The structure described by Tb3TaO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Tb sites. In the first Tb site, Tb(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 TbO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Tb(1)O7 pentagonal bipyramid, edges with two equivalent Ta(1)O6 octahedra, and edges with three equivalent Tb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-49°. In the second Tb site, Tb(2) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. Ta(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with two equivalent Ta(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 41°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1) and two equivalent Ta(1) atoms to form distorted OTb2Ta2 trigonal pyramids that share corners with two equivalent O(4)Tb4 tetrahedra, corners with four equivalent O(5)Tb3Ta tetrahedra, corners with two equivalent O(1)Tb2Ta2 trigonal pyramids,  an edgeedge with one O(2)Tb4 tetrahedra, and edges with two equivalent O(5)Tb3Ta tetrahedra. In the second O site, O(2) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with two equivalent O(2)Tb4 tetrahedra, corners with four equivalent O(5)Tb3Ta tetrahedra, corners with four equivalent O(4)Tb4 tetrahedra,  an edgeedge with one O(4)Tb4 tetrahedra, edges with two equivalent O(5)Tb3Ta tetrahedra, and  an edgeedge with one O(1)Tb2Ta2 trigonal pyramid. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Tb(2), two equivalent Tb(1), and one Ta(1) atom. In the fourth O site, O(4) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with two equivalent O(4)Tb4 tetrahedra, corners with four equivalent O(5)Tb3Ta tetrahedra, corners with four equivalent O(2)Tb4 tetrahedra, corners with two equivalent O(1)Tb2Ta2 trigonal pyramids,  an edgeedge with one O(2)Tb4 tetrahedra, and edges with two equivalent O(5)Tb3Ta tetrahedra. In the fifth O site, O(5) is bonded to one Tb(2), two equivalent Tb(1), and one Ta(1) atom to form distorted OTb3Ta tetrahedra that share corners with two equivalent O(5)Tb3Ta tetrahedra, corners with two equivalent O(2)Tb4 tetrahedra, corners with two equivalent O(4)Tb4 tetrahedra, corners with two equivalent O(1)Tb2Ta2 trigonal pyramids,  an edgeedge with one O(5)Tb3Ta tetrahedra,  an edgeedge with one O(2)Tb4 tetrahedra,  an edgeedge with one O(4)Tb4 tetrahedra, and  an edgeedge with one O(1)Tb2Ta2 trigonal pyramid. is represented by the CIF file [CIF]
data_Tb3TaO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.470
_cell_length_b   6.470
_cell_length_c   7.460
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   108.871
_symmetry_Int_Tables_number   1
_cell_volume   295.504
_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  0.465  0.000  0.258  1.0
  Tb  Tb1  1  1.000  0.535  0.242  1.0
  Tb  Tb2  1  0.467  0.467  0.000  1.0
  Tb  Tb3  1  0.533  0.533  0.500  1.0
  Tb  Tb4  1  0.535  1.000  0.758  1.0
  Tb  Tb5  1  0.000  0.465  0.742  1.0
  Ta  Ta6  1  0.002  0.002  0.500  1.0
  Ta  Ta7  1  0.998  0.998  0.000  1.0
  O  O8  1  0.933  0.067  0.750  1.0
  O  O9  1  0.639  0.361  0.750  1.0
  O  O10  1  0.309  0.052  0.542  1.0
  O  O11  1  0.948  0.691  0.958  1.0
  O  O12  1  0.629  0.371  0.250  1.0
  O  O13  1  0.918  0.673  0.525  1.0
  O  O14  1  0.327  0.082  0.975  1.0
  O  O15  1  0.082  0.327  0.025  1.0
  O  O16  1  0.673  0.918  0.475  1.0
  O  O17  1  0.371  0.629  0.750  1.0
  O  O18  1  0.691  0.948  0.042  1.0
  O  O19  1  0.052  0.309  0.458  1.0
  O  O20  1  0.361  0.639  0.250  1.0
  O  O21  1  0.067  0.933  0.250  1.0
[/CIF]
