The crystal structure described by Ba8Fe8O21 crystallizes in the triclinic P-1 space group. There are five inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to one O(2), one O(4), one O(6), one O(7), one O(9), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. In the third Ba site, Ba(3) is bonded in a distorted q6 geometry to two equivalent O(10), two equivalent O(11), two equivalent O(12), two equivalent O(13), and two equivalent O(8) atoms. In the fourth Ba site, Ba(4) is bonded in a distorted q6 geometry to one O(10), one O(11), one O(6), one O(7), one O(8), one O(9), two equivalent O(12), and two equivalent O(13) atoms. In the fifth Ba site, Ba(5) is bonded in a distorted q6 geometry to one O(1), one O(12), one O(13), one O(3), one O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form FeO5 square pyramids that share corners with three equivalent Fe(3)O6 octahedra and corners with two equivalent Fe(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 1-15°. In the second Fe site, Fe(2) is bonded to one O(12), one O(13), one O(6), one O(7), and one O(9) atom to form FeO5 square pyramids that share corners with three equivalent Fe(3)O6 octahedra and corners with two equivalent Fe(4)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-17°. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(9) atom to form corner-sharing FeO6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(10), one O(11), one O(12), one O(13), and one O(8) atom to form corner-sharing FeO5 square pyramids. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(2), one Ba(5), two equivalent Ba(1), one Fe(1), and one Fe(3) atom. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Fe(1) atoms to form a mixture of distorted face and corner-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(5), two equivalent Ba(1), one Fe(1), and one Fe(3) atom. In the fourth O site, O(4) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Fe(1) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the fifth O site, O(5) is bonded to one Ba(2), one Ba(5), two equivalent Ba(1), one Fe(1), and one Fe(3) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(4), two equivalent Ba(5), one Fe(2), and one Fe(3) atom. In the seventh O site, O(7) is bonded to one Ba(1), one Ba(4), two equivalent Ba(5), one Fe(2), and one Fe(3) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-62°. In the eighth O site, O(8) is bonded in a distorted linear geometry to two equivalent Ba(3), two equivalent Ba(4), and two equivalent Fe(4) atoms. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Ba(1), one Ba(4), two equivalent Ba(5), one Fe(2), and one Fe(3) atom. In the tenth O site, O(10) is bonded to two equivalent Ba(3), two equivalent Ba(4), and two equivalent Fe(4) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the eleventh O site, O(11) is bonded to two equivalent Ba(3), two equivalent Ba(4), and two equivalent Fe(4) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the twelfth O site, O(12) is bonded to one Ba(3), one Ba(5), two equivalent Ba(4), one Fe(2), and one Fe(4) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the thirteenth O site, O(13) is bonded to one Ba(3), one Ba(5), two equivalent Ba(4), one Fe(2), and one Fe(4) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba8Fe8O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.744
_cell_length_b   5.816
_cell_length_c   19.095
_cell_angle_alpha   99.303
_cell_angle_beta   98.082
_cell_angle_gamma   60.029
_symmetry_Int_Tables_number   1
_cell_volume   544.042
_cell_formula_units_Z   1
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
  Ba  Ba0  1  0.752  0.751  0.252  1.0
  Ba  Ba1  1  0.375  0.375  0.125  1.0
  Ba  Ba2  1  0.998  0.999  0.998  1.0
  Ba  Ba3  1  0.875  0.875  0.625  1.0
  Ba  Ba4  1  0.496  0.507  0.497  1.0
  Ba  Ba5  1  0.123  0.127  0.371  1.0
  Ba  Ba6  1  0.627  0.623  0.879  1.0
  Ba  Ba7  1  0.254  0.243  0.753  1.0
  Fe  Fe8  1  0.663  0.660  0.056  1.0
  Fe  Fe9  1  0.785  0.863  0.429  1.0
  Fe  Fe10  1  0.087  0.090  0.194  1.0
  Fe  Fe11  1  0.440  0.453  0.311  1.0
  Fe  Fe12  1  0.965  0.887  0.821  1.0
  Fe  Fe13  1  0.204  0.160  0.569  1.0
  Fe  Fe14  1  0.546  0.590  0.681  1.0
  Fe  Fe15  1  0.310  0.297  0.939  1.0
  O  O16  1  0.494  0.481  0.998  1.0
  O  O17  1  0.375  0.875  0.125  1.0
  O  O18  1  0.990  0.517  0.008  1.0
  O  O19  1  0.875  0.375  0.125  1.0
  O  O20  1  0.246  0.758  0.248  1.0
  O  O21  1  0.504  0.992  0.002  1.0
  O  O22  1  0.115  0.628  0.384  1.0
  O  O23  1  0.760  0.233  0.242  1.0
  O  O24  1  0.629  0.631  0.376  1.0
  O  O25  1  0.256  0.269  0.252  1.0
  O  O26  1  0.375  0.875  0.625  1.0
  O  O27  1  0.618  0.149  0.372  1.0
  O  O28  1  0.875  0.375  0.625  1.0
  O  O29  1  0.375  0.375  0.625  1.0
  O  O30  1  0.756  0.730  0.749  1.0
  O  O31  1  0.994  0.020  0.501  1.0
  O  O32  1  0.500  0.005  0.499  1.0
  O  O33  1  0.250  0.745  0.751  1.0
  O  O34  1  0.132  0.601  0.878  1.0
  O  O35  1  0.121  0.119  0.874  1.0
  O  O36  1  0.635  0.122  0.866  1.0
[/CIF]
.
