The compound described by Ti2Fe4O9 is Ilmenite-like structured and crystallizes in the monoclinic Cc space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted TiO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, corners with three equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-59°. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(9) atom to form distorted TiO6 octahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-64°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(9) atom to form distorted FeO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(4)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and  a faceface with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-64°. In the second Fe site, Fe(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form distorted FeO6 octahedra that share  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(4)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and  a faceface with one Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-59°. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(4), one O(7), one O(8), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and  a faceface with one Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-65°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(4), one O(7), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra,  an edgeedge with one Ti(2)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and  a faceface with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-65°. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a distorted see-saw-like geometry to one Ti(1), one Fe(1), one Fe(3), and one Fe(4) atom. In the second O site, O(8) is bonded to one Ti(1), one Fe(2), one Fe(3), and one Fe(4) atom to form distorted OTiFe3 trigonal pyramids that share corners with two equivalent O(6)Ti2Fe2 trigonal pyramids and corners with two equivalent O(3)TiFe3 trigonal pyramids. In the third O site, O(9) is bonded in a distorted see-saw-like geometry to one Ti(2), one Fe(1), one Fe(3), and one Fe(4) atom. In the fourth O site, O(1) is bonded in a distorted see-saw-like geometry to one Ti(2), one Fe(1), one Fe(3), and one Fe(4) atom. In the fifth O site, O(2) is bonded in a distorted see-saw-like geometry to one Ti(1), one Ti(2), one Fe(2), and one Fe(4) atom. In the sixth O site, O(3) is bonded to one Ti(2), one Fe(1), one Fe(2), and one Fe(3) atom to form distorted OTiFe3 trigonal pyramids that share  a cornercorner with one O(6)Ti2Fe2 trigonal pyramid, corners with two equivalent O(8)TiFe3 trigonal pyramids, and  an edgeedge with one O(6)Ti2Fe2 trigonal pyramid. In the seventh O site, O(4) is bonded in a see-saw-like geometry to one Ti(1), one Fe(2), one Fe(3), and one Fe(4) atom. In the eighth O site, O(5) is bonded in a distorted see-saw-like geometry to one Ti(1), one Ti(2), one Fe(1), and one Fe(2) atom. In the ninth O site, O(6) is bonded to one Ti(1), one Ti(2), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner and edge-sharing OTi2Fe2 trigonal pyramids. is represented by the CIF card [CIF]
data_Ti2Fe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.519
_cell_length_b   5.519
_cell_length_c   12.906
_cell_angle_alpha   86.882
_cell_angle_beta   86.882
_cell_angle_gamma   55.773
_symmetry_Int_Tables_number   1
_cell_volume   324.352
_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
  Ti  Ti0  1  0.197  0.188  0.545  1.0
  Ti  Ti1  1  0.188  0.197  0.045  1.0
  Ti  Ti2  1  0.856  0.866  0.722  1.0
  Ti  Ti3  1  0.866  0.856  0.222  1.0
  Fe  Fe4  1  0.136  0.146  0.783  1.0
  Fe  Fe5  1  0.472  0.472  0.618  1.0
  Fe  Fe6  1  0.146  0.136  0.283  1.0
  Fe  Fe7  1  0.472  0.472  0.118  1.0
  Fe  Fe8  1  0.528  0.532  0.881  1.0
  Fe  Fe9  1  0.812  0.811  0.953  1.0
  Fe  Fe10  1  0.532  0.528  0.381  1.0
  Fe  Fe11  1  0.811  0.812  0.453  1.0
  O  O12  1  0.787  0.113  0.343  1.0
  O  O13  1  0.631  0.031  0.597  1.0
  O  O14  1  0.685  0.303  0.751  1.0
  O  O15  1  0.507  0.257  0.983  1.0
  O  O16  1  0.466  0.111  0.180  1.0
  O  O17  1  0.111  0.466  0.680  1.0
  O  O18  1  0.257  0.507  0.483  1.0
  O  O19  1  0.907  0.203  0.139  1.0
  O  O20  1  0.968  0.351  0.928  1.0
  O  O21  1  0.303  0.685  0.251  1.0
  O  O22  1  0.031  0.631  0.097  1.0
  O  O23  1  0.113  0.787  0.843  1.0
  O  O24  1  0.791  0.435  0.520  1.0
  O  O25  1  0.848  0.589  0.308  1.0
  O  O26  1  0.589  0.848  0.808  1.0
  O  O27  1  0.435  0.791  0.020  1.0
  O  O28  1  0.351  0.968  0.428  1.0
  O  O29  1  0.203  0.907  0.639  1.0
[/CIF]
.
