The compound described by GdTa3O9 crystallizes in the orthorhombic Pnma space group. Gd(1) is bonded in a 9-coordinate geometry to one O(2), one O(4), one O(5), two equivalent O(3), and four equivalent O(6) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) 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(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 33°. In the second Ta site, Ta(2) is bonded to one O(4), one O(5), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted TaO7 pentagonal bipyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids,  an edgeedge with one Ta(1)O6 octahedra, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ta(1) and two equivalent Ta(2) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Gd(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Gd(1) and two equivalent Ta(2) atoms. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Gd(1) and two equivalent Ta(2) atoms. In the fifth O site, O(5) is bonded in a distorted linear geometry to one Gd(1) and two equivalent Ta(2) atoms. In the sixth O site, O(6) is bonded to two equivalent Gd(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted corner and edge-sharing OGd2Ta2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_GdTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.525
_cell_length_b   7.667
_cell_length_c   12.661
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   633.406
_cell_formula_units_Z   4
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
  Gd  Gd0  1  0.055  0.250  0.466  1.0
  Gd  Gd1  1  0.445  0.750  0.966  1.0
  Gd  Gd2  1  0.555  0.250  0.034  1.0
  Gd  Gd3  1  0.945  0.750  0.534  1.0
  Ta  Ta4  1  0.000  0.000  0.000  1.0
  Ta  Ta5  1  0.000  0.500  0.000  1.0
  Ta  Ta6  1  0.210  0.003  0.714  1.0
  Ta  Ta7  1  0.210  0.497  0.714  1.0
  Ta  Ta8  1  0.290  0.503  0.214  1.0
  Ta  Ta9  1  0.290  0.997  0.214  1.0
  Ta  Ta10  1  0.500  0.000  0.500  1.0
  Ta  Ta11  1  0.500  0.500  0.500  1.0
  Ta  Ta12  1  0.710  0.003  0.786  1.0
  Ta  Ta13  1  0.710  0.497  0.786  1.0
  Ta  Ta14  1  0.790  0.503  0.286  1.0
  Ta  Ta15  1  0.790  0.997  0.286  1.0
  O  O16  1  0.020  0.039  0.844  1.0
  O  O17  1  0.020  0.461  0.844  1.0
  O  O18  1  0.074  0.750  0.977  1.0
  O  O19  1  0.098  0.031  0.333  1.0
  O  O20  1  0.098  0.469  0.333  1.0
  O  O21  1  0.175  0.250  0.674  1.0
  O  O22  1  0.203  0.750  0.698  1.0
  O  O23  1  0.209  0.967  0.538  1.0
  O  O24  1  0.209  0.533  0.538  1.0
  O  O25  1  0.291  0.033  0.038  1.0
  O  O26  1  0.291  0.467  0.038  1.0
  O  O27  1  0.297  0.250  0.198  1.0
  O  O28  1  0.325  0.750  0.174  1.0
  O  O29  1  0.402  0.531  0.833  1.0
  O  O30  1  0.402  0.969  0.833  1.0
  O  O31  1  0.426  0.250  0.477  1.0
  O  O32  1  0.480  0.539  0.344  1.0
  O  O33  1  0.480  0.961  0.344  1.0
  O  O34  1  0.520  0.039  0.656  1.0
  O  O35  1  0.520  0.461  0.656  1.0
  O  O36  1  0.574  0.750  0.523  1.0
  O  O37  1  0.598  0.031  0.167  1.0
  O  O38  1  0.598  0.469  0.167  1.0
  O  O39  1  0.675  0.250  0.826  1.0
  O  O40  1  0.703  0.750  0.802  1.0
  O  O41  1  0.709  0.533  0.962  1.0
  O  O42  1  0.709  0.967  0.962  1.0
  O  O43  1  0.791  0.033  0.462  1.0
  O  O44  1  0.791  0.467  0.462  1.0
  O  O45  1  0.797  0.250  0.302  1.0
  O  O46  1  0.825  0.750  0.326  1.0
  O  O47  1  0.902  0.531  0.667  1.0
  O  O48  1  0.902  0.969  0.667  1.0
  O  O49  1  0.926  0.250  0.023  1.0
  O  O50  1  0.980  0.539  0.156  1.0
  O  O51  1  0.980  0.961  0.156  1.0
[/CIF]
.
