The material described by Sr3CuNb2O9 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 12-coordinate geometry to one O(1), two equivalent O(4), three equivalent O(2), and six equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded to two equivalent O(1), two equivalent O(2), four equivalent O(3), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with six equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Cu(1)O6 octahedra, and faces with six equivalent Nb(1)O6 octahedra. Nb(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, and faces with three equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-17°. Cu(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CuO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra and faces with two equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 13-17°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Nb(1) atoms to form distorted corner-sharing OSr4Nb2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Sr(2), three equivalent Sr(1), one Nb(1), and one Cu(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Sr(2), three equivalent Sr(1), one Nb(1), and one Cu(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Nb(1) atoms. is represented by the CIF file [CIF]
data_Sr3Nb2CuO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.832
_cell_length_b   5.832
_cell_length_c   7.100
_cell_angle_alpha   86.313
_cell_angle_beta   86.313
_cell_angle_gamma   57.490
_symmetry_Int_Tables_number   1
_cell_volume   203.115
_cell_formula_units_Z   1
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
  Sr  Sr0  1  0.833  0.833  0.327  1.0
  Sr  Sr1  1  0.500  0.500  0.000  1.0
  Sr  Sr2  1  0.167  0.167  0.673  1.0
  Nb  Nb3  1  0.844  0.844  0.819  1.0
  Nb  Nb4  1  0.156  0.156  0.181  1.0
  Cu  Cu5  1  0.500  0.500  0.500  1.0
  O  O6  1  0.000  0.000  0.000  1.0
  O  O7  1  0.706  0.706  0.650  1.0
  O  O8  1  0.294  0.294  0.350  1.0
  O  O9  1  0.802  0.313  0.314  1.0
  O  O10  1  0.500  0.000  0.000  1.0
  O  O11  1  0.198  0.687  0.686  1.0
  O  O12  1  0.313  0.802  0.314  1.0
  O  O13  1  0.000  0.500  0.000  1.0
  O  O14  1  0.687  0.198  0.686  1.0
[/CIF]
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The material described by Sr3CuNb2O9 crystallizes in the monoclinic C2/m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 12-coordinate geometry to one O(1), two equivalent O(4), three equivalent O(2), and six equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded to two equivalent O(1), two equivalent O(2), four equivalent O(3), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with six equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Cu(1)O6 octahedra, and faces with six equivalent Nb(1)O6 octahedra. Nb(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Cu(1)O6 octahedra, and faces with three equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-17°. Cu(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form CuO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra and faces with two equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 13-17°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Nb(1) atoms to form distorted corner-sharing OSr4Nb2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Sr(2), three equivalent Sr(1), one Nb(1), and one Cu(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Sr(2), three equivalent Sr(1), one Nb(1), and one Cu(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Nb(1) atoms. is represented by the CIF file [CIF]
data_Sr3Nb2CuO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.832
_cell_length_b   5.832
_cell_length_c   7.100
_cell_angle_alpha   86.313
_cell_angle_beta   86.313
_cell_angle_gamma   57.490
_symmetry_Int_Tables_number   1
_cell_volume   203.115
_cell_formula_units_Z   1
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
  Sr  Sr0  1  0.833  0.833  0.327  1.0
  Sr  Sr1  1  0.500  0.500  0.000  1.0
  Sr  Sr2  1  0.167  0.167  0.673  1.0
  Nb  Nb3  1  0.844  0.844  0.819  1.0
  Nb  Nb4  1  0.156  0.156  0.181  1.0
  Cu  Cu5  1  0.500  0.500  0.500  1.0
  O  O6  1  0.000  0.000  0.000  1.0
  O  O7  1  0.706  0.706  0.650  1.0
  O  O8  1  0.294  0.294  0.350  1.0
  O  O9  1  0.802  0.313  0.314  1.0
  O  O10  1  0.500  0.000  0.000  1.0
  O  O11  1  0.198  0.687  0.686  1.0
  O  O12  1  0.313  0.802  0.314  1.0
  O  O13  1  0.000  0.500  0.000  1.0
  O  O14  1  0.687  0.198  0.686  1.0
[/CIF]
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