The compound described by Tm3TaO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Tm sites. In the first Tm site, Tm(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 TmO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Tm(1)O7 pentagonal bipyramid, edges with two equivalent Ta(1)O6 octahedra, and edges with three equivalent Tm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-50°. In the second Tm site, Tm(2) is bonded in a 6-coordinate geometry to two equivalent O(2), 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 Tm(1)O7 pentagonal bipyramids, and edges with four equivalent Tm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tm(1) and two equivalent Ta(1) atoms to form distorted OTm2Ta2 tetrahedra that share corners with two equivalent O(1)Tm2Ta2 tetrahedra, corners with two equivalent O(4)Tm4 tetrahedra, corners with four equivalent O(5)Tm3Ta tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and edges with two equivalent O(5)Tm3Ta tetrahedra. In the second O site, O(2) is bonded to two equivalent Tm(1) and two equivalent Tm(2) atoms to form OTm4 tetrahedra that share corners with two equivalent O(2)Tm4 tetrahedra, corners with four equivalent O(5)Tm3Ta tetrahedra, corners with four equivalent O(4)Tm4 tetrahedra,  an edgeedge with one O(1)Tm2Ta2 tetrahedra,  an edgeedge with one O(4)Tm4 tetrahedra, and edges with two equivalent O(5)Tm3Ta tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Tm(1) and one Ta(1) atom. In the fourth O site, O(4) is bonded to two equivalent Tm(1) and two equivalent Tm(2) atoms to form OTm4 tetrahedra that share corners with two equivalent O(1)Tm2Ta2 tetrahedra, corners with two equivalent O(4)Tm4 tetrahedra, corners with four equivalent O(5)Tm3Ta tetrahedra, corners with four equivalent O(2)Tm4 tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and edges with two equivalent O(5)Tm3Ta tetrahedra. In the fifth O site, O(5) is bonded to one Tm(2), two equivalent Tm(1), and one Ta(1) atom to form distorted OTm3Ta tetrahedra that share corners with two equivalent O(1)Tm2Ta2 tetrahedra, corners with two equivalent O(5)Tm3Ta tetrahedra, corners with two equivalent O(2)Tm4 tetrahedra, corners with two equivalent O(4)Tm4 tetrahedra,  an edgeedge with one O(1)Tm2Ta2 tetrahedra,  an edgeedge with one O(5)Tm3Ta tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and  an edgeedge with one O(4)Tm4 tetrahedra. is represented by the CIF file [CIF]
data_Tm3TaO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.361
_cell_length_b   6.361
_cell_length_c   7.322
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   108.680
_symmetry_Int_Tables_number   1
_cell_volume   280.623
_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
  Tm  Tm0  1  0.465  0.999  0.259  1.0
  Tm  Tm1  1  0.001  0.535  0.241  1.0
  Tm  Tm2  1  0.464  0.464  0.000  1.0
  Tm  Tm3  1  0.536  0.536  0.500  1.0
  Tm  Tm4  1  0.535  0.001  0.759  1.0
  Tm  Tm5  1  0.999  0.465  0.741  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  0.927  0.073  0.750  1.0
  O  O9  1  0.640  0.360  0.750  1.0
  O  O10  1  0.311  0.052  0.546  1.0
  O  O11  1  0.948  0.689  0.954  1.0
  O  O12  1  0.629  0.371  0.250  1.0
  O  O13  1  0.915  0.668  0.525  1.0
  O  O14  1  0.332  0.085  0.975  1.0
  O  O15  1  0.085  0.332  0.025  1.0
  O  O16  1  0.668  0.915  0.475  1.0
  O  O17  1  0.371  0.629  0.750  1.0
  O  O18  1  0.689  0.948  0.046  1.0
  O  O19  1  0.052  0.311  0.454  1.0
  O  O20  1  0.360  0.640  0.250  1.0
  O  O21  1  0.073  0.927  0.250  1.0
[/CIF]
