The material described by Pr2Ta2O9 crystallizes in the monoclinic C2/m space group. Pr(1) is bonded in a 9-coordinate geometry to one O(4), two equivalent O(1), three equivalent O(2), and three equivalent O(5) atoms. Ta(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Pr(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OPr2Ta2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to three equivalent Pr(1) atoms. In the third O site, O(3) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Pr(1) and two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to three equivalent Pr(1) and one Ta(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr2Ta2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.065
_cell_length_b   8.065
_cell_length_c   6.755
_cell_angle_alpha   68.256
_cell_angle_beta   68.256
_cell_angle_gamma   28.045
_symmetry_Int_Tables_number   1
_cell_volume   190.912
_cell_formula_units_Z   1
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
  Pr  Pr0  1  0.695  0.695  0.314  1.0
  Pr  Pr1  1  0.305  0.305  0.686  1.0
  Ta  Ta2  1  0.961  0.961  0.305  1.0
  Ta  Ta3  1  0.039  0.039  0.695  1.0
  O  O4  1  0.919  0.919  0.657  1.0
  O  O5  1  0.081  0.081  0.343  1.0
  O  O6  1  0.281  0.281  0.062  1.0
  O  O7  1  0.719  0.719  0.938  1.0
  O  O8  1  0.000  0.000  0.000  1.0
  O  O9  1  0.453  0.453  0.340  1.0
  O  O10  1  0.547  0.547  0.660  1.0
  O  O11  1  0.825  0.825  0.420  1.0
  O  O12  1  0.175  0.175  0.580  1.0
[/CIF]
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The material described by Pr2Ta2O9 crystallizes in the monoclinic C2/m space group. Pr(1) is bonded in a 9-coordinate geometry to one O(4), two equivalent O(1), three equivalent O(2), and three equivalent O(5) atoms. Ta(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Pr(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OPr2Ta2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to three equivalent Pr(1) atoms. In the third O site, O(3) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Pr(1) and two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to three equivalent Pr(1) and one Ta(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr2Ta2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.065
_cell_length_b   8.065
_cell_length_c   6.755
_cell_angle_alpha   68.256
_cell_angle_beta   68.256
_cell_angle_gamma   28.045
_symmetry_Int_Tables_number   1
_cell_volume   190.912
_cell_formula_units_Z   1
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
  Pr  Pr0  1  0.695  0.695  0.314  1.0
  Pr  Pr1  1  0.305  0.305  0.686  1.0
  Ta  Ta2  1  0.961  0.961  0.305  1.0
  Ta  Ta3  1  0.039  0.039  0.695  1.0
  O  O4  1  0.919  0.919  0.657  1.0
  O  O5  1  0.081  0.081  0.343  1.0
  O  O6  1  0.281  0.281  0.062  1.0
  O  O7  1  0.719  0.719  0.938  1.0
  O  O8  1  0.000  0.000  0.000  1.0
  O  O9  1  0.453  0.453  0.340  1.0
  O  O10  1  0.547  0.547  0.660  1.0
  O  O11  1  0.825  0.825  0.420  1.0
  O  O12  1  0.175  0.175  0.580  1.0
[/CIF]
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