7  1  0.567  0.567  0.669  1.0
  O  O8  1  0.436  0.436  0.352  1.0
  O  O9  1  0.870  0.870  0.706  1.0
  O  O10  1  0.895  0.895  0.967  1.0
  O  O11  1  0.241  0.241  0.636  1.0
  O  O12  1  0.115  0.115  0.055  1.0
  O  O13  1  0.763  0.763  0.382  1.0
[/CIF]
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The material structure described by CaFe2O4 crystallizes in the monoclinic Cm 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(2), one O(4), two equivalent O(6), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(5), and two equivalent O(8) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 52-56°. In the second Fe site, Fe(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(3), two equivalent O(1), and two equivalent O(7) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O5 square pyramids. The corner-sharing octahedral tilt angles range from 51-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Fe(3), and two equivalent Fe(4) atoms. 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(3) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Fe(4), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Fe(1) atoms. In the sixth O site, O(6) is bonded to two equivalent Ca(1), one Fe(3), and two equivalent Fe(2) atoms to form distorted edge-sharing OCa2Fe3 trigonal bipyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Fe(4) atoms. In the eighth O site, O(8) is bonded to two equivalent Ca(2), one Fe(2), and two equivalent Fe(3) atoms to form edge-sharing OCa2Fe3 square pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca(FeO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.469
_cell_length_b   7.469
_cell_length_c   9.204
_cell_angle_alpha   61.439
_cell_angle_beta   61.439
_cell_angle_gamma   23.554
_symmetry_Int_Tables_number   1
_cell_volume   179.044
_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  0.659  0.659  0.845  1.0
  Ca  Ca1  1  0.353  0.353  0.176  1.0
  Fe  Fe2  1  0.415  0.415  0.798  1.0
  Fe  Fe3  1  0.850  0.850  0.504  1.0
  Fe  Fe4  1  0.153  0.153  0.518  1.0
  Fe  Fe5  1  0.590  0.590  0.226  1.0
  O  O6  1  0.126  0.126  0.327  1.0
  O  O7  1  0.567  0.567  0.669  1.0
  O  O8  1  0.436  0.436  0.352  1.0
  O  O9  1  0.870  0.870  0.706  1.0
  O  O10  1  0.895  0.895  0.967  1.0
  O  O11  1  0.241  0.241  0.636  1.0
  O  O12  1  0.115  0.115  0.055  1.0
  O  O13  1  0.763  0.763  0.382  1.0
[/CIF]
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