The compound described by LaNb3O9 crystallizes in the triclinic P1 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to one O(1), one O(11), one O(12), one O(13), one O(15), one O(2), one O(3), one O(4), one O(8), one O(9), and two equivalent O(5) atoms to form LaO12 cuboctahedra that share  a cornercorner with one La(2)O12 cuboctahedra, corners with two equivalent La(1)O12 cuboctahedra, faces with two equivalent La(2)O12 cuboctahedra,  a faceface with one Nb(1)O6 octahedra,  a faceface with one Nb(3)O6 octahedra,  a faceface with one Nb(5)O6 octahedra,  a faceface with one Nb(6)O6 octahedra, faces with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Nb(4)O6 octahedra. In the second La site, La(2) is bonded to one O(1), one O(10), one O(12), one O(13), one O(15), one O(16), one O(17), one O(18), one O(5), one O(8), and two equivalent O(4) atoms to form LaO12 cuboctahedra that share  a cornercorner with one La(1)O12 cuboctahedra, corners with two equivalent La(2)O12 cuboctahedra, faces with two equivalent La(1)O12 cuboctahedra,  a faceface with one Nb(1)O6 octahedra,  a faceface with one Nb(2)O6 octahedra,  a faceface with one Nb(4)O6 octahedra,  a faceface with one Nb(6)O6 octahedra, faces with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Nb(5)O6 octahedra. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(11), one O(17), one O(18), one O(7), and one O(9) atom to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(4)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and  a faceface with one La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-15°. In the second Nb site, Nb(2) is bonded to one O(12), one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Nb(6)O6 octahedra,  a faceface with one La(2)O12 cuboctahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the third Nb site, Nb(3) is bonded to one O(10), one O(12), one O(16), one O(4), one O(6), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(6)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and faces with two equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the fourth Nb site, Nb(4) is bonded to one O(11), one O(13), one O(15), one O(5), one O(6), and one O(9) atom to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra,  a faceface with one La(2)O12 cuboctahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-18°. In the fifth Nb site, Nb(5) is bonded to one O(13), one O(14), one O(15), one O(17), one O(18), and one O(4) atom to form distorted NbO6 octahedra that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(4)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and faces with two equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-18°. In the sixth Nb site, Nb(6) is bonded to one O(1), one O(10), one O(14), one O(16), one O(2), and one O(3) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and  a faceface with one La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-14°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one La(1), one La(2), one Nb(1), and one Nb(6) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one La(1), one Nb(2), and one Nb(6) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one La(1), one Nb(2), and one Nb(6) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Nb(3), and one Nb(5) atom. In the fifth O site, O(5) is bonded to one La(2), two equivalent La(1), one Nb(2), and one Nb(4) atom to form distorted corner-sharing OLa3Nb2 square pyramids. In the sixth O site, O(6) is bonded in a linear geometry to one Nb(3) and one Nb(4) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(2), and one Nb(3) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one La(1), one Nb(1), and one Nb(4) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one La(2), one Nb(3), and one Nb(6) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one La(1), one Nb(1), and one Nb(4) atom. In the twelfth O site, O(12) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(2), and one Nb(3) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(4), and one Nb(5) atom. In the fourteenth O site, O(14) is bonded in a linear geometry to one Nb(5) and one Nb(6) atom. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(4), and one Nb(5) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one La(2), one Nb(3), and one Nb(6) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one La(2), one Nb(1), and one Nb(5) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one La(2), one Nb(1), and one Nb(5) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_LaNb3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.621
_cell_length_b   8.890
_cell_length_c   8.965
_cell_angle_alpha   66.608
_cell_angle_beta   71.743
_cell_angle_gamma   71.603
_symmetry_Int_Tables_number   1
_cell_volume   380.973
_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
  La  La0  1  0.673  0.659  0.001  1.0
  La  La1  1  0.339  0.336  0.002  1.0
  Nb  Nb2  1  0.418  0.917  0.253  1.0
  Nb  Nb3  1  0.258  0.758  0.736  1.0
  Nb  Nb4  1  0.930  0.408  0.744  1.0
  Nb  Nb5  1  0.077  0.590  0.260  1.0
  Nb  Nb6  1  0.750  0.240  0.268  1.0
  Nb  Nb7  1  0.592  0.078  0.751  1.0
  O  O8  1  0.500  0.999  0.000  1.0
  O  O9  1  0.904  0.904  0.771  1.0
  O  O10  1  0.422  0.906  0.766  1.0
  O  O11  1  0.823  0.352  0.998  1.0
  O  O12  1  0.172  0.652  0.002  1.0
  O  O13  1  0.996  0.503  0.501  1.0
  O  O14  1  0.332  0.833  0.498  1.0
  O  O15  1  0.571  0.577  0.777  1.0
  O  O16  1  0.749  0.749  0.234  1.0
  O  O17  1  0.730  0.253  0.767  1.0
  O  O18  1  0.269  0.749  0.235  1.0
  O  O19  1  0.071  0.579  0.775  1.0
  O  O20  1  0.925  0.425  0.225  1.0
  O  O21  1  0.664  0.167  0.503  1.0
  O  O22  1  0.426  0.425  0.225  1.0
  O  O23  1  0.251  0.253  0.771  1.0
  O  O24  1  0.580  0.097  0.231  1.0
  O  O25  1  0.097  0.099  0.231  1.0
[/CIF]
.
