The material described by Tb3NbO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to one O(3), two equivalent O(1), and four equivalent O(2) atoms to form distorted TbO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent Tb(1)O7 pentagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Tb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. In the second Tb site, Tb(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Nb(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Tb(1)O7 pentagonal bipyramids, and edges with four equivalent Tb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 33°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with six equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(2)Tb3Nb trigonal pyramids,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with four equivalent O(2)Tb3Nb trigonal pyramids. In the second O site, O(2) is bonded to one Tb(2), two equivalent Tb(1), and one Nb(1) atom to form distorted OTb3Nb trigonal pyramids that share corners with four equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(2)Tb3Nb trigonal pyramids, edges with two equivalent O(1)Tb4 tetrahedra, and edges with two equivalent O(2)Tb3Nb trigonal pyramids. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Tb(1) and two equivalent Nb(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Tb3NbO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.475
_cell_length_b   6.475
_cell_length_c   7.578
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   110.401
_symmetry_Int_Tables_number   1
_cell_volume   297.797
_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
  Tb  Tb0  1  0.515  0.056  0.250  1.0
  Tb  Tb1  1  0.944  0.485  0.750  1.0
  Tb  Tb2  1  0.000  0.000  0.000  1.0
  Tb  Tb3  1  0.000  0.000  0.500  1.0
  Tb  Tb4  1  0.056  0.515  0.250  1.0
  Tb  Tb5  1  0.485  0.944  0.750  1.0
  Nb  Nb6  1  0.500  0.500  0.000  1.0
  Nb  Nb7  1  0.500  0.500  0.500  1.0
  O  O8  1  0.887  0.152  0.250  1.0
  O  O9  1  0.848  0.113  0.750  1.0
  O  O10  1  0.434  0.176  0.534  1.0
  O  O11  1  0.824  0.566  0.034  1.0
  O  O12  1  0.824  0.566  0.466  1.0
  O  O13  1  0.434  0.176  0.966  1.0
  O  O14  1  0.423  0.423  0.250  1.0
  O  O15  1  0.577  0.577  0.750  1.0
  O  O16  1  0.176  0.434  0.534  1.0
  O  O17  1  0.566  0.824  0.034  1.0
  O  O18  1  0.566  0.824  0.466  1.0
  O  O19  1  0.176  0.434  0.966  1.0
  O  O20  1  0.152  0.887  0.250  1.0
  O  O21  1  0.113  0.848  0.750  1.0
[/CIF]
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The material described by Tb3NbO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to one O(3), two equivalent O(1), and four equivalent O(2) atoms to form distorted TbO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent Tb(1)O7 pentagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Tb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. In the second Tb site, Tb(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Nb(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Tb(1)O7 pentagonal bipyramids, and edges with four equivalent Tb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 33°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with six equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(2)Tb3Nb trigonal pyramids,  an edgeedge with one O(1)Tb4 tetrahedra, and edges with four equivalent O(2)Tb3Nb trigonal pyramids. In the second O site, O(2) is bonded to one Tb(2), two equivalent Tb(1), and one Nb(1) atom to form distorted OTb3Nb trigonal pyramids that share corners with four equivalent O(1)Tb4 tetrahedra, corners with eight equivalent O(2)Tb3Nb trigonal pyramids, edges with two equivalent O(1)Tb4 tetrahedra, and edges with two equivalent O(2)Tb3Nb trigonal pyramids. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Tb(1) and two equivalent Nb(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Tb3NbO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.475
_cell_length_b   6.475
_cell_length_c   7.578
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   110.401
_symmetry_Int_Tables_number   1
_cell_volume   297.797
_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
  Tb  Tb0  1  0.515  0.056  0.250  1.0
  Tb  Tb1  1  0.944  0.485  0.750  1.0
  Tb  Tb2  1  0.000  0.000  0.000  1.0
  Tb  Tb3  1  0.000  0.000  0.500  1.0
  Tb  Tb4  1  0.056  0.515  0.250  1.0
  Tb  Tb5  1  0.485  0.944  0.750  1.0
  Nb  Nb6  1  0.500  0.500  0.000  1.0
  Nb  Nb7  1  0.500  0.500  0.500  1.0
  O  O8  1  0.887  0.152  0.250  1.0
  O  O9  1  0.848  0.113  0.750  1.0
  O  O10  1  0.434  0.176  0.534  1.0
  O  O11  1  0.824  0.566  0.034  1.0
  O  O12  1  0.824  0.566  0.466  1.0
  O  O13  1  0.434  0.176  0.966  1.0
  O  O14  1  0.423  0.423  0.250  1.0
  O  O15  1  0.577  0.577  0.750  1.0
  O  O16  1  0.176  0.434  0.534  1.0
  O  O17  1  0.566  0.824  0.034  1.0
  O  O18  1  0.566  0.824  0.466  1.0
  O  O19  1  0.176  0.434  0.966  1.0
  O  O20  1  0.152  0.887  0.250  1.0
  O  O21  1  0.113  0.848  0.750  1.0
[/CIF]
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