The compound described by Bi2Fe4O9 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) 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 four equivalent Fe(2)O4 tetrahedra and edges with two equivalent Fe(1)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form FeO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-62°. Bi(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Bi(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(2) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Fe(1) and two equivalent Bi(1) atoms to form a mixture of distorted corner and edge-sharing OFe2Bi2 tetrahedra. is represented by the CIF file [CIF]
data_Fe4Bi2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.046
_cell_length_b   8.015
_cell_length_c   8.458
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   409.877
_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
  Fe  Fe0  1  0.256  0.000  0.500  1.0
  Fe  Fe1  1  0.744  0.500  0.000  1.0
  Fe  Fe2  1  0.744  0.000  0.500  1.0
  Fe  Fe3  1  0.256  0.500  0.000  1.0
  Fe  Fe4  1  0.500  0.854  0.168  1.0
  Fe  Fe5  1  0.500  0.146  0.832  1.0
  Fe  Fe6  1  0.500  0.354  0.332  1.0
  Fe  Fe7  1  0.500  0.646  0.668  1.0
  Bi  Bi8  1  0.000  0.676  0.326  1.0
  Bi  Bi9  1  0.000  0.324  0.674  1.0
  Bi  Bi10  1  0.000  0.176  0.174  1.0
  Bi  Bi11  1  0.000  0.824  0.826  1.0
  O  O12  1  0.500  0.500  0.500  1.0
  O  O13  1  0.500  0.000  0.000  1.0
  O  O14  1  0.239  0.869  0.294  1.0
  O  O15  1  0.239  0.131  0.706  1.0
  O  O16  1  0.761  0.369  0.206  1.0
  O  O17  1  0.761  0.631  0.794  1.0
  O  O18  1  0.761  0.131  0.706  1.0
  O  O19  1  0.761  0.869  0.294  1.0
  O  O20  1  0.239  0.631  0.794  1.0
  O  O21  1  0.239  0.369  0.206  1.0
  O  O22  1  0.500  0.631  0.098  1.0
  O  O23  1  0.500  0.369  0.902  1.0
  O  O24  1  0.500  0.131  0.402  1.0
  O  O25  1  0.500  0.869  0.598  1.0
  O  O26  1  0.000  0.652  0.068  1.0
  O  O27  1  0.000  0.348  0.932  1.0
  O  O28  1  0.000  0.152  0.432  1.0
  O  O29  1  0.000  0.848  0.568  1.0
[/CIF]
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The compound described by Bi2Fe4O9 crystallizes in the orthorhombic Pbam space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) 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 four equivalent Fe(2)O4 tetrahedra and edges with two equivalent Fe(1)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form FeO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra and  a cornercorner with one Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-62°. Bi(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Fe(2) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Bi(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Fe(2) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Fe(1) and two equivalent Bi(1) atoms to form a mixture of distorted corner and edge-sharing OFe2Bi2 tetrahedra. is represented by the CIF file [CIF]
data_Fe4Bi2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.046
_cell_length_b   8.015
_cell_length_c   8.458
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   409.877
_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
  Fe  Fe0  1  0.256  0.000  0.500  1.0
  Fe  Fe1  1  0.744  0.500  0.000  1.0
  Fe  Fe2  1  0.744  0.000  0.500  1.0
  Fe  Fe3  1  0.256  0.500  0.000  1.0
  Fe  Fe4  1  0.500  0.854  0.168  1.0
  Fe  Fe5  1  0.500  0.146  0.832  1.0
  Fe  Fe6  1  0.500  0.354  0.332  1.0
  Fe  Fe7  1  0.500  0.646  0.668  1.0
  Bi  Bi8  1  0.000  0.676  0.326  1.0
  Bi  Bi9  1  0.000  0.324  0.674  1.0
  Bi  Bi10  1  0.000  0.176  0.174  1.0
  Bi  Bi11  1  0.000  0.824  0.826  1.0
  O  O12  1  0.500  0.500  0.500  1.0
  O  O13  1  0.500  0.000  0.000  1.0
  O  O14  1  0.239  0.869  0.294  1.0
  O  O15  1  0.239  0.131  0.706  1.0
  O  O16  1  0.761  0.369  0.206  1.0
  O  O17  1  0.761  0.631  0.794  1.0
  O  O18  1  0.761  0.131  0.706  1.0
  O  O19  1  0.761  0.869  0.294  1.0
  O  O20  1  0.239  0.631  0.794  1.0
  O  O21  1  0.239  0.369  0.206  1.0
  O  O22  1  0.500  0.631  0.098  1.0
  O  O23  1  0.500  0.369  0.902  1.0
  O  O24  1  0.500  0.131  0.402  1.0
  O  O25  1  0.500  0.869  0.598  1.0
  O  O26  1  0.000  0.652  0.068  1.0
  O  O27  1  0.000  0.348  0.932  1.0
  O  O28  1  0.000  0.152  0.432  1.0
  O  O29  1  0.000  0.848  0.568  1.0
[/CIF]
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