The structure described by Sr3Fe2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to four equivalent O(3) and five equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Sr(2)O12 cuboctahedra, and faces with eight equivalent Fe(1)O6 octahedra. Fe(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form FeO6 octahedra that share corners with five equivalent Fe(1)O6 octahedra and faces with four equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(2) and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(2)Sr5Fe octahedra, corners with four equivalent O(1)Sr4Fe2 octahedra, corners with sixteen equivalent O(3)Sr4Fe2 octahedra, edges with four equivalent O(1)Sr4Fe2 octahedra, and faces with eight equivalent O(3)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded to five equivalent Sr(1) and one Fe(1) atom to form distorted OSr5Fe octahedra that share  a cornercorner with one O(1)Sr4Fe2 octahedra, corners with four equivalent O(2)Sr5Fe octahedra, corners with twelve equivalent O(3)Sr4Fe2 octahedra, edges with eight equivalent O(2)Sr5Fe octahedra, and faces with four equivalent O(3)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-56°. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with four equivalent O(1)Sr4Fe2 octahedra, corners with six equivalent O(2)Sr5Fe octahedra, corners with eight equivalent O(3)Sr4Fe2 octahedra, edges with three equivalent O(3)Sr4Fe2 octahedra, faces with two equivalent O(1)Sr4Fe2 octahedra, faces with two equivalent O(2)Sr5Fe octahedra, and faces with four equivalent O(3)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the CIF file [CIF]
data_Sr3Fe2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.825
_cell_length_b   3.825
_cell_length_c   10.448
_cell_angle_alpha   100.541
_cell_angle_beta   100.541
_cell_angle_gamma   89.999
_symmetry_Int_Tables_number   1
_cell_volume   147.640
_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
  Sr  Sr0  1  0.683  0.683  0.366  1.0
  Sr  Sr1  1  0.317  0.317  0.634  1.0
  Sr  Sr2  1  0.500  0.500  0.000  1.0
  Fe  Fe3  1  0.903  0.903  0.807  1.0
  Fe  Fe4  1  0.097  0.097  0.193  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.808  0.808  0.615  1.0
  O  O7  1  0.192  0.192  0.385  1.0
  O  O8  1  0.905  0.405  0.810  1.0
  O  O9  1  0.405  0.905  0.810  1.0
  O  O10  1  0.595  0.095  0.190  1.0
  O  O11  1  0.095  0.595  0.190  1.0
[/CIF]
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The structure described by Sr3Fe2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to four equivalent O(3) and five equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Sr(2)O12 cuboctahedra, and faces with eight equivalent Fe(1)O6 octahedra. Fe(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form FeO6 octahedra that share corners with five equivalent Fe(1)O6 octahedra and faces with four equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(2) and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(2)Sr5Fe octahedra, corners with four equivalent O(1)Sr4Fe2 octahedra, corners with sixteen equivalent O(3)Sr4Fe2 octahedra, edges with four equivalent O(1)Sr4Fe2 octahedra, and faces with eight equivalent O(3)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded to five equivalent Sr(1) and one Fe(1) atom to form distorted OSr5Fe octahedra that share  a cornercorner with one O(1)Sr4Fe2 octahedra, corners with four equivalent O(2)Sr5Fe octahedra, corners with twelve equivalent O(3)Sr4Fe2 octahedra, edges with eight equivalent O(2)Sr5Fe octahedra, and faces with four equivalent O(3)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-56°. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with four equivalent O(1)Sr4Fe2 octahedra, corners with six equivalent O(2)Sr5Fe octahedra, corners with eight equivalent O(3)Sr4Fe2 octahedra, edges with three equivalent O(3)Sr4Fe2 octahedra, faces with two equivalent O(1)Sr4Fe2 octahedra, faces with two equivalent O(2)Sr5Fe octahedra, and faces with four equivalent O(3)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the CIF file [CIF]
data_Sr3Fe2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.825
_cell_length_b   3.825
_cell_length_c   10.448
_cell_angle_alpha   100.541
_cell_angle_beta   100.541
_cell_angle_gamma   89.999
_symmetry_Int_Tables_number   1
_cell_volume   147.640
_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
  Sr  Sr0  1  0.683  0.683  0.366  1.0
  Sr  Sr1  1  0.317  0.317  0.634  1.0
  Sr  Sr2  1  0.500  0.500  0.000  1.0
  Fe  Fe3  1  0.903  0.903  0.807  1.0
  Fe  Fe4  1  0.097  0.097  0.193  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.808  0.808  0.615  1.0
  O  O7  1  0.192  0.192  0.385  1.0
  O  O8  1  0.905  0.405  0.810  1.0
  O  O9  1  0.405  0.905  0.810  1.0
  O  O10  1  0.595  0.095  0.190  1.0
  O  O11  1  0.095  0.595  0.190  1.0
[/CIF]
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