The crystal structure described by Sm3NbO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to one O(1), one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one Sm(1)O7 pentagonal bipyramid, edges with two equivalent Nb(1)O6 octahedra, and edges with three equivalent Sm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 38-50°. In the second Sm site, Sm(2) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Nb(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Sm(1)O7 pentagonal bipyramids, and edges with four equivalent Sm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sm(1) and two equivalent Nb(1) atoms to form distorted OSm2Nb2 trigonal pyramids that share corners with two equivalent O(4)Sm4 tetrahedra, corners with four equivalent O(5)Sm3Nb tetrahedra, corners with two equivalent O(1)Sm2Nb2 trigonal pyramids,  an edgeedge with one O(2)Sm4 tetrahedra, and edges with two equivalent O(5)Sm3Nb tetrahedra. In the second O site, O(2) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(2)Sm4 tetrahedra, corners with four equivalent O(5)Sm3Nb tetrahedra, corners with four equivalent O(4)Sm4 tetrahedra,  an edgeedge with one O(4)Sm4 tetrahedra, edges with two equivalent O(5)Sm3Nb tetrahedra, and  an edgeedge with one O(1)Sm2Nb2 trigonal pyramid. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Sm(1) and one Nb(1) atom. In the fourth O site, O(4) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(4)Sm4 tetrahedra, corners with four equivalent O(5)Sm3Nb tetrahedra, corners with four equivalent O(2)Sm4 tetrahedra, corners with two equivalent O(1)Sm2Nb2 trigonal pyramids,  an edgeedge with one O(2)Sm4 tetrahedra, and edges with two equivalent O(5)Sm3Nb tetrahedra. In the fifth O site, O(5) is bonded to one Sm(2), two equivalent Sm(1), and one Nb(1) atom to form distorted OSm3Nb tetrahedra that share corners with two equivalent O(5)Sm3Nb tetrahedra, corners with two equivalent O(2)Sm4 tetrahedra, corners with two equivalent O(4)Sm4 tetrahedra, corners with two equivalent O(1)Sm2Nb2 trigonal pyramids,  an edgeedge with one O(5)Sm3Nb tetrahedra,  an edgeedge with one O(2)Sm4 tetrahedra,  an edgeedge with one O(4)Sm4 tetrahedra, and  an edgeedge with one O(1)Sm2Nb2 trigonal pyramid. is represented by the CIF file [CIF]
data_Sm3NbO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.599
_cell_length_b   6.599
_cell_length_c   7.605
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   108.856
_symmetry_Int_Tables_number   1
_cell_volume   313.426
_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
  Sm  Sm0  1  0.463  0.001  0.260  1.0
  Sm  Sm1  1  0.999  0.537  0.240  1.0
  Sm  Sm2  1  0.466  0.466  0.000  1.0
  Sm  Sm3  1  0.534  0.534  0.500  1.0
  Sm  Sm4  1  0.537  0.999  0.760  1.0
  Sm  Sm5  1  0.001  0.463  0.740  1.0
  Nb  Nb6  1  0.002  0.002  0.500  1.0
  Nb  Nb7  1  0.998  0.998  0.000  1.0
  O  O8  1  0.934  0.066  0.750  1.0
  O  O9  1  0.638  0.362  0.750  1.0
  O  O10  1  0.303  0.050  0.544  1.0
  O  O11  1  0.950  0.697  0.956  1.0
  O  O12  1  0.629  0.371  0.250  1.0
  O  O13  1  0.918  0.673  0.522  1.0
  O  O14  1  0.327  0.082  0.978  1.0
  O  O15  1  0.082  0.327  0.022  1.0
  O  O16  1  0.673  0.918  0.478  1.0
  O  O17  1  0.371  0.629  0.750  1.0
  O  O18  1  0.697  0.950  0.044  1.0
  O  O19  1  0.050  0.303  0.456  1.0
  O  O20  1  0.362  0.638  0.250  1.0
  O  O21  1  0.066  0.934  0.250  1.0
[/CIF]
.
