The material described by Fe2SiO4 is Ilmenite-like structured and crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-66°. 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 four equivalent Fe(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-66°. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-65°. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the second O site, O(2) is bonded to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom to form distorted corner-sharing OFe3Si tetrahedra. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(3), two equivalent Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.820
_cell_length_b   6.057
_cell_length_c   10.377
_cell_angle_alpha   90.010
_cell_angle_beta   89.991
_cell_angle_gamma   90.110
_symmetry_Int_Tables_number   1
_cell_volume   302.975
_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
  Fe  Fe0  1  0.985  0.249  0.280  1.0
  Fe  Fe1  1  0.015  0.751  0.720  1.0
  Fe  Fe2  1  0.000  0.500  1.000  1.0
  Fe  Fe3  1  1.000  0.000  1.000  1.0
  Fe  Fe4  1  0.485  0.749  0.220  1.0
  Fe  Fe5  1  0.515  0.251  0.780  1.0
  Fe  Fe6  1  0.500  0.500  0.500  1.0
  Fe  Fe7  1  0.500  1.000  0.500  1.0
  Si  Si8  1  0.932  0.750  0.402  1.0
  Si  Si9  1  0.432  0.250  0.098  1.0
  Si  Si10  1  0.068  0.250  0.598  1.0
  Si  Si11  1  0.568  0.750  0.902  1.0
  O  O12  1  0.792  0.751  0.548  1.0
  O  O13  1  0.292  0.251  0.953  1.0
  O  O14  1  0.208  0.249  0.452  1.0
  O  O15  1  0.708  0.749  0.047  1.0
  O  O16  1  0.230  0.750  0.909  1.0
  O  O17  1  0.730  0.250  0.590  1.0
  O  O18  1  0.770  0.250  0.091  1.0
  O  O19  1  0.270  0.750  0.410  1.0
  O  O20  1  0.208  0.467  0.666  1.0
  O  O21  1  0.709  0.536  0.832  1.0
  O  O22  1  0.791  0.964  0.332  1.0
  O  O23  1  0.291  0.033  0.167  1.0
  O  O24  1  0.792  0.533  0.334  1.0
  O  O25  1  0.291  0.464  0.168  1.0
  O  O26  1  0.209  0.036  0.668  1.0
  O  O27  1  0.709  0.967  0.833  1.0
[/CIF]
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The material described by Fe2SiO4 is Ilmenite-like structured and crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-66°. 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 four equivalent Fe(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-66°. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-65°. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the second O site, O(2) is bonded to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom to form distorted corner-sharing OFe3Si tetrahedra. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(3), two equivalent Fe(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe2SiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.820
_cell_length_b   6.057
_cell_length_c   10.377
_cell_angle_alpha   90.010
_cell_angle_beta   89.991
_cell_angle_gamma   90.110
_symmetry_Int_Tables_number   1
_cell_volume   302.975
_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
  Fe  Fe0  1  0.985  0.249  0.280  1.0
  Fe  Fe1  1  0.015  0.751  0.720  1.0
  Fe  Fe2  1  0.000  0.500  1.000  1.0
  Fe  Fe3  1  1.000  0.000  1.000  1.0
  Fe  Fe4  1  0.485  0.749  0.220  1.0
  Fe  Fe5  1  0.515  0.251  0.780  1.0
  Fe  Fe6  1  0.500  0.500  0.500  1.0
  Fe  Fe7  1  0.500  1.000  0.500  1.0
  Si  Si8  1  0.932  0.750  0.402  1.0
  Si  Si9  1  0.432  0.250  0.098  1.0
  Si  Si10  1  0.068  0.250  0.598  1.0
  Si  Si11  1  0.568  0.750  0.902  1.0
  O  O12  1  0.792  0.751  0.548  1.0
  O  O13  1  0.292  0.251  0.953  1.0
  O  O14  1  0.208  0.249  0.452  1.0
  O  O15  1  0.708  0.749  0.047  1.0
  O  O16  1  0.230  0.750  0.909  1.0
  O  O17  1  0.730  0.250  0.590  1.0
  O  O18  1  0.770  0.250  0.091  1.0
  O  O19  1  0.270  0.750  0.410  1.0
  O  O20  1  0.208  0.467  0.666  1.0
  O  O21  1  0.709  0.536  0.832  1.0
  O  O22  1  0.791  0.964  0.332  1.0
  O  O23  1  0.291  0.033  0.167  1.0
  O  O24  1  0.792  0.533  0.334  1.0
  O  O25  1  0.291  0.464  0.168  1.0
  O  O26  1  0.209  0.036  0.668  1.0
  O  O27  1  0.709  0.967  0.833  1.0
[/CIF]
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