The material described by GdTa3O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(13), one O(15), one O(2), one O(4), one O(5), two equivalent O(16), two equivalent O(7), and three equivalent O(3) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(2)O12 cuboctahedra, corners with two equivalent Gd(1)O12 cuboctahedra, faces with two equivalent Gd(1)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Ta(4)O6 octahedra. In the second Gd site, Gd(2) is bonded to one O(17), one O(18), one O(2), one O(8), one O(9), two equivalent O(14), two equivalent O(6), and three equivalent O(1) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(1)O12 cuboctahedra, corners with two equivalent Gd(2)O12 cuboctahedra, faces with two equivalent Gd(2)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Ta(6)O6 octahedra. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(15), one O(17), one O(2), one O(4), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(5)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-16°. In the second Ta site, Ta(2) is bonded to one O(11), one O(13), one O(16), one O(3), one O(5), and one O(7) atom to form TaO6 octahedra that share corners with three equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(5)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the third Ta site, Ta(3) is bonded to one O(1), one O(12), one O(14), one O(18), one O(6), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(4)O6 octahedra, corners with two equivalent Ta(5)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-21°. In the fourth Ta site, Ta(4) is bonded to one O(12), one O(15), one O(16), one O(3), one O(4), and one O(7) atom to form TaO6 octahedra that share  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-17°. In the fifth Ta site, Ta(5) is bonded to one O(11), one O(13), one O(18), one O(2), one O(5), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the sixth Ta site, Ta(6) is bonded to one O(1), one O(10), one O(14), one O(17), one O(6), and one O(9) atom to form distorted TaO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-21°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to three equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Gd(1), one Gd(2), one Ta(1), and one Ta(5) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to three equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the eighth O site, O(8) is bonded in a distorted linear geometry to one Gd(2), one Ta(3), and one Ta(5) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Ta(6) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Ta(2) and one Ta(5) atom. In the twelfth O site, O(12) is bonded in a linear geometry to one Ta(3) and one Ta(4) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the sixteenth O site, O(16) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(3), and one Ta(5) atom. is represented by the CIF file [CIF]
data_GdTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.587
_cell_length_b   9.706
_cell_length_c   13.697
_cell_angle_alpha   89.623
_cell_angle_beta   89.998
_cell_angle_gamma   89.992
_symmetry_Int_Tables_number   1
_cell_volume   742.796
_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  0.275  0.084  0.918  1.0
  Gd  Gd1  1  0.277  0.426  0.574  1.0
  Gd  Gd2  1  0.723  0.574  0.426  1.0
  Gd  Gd3  1  0.725  0.916  0.082  1.0
  Ta  Ta4  1  0.747  0.916  0.333  1.0
  Ta  Ta5  1  0.754  0.261  0.001  1.0
  Ta  Ta6  1  0.754  0.585  0.674  1.0
  Ta  Ta7  1  0.245  0.084  0.172  1.0
  Ta  Ta8  1  0.252  0.417  0.834  1.0
  Ta  Ta9  1  0.246  0.763  0.501  1.0
  Ta  Ta10  1  0.754  0.237  0.499  1.0
  Ta  Ta11  1  0.748  0.583  0.166  1.0
  Ta  Ta12  1  0.755  0.916  0.828  1.0
  Ta  Ta13  1  0.246  0.415  0.326  1.0
  Ta  Ta14  1  0.246  0.739  0.999  1.0
  Ta  Ta15  1  0.253  0.084  0.667  1.0
  O  O16  1  0.730  0.425  0.575  1.0
  O  O17  1  0.755  0.751  0.249  1.0
  O  O18  1  0.745  0.074  0.926  1.0
  O  O19  1  0.255  0.926  0.074  1.0
  O  O20  1  0.245  0.249  0.751  1.0
  O  O21  1  0.270  0.575  0.425  1.0
  O  O22  1  0.513  0.987  0.236  1.0
  O  O23  1  0.488  0.311  0.913  1.0
  O  O24  1  0.500  0.648  0.574  1.0
  O  O25  1  0.500  0.352  0.426  1.0
  O  O26  1  0.512  0.689  0.087  1.0
  O  O27  1  0.487  0.013  0.764  1.0
  O  O28  1  0.000  0.152  0.076  1.0
  O  O29  1  0.008  0.492  0.742  1.0
  O  O30  1  0.993  0.821  0.415  1.0
  O  O31  1  0.992  0.508  0.258  1.0
  O  O32  1  1.000  0.848  0.924  1.0
  O  O33  1  0.007  0.179  0.585  1.0
  O  O34  1  0.743  0.084  0.413  1.0
  O  O35  1  0.743  0.420  0.083  1.0
  O  O36  1  0.745  0.752  0.748  1.0
  O  O37  1  0.255  0.248  0.252  1.0
  O  O38  1  0.257  0.580  0.917  1.0
  O  O39  1  0.257  0.916  0.587  1.0
  O  O40  1  0.010  0.317  0.914  1.0
  O  O41  1  0.000  0.643  0.572  1.0
  O  O42  1  0.990  0.991  0.240  1.0
  O  O43  1  0.500  0.852  0.926  1.0
  O  O44  1  0.487  0.185  0.585  1.0
  O  O45  1  0.513  0.509  0.261  1.0
  O  O46  1  0.990  0.683  0.086  1.0
  O  O47  1  0.010  0.009  0.760  1.0
  O  O48  1  1.000  0.357  0.428  1.0
  O  O49  1  0.487  0.491  0.739  1.0
  O  O50  1  0.513  0.815  0.415  1.0
  O  O51  1  0.500  0.148  0.074  1.0
[/CIF]
.
