The structure described by Zn4Nb2O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Nb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NbO6 pentagonal pyramids that share corners with six equivalent Zn(1)O6 octahedra and  a faceface with one Nb(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 48-57°. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to six equivalent O(2) atoms to form ZnO6 octahedra that share corners with six equivalent Nb(1)O6 pentagonal pyramids and edges with three equivalent Zn(1)O6 octahedra. In the second Zn site, Zn(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nb(1) and two equivalent Zn(2) atoms to form a mixture of distorted corner and edge-sharing ONb2Zn2 trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Nb(1), one Zn(2), and two equivalent Zn(1) atoms. is represented by the CIF file [CIF]
data_Nb2Zn4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.260
_cell_length_b   5.260
_cell_length_c   14.382
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   344.665
_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
  Nb  Nb0  1  0.000  0.000  0.361  1.0
  Nb  Nb1  1  0.000  0.000  0.139  1.0
  Nb  Nb2  1  0.000  0.000  0.639  1.0
  Nb  Nb3  1  0.000  0.000  0.861  1.0
  Zn  Zn4  1  0.333  0.667  0.014  1.0
  Zn  Zn5  1  0.667  0.333  0.486  1.0
  Zn  Zn6  1  0.667  0.333  0.986  1.0
  Zn  Zn7  1  0.333  0.667  0.514  1.0
  Zn  Zn8  1  0.333  0.667  0.795  1.0
  Zn  Zn9  1  0.667  0.333  0.705  1.0
  Zn  Zn10  1  0.667  0.333  0.205  1.0
  Zn  Zn11  1  0.333  0.667  0.295  1.0
  O  O12  1  0.286  0.286  0.750  1.0
  O  O13  1  0.000  0.714  0.750  1.0
  O  O14  1  0.714  0.000  0.750  1.0
  O  O15  1  0.714  0.714  0.250  1.0
  O  O16  1  0.000  0.286  0.250  1.0
  O  O17  1  0.286  0.000  0.250  1.0
  O  O18  1  0.680  0.660  0.584  1.0
  O  O19  1  0.340  0.020  0.584  1.0
  O  O20  1  0.980  0.320  0.584  1.0
  O  O21  1  0.020  0.340  0.916  1.0
  O  O22  1  0.320  0.980  0.916  1.0
  O  O23  1  0.660  0.680  0.916  1.0
  O  O24  1  0.340  0.320  0.084  1.0
  O  O25  1  0.680  0.020  0.084  1.0
  O  O26  1  0.980  0.660  0.084  1.0
  O  O27  1  0.020  0.680  0.416  1.0
  O  O28  1  0.660  0.980  0.416  1.0
  O  O29  1  0.320  0.340  0.416  1.0
[/CIF]
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The structure described by Zn4Nb2O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. Nb(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NbO6 pentagonal pyramids that share corners with six equivalent Zn(1)O6 octahedra and  a faceface with one Nb(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 48-57°. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to six equivalent O(2) atoms to form ZnO6 octahedra that share corners with six equivalent Nb(1)O6 pentagonal pyramids and edges with three equivalent Zn(1)O6 octahedra. In the second Zn site, Zn(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Nb(1) and two equivalent Zn(2) atoms to form a mixture of distorted corner and edge-sharing ONb2Zn2 trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Nb(1), one Zn(2), and two equivalent Zn(1) atoms. is represented by the CIF file [CIF]
data_Nb2Zn4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.260
_cell_length_b   5.260
_cell_length_c   14.382
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   344.665
_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
  Nb  Nb0  1  0.000  0.000  0.361  1.0
  Nb  Nb1  1  0.000  0.000  0.139  1.0
  Nb  Nb2  1  0.000  0.000  0.639  1.0
  Nb  Nb3  1  0.000  0.000  0.861  1.0
  Zn  Zn4  1  0.333  0.667  0.014  1.0
  Zn  Zn5  1  0.667  0.333  0.486  1.0
  Zn  Zn6  1  0.667  0.333  0.986  1.0
  Zn  Zn7  1  0.333  0.667  0.514  1.0
  Zn  Zn8  1  0.333  0.667  0.795  1.0
  Zn  Zn9  1  0.667  0.333  0.705  1.0
  Zn  Zn10  1  0.667  0.333  0.205  1.0
  Zn  Zn11  1  0.333  0.667  0.295  1.0
  O  O12  1  0.286  0.286  0.750  1.0
  O  O13  1  0.000  0.714  0.750  1.0
  O  O14  1  0.714  0.000  0.750  1.0
  O  O15  1  0.714  0.714  0.250  1.0
  O  O16  1  0.000  0.286  0.250  1.0
  O  O17  1  0.286  0.000  0.250  1.0
  O  O18  1  0.680  0.660  0.584  1.0
  O  O19  1  0.340  0.020  0.584  1.0
  O  O20  1  0.980  0.320  0.584  1.0
  O  O21  1  0.020  0.340  0.916  1.0
  O  O22  1  0.320  0.980  0.916  1.0
  O  O23  1  0.660  0.680  0.916  1.0
  O  O24  1  0.340  0.320  0.084  1.0
  O  O25  1  0.680  0.020  0.084  1.0
  O  O26  1  0.980  0.660  0.084  1.0
  O  O27  1  0.020  0.680  0.416  1.0
  O  O28  1  0.660  0.980  0.416  1.0
  O  O29  1  0.320  0.340  0.416  1.0
[/CIF]
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