The material structure described by CaFe4O9 crystallizes in the tetragonal P4/n space group. Ca(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), and three equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Fe(1) atoms to form a mixture of distorted edge and corner-sharing OFe4 trigonal pyramids. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one Fe(1) atom. In the third O site, O(3) is bonded to one Ca(1) and three equivalent Fe(1) atoms to form distorted OCaFe3 tetrahedra that share corners with three equivalent O(3)CaFe3 tetrahedra,  a cornercorner with one O(1)Fe4 trigonal pyramid, edges with three equivalent O(3)CaFe3 tetrahedra, and  an edgeedge with one O(1)Fe4 trigonal pyramid. is represented by the CIF card [CIF]
data_CaFe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.364
_cell_length_b   8.364
_cell_length_c   5.438
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   380.360
_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  0.500  0.000  0.832  1.0
  Ca  Ca1  1  0.000  0.500  0.168  1.0
  Fe  Fe2  1  0.214  0.908  0.376  1.0
  Fe  Fe3  1  0.908  0.786  0.624  1.0
  Fe  Fe4  1  0.408  0.286  0.376  1.0
  Fe  Fe5  1  0.714  0.408  0.624  1.0
  Fe  Fe6  1  0.786  0.092  0.376  1.0
  Fe  Fe7  1  0.592  0.714  0.376  1.0
  Fe  Fe8  1  0.286  0.592  0.624  1.0
  Fe  Fe9  1  0.092  0.214  0.624  1.0
  O  O10  1  0.000  0.000  0.500  1.0
  O  O11  1  0.500  0.500  0.500  1.0
  O  O12  1  0.076  0.270  0.944  1.0
  O  O13  1  0.230  0.576  0.944  1.0
  O  O14  1  0.770  0.424  0.944  1.0
  O  O15  1  0.924  0.730  0.944  1.0
  O  O16  1  0.424  0.230  0.056  1.0
  O  O17  1  0.270  0.924  0.056  1.0
  O  O18  1  0.730  0.076  0.056  1.0
  O  O19  1  0.576  0.770  0.056  1.0
  O  O20  1  0.706  0.895  0.535  1.0
  O  O21  1  0.605  0.206  0.535  1.0
  O  O22  1  0.395  0.794  0.535  1.0
  O  O23  1  0.294  0.105  0.535  1.0
  O  O24  1  0.206  0.395  0.465  1.0
  O  O25  1  0.895  0.294  0.465  1.0
  O  O26  1  0.105  0.706  0.465  1.0
  O  O27  1  0.794  0.605  0.465  1.0
[/CIF]
.
The material structure described by CaFe4O9 crystallizes in the tetragonal P4/n space group. Ca(1) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(3) atoms. Fe(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), and three equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Fe(1) atoms to form a mixture of distorted edge and corner-sharing OFe4 trigonal pyramids. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one Fe(1) atom. In the third O site, O(3) is bonded to one Ca(1) and three equivalent Fe(1) atoms to form distorted OCaFe3 tetrahedra that share corners with three equivalent O(3)CaFe3 tetrahedra,  a cornercorner with one O(1)Fe4 trigonal pyramid, edges with three equivalent O(3)CaFe3 tetrahedra, and  an edgeedge with one O(1)Fe4 trigonal pyramid. is represented by the CIF card [CIF]
data_CaFe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.364
_cell_length_b   8.364
_cell_length_c   5.438
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   380.360
_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  0.500  0.000  0.832  1.0
  Ca  Ca1  1  0.000  0.500  0.168  1.0
  Fe  Fe2  1  0.214  0.908  0.376  1.0
  Fe  Fe3  1  0.908  0.786  0.624  1.0
  Fe  Fe4  1  0.408  0.286  0.376  1.0
  Fe  Fe5  1  0.714  0.408  0.624  1.0
  Fe  Fe6  1  0.786  0.092  0.376  1.0
  Fe  Fe7  1  0.592  0.714  0.376  1.0
  Fe  Fe8  1  0.286  0.592  0.624  1.0
  Fe  Fe9  1  0.092  0.214  0.624  1.0
  O  O10  1  0.000  0.000  0.500  1.0
  O  O11  1  0.500  0.500  0.500  1.0
  O  O12  1  0.076  0.270  0.944  1.0
  O  O13  1  0.230  0.576  0.944  1.0
  O  O14  1  0.770  0.424  0.944  1.0
  O  O15  1  0.924  0.730  0.944  1.0
  O  O16  1  0.424  0.230  0.056  1.0
  O  O17  1  0.270  0.924  0.056  1.0
  O  O18  1  0.730  0.076  0.056  1.0
  O  O19  1  0.576  0.770  0.056  1.0
  O  O20  1  0.706  0.895  0.535  1.0
  O  O21  1  0.605  0.206  0.535  1.0
  O  O22  1  0.395  0.794  0.535  1.0
  O  O23  1  0.294  0.105  0.535  1.0
  O  O24  1  0.206  0.395  0.465  1.0
  O  O25  1  0.895  0.294  0.465  1.0
  O  O26  1  0.105  0.706  0.465  1.0
  O  O27  1  0.794  0.605  0.465  1.0
[/CIF]
.