The compound described by Fe2Zn3(Si2O7)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Zn(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Zn(2)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Zn(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Zn(1)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one O(1), one O(2), and two equivalent O(7) atoms to form distorted ZnO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Zn(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Zn(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-77°. In the second Zn site, Zn(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted ZnO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Zn(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Zn(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-57°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Zn(1)O4 tetrahedra, corners with two equivalent Zn(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 63-71°. There are seven inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), one Zn(1), one Zn(2), and one Si(2) atom to form distorted corner-sharing OZn2FeSi tetrahedra. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Zn(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Fe(1), one Zn(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Zn(1) and one Si(1) atom. is represented by the CIF file [CIF]
data_Zn3Fe2(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.117
_cell_length_b   9.117
_cell_length_c   9.895
_cell_angle_alpha   60.963
_cell_angle_beta   60.963
_cell_angle_gamma   50.692
_symmetry_Int_Tables_number   1
_cell_volume   536.745
_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
  Zn  Zn0  1  0.058  0.280  0.098  1.0
  Zn  Zn1  1  0.720  0.942  0.402  1.0
  Zn  Zn2  1  0.280  0.058  0.598  1.0
  Zn  Zn3  1  0.394  0.606  0.750  1.0
  Zn  Zn4  1  0.942  0.720  0.902  1.0
  Zn  Zn5  1  0.606  0.394  0.250  1.0
  Fe  Fe6  1  0.794  0.206  0.750  1.0
  Fe  Fe7  1  0.206  0.794  0.250  1.0
  Fe  Fe8  1  0.000  0.000  0.000  1.0
  Fe  Fe9  1  0.000  0.000  0.500  1.0
  Si  Si10  1  0.531  0.101  0.709  1.0
  Si  Si11  1  0.101  0.531  0.209  1.0
  Si  Si12  1  0.518  0.242  0.103  1.0
  Si  Si13  1  0.242  0.518  0.603  1.0
  Si  Si14  1  0.899  0.469  0.791  1.0
  Si  Si15  1  0.482  0.758  0.897  1.0
  Si  Si16  1  0.758  0.482  0.397  1.0
  Si  Si17  1  0.469  0.899  0.291  1.0
  O  O18  1  0.834  0.300  0.330  1.0
  O  O19  1  0.957  0.883  0.417  1.0
  O  O20  1  0.459  0.639  0.087  1.0
  O  O21  1  0.883  0.957  0.917  1.0
  O  O22  1  0.252  0.944  0.323  1.0
  O  O23  1  0.059  0.505  0.626  1.0
  O  O24  1  0.639  0.459  0.587  1.0
  O  O25  1  0.056  0.748  0.177  1.0
  O  O26  1  0.941  0.495  0.374  1.0
  O  O27  1  0.634  0.676  0.267  1.0
  O  O28  1  0.043  0.117  0.583  1.0
  O  O29  1  0.748  0.056  0.677  1.0
  O  O30  1  0.495  0.941  0.874  1.0
  O  O31  1  0.300  0.834  0.830  1.0
  O  O32  1  0.676  0.634  0.767  1.0
  O  O33  1  0.944  0.252  0.823  1.0
  O  O34  1  0.904  0.506  0.934  1.0
  O  O35  1  0.366  0.324  0.733  1.0
  O  O36  1  0.494  0.096  0.566  1.0
  O  O37  1  0.324  0.366  0.233  1.0
  O  O38  1  0.505  0.059  0.126  1.0
  O  O39  1  0.117  0.043  0.083  1.0
  O  O40  1  0.506  0.904  0.434  1.0
  O  O41  1  0.541  0.361  0.913  1.0
  O  O42  1  0.096  0.494  0.066  1.0
  O  O43  1  0.361  0.541  0.413  1.0
  O  O44  1  0.700  0.166  0.170  1.0
  O  O45  1  0.166  0.700  0.670  1.0
[/CIF]
.
