The material described by Mg3Fe2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. In the second Mg site, Mg(2) is bonded to one O(3), two equivalent O(2), and three equivalent O(1) atoms to form distorted MgO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with eight equivalent Mg(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-73°. Fe(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with five equivalent Fe(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  a faceface with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-63°. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mg(2) and one Fe(1) atom to form distorted OMg3Fe tetrahedra that share corners with six equivalent O(1)Mg3Fe tetrahedra and  a cornercorner with one O(4)Mg2Fe2 trigonal pyramid. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Mg(2), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(2), two equivalent Mg(1), and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Fe(1) atoms to form OMg2Fe2 trigonal pyramids that share corners with two equivalent O(1)Mg3Fe tetrahedra and corners with two equivalent O(4)Mg2Fe2 trigonal pyramids. is represented by the CIF file [CIF]
data_Mg3Fe2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.430
_cell_length_b   5.118
_cell_length_c   9.142
_cell_angle_alpha   106.274
_cell_angle_beta   90.002
_cell_angle_gamma   89.989
_symmetry_Int_Tables_number   1
_cell_volume   243.849
_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
  Mg  Mg0  1  0.682  0.765  1.000  1.0
  Mg  Mg1  1  0.182  0.235  0.000  1.0
  Mg  Mg2  1  0.830  0.566  0.616  1.0
  Mg  Mg3  1  0.330  0.434  0.384  1.0
  Mg  Mg4  1  0.830  0.950  0.384  1.0
  Mg  Mg5  1  0.330  0.050  0.616  1.0
  Fe  Fe6  1  0.752  0.355  0.209  1.0
  Fe  Fe7  1  0.252  0.645  0.791  1.0
  Fe  Fe8  1  0.252  0.854  0.209  1.0
  Fe  Fe9  1  0.752  0.146  0.791  1.0
  O  O10  1  0.701  0.923  0.588  1.0
  O  O11  1  0.201  0.077  0.412  1.0
  O  O12  1  0.201  0.665  0.588  1.0
  O  O13  1  0.701  0.335  0.412  1.0
  O  O14  1  0.058  0.316  0.732  1.0
  O  O15  1  0.558  0.683  0.268  1.0
  O  O16  1  0.558  0.416  0.732  1.0
  O  O17  1  0.058  0.584  0.268  1.0
  O  O18  1  0.923  0.860  0.844  1.0
  O  O19  1  0.423  0.140  0.156  1.0
  O  O20  1  0.809  0.380  1.000  1.0
  O  O21  1  0.309  0.620  0.000  1.0
  O  O22  1  0.923  0.016  0.156  1.0
  O  O23  1  0.423  0.984  0.844  1.0
[/CIF]
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The material described by Mg3Fe2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. In the second Mg site, Mg(2) is bonded to one O(3), two equivalent O(2), and three equivalent O(1) atoms to form distorted MgO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with eight equivalent Mg(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-73°. Fe(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with five equivalent Fe(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  a faceface with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-63°. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mg(2) and one Fe(1) atom to form distorted OMg3Fe tetrahedra that share corners with six equivalent O(1)Mg3Fe tetrahedra and  a cornercorner with one O(4)Mg2Fe2 trigonal pyramid. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Mg(2), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(2), two equivalent Mg(1), and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Fe(1) atoms to form OMg2Fe2 trigonal pyramids that share corners with two equivalent O(1)Mg3Fe tetrahedra and corners with two equivalent O(4)Mg2Fe2 trigonal pyramids. is represented by the CIF file [CIF]
data_Mg3Fe2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.430
_cell_length_b   5.118
_cell_length_c   9.142
_cell_angle_alpha   106.274
_cell_angle_beta   90.002
_cell_angle_gamma   89.989
_symmetry_Int_Tables_number   1
_cell_volume   243.849
_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
  Mg  Mg0  1  0.682  0.765  1.000  1.0
  Mg  Mg1  1  0.182  0.235  0.000  1.0
  Mg  Mg2  1  0.830  0.566  0.616  1.0
  Mg  Mg3  1  0.330  0.434  0.384  1.0
  Mg  Mg4  1  0.830  0.950  0.384  1.0
  Mg  Mg5  1  0.330  0.050  0.616  1.0
  Fe  Fe6  1  0.752  0.355  0.209  1.0
  Fe  Fe7  1  0.252  0.645  0.791  1.0
  Fe  Fe8  1  0.252  0.854  0.209  1.0
  Fe  Fe9  1  0.752  0.146  0.791  1.0
  O  O10  1  0.701  0.923  0.588  1.0
  O  O11  1  0.201  0.077  0.412  1.0
  O  O12  1  0.201  0.665  0.588  1.0
  O  O13  1  0.701  0.335  0.412  1.0
  O  O14  1  0.058  0.316  0.732  1.0
  O  O15  1  0.558  0.683  0.268  1.0
  O  O16  1  0.558  0.416  0.732  1.0
  O  O17  1  0.058  0.584  0.268  1.0
  O  O18  1  0.923  0.860  0.844  1.0
  O  O19  1  0.423  0.140  0.156  1.0
  O  O20  1  0.809  0.380  1.000  1.0
  O  O21  1  0.309  0.620  0.000  1.0
  O  O22  1  0.923  0.016  0.156  1.0
  O  O23  1  0.423  0.984  0.844  1.0
[/CIF]
.