The compound described by CeTa3O9 crystallizes in the monoclinic C2/m space group. Ce(1) is bonded in a 8-coordinate geometry to one O(4), one O(6), two equivalent O(3), and four equivalent O(1) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form TaO7 pentagonal bipyramids that share  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Ta(1)O7 pentagonal bipyramids,  an edgeedge with one Ta(2)O6 octahedra, and edges with two equivalent Ta(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(1)O7 pentagonal bipyramids, and edges with two equivalent Ta(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. There are six inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Ta(2) atoms. In the second O site, O(1) is bonded to two equivalent Ce(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted edge and corner-sharing OCe2Ta2 tetrahedra. In the third O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ta(2) and two equivalent Ta(1) atoms. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Ta(1) atoms. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Ta(1) atoms. In the sixth O site, O(5) is bonded in a linear geometry to two equivalent Ta(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_CeTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.310
_cell_length_b   7.310
_cell_length_c   6.593
_cell_angle_alpha   86.922
_cell_angle_beta   86.922
_cell_angle_gamma   63.064
_symmetry_Int_Tables_number   1
_cell_volume   313.425
_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
  Ce  Ce0  1  0.260  0.260  0.048  1.0
  Ce  Ce1  1  0.740  0.740  0.952  1.0
  Ta  Ta2  1  0.781  0.283  0.238  1.0
  Ta  Ta3  1  0.717  0.219  0.762  1.0
  Ta  Ta4  1  0.219  0.717  0.762  1.0
  Ta  Ta5  1  0.283  0.781  0.238  1.0
  Ta  Ta6  1  0.500  1.000  0.500  1.0
  Ta  Ta7  1  1.000  0.500  0.500  1.0
  O  O8  1  0.921  0.490  0.222  1.0
  O  O9  1  0.510  0.079  0.778  1.0
  O  O10  1  0.079  0.510  0.778  1.0
  O  O11  1  0.490  0.921  0.222  1.0
  O  O12  1  0.309  0.874  0.548  1.0
  O  O13  1  0.126  0.691  0.452  1.0
  O  O14  1  0.691  0.126  0.452  1.0
  O  O15  1  0.874  0.309  0.548  1.0
  O  O16  1  0.639  0.178  0.066  1.0
  O  O17  1  0.822  0.361  0.934  1.0
  O  O18  1  0.361  0.822  0.934  1.0
  O  O19  1  0.178  0.639  0.066  1.0
  O  O20  1  0.067  0.067  0.204  1.0
  O  O21  1  0.933  0.933  0.796  1.0
  O  O22  1  0.462  0.462  0.726  1.0
  O  O23  1  0.538  0.538  0.274  1.0
  O  O24  1  0.269  0.269  0.425  1.0
  O  O25  1  0.731  0.731  0.575  1.0
[/CIF]
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The compound described by CeTa3O9 crystallizes in the monoclinic C2/m space group. Ce(1) is bonded in a 8-coordinate geometry to one O(4), one O(6), two equivalent O(3), and four equivalent O(1) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form TaO7 pentagonal bipyramids that share  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Ta(1)O7 pentagonal bipyramids,  an edgeedge with one Ta(2)O6 octahedra, and edges with two equivalent Ta(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(1)O7 pentagonal bipyramids, and edges with two equivalent Ta(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 31°. There are six inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Ta(2) atoms. In the second O site, O(1) is bonded to two equivalent Ce(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted edge and corner-sharing OCe2Ta2 tetrahedra. In the third O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ta(2) and two equivalent Ta(1) atoms. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Ta(1) atoms. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Ta(1) atoms. In the sixth O site, O(5) is bonded in a linear geometry to two equivalent Ta(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_CeTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.310
_cell_length_b   7.310
_cell_length_c   6.593
_cell_angle_alpha   86.922
_cell_angle_beta   86.922
_cell_angle_gamma   63.064
_symmetry_Int_Tables_number   1
_cell_volume   313.425
_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
  Ce  Ce0  1  0.260  0.260  0.048  1.0
  Ce  Ce1  1  0.740  0.740  0.952  1.0
  Ta  Ta2  1  0.781  0.283  0.238  1.0
  Ta  Ta3  1  0.717  0.219  0.762  1.0
  Ta  Ta4  1  0.219  0.717  0.762  1.0
  Ta  Ta5  1  0.283  0.781  0.238  1.0
  Ta  Ta6  1  0.500  1.000  0.500  1.0
  Ta  Ta7  1  1.000  0.500  0.500  1.0
  O  O8  1  0.921  0.490  0.222  1.0
  O  O9  1  0.510  0.079  0.778  1.0
  O  O10  1  0.079  0.510  0.778  1.0
  O  O11  1  0.490  0.921  0.222  1.0
  O  O12  1  0.309  0.874  0.548  1.0
  O  O13  1  0.126  0.691  0.452  1.0
  O  O14  1  0.691  0.126  0.452  1.0
  O  O15  1  0.874  0.309  0.548  1.0
  O  O16  1  0.639  0.178  0.066  1.0
  O  O17  1  0.822  0.361  0.934  1.0
  O  O18  1  0.361  0.822  0.934  1.0
  O  O19  1  0.178  0.639  0.066  1.0
  O  O20  1  0.067  0.067  0.204  1.0
  O  O21  1  0.933  0.933  0.796  1.0
  O  O22  1  0.462  0.462  0.726  1.0
  O  O23  1  0.538  0.538  0.274  1.0
  O  O24  1  0.269  0.269  0.425  1.0
  O  O25  1  0.731  0.731  0.575  1.0
[/CIF]
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