The crystal structure described by Ba8Fe8O21 crystallizes in the triclinic P-1 space group. There are five inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a distorted q6 geometry to one O(2), one O(4), one O(6), one O(7), one O(9), two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. In the third Ba site, Ba(3) is bonded in a distorted q6 geometry to two equivalent O(10), two equivalent O(11), two equivalent O(12), two equivalent O(13), and two equivalent O(8) atoms. In the fourth Ba site, Ba(4) is bonded in a distorted q6 geometry to one O(10), one O(11), one O(6), one O(7), one O(8), one O(9), two equivalent O(12), and two equivalent O(13) atoms. In the fifth Ba site, Ba(5) is bonded in a distorted q6 geometry to one O(1), one O(12), one O(13), one O(3), one O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form FeO5 square pyramids that share corners with three equivalent Fe(3)O6 octahedra and corners with two equivalent Fe(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 1-15°. In the second Fe site, Fe(2) is bonded to one O(12), one O(13), one O(6), one O(7), and one O(9) atom to form FeO5 square pyramids that share corners with three equivalent Fe(3)O6 octahedra and corners with two equivalent Fe(4)O5 square pyramids. The corner-sharing octahedral tilt angles range from 0-17°. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(9) atom to form corner-sharing FeO6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(10), one O(11), one O(12), one O(13), and one O(8) atom to form corner-sharing FeO5 square pyramids. There are thirteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(2), one Ba(5), two equivalent Ba(1), one Fe(1), and one Fe(3) atom. In the second O site, O(2) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Fe(1) atoms to form a mixture of distorted face and corner-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(5), two equivalent Ba(1), one Fe(1), and one Fe(3) atom. In the fourth O site, O(4) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Fe(1) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the fifth O site, O(5) is bonded to one Ba(2), one Ba(5), two equivalent Ba(1), one Fe(1), and one Fe(3) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Ba(1), one Ba(4), two equivalent Ba(5), one Fe(2), and one Fe(3) atom. In the seventh O site, O(7) is bonded to one Ba(1), one Ba(4), two equivalent Ba(5), one Fe(2), and one Fe(3) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-62°. In the eighth O site, O(8) is bonded in a distorted linear geometry to two equivalent Ba(3), two equivalent Ba(4), and two equivalent Fe(4) atoms. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Ba(1), one Ba(4), two equivalent Ba(5), one Fe(2), and one Fe(3) atom. In the tenth O site, O(10) is bonded to two equivalent Ba(3), two equivalent Ba(4), and two equivalent Fe(4) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the eleventh O site, O(11) is bonded to two equivalent Ba(3), two equivalent Ba(4), and two equivalent Fe(4) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the twelfth O site, O(12) is bonded to one Ba(3), one Ba(5), two equivalent Ba(4), one Fe(2), and one Fe(4) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the thirteenth O site, O(13) is bonded to one Ba(3), one Ba(5), two equivalent Ba(4), one Fe(2), and one Fe(4) atom to form a mixture of distorted face, corner, and edge-sharing OBa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-62°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba8Fe8O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.744
_cell_length_b   5.816
_cell_length_c   19.095
_cell_angle_alpha   99.303
_cell_angle_beta   98.082
_cell_angle_gamma   60.029
_symmetry_Int_Tables_number   1
_cell_volume   544.042
_cell_formula_units_Z   1
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
  Ba  Ba0  1  0.752  0.751  0.252  1.0
  Ba  Ba1  1  0.375  0.375  0.125  1.0
  Ba  Ba2  1  0.998  0.999  0.998  1.0
  Ba  Ba3  1  0.875  0.875  0.625  1.0
  Ba  Ba4  1  0.496  0.507  0.497  1.0
  Ba  Ba5  1  0.123  0.127  0.371  1.0
  Ba  Ba6  1  0.627  0.623  0.879  1.0
  Ba  Ba7  1  0.254  0.243  0.753  1.0
  Fe  Fe8  1  0.663  0.660  0.056  1.0
  Fe  Fe9  1  0.785  0.863  0.429  1.0
  Fe  Fe10  1  0.087  0.090  0.194  1.0
  Fe  Fe11  1  0.440  0.453  0.311  1.0
  Fe  Fe12  1  0.965  0.887  0.821  1.0
  Fe  Fe13  1  0.204  0.160  0.569  1.0
  Fe  Fe14  1  0.546  0.590  0.681  1.0
  Fe  Fe15  1  0.310  0.297  0.939  1.0
  O  O16  1  0.494  0.481  0.998  1.0
  O  O17  1  0.375  0.875  0.125  1.0
  O  O18  1  0.990  0.517  0.008  1.0
  O  O19  1  0.875  0.375  0.125  1.0
  O  O20  1  0.246  0.758  0.248  1.0
  O  O21  1  0.504  0.992  0.002  1.0
  O  O22  1  0.115  0.628  0.384  1.0
  O  O23  1  0.760  0.233  0.242  1.0
  O  O24  1  0.629  0.631  0.376  1.0
  O  O25  1  0.256  0.269  0.252  1.0
  O  O26  1  0.375  0.875  0.625  1.0
  O  O27  1  0.618  0.149  0.372  1.0
  O  O28  1  0.875  0.375  0.625  1.0
  O  O29  1  0.375  0.375  0.625  1.0
  O  O30  1  0.756  0.730  0.749  1.0
  O  O31  1  0.994  0.020  0.501  1.0
  O  O32  1  0.500  0.005  0.499  1.0
  O  O33  1  0.250  0.745  0.751  1.0
  O  O34  1  0.132  0.601  0.878  1.0
  O  O35  1  0.121  0.119  0.874  1.0
  O  O36  1  0.635  0.122  0.866  1.0
[/CIF]
.