The compound described by GdTa3O9 crystallizes in the orthorhombic Pnma space group. Gd(1) is bonded in a 9-coordinate geometry to one O(2), one O(4), one O(5), two equivalent O(3), and four equivalent O(6) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) 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(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 33°. In the second Ta site, Ta(2) is bonded to one O(4), one O(5), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted TaO7 pentagonal bipyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids,  an edgeedge with one Ta(1)O6 octahedra, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ta(1) and two equivalent Ta(2) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Gd(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Gd(1) and two equivalent Ta(2) atoms. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Gd(1) and two equivalent Ta(2) atoms. In the fifth O site, O(5) is bonded in a distorted linear geometry to one Gd(1) and two equivalent Ta(2) atoms. In the sixth O site, O(6) is bonded to two equivalent Gd(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted corner and edge-sharing OGd2Ta2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_GdTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.525
_cell_length_b   7.667
_cell_length_c   12.661
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   633.406
_cell_formula_units_Z   4
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
  Gd  Gd0  1  0.055  0.250  0.466  1.0
  Gd  Gd1  1  0.445  0.750  0.966  1.0
  Gd  Gd2  1  0.555  0.250  0.034  1.0
  Gd  Gd3  1  0.945  0.750  0.534  1.0
  Ta  Ta4  1  0.000  0.000  0.000  1.0
  Ta  Ta5  1  0.000  0.500  0.000  1.0
  Ta  Ta6  1  0.210  0.003  0.714  1.0
  Ta  Ta7  1  0.210  0.497  0.714  1.0
  Ta  Ta8  1  0.290  0.503  0.214  1.0
  Ta  Ta9  1  0.290  0.997  0.214  1.0
  Ta  Ta10  1  0.500  0.000  0.500  1.0
  Ta  Ta11  1  0.500  0.500  0.500  1.0
  Ta  Ta12  1  0.710  0.003  0.786  1.0
  Ta  Ta13  1  0.710  0.497  0.786  1.0
  Ta  Ta14  1  0.790  0.503  0.286  1.0
  Ta  Ta15  1  0.790  0.997  0.286  1.0
  O  O16  1  0.020  0.039  0.844  1.0
  O  O17  1  0.020  0.461  0.844  1.0
  O  O18  1  0.074  0.750  0.977  1.0
  O  O19  1  0.098  0.031  0.333  1.0
  O  O20  1  0.098  0.469  0.333  1.0
  O  O21  1  0.175  0.250  0.674  1.0
  O  O22  1  0.203  0.750  0.698  1.0
  O  O23  1  0.209  0.967  0.538  1.0
  O  O24  1  0.209  0.533  0.538  1.0
  O  O25  1  0.291  0.033  0.038  1.0
  O  O26  1  0.291  0.467  0.038  1.0
  O  O27  1  0.297  0.250  0.198  1.0
  O  O28  1  0.325  0.750  0.174  1.0
  O  O29  1  0.402  0.531  0.833  1.0
  O  O30  1  0.402  0.969  0.833  1.0
  O  O31  1  0.426  0.250  0.477  1.0
  O  O32  1  0.480  0.539  0.344  1.0
  O  O33  1  0.480  0.961  0.344  1.0
  O  O34  1  0.520  0.039  0.656  1.0
  O  O35  1  0.520  0.461  0.656  1.0
  O  O36  1  0.574  0.750  0.523  1.0
  O  O37  1  0.598  0.031  0.167  1.0
  O  O38  1  0.598  0.469  0.167  1.0
  O  O39  1  0.675  0.250  0.826  1.0
  O  O40  1  0.703  0.750  0.802  1.0
  O  O41  1  0.709  0.533  0.962  1.0
  O  O42  1  0.709  0.967  0.962  1.0
  O  O43  1  0.791  0.033  0.462  1.0
  O  O44  1  0.791  0.467  0.462  1.0
  O  O45  1  0.797  0.250  0.302  1.0
  O  O46  1  0.825  0.750  0.326  1.0
  O  O47  1  0.902  0.531  0.667  1.0
  O  O48  1  0.902  0.969  0.667  1.0
  O  O49  1  0.926  0.250  0.023  1.0
  O  O50  1  0.980  0.539  0.156  1.0
  O  O51  1  0.980  0.961  0.156  1.0
[/CIF]
.