The material described by La2Ta2O9 crystallizes in the monoclinic C2/m space group. La(1) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), three equivalent O(4), and three equivalent O(5) atoms. Ta(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted corner and edge-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-12°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one La(1) and two equivalent Ta(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 4-coordinate geometry to three equivalent La(1) and one Ta(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to three equivalent La(1) atoms. is represented by the CIF card [CIF]
data_La2Ta2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.119
_cell_length_b   8.119
_cell_length_c   6.791
_cell_angle_alpha   68.378
_cell_angle_beta   68.378
_cell_angle_gamma   27.967
_symmetry_Int_Tables_number   1
_cell_volume   194.208
_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
  La  La0  1  0.305  0.305  0.186  1.0
  La  La1  1  0.695  0.695  0.814  1.0
  Ta  Ta2  1  0.038  0.038  0.196  1.0
  Ta  Ta3  1  0.962  0.962  0.804  1.0
  O  O4  1  0.079  0.079  0.845  1.0
  O  O5  1  0.921  0.921  0.155  1.0
  O  O6  1  0.547  0.547  0.163  1.0
  O  O7  1  0.453  0.453  0.837  1.0
  O  O8  1  0.000  0.000  0.500  1.0
  O  O9  1  0.174  0.174  0.081  1.0
  O  O10  1  0.826  0.826  0.919  1.0
  O  O11  1  0.722  0.722  0.436  1.0
  O  O12  1  0.278  0.278  0.564  1.0
[/CIF]
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The material described by La2Ta2O9 crystallizes in the monoclinic C2/m space group. La(1) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), three equivalent O(4), and three equivalent O(5) atoms. Ta(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of distorted corner and edge-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-12°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one La(1) and two equivalent Ta(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 4-coordinate geometry to three equivalent La(1) and one Ta(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to three equivalent La(1) atoms. is represented by the CIF card [CIF]
data_La2Ta2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.119
_cell_length_b   8.119
_cell_length_c   6.791
_cell_angle_alpha   68.378
_cell_angle_beta   68.378
_cell_angle_gamma   27.967
_symmetry_Int_Tables_number   1
_cell_volume   194.208
_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
  La  La0  1  0.305  0.305  0.186  1.0
  La  La1  1  0.695  0.695  0.814  1.0
  Ta  Ta2  1  0.038  0.038  0.196  1.0
  Ta  Ta3  1  0.962  0.962  0.804  1.0
  O  O4  1  0.079  0.079  0.845  1.0
  O  O5  1  0.921  0.921  0.155  1.0
  O  O6  1  0.547  0.547  0.163  1.0
  O  O7  1  0.453  0.453  0.837  1.0
  O  O8  1  0.000  0.000  0.500  1.0
  O  O9  1  0.174  0.174  0.081  1.0
  O  O10  1  0.826  0.826  0.919  1.0
  O  O11  1  0.722  0.722  0.436  1.0
  O  O12  1  0.278  0.278  0.564  1.0
[/CIF]
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