The crystal structure described by Pb3MgNb2O9 is Pb (Zr_0.50 Ti_0.48) O_3-derived structured and crystallizes in the monoclinic Cm space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-18°. Nb(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-21°. There are two inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(5) atom. In the second Pb site, Pb(2) is bonded in a 3-coordinate geometry to one O(5) and two equivalent O(2) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Nb(1), and one Pb(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Nb(1), one Pb(1), and one Pb(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Nb(1) and one Pb(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Nb(1) atoms. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Pb(2), and two equivalent Pb(1) atoms to form distorted corner-sharing OMg2Pb3 square pyramids. is represented by the CIF file [CIF]
data_MgNb2(PbO3)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.290
_cell_length_b   5.741
_cell_length_c   9.093
_cell_angle_alpha   71.602
_cell_angle_beta   89.831
_cell_angle_gamma   89.469
_symmetry_Int_Tables_number   1
_cell_volume   212.471
_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
  Mg  Mg0  1  0.468  0.484  0.005  1.0
  Nb  Nb1  1  0.451  0.827  0.344  1.0
  Nb  Nb2  1  0.451  0.166  0.667  1.0
  Pb  Pb3  1  0.918  0.633  0.717  1.0
  Pb  Pb4  1  0.920  0.344  0.293  1.0
  Pb  Pb5  1  0.906  0.938  0.006  1.0
  O  O6  1  0.517  0.339  0.821  1.0
  O  O7  1  0.533  0.672  0.177  1.0
  O  O8  1  0.530  0.968  0.516  1.0
  O  O9  1  0.533  0.845  0.834  1.0
  O  O10  1  0.530  0.479  0.495  1.0
  O  O11  1  0.517  0.154  0.190  1.0
  O  O12  1  0.018  0.159  0.671  1.0
  O  O13  1  0.018  0.824  0.341  1.0
  O  O14  1  0.992  0.522  0.006  1.0
[/CIF]
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The crystal structure described by Pb3MgNb2O9 is Pb (Zr_0.50 Ti_0.48) O_3-derived structured and crystallizes in the monoclinic Cm space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 12-18°. Nb(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-21°. There are two inequivalent Pb sites. In the first Pb site, Pb(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(5) atom. In the second Pb site, Pb(2) is bonded in a 3-coordinate geometry to one O(5) and two equivalent O(2) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Nb(1), and one Pb(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Nb(1), one Pb(1), and one Pb(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Nb(1) and one Pb(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Nb(1) atoms. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Pb(2), and two equivalent Pb(1) atoms to form distorted corner-sharing OMg2Pb3 square pyramids. is represented by the CIF file [CIF]
data_MgNb2(PbO3)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.290
_cell_length_b   5.741
_cell_length_c   9.093
_cell_angle_alpha   71.602
_cell_angle_beta   89.831
_cell_angle_gamma   89.469
_symmetry_Int_Tables_number   1
_cell_volume   212.471
_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
  Mg  Mg0  1  0.468  0.484  0.005  1.0
  Nb  Nb1  1  0.451  0.827  0.344  1.0
  Nb  Nb2  1  0.451  0.166  0.667  1.0
  Pb  Pb3  1  0.918  0.633  0.717  1.0
  Pb  Pb4  1  0.920  0.344  0.293  1.0
  Pb  Pb5  1  0.906  0.938  0.006  1.0
  O  O6  1  0.517  0.339  0.821  1.0
  O  O7  1  0.533  0.672  0.177  1.0
  O  O8  1  0.530  0.968  0.516  1.0
  O  O9  1  0.533  0.845  0.834  1.0
  O  O10  1  0.530  0.479  0.495  1.0
  O  O11  1  0.517  0.154  0.190  1.0
  O  O12  1  0.018  0.159  0.671  1.0
  O  O13  1  0.018  0.824  0.341  1.0
  O  O14  1  0.992  0.522  0.006  1.0
[/CIF]
.