The compound described by LaNb3O9 crystallizes in the triclinic P1 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to one O(1), one O(11), one O(12), one O(13), one O(15), one O(2), one O(3), one O(4), one O(8), one O(9), and two equivalent O(5) atoms to form LaO12 cuboctahedra that share  a cornercorner with one La(2)O12 cuboctahedra, corners with two equivalent La(1)O12 cuboctahedra, faces with two equivalent La(2)O12 cuboctahedra,  a faceface with one Nb(1)O6 octahedra,  a faceface with one Nb(3)O6 octahedra,  a faceface with one Nb(5)O6 octahedra,  a faceface with one Nb(6)O6 octahedra, faces with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Nb(4)O6 octahedra. In the second La site, La(2) is bonded to one O(1), one O(10), one O(12), one O(13), one O(15), one O(16), one O(17), one O(18), one O(5), one O(8), and two equivalent O(4) atoms to form LaO12 cuboctahedra that share  a cornercorner with one La(1)O12 cuboctahedra, corners with two equivalent La(2)O12 cuboctahedra, faces with two equivalent La(1)O12 cuboctahedra,  a faceface with one Nb(1)O6 octahedra,  a faceface with one Nb(2)O6 octahedra,  a faceface with one Nb(4)O6 octahedra,  a faceface with one Nb(6)O6 octahedra, faces with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Nb(5)O6 octahedra. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(11), one O(17), one O(18), one O(7), and one O(9) atom to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(4)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and  a faceface with one La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-15°. In the second Nb site, Nb(2) is bonded to one O(12), one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Nb(6)O6 octahedra,  a faceface with one La(2)O12 cuboctahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the third Nb site, Nb(3) is bonded to one O(10), one O(12), one O(16), one O(4), one O(6), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(4)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(6)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and faces with two equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the fourth Nb site, Nb(4) is bonded to one O(11), one O(13), one O(15), one O(5), one O(6), and one O(9) atom to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra,  a faceface with one La(2)O12 cuboctahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-18°. In the fifth Nb site, Nb(5) is bonded to one O(13), one O(14), one O(15), one O(17), one O(18), and one O(4) atom to form distorted NbO6 octahedra that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(4)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and faces with two equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-18°. In the sixth Nb site, Nb(6) is bonded to one O(1), one O(10), one O(14), one O(16), one O(2), and one O(3) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra,  a faceface with one La(1)O12 cuboctahedra, and  a faceface with one La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-14°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one La(1), one La(2), one Nb(1), and one Nb(6) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one La(1), one Nb(2), and one Nb(6) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one La(1), one Nb(2), and one Nb(6) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one La(1), two equivalent La(2), one Nb(3), and one Nb(5) atom. In the fifth O site, O(5) is bonded to one La(2), two equivalent La(1), one Nb(2), and one Nb(4) atom to form distorted corner-sharing OLa3Nb2 square pyramids. In the sixth O site, O(6) is bonded in a linear geometry to one Nb(3) and one Nb(4) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(2), and one Nb(3) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one La(1), one Nb(1), and one Nb(4) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one La(2), one Nb(3), and one Nb(6) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one La(1), one Nb(1), and one Nb(4) atom. In the twelfth O site, O(12) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(2), and one Nb(3) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(4), and one Nb(5) atom. In the fourteenth O site, O(14) is bonded in a linear geometry to one Nb(5) and one Nb(6) atom. In the fifteenth O site, O(15) is bonded in a distorted rectangular see-saw-like geometry to one La(1), one La(2), one Nb(4), and one Nb(5) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one La(2), one Nb(3), and one Nb(6) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one La(2), one Nb(1), and one Nb(5) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one La(2), one Nb(1), and one Nb(5) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_LaNb3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.621
_cell_length_b   8.890
_cell_length_c   8.965
_cell_angle_alpha   66.608
_cell_angle_beta   71.743
_cell_angle_gamma   71.603
_symmetry_Int_Tables_number   1
_cell_volume   380.973
_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
  La  La0  1  0.673  0.659  0.001  1.0
  La  La1  1  0.339  0.336  0.002  1.0
  Nb  Nb2  1  0.418  0.917  0.253  1.0
  Nb  Nb3  1  0.258  0.758  0.736  1.0
  Nb  Nb4  1  0.930  0.408  0.744  1.0
  Nb  Nb5  1  0.077  0.590  0.260  1.0
  Nb  Nb6  1  0.750  0.240  0.268  1.0
  Nb  Nb7  1  0.592  0.078  0.751  1.0
  O  O8  1  0.500  0.999  0.000  1.0
  O  O9  1  0.904  0.904  0.771  1.0
  O  O10  1  0.422  0.906  0.766  1.0
  O  O11  1  0.823  0.352  0.998  1.0
  O  O12  1  0.172  0.652  0.002  1.0
  O  O13  1  0.996  0.503  0.501  1.0
  O  O14  1  0.332  0.833  0.498  1.0
  O  O15  1  0.571  0.577  0.777  1.0
  O  O16  1  0.749  0.749  0.234  1.0
  O  O17  1  0.730  0.253  0.767  1.0
  O  O18  1  0.269  0.749  0.235  1.0
  O  O19  1  0.071  0.579  0.775  1.0
  O  O20  1  0.925  0.425  0.225  1.0
  O  O21  1  0.664  0.167  0.503  1.0
  O  O22  1  0.426  0.425  0.225  1.0
  O  O23  1  0.251  0.253  0.771  1.0
  O  O24  1  0.580  0.097  0.231  1.0
  O  O25  1  0.097  0.099  0.231  1.0
[/CIF]
.