The crystal structure described by Fe4Ta2O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Ta(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted TaO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with six equivalent Fe(1)O6 octahedra, edges with three equivalent Fe(2)O6 octahedra, and  a faceface with one Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to six equivalent O(1) atoms to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with six equivalent Ta(1)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-68°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ta(1), one Fe(2), and two equivalent Fe(1) atoms to form distorted OTaFe3 trigonal pyramids that share corners with four equivalent O(2)Ta2Fe2 trigonal pyramids, corners with eight equivalent O(1)TaFe3 trigonal pyramids,  an edgeedge with one O(2)Ta2Fe2 trigonal pyramid, and edges with three equivalent O(1)TaFe3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Ta(1) and two equivalent Fe(2) atoms to form distorted OTa2Fe2 trigonal pyramids that share corners with four equivalent O(2)Ta2Fe2 trigonal pyramids, corners with eight equivalent O(1)TaFe3 trigonal pyramids, edges with two equivalent O(2)Ta2Fe2 trigonal pyramids, and edges with two equivalent O(1)TaFe3 trigonal pyramids. is represented by the CIF card [CIF]
data_Ta2Fe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.335
_cell_length_b   5.335
_cell_length_c   14.245
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   351.142
_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
  Ta  Ta0  1  0.000  0.000  0.642  1.0
  Ta  Ta1  1  0.000  0.000  0.358  1.0
  Ta  Ta2  1  0.000  0.000  0.858  1.0
  Ta  Ta3  1  0.000  0.000  0.142  1.0
  Fe  Fe4  1  0.333  0.667  0.516  1.0
  Fe  Fe5  1  0.667  0.333  0.484  1.0
  Fe  Fe6  1  0.667  0.333  0.984  1.0
  Fe  Fe7  1  0.333  0.667  0.016  1.0
  Fe  Fe8  1  0.333  0.667  0.808  1.0
  Fe  Fe9  1  0.667  0.333  0.192  1.0
  Fe  Fe10  1  0.667  0.333  0.692  1.0
  Fe  Fe11  1  0.333  0.667  0.308  1.0
  O  O12  1  0.336  0.312  0.584  1.0
  O  O13  1  0.664  0.688  0.416  1.0
  O  O14  1  0.688  0.024  0.584  1.0
  O  O15  1  0.312  0.336  0.916  1.0
  O  O16  1  0.312  0.976  0.416  1.0
  O  O17  1  0.688  0.664  0.084  1.0
  O  O18  1  0.976  0.664  0.584  1.0
  O  O19  1  0.024  0.688  0.916  1.0
  O  O20  1  0.024  0.336  0.416  1.0
  O  O21  1  0.976  0.312  0.084  1.0
  O  O22  1  0.664  0.976  0.916  1.0
  O  O23  1  0.336  0.024  0.084  1.0
  O  O24  1  0.280  0.000  0.750  1.0
  O  O25  1  0.720  0.000  0.250  1.0
  O  O26  1  0.000  0.280  0.750  1.0
  O  O27  1  0.000  0.720  0.250  1.0
  O  O28  1  0.720  0.720  0.750  1.0
  O  O29  1  0.280  0.280  0.250  1.0
[/CIF]
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The crystal structure described by Fe4Ta2O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Ta(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted TaO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with six equivalent Fe(1)O6 octahedra, edges with three equivalent Fe(2)O6 octahedra, and  a faceface with one Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to six equivalent O(1) atoms to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with six equivalent Ta(1)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted FeO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-68°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Ta(1), one Fe(2), and two equivalent Fe(1) atoms to form distorted OTaFe3 trigonal pyramids that share corners with four equivalent O(2)Ta2Fe2 trigonal pyramids, corners with eight equivalent O(1)TaFe3 trigonal pyramids,  an edgeedge with one O(2)Ta2Fe2 trigonal pyramid, and edges with three equivalent O(1)TaFe3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Ta(1) and two equivalent Fe(2) atoms to form distorted OTa2Fe2 trigonal pyramids that share corners with four equivalent O(2)Ta2Fe2 trigonal pyramids, corners with eight equivalent O(1)TaFe3 trigonal pyramids, edges with two equivalent O(2)Ta2Fe2 trigonal pyramids, and edges with two equivalent O(1)TaFe3 trigonal pyramids. is represented by the CIF card [CIF]
data_Ta2Fe4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.335
_cell_length_b   5.335
_cell_length_c   14.245
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   351.142
_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
  Ta  Ta0  1  0.000  0.000  0.642  1.0
  Ta  Ta1  1  0.000  0.000  0.358  1.0
  Ta  Ta2  1  0.000  0.000  0.858  1.0
  Ta  Ta3  1  0.000  0.000  0.142  1.0
  Fe  Fe4  1  0.333  0.667  0.516  1.0
  Fe  Fe5  1  0.667  0.333  0.484  1.0
  Fe  Fe6  1  0.667  0.333  0.984  1.0
  Fe  Fe7  1  0.333  0.667  0.016  1.0
  Fe  Fe8  1  0.333  0.667  0.808  1.0
  Fe  Fe9  1  0.667  0.333  0.192  1.0
  Fe  Fe10  1  0.667  0.333  0.692  1.0
  Fe  Fe11  1  0.333  0.667  0.308  1.0
  O  O12  1  0.336  0.312  0.584  1.0
  O  O13  1  0.664  0.688  0.416  1.0
  O  O14  1  0.688  0.024  0.584  1.0
  O  O15  1  0.312  0.336  0.916  1.0
  O  O16  1  0.312  0.976  0.416  1.0
  O  O17  1  0.688  0.664  0.084  1.0
  O  O18  1  0.976  0.664  0.584  1.0
  O  O19  1  0.024  0.688  0.916  1.0
  O  O20  1  0.024  0.336  0.416  1.0
  O  O21  1  0.976  0.312  0.084  1.0
  O  O22  1  0.664  0.976  0.916  1.0
  O  O23  1  0.336  0.024  0.084  1.0
  O  O24  1  0.280  0.000  0.750  1.0
  O  O25  1  0.720  0.000  0.250  1.0
  O  O26  1  0.000  0.280  0.750  1.0
  O  O27  1  0.000  0.720  0.250  1.0
  O  O28  1  0.720  0.720  0.750  1.0
  O  O29  1  0.280  0.280  0.250  1.0
[/CIF]
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