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The compound described by Tm3TaO7 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent Tm sites. In the first Tm site, Tm(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 TmO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Tm(1)O7 pentagonal bipyramid, edges with two equivalent Ta(1)O6 octahedra, and edges with three equivalent Tm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-50°. In the second Tm site, Tm(2) is bonded in a 6-coordinate geometry to two equivalent O(2), 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 Tm(1)O7 pentagonal bipyramids, and edges with four equivalent Tm(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Tm(1) and two equivalent Ta(1) atoms to form distorted OTm2Ta2 tetrahedra that share corners with two equivalent O(1)Tm2Ta2 tetrahedra, corners with two equivalent O(4)Tm4 tetrahedra, corners with four equivalent O(5)Tm3Ta tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and edges with two equivalent O(5)Tm3Ta tetrahedra. In the second O site, O(2) is bonded to two equivalent Tm(1) and two equivalent Tm(2) atoms to form OTm4 tetrahedra that share corners with two equivalent O(2)Tm4 tetrahedra, corners with four equivalent O(5)Tm3Ta tetrahedra, corners with four equivalent O(4)Tm4 tetrahedra,  an edgeedge with one O(1)Tm2Ta2 tetrahedra,  an edgeedge with one O(4)Tm4 tetrahedra, and edges with two equivalent O(5)Tm3Ta tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Tm(1) and one Ta(1) atom. In the fourth O site, O(4) is bonded to two equivalent Tm(1) and two equivalent Tm(2) atoms to form OTm4 tetrahedra that share corners with two equivalent O(1)Tm2Ta2 tetrahedra, corners with two equivalent O(4)Tm4 tetrahedra, corners with four equivalent O(5)Tm3Ta tetrahedra, corners with four equivalent O(2)Tm4 tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and edges with two equivalent O(5)Tm3Ta tetrahedra. In the fifth O site, O(5) is bonded to one Tm(2), two equivalent Tm(1), and one Ta(1) atom to form distorted OTm3Ta tetrahedra that share corners with two equivalent O(1)Tm2Ta2 tetrahedra, corners with two equivalent O(5)Tm3Ta tetrahedra, corners with two equivalent O(2)Tm4 tetrahedra, corners with two equivalent O(4)Tm4 tetrahedra,  an edgeedge with one O(1)Tm2Ta2 tetrahedra,  an edgeedge with one O(5)Tm3Ta tetrahedra,  an edgeedge with one O(2)Tm4 tetrahedra, and  an edgeedge with one O(4)Tm4 tetrahedra. is represented by the CIF file [CIF]
data_Tm3TaO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.361
_cell_length_b   6.361
_cell_length_c   7.322
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   108.680
_symmetry_Int_Tables_number   1
_cell_volume   280.623
_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
  Tm  Tm0  1  0.465  0.999  0.259  1.0
  Tm  Tm1  1  0.001  0.535  0.241  1.0
  Tm  Tm2  1  0.464  0.464  0.000  1.0
  Tm  Tm3  1  0.536  0.536  0.500  1.0
  Tm  Tm4  1  0.535  0.001  0.759  1.0
  Tm  Tm5  1  0.999  0.465  0.741  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  0.927  0.073  0.750  1.0
  O  O9  1  0.640  0.360  0.750  1.0
  O  O10  1  0.311  0.052  0.546  1.0
  O  O11  1  0.948  0.689  0.954  1.0
  O  O12  1  0.629  0.371  0.250  1.0
  O  O13  1  0.915  0.668  0.525  1.0
  O  O14  1  0.332  0.085  0.975  1.0
  O  O15  1  0.085  0.332  0.025  1.0
  O  O16  1  0.668  0.915  0.475  1.0
  O  O17  1  0.371  0.629  0.750  1.0
  O  O18  1  0.689  0.948  0.046  1.0
  O  O19  1  0.052  0.311  0.454  1.0
  O  O20  1  0.360  0.640  0.250  1.0
  O  O21  1  0.073  0.927  0.250  1.0
[/CIF]
.