The compound described by Ti2Fe4O9 is Ilmenite-like structured and crystallizes in the monoclinic Cc space group. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted TiO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, corners with three equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra, edges with two equivalent Fe(4)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-59°. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(9) atom to form distorted TiO6 octahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-64°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(5), one O(6), one O(7), and one O(9) atom to form distorted FeO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(4)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and  a faceface with one Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-64°. In the second Fe site, Fe(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form distorted FeO6 octahedra that share  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(4)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and  a faceface with one Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-59°. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(4), one O(7), one O(8), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and  a faceface with one Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-65°. In the fourth Fe site, Fe(4) is bonded to one O(1), one O(2), one O(4), one O(7), one O(8), and one O(9) atom to form distorted FeO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra,  an edgeedge with one Ti(2)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and  a faceface with one Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-65°. There are nine inequivalent O sites. In the first O site, O(7) is bonded in a distorted see-saw-like geometry to one Ti(1), one Fe(1), one Fe(3), and one Fe(4) atom. In the second O site, O(8) is bonded to one Ti(1), one Fe(2), one Fe(3), and one Fe(4) atom to form distorted OTiFe3 trigonal pyramids that share corners with two equivalent O(6)Ti2Fe2 trigonal pyramids and corners with two equivalent O(3)TiFe3 trigonal pyramids. In the third O site, O(9) is bonded in a distorted see-saw-like geometry to one Ti(2), one Fe(1), one Fe(3), and one Fe(4) atom. In the fourth O site, O(1) is bonded in a distorted see-saw-like geometry to one Ti(2), one Fe(1), one Fe(3), and one Fe(4) atom. In the fifth O site, O(2) is bonded in a distorted see-saw-like geometry to one Ti(1), one Ti(2), one Fe(2), and one Fe(4) atom. In the sixth O site, O(3) is bonded to one Ti(2), one Fe(1), one Fe(2), and one Fe(3) atom to form distorted OTiFe3 trigonal pyramids that share  a cornercorner with one O(6)Ti2Fe2 trigonal pyramid, corners with two equivalent O(8)TiFe3 trigonal pyramids, and  an edgeedge with one O(6)Ti2Fe2 trigonal pyramid. In the seventh O site, O(4) is bonded in a see-saw-like geometry to one Ti(1), one Fe(2), one Fe(3), and one Fe(4) atom. In the eighth O site, O(5) is bonded in a distorted see-saw-like geometry to one Ti(1), one Ti(2), one Fe(1), and one Fe(2) atom. In the ninth O site, O(6) is bonded to one Ti(1), one Ti(2), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner and edge-sharing OTi2Fe2 trigonal pyramids. is represented by the CIF card [CIF]
data_Ti2Fe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.519
_cell_length_b   5.519
_cell_length_c   12.906
_cell_angle_alpha   86.882
_cell_angle_beta   86.882
_cell_angle_gamma   55.773
_symmetry_Int_Tables_number   1
_cell_volume   324.352
_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
  Ti  Ti0  1  0.197  0.188  0.545  1.0
  Ti  Ti1  1  0.188  0.197  0.045  1.0
  Ti  Ti2  1  0.856  0.866  0.722  1.0
  Ti  Ti3  1  0.866  0.856  0.222  1.0
  Fe  Fe4  1  0.136  0.146  0.783  1.0
  Fe  Fe5  1  0.472  0.472  0.618  1.0
  Fe  Fe6  1  0.146  0.136  0.283  1.0
  Fe  Fe7  1  0.472  0.472  0.118  1.0
  Fe  Fe8  1  0.528  0.532  0.881  1.0
  Fe  Fe9  1  0.812  0.811  0.953  1.0
  Fe  Fe10  1  0.532  0.528  0.381  1.0
  Fe  Fe11  1  0.811  0.812  0.453  1.0
  O  O12  1  0.787  0.113  0.343  1.0
  O  O13  1  0.631  0.031  0.597  1.0
  O  O14  1  0.685  0.303  0.751  1.0
  O  O15  1  0.507  0.257  0.983  1.0
  O  O16  1  0.466  0.111  0.180  1.0
  O  O17  1  0.111  0.466  0.680  1.0
  O  O18  1  0.257  0.507  0.483  1.0
  O  O19  1  0.907  0.203  0.139  1.0
  O  O20  1  0.968  0.351  0.928  1.0
  O  O21  1  0.303  0.685  0.251  1.0
  O  O22  1  0.031  0.631  0.097  1.0
  O  O23  1  0.113  0.787  0.843  1.0
  O  O24  1  0.791  0.435  0.520  1.0
  O  O25  1  0.848  0.589  0.308  1.0
  O  O26  1  0.589  0.848  0.808  1.0
  O  O27  1  0.435  0.791  0.020  1.0
  O  O28  1  0.351  0.968  0.428  1.0
  O  O29  1  0.203  0.907  0.639  1.0
[/CIF]
.