The crystal structure described by Sm3NbO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to one O(1), one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one Sm(1)O7 pentagonal bipyramid, edges with two equivalent Nb(1)O6 octahedra, and edges with three equivalent Sm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 38-50°. In the second Sm site, Sm(2) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Nb(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Sm(1)O7 pentagonal bipyramids, and edges with four equivalent Sm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 41°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sm(1) and two equivalent Nb(1) atoms to form distorted OSm2Nb2 trigonal pyramids that share corners with two equivalent O(4)Sm4 tetrahedra, corners with four equivalent O(5)Sm3Nb tetrahedra, corners with two equivalent O(1)Sm2Nb2 trigonal pyramids,  an edgeedge with one O(2)Sm4 tetrahedra, and edges with two equivalent O(5)Sm3Nb tetrahedra. In the second O site, O(2) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(2)Sm4 tetrahedra, corners with four equivalent O(5)Sm3Nb tetrahedra, corners with four equivalent O(4)Sm4 tetrahedra,  an edgeedge with one O(4)Sm4 tetrahedra, edges with two equivalent O(5)Sm3Nb tetrahedra, and  an edgeedge with one O(1)Sm2Nb2 trigonal pyramid. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Sm(1) and one Nb(1) atom. In the fourth O site, O(4) is bonded to two equivalent Sm(1) and two equivalent Sm(2) atoms to form OSm4 tetrahedra that share corners with two equivalent O(4)Sm4 tetrahedra, corners with four equivalent O(5)Sm3Nb tetrahedra, corners with four equivalent O(2)Sm4 tetrahedra, corners with two equivalent O(1)Sm2Nb2 trigonal pyramids,  an edgeedge with one O(2)Sm4 tetrahedra, and edges with two equivalent O(5)Sm3Nb tetrahedra. In the fifth O site, O(5) is bonded to one Sm(2), two equivalent Sm(1), and one Nb(1) atom to form distorted OSm3Nb tetrahedra that share corners with two equivalent O(5)Sm3Nb tetrahedra, corners with two equivalent O(2)Sm4 tetrahedra, corners with two equivalent O(4)Sm4 tetrahedra, corners with two equivalent O(1)Sm2Nb2 trigonal pyramids,  an edgeedge with one O(5)Sm3Nb tetrahedra,  an edgeedge with one O(2)Sm4 tetrahedra,  an edgeedge with one O(4)Sm4 tetrahedra, and  an edgeedge with one O(1)Sm2Nb2 trigonal pyramid. is represented by the CIF file [CIF]
data_Sm3NbO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.599
_cell_length_b   6.599
_cell_length_c   7.605
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   108.856
_symmetry_Int_Tables_number   1
_cell_volume   313.426
_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
  Sm  Sm0  1  0.463  0.001  0.260  1.0
  Sm  Sm1  1  0.999  0.537  0.240  1.0
  Sm  Sm2  1  0.466  0.466  0.000  1.0
  Sm  Sm3  1  0.534  0.534  0.500  1.0
  Sm  Sm4  1  0.537  0.999  0.760  1.0
  Sm  Sm5  1  0.001  0.463  0.740  1.0
  Nb  Nb6  1  0.002  0.002  0.500  1.0
  Nb  Nb7  1  0.998  0.998  0.000  1.0
  O  O8  1  0.934  0.066  0.750  1.0
  O  O9  1  0.638  0.362  0.750  1.0
  O  O10  1  0.303  0.050  0.544  1.0
  O  O11  1  0.950  0.697  0.956  1.0
  O  O12  1  0.629  0.371  0.250  1.0
  O  O13  1  0.918  0.673  0.522  1.0
  O  O14  1  0.327  0.082  0.978  1.0
  O  O15  1  0.082  0.327  0.022  1.0
  O  O16  1  0.673  0.918  0.478  1.0
  O  O17  1  0.371  0.629  0.750  1.0
  O  O18  1  0.697  0.950  0.044  1.0
  O  O19  1  0.050  0.303  0.456  1.0
  O  O20  1  0.362  0.638  0.250  1.0
  O  O21  1  0.066  0.934  0.250  1.0
[/CIF]
.