The material described by SrFe2(PO4)2 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(7), and two equivalent O(6) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(8), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(7), and one O(8) atom. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-64°. In the second P site, P(2) is bonded to one O(5), 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. The corner-sharing octahedral tilt angles are 53°. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Fe(1), and one P(1) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(2), and one P(2) atom. In the third O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the fourth O site, O(7) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(2), and one P(2) atom. In the fifth O site, O(8) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(2) atom. In the sixth O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. In the seventh O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Fe(1), one Fe(2), and one P(1) atom. In the eighth O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Fe(1), one Fe(2), and one P(1) atom. is represented by the CIF file [CIF]
data_SrFe2(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.960
_cell_length_b   9.532
_cell_length_c   10.696
_cell_angle_alpha   70.208
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   667.698
_cell_formula_units_Z   4
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  0.880  0.305  0.982  1.0
  Sr  Sr1  1  0.380  0.695  0.518  1.0
  Sr  Sr2  1  0.120  0.695  0.018  1.0
  Sr  Sr3  1  0.620  0.305  0.482  1.0
  Fe  Fe4  1  0.348  0.079  0.882  1.0
  Fe  Fe5  1  0.848  0.921  0.618  1.0
  Fe  Fe6  1  0.652  0.921  0.118  1.0
  Fe  Fe7  1  0.152  0.079  0.382  1.0
  Fe  Fe8  1  0.107  0.288  0.667  1.0
  Fe  Fe9  1  0.607  0.712  0.833  1.0
  Fe  Fe10  1  0.893  0.712  0.333  1.0
  Fe  Fe11  1  0.393  0.288  0.167  1.0
  P  P12  1  0.826  0.035  0.827  1.0
  P  P13  1  0.326  0.965  0.673  1.0
  P  P14  1  0.174  0.965  0.173  1.0
  P  P15  1  0.674  0.035  0.327  1.0
  P  P16  1  0.145  0.422  0.380  1.0
  P  P17  1  0.645  0.578  0.120  1.0
  P  P18  1  0.855  0.578  0.620  1.0
  P  P19  1  0.355  0.422  0.880  1.0
  O  O20  1  0.787  0.107  0.676  1.0
  O  O21  1  0.287  0.893  0.824  1.0
  O  O22  1  0.213  0.893  0.324  1.0
  O  O23  1  0.713  0.107  0.176  1.0
  O  O24  1  0.008  0.111  0.859  1.0
  O  O25  1  0.508  0.889  0.641  1.0
  O  O26  1  0.992  0.889  0.141  1.0
  O  O27  1  0.492  0.111  0.359  1.0
  O  O28  1  0.347  0.135  0.645  1.0
  O  O29  1  0.847  0.865  0.855  1.0
  O  O30  1  0.653  0.865  0.355  1.0
  O  O31  1  0.153  0.135  0.145  1.0
  O  O32  1  0.656  0.062  0.914  1.0
  O  O33  1  0.156  0.938  0.586  1.0
  O  O34  1  0.344  0.938  0.086  1.0
  O  O35  1  0.844  0.062  0.414  1.0
  O  O36  1  0.920  0.432  0.726  1.0
  O  O37  1  0.420  0.568  0.774  1.0
  O  O38  1  0.080  0.568  0.274  1.0
  O  O39  1  0.580  0.432  0.226  1.0
  O  O40  1  0.314  0.449  0.464  1.0
  O  O41  1  0.814  0.551  0.036  1.0
  O  O42  1  0.686  0.551  0.536  1.0
  O  O43  1  0.186  0.449  0.964  1.0
  O  O44  1  0.983  0.345  0.481  1.0
  O  O45  1  0.483  0.655  0.019  1.0
  O  O46  1  0.017  0.655  0.519  1.0
  O  O47  1  0.517  0.345  0.981  1.0
  O  O48  1  0.303  0.307  0.810  1.0
  O  O49  1  0.803  0.693  0.690  1.0
  O  O50  1  0.697  0.693  0.190  1.0
  O  O51  1  0.197  0.307  0.310  1.0
[/CIF]
.
