The material described by MgFe4(PO4)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-61°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-61°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form distorted FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-56°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-61°. In the second P site, P(2) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(2), and one P(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(1), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe4(PO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.164
_cell_length_b   5.990
_cell_length_c   4.886
_cell_angle_alpha   89.536
_cell_angle_beta   87.761
_cell_angle_gamma   90.078
_symmetry_Int_Tables_number   1
_cell_volume   297.237
_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
  Mg  Mg0  1  1.000  0.000  0.000  1.0
  Fe  Fe1  1  0.765  0.256  0.520  1.0
  Fe  Fe2  1  0.709  0.746  0.031  1.0
  Fe  Fe3  1  0.291  0.254  0.969  1.0
  Fe  Fe4  1  0.235  0.744  0.480  1.0
  P  P5  1  0.099  0.246  0.410  1.0
  P  P6  1  0.406  0.753  0.920  1.0
  P  P7  1  0.594  0.247  0.080  1.0
  P  P8  1  0.901  0.754  0.590  1.0
  O  O9  1  0.553  0.752  0.824  1.0
  O  O10  1  0.888  0.774  0.276  1.0
  O  O11  1  0.838  0.960  0.756  1.0
  O  O12  1  0.822  0.559  0.723  1.0
  O  O13  1  0.046  0.759  0.679  1.0
  O  O14  1  0.112  0.226  0.724  1.0
  O  O15  1  0.162  0.040  0.244  1.0
  O  O16  1  0.178  0.441  0.277  1.0
  O  O17  1  0.332  0.547  0.791  1.0
  O  O18  1  0.668  0.453  0.209  1.0
  O  O19  1  0.393  0.753  0.229  1.0
  O  O20  1  0.447  0.248  0.176  1.0
  O  O21  1  0.954  0.241  0.321  1.0
  O  O22  1  0.607  0.247  0.771  1.0
  O  O23  1  0.667  0.042  0.213  1.0
  O  O24  1  0.333  0.958  0.787  1.0
[/CIF]
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The material described by MgFe4(PO4)4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 58-61°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-61°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form distorted FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-56°. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-61°. In the second P site, P(2) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(2), and one P(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(1), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Fe(1) and one P(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe4(PO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.164
_cell_length_b   5.990
_cell_length_c   4.886
_cell_angle_alpha   89.536
_cell_angle_beta   87.761
_cell_angle_gamma   90.078
_symmetry_Int_Tables_number   1
_cell_volume   297.237
_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
  Mg  Mg0  1  1.000  0.000  0.000  1.0
  Fe  Fe1  1  0.765  0.256  0.520  1.0
  Fe  Fe2  1  0.709  0.746  0.031  1.0
  Fe  Fe3  1  0.291  0.254  0.969  1.0
  Fe  Fe4  1  0.235  0.744  0.480  1.0
  P  P5  1  0.099  0.246  0.410  1.0
  P  P6  1  0.406  0.753  0.920  1.0
  P  P7  1  0.594  0.247  0.080  1.0
  P  P8  1  0.901  0.754  0.590  1.0
  O  O9  1  0.553  0.752  0.824  1.0
  O  O10  1  0.888  0.774  0.276  1.0
  O  O11  1  0.838  0.960  0.756  1.0
  O  O12  1  0.822  0.559  0.723  1.0
  O  O13  1  0.046  0.759  0.679  1.0
  O  O14  1  0.112  0.226  0.724  1.0
  O  O15  1  0.162  0.040  0.244  1.0
  O  O16  1  0.178  0.441  0.277  1.0
  O  O17  1  0.332  0.547  0.791  1.0
  O  O18  1  0.668  0.453  0.209  1.0
  O  O19  1  0.393  0.753  0.229  1.0
  O  O20  1  0.447  0.248  0.176  1.0
  O  O21  1  0.954  0.241  0.321  1.0
  O  O22  1  0.607  0.247  0.771  1.0
  O  O23  1  0.667  0.042  0.213  1.0
  O  O24  1  0.333  0.958  0.787  1.0
[/CIF]
.