The material described by GdTa3O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(13), one O(15), one O(2), one O(4), one O(5), two equivalent O(16), two equivalent O(7), and three equivalent O(3) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(2)O12 cuboctahedra, corners with two equivalent Gd(1)O12 cuboctahedra, faces with two equivalent Gd(1)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Ta(4)O6 octahedra. In the second Gd site, Gd(2) is bonded to one O(17), one O(18), one O(2), one O(8), one O(9), two equivalent O(14), two equivalent O(6), and three equivalent O(1) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(1)O12 cuboctahedra, corners with two equivalent Gd(2)O12 cuboctahedra, faces with two equivalent Gd(2)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Ta(6)O6 octahedra. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(15), one O(17), one O(2), one O(4), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(5)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-16°. In the second Ta site, Ta(2) is bonded to one O(11), one O(13), one O(16), one O(3), one O(5), and one O(7) atom to form TaO6 octahedra that share corners with three equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(5)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the third Ta site, Ta(3) is bonded to one O(1), one O(12), one O(14), one O(18), one O(6), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(4)O6 octahedra, corners with two equivalent Ta(5)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-21°. In the fourth Ta site, Ta(4) is bonded to one O(12), one O(15), one O(16), one O(3), one O(4), and one O(7) atom to form TaO6 octahedra that share  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-17°. In the fifth Ta site, Ta(5) is bonded to one O(11), one O(13), one O(18), one O(2), one O(5), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the sixth Ta site, Ta(6) is bonded to one O(1), one O(10), one O(14), one O(17), one O(6), and one O(9) atom to form distorted TaO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-21°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to three equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Gd(1), one Gd(2), one Ta(1), and one Ta(5) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to three equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the eighth O site, O(8) is bonded in a distorted linear geometry to one Gd(2), one Ta(3), and one Ta(5) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Ta(6) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Ta(2) and one Ta(5) atom. In the twelfth O site, O(12) is bonded in a linear geometry to one Ta(3) and one Ta(4) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the sixteenth O site, O(16) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(3), and one Ta(5) atom. is represented by the CIF file [CIF]
data_GdTa3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.587
_cell_length_b   9.706
_cell_length_c   13.697
_cell_angle_alpha   89.623
_cell_angle_beta   89.998
_cell_angle_gamma   89.992
_symmetry_Int_Tables_number   1
_cell_volume   742.796
_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  0.275  0.084  0.918  1.0
  Gd  Gd1  1  0.277  0.426  0.574  1.0
  Gd  Gd2  1  0.723  0.574  0.426  1.0
  Gd  Gd3  1  0.725  0.916  0.082  1.0
  Ta  Ta4  1  0.747  0.916  0.333  1.0
  Ta  Ta5  1  0.754  0.261  0.001  1.0
  Ta  Ta6  1  0.754  0.585  0.674  1.0
  Ta  Ta7  1  0.245  0.084  0.172  1.0
  Ta  Ta8  1  0.252  0.417  0.834  1.0
  Ta  Ta9  1  0.246  0.763  0.501  1.0
  Ta  Ta10  1  0.754  0.237  0.499  1.0
  Ta  Ta11  1  0.748  0.583  0.166  1.0
  Ta  Ta12  1  0.755  0.916  0.828  1.0
  Ta  Ta13  1  0.246  0.415  0.326  1.0
  Ta  Ta14  1  0.246  0.739  0.999  1.0
  Ta  Ta15  1  0.253  0.084  0.667  1.0
  O  O16  1  0.730  0.425  0.575  1.0
  O  O17  1  0.755  0.751  0.249  1.0
  O  O18  1  0.745  0.074  0.926  1.0
  O  O19  1  0.255  0.926  0.074  1.0
  O  O20  1  0.245  0.249  0.751  1.0
  O  O21  1  0.270  0.575  0.425  1.0
  O  O22  1  0.513  0.987  0.236  1.0
  O  O23  1  0.488  0.311  0.913  1.0
  O  O24  1  0.500  0.648  0.574  1.0
  O  O25  1  0.500  0.352  0.426  1.0
  O  O26  1  0.512  0.689  0.087  1.0
  O  O27  1  0.487  0.013  0.764  1.0
  O  O28  1  0.000  0.152  0.076  1.0
  O  O29  1  0.008  0.492  0.742  1.0
  O  O30  1  0.993  0.821  0.415  1.0
  O  O31  1  0.992  0.508  0.258  1.0
  O  O32  1  1.000  0.848  0.924  1.0
  O  O33  1  0.007  0.179  0.585  1.0
  O  O34  1  0.743  0.084  0.413  1.0
  O  O35  1  0.743  0.420  0.083  1.0
  O  O36  1  0.745  0.752  0.748  1.0
  O  O37  1  0.255  0.248  0.252  1.0
  O  O38  1  0.257  0.580  0.917  1.0
  O  O39  1  0.257  0.916  0.587  1.0
  O  O40  1  0.010  0.317  0.914  1.0
  O  O41  1  0.000  0.643  0.572  1.0
  O  O42  1  0.990  0.991  0.240  1.0
  O  O43  1  0.500  0.852  0.926  1.0
  O  O44  1  0.487  0.185  0.585  1.0
  O  O45  1  0.513  0.509  0.261  1.0
  O  O46  1  0.990  0.683  0.086  1.0
  O  O47  1  0.010  0.009  0.760  1.0
  O  O48  1  1.000  0.357  0.428  1.0
  O  O49  1  0.487  0.491  0.739  1.0
  O  O50  1  0.513  0.815  0.415  1.0
  O  O51  1  0.500  0.148  0.074  1.0
[/CIF]
.