The material described by SrFe2(PO4)2 crystallizes in the monoclinic P2_1/c space group. Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(7), and two equivalent O(6) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(8), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), one O(7), and one O(8) atom. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-64°. In the second P site, P(2) is bonded to one O(5), 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. The corner-sharing octahedral tilt angles are 53°. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Fe(1), and one P(1) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(2), and one P(2) atom. In the third O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the fourth O site, O(7) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(2), and one P(2) atom. In the fifth O site, O(8) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(2) atom. In the sixth O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1), one Fe(1), and one P(1) atom. In the seventh O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), one Fe(1), one Fe(2), and one P(1) atom. In the eighth O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Fe(1), one Fe(2), and one P(1) atom. is represented by the CIF file [CIF]
data_SrFe2(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.960
_cell_length_b   9.532
_cell_length_c   10.696
_cell_angle_alpha   70.208
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   667.698
_cell_formula_units_Z   4
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  0.880  0.305  0.982  1.0
  Sr  Sr1  1  0.380  0.695  0.518  1.0
  Sr  Sr2  1  0.120  0.695  0.018  1.0
  Sr  Sr3  1  0.620  0.305  0.482  1.0
  Fe  Fe4  1  0.348  0.079  0.882  1.0
  Fe  Fe5  1  0.848  0.921  0.618  1.0
  Fe  Fe6  1  0.652  0.921  0.118  1.0
  Fe  Fe7  1  0.152  0.079  0.382  1.0
  Fe  Fe8  1  0.107  0.288  0.667  1.0
  Fe  Fe9  1  0.607  0.712  0.833  1.0
  Fe  Fe10  1  0.893  0.712  0.333  1.0
  Fe  Fe11  1  0.393  0.288  0.167  1.0
  P  P12  1  0.826  0.035  0.827  1.0
  P  P13  1  0.326  0.965  0.673  1.0
  P  P14  1  0.174  0.965  0.173  1.0
  P  P15  1  0.674  0.035  0.327  1.0
  P  P16  1  0.145  0.422  0.380  1.0
  P  P17  1  0.645  0.578  0.120  1.0
  P  P18  1  0.855  0.578  0.620  1.0
  P  P19  1  0.355  0.422  0.880  1.0
  O  O20  1  0.787  0.107  0.676  1.0
  O  O21  1  0.287  0.893  0.824  1.0
  O  O22  1  0.213  0.893  0.324  1.0
  O  O23  1  0.713  0.107  0.176  1.0
  O  O24  1  0.008  0.111  0.859  1.0
  O  O25  1  0.508  0.889  0.641  1.0
  O  O26  1  0.992  0.889  0.141  1.0
  O  O27  1  0.492  0.111  0.359  1.0
  O  O28  1  0.347  0.135  0.645  1.0
  O  O29  1  0.847  0.865  0.855  1.0
  O  O30  1  0.653  0.865  0.355  1.0
  O  O31  1  0.153  0.135  0.145  1.0
  O  O32  1  0.656  0.062  0.914  1.0
  O  O33  1  0.156  0.938  0.586  1.0
  O  O34  1  0.344  0.938  0.086  1.0
  O  O35  1  0.844  0.062  0.414  1.0
  O  O36  1  0.920  0.432  0.726  1.0
  O  O37  1  0.420  0.568  0.774  1.0
  O  O38  1  0.080  0.568  0.274  1.0
  O  O39  1  0.580  0.432  0.226  1.0
  O  O40  1  0.314  0.449  0.464  1.0
  O  O41  1  0.814  0.551  0.036  1.0
  O  O42  1  0.686  0.551  0.536  1.0
  O  O43  1  0.186  0.449  0.964  1.0
  O  O44  1  0.983  0.345  0.481  1.0
  O  O45  1  0.483  0.655  0.019  1.0
  O  O46  1  0.017  0.655  0.519  1.0
  O  O47  1  0.517  0.345  0.981  1.0
  O  O48  1  0.303  0.307  0.810  1.0
  O  O49  1  0.803  0.693  0.690  1.0
  O  O50  1  0.697  0.693  0.190  1.0
  O  O51  1  0.197  0.307  0.310  1.0
[/CIF]
.