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The structure described by Tb3TaO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Tb sites. In the first Tb site, Tb(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 TbO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Tb(1)O7 pentagonal bipyramid, edges with two equivalent Ta(1)O6 octahedra, and edges with three equivalent Tb(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-49°. In the second Tb site, Tb(2) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms. Ta(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with two equivalent Ta(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 41°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tb(1) and two equivalent Ta(1) atoms to form distorted OTb2Ta2 trigonal pyramids that share corners with two equivalent O(4)Tb4 tetrahedra, corners with four equivalent O(5)Tb3Ta tetrahedra, corners with two equivalent O(1)Tb2Ta2 trigonal pyramids,  an edgeedge with one O(2)Tb4 tetrahedra, and edges with two equivalent O(5)Tb3Ta tetrahedra. In the second O site, O(2) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with two equivalent O(2)Tb4 tetrahedra, corners with four equivalent O(5)Tb3Ta tetrahedra, corners with four equivalent O(4)Tb4 tetrahedra,  an edgeedge with one O(4)Tb4 tetrahedra, edges with two equivalent O(5)Tb3Ta tetrahedra, and  an edgeedge with one O(1)Tb2Ta2 trigonal pyramid. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Tb(2), two equivalent Tb(1), and one Ta(1) atom. In the fourth O site, O(4) is bonded to two equivalent Tb(1) and two equivalent Tb(2) atoms to form OTb4 tetrahedra that share corners with two equivalent O(4)Tb4 tetrahedra, corners with four equivalent O(5)Tb3Ta tetrahedra, corners with four equivalent O(2)Tb4 tetrahedra, corners with two equivalent O(1)Tb2Ta2 trigonal pyramids,  an edgeedge with one O(2)Tb4 tetrahedra, and edges with two equivalent O(5)Tb3Ta tetrahedra. In the fifth O site, O(5) is bonded to one Tb(2), two equivalent Tb(1), and one Ta(1) atom to form distorted OTb3Ta tetrahedra that share corners with two equivalent O(5)Tb3Ta tetrahedra, corners with two equivalent O(2)Tb4 tetrahedra, corners with two equivalent O(4)Tb4 tetrahedra, corners with two equivalent O(1)Tb2Ta2 trigonal pyramids,  an edgeedge with one O(5)Tb3Ta tetrahedra,  an edgeedge with one O(2)Tb4 tetrahedra,  an edgeedge with one O(4)Tb4 tetrahedra, and  an edgeedge with one O(1)Tb2Ta2 trigonal pyramid. is represented by the CIF file [CIF]
data_Tb3TaO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.470
_cell_length_b   6.470
_cell_length_c   7.460
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   108.871
_symmetry_Int_Tables_number   1
_cell_volume   295.504
_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  0.465  0.000  0.258  1.0
  Tb  Tb1  1  1.000  0.535  0.242  1.0
  Tb  Tb2  1  0.467  0.467  0.000  1.0
  Tb  Tb3  1  0.533  0.533  0.500  1.0
  Tb  Tb4  1  0.535  1.000  0.758  1.0
  Tb  Tb5  1  0.000  0.465  0.742  1.0
  Ta  Ta6  1  0.002  0.002  0.500  1.0
  Ta  Ta7  1  0.998  0.998  0.000  1.0
  O  O8  1  0.933  0.067  0.750  1.0
  O  O9  1  0.639  0.361  0.750  1.0
  O  O10  1  0.309  0.052  0.542  1.0
  O  O11  1  0.948  0.691  0.958  1.0
  O  O12  1  0.629  0.371  0.250  1.0
  O  O13  1  0.918  0.673  0.525  1.0
  O  O14  1  0.327  0.082  0.975  1.0
  O  O15  1  0.082  0.327  0.025  1.0
  O  O16  1  0.673  0.918  0.475  1.0
  O  O17  1  0.371  0.629  0.750  1.0
  O  O18  1  0.691  0.948  0.042  1.0
  O  O19  1  0.052  0.309  0.458  1.0
  O  O20  1  0.361  0.639  0.250  1.0
  O  O21  1  0.067  0.933  0.250  1.0
[/CIF]
.