The compound described by Fe2Zn3(Si2O7)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Zn(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Zn(2)O4 tetrahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Zn(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Zn(1)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one O(1), one O(2), and two equivalent O(7) atoms to form distorted ZnO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Zn(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Zn(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-77°. In the second Zn site, Zn(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form distorted ZnO4 tetrahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Zn(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Zn(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-57°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Zn(1)O4 tetrahedra, corners with two equivalent Zn(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 63-71°. There are seven inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), one Zn(1), one Zn(2), and one Si(2) atom to form distorted corner-sharing OZn2FeSi tetrahedra. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1), one Fe(2), and one Zn(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Fe(1), one Zn(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to two equivalent Zn(1) and one Si(1) atom. is represented by the CIF file [CIF]
data_Zn3Fe2(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.117
_cell_length_b   9.117
_cell_length_c   9.895
_cell_angle_alpha   60.963
_cell_angle_beta   60.963
_cell_angle_gamma   50.692
_symmetry_Int_Tables_number   1
_cell_volume   536.745
_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
  Zn  Zn0  1  0.058  0.280  0.098  1.0
  Zn  Zn1  1  0.720  0.942  0.402  1.0
  Zn  Zn2  1  0.280  0.058  0.598  1.0
  Zn  Zn3  1  0.394  0.606  0.750  1.0
  Zn  Zn4  1  0.942  0.720  0.902  1.0
  Zn  Zn5  1  0.606  0.394  0.250  1.0
  Fe  Fe6  1  0.794  0.206  0.750  1.0
  Fe  Fe7  1  0.206  0.794  0.250  1.0
  Fe  Fe8  1  0.000  0.000  0.000  1.0
  Fe  Fe9  1  0.000  0.000  0.500  1.0
  Si  Si10  1  0.531  0.101  0.709  1.0
  Si  Si11  1  0.101  0.531  0.209  1.0
  Si  Si12  1  0.518  0.242  0.103  1.0
  Si  Si13  1  0.242  0.518  0.603  1.0
  Si  Si14  1  0.899  0.469  0.791  1.0
  Si  Si15  1  0.482  0.758  0.897  1.0
  Si  Si16  1  0.758  0.482  0.397  1.0
  Si  Si17  1  0.469  0.899  0.291  1.0
  O  O18  1  0.834  0.300  0.330  1.0
  O  O19  1  0.957  0.883  0.417  1.0
  O  O20  1  0.459  0.639  0.087  1.0
  O  O21  1  0.883  0.957  0.917  1.0
  O  O22  1  0.252  0.944  0.323  1.0
  O  O23  1  0.059  0.505  0.626  1.0
  O  O24  1  0.639  0.459  0.587  1.0
  O  O25  1  0.056  0.748  0.177  1.0
  O  O26  1  0.941  0.495  0.374  1.0
  O  O27  1  0.634  0.676  0.267  1.0
  O  O28  1  0.043  0.117  0.583  1.0
  O  O29  1  0.748  0.056  0.677  1.0
  O  O30  1  0.495  0.941  0.874  1.0
  O  O31  1  0.300  0.834  0.830  1.0
  O  O32  1  0.676  0.634  0.767  1.0
  O  O33  1  0.944  0.252  0.823  1.0
  O  O34  1  0.904  0.506  0.934  1.0
  O  O35  1  0.366  0.324  0.733  1.0
  O  O36  1  0.494  0.096  0.566  1.0
  O  O37  1  0.324  0.366  0.233  1.0
  O  O38  1  0.505  0.059  0.126  1.0
  O  O39  1  0.117  0.043  0.083  1.0
  O  O40  1  0.506  0.904  0.434  1.0
  O  O41  1  0.541  0.361  0.913  1.0
  O  O42  1  0.096  0.494  0.066  1.0
  O  O43  1  0.361  0.541  0.413  1.0
  O  O44  1  0.700  0.166  0.170  1.0
  O  O45  1  0.166  0.700  0.670  1.0
[/CIF]
.