The material structure described by Y11Ta5O28 crystallizes in the monoclinic Pm space group. There are nine inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(1), one O(15), one O(16), one O(17), one O(2), one O(3), and one O(4) atom. In the second Y site, Y(2) is bonded to one O(3), one O(5), one O(9), two equivalent O(1), and two equivalent O(8) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(4)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Y(4)O7 pentagonal bipyramid, and edges with two equivalent Y(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. In the third Y site, Y(3) is bonded to one O(20), one O(4), one O(6), two equivalent O(1), and two equivalent O(8) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Y(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 61°. In the fourth Y site, Y(4) is bonded to one O(3), one O(5), one O(9), two equivalent O(2), and two equivalent O(7) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(2)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra, and  an edgeedge with one Y(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 47°. In the fifth Y site, Y(5) is bonded in a 7-coordinate geometry to one O(20), one O(4), one O(6), two equivalent O(2), and two equivalent O(7) atoms. In the sixth Y site, Y(6) is bonded in a distorted body-centered cubic geometry to one O(11), one O(12), one O(13), one O(14), one O(5), one O(6), one O(7), and one O(8) atom. In the seventh Y site, Y(7) is bonded to one O(13), one O(15), one O(19), two equivalent O(11), and two equivalent O(18) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Ta(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Ta(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 51°. In the eighth Y site, Y(8) is bonded in a 7-coordinate geometry to one O(13), one O(15), one O(19), two equivalent O(12), and two equivalent O(17) atoms. In the ninth Y site, Y(9) is bonded to one O(10), one O(14), one O(16), two equivalent O(12), and two equivalent O(17) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Ta(3)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra, and  an edgeedge with one Ta(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 54°. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(17), one O(18), one O(19), one O(2), and one O(20) atom to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(2)O7 pentagonal bipyramid,  a cornercorner with one Y(4)O7 pentagonal bipyramid,  a cornercorner with one Y(9)O7 pentagonal bipyramid,  a cornercorner with one Ta(3)O7 pentagonal bipyramid,  an edgeedge with one Y(7)O7 hexagonal pyramid, and  an edgeedge with one Y(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 42-45°. In the second Ta site, Ta(2) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form distorted TaO6 octahedra that share  a cornercorner with one Y(7)O7 hexagonal pyramid, corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(3)O7 pentagonal bipyramid,  an edgeedge with one Y(2)O7 pentagonal bipyramid,  an edgeedge with one Y(4)O7 pentagonal bipyramid,  an edgeedge with one Y(9)O7 pentagonal bipyramid, and  an edgeedge with one Ta(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 32-69°. In the third Ta site, Ta(3) is bonded to one O(10), one O(14), one O(16), two equivalent O(11), and two equivalent O(18) atoms to form TaO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(9)O7 pentagonal bipyramid, edges with two equivalent Y(7)O7 hexagonal pyramids, edges with two equivalent Ta(2)O6 octahedra, and  an edgeedge with one Y(9)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 28°. There are twenty inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), one Y(3), and one Ta(1) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(16)Y3Ta tetrahedra,  a cornercorner with one O(15)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4 tetrahedra, corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra,  a cornercorner with one O(19)Y2Ta2 trigonal pyramid,  a cornercorner with one O(9)Y2Ta2 trigonal pyramid,  an edgeedge with one O(17)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(3)Y4 tetrahedra, and  an edgeedge with one O(4)Y4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(1), one Y(4), one Y(5), and one Ta(1) atom. In the third O site, O(3) is bonded to one Y(2), one Y(4), and two equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(16)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra,  an edgeedge with one O(15)Y4 tetrahedra, edges with two equivalent O(1)Y3Ta tetrahedra, and  an edgeedge with one O(9)Y2Ta2 trigonal pyramid. In the fourth O site, O(4) is bonded to one Y(3), one Y(5), and two equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(3)Y4 tetrahedra, corners with two equivalent O(6)Y4 tetrahedra,  an edgeedge with one O(16)Y3Ta tetrahedra, and edges with two equivalent O(1)Y3Ta tetrahedra. In the fifth O site, O(5) is bonded to one Y(2), one Y(4), and two equivalent Y(6) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(3)Y4 tetrahedra, corners with two equivalent O(6)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids, corners with two equivalent O(9)Y2Ta2 trigonal pyramids,  an edgeedge with one O(13)Y4 tetrahedra, edges with two equivalent O(7)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the sixth O site, O(6) is bonded to one Y(3), one Y(5), and two equivalent Y(6) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(13)Y4 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(14)Y3Ta tetrahedra, edges with two equivalent O(7)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the seventh O site, O(7) is bonded to one Y(4), one Y(5), one Y(6), and one Ta(2) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(14)Y3Ta tetrahedra,  a cornercorner with one O(13)Y4 tetrahedra,  a cornercorner with one O(3)Y4 tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(10)YTa3 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(6)Y4 tetrahedra,  an edgeedge with one O(11)Y2Ta2 trigonal pyramid, and  an edgeedge with one O(9)Y2Ta2 trigonal pyramid. In the eighth O site, O(8) is bonded to one Y(2), one Y(3), one Y(6), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(14)Y3Ta tetrahedra,  a cornercorner with one O(13)Y4 tetrahedra,  a cornercorner with one O(3)Y4 tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(10)YTa3 tetrahedra, corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(1)Y3Ta tetrahedra,  an edgeedge with one O(12)Y3Ta tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(6)Y4 tetrahedra, and  an edgeedge with one O(9)Y2Ta2 trigonal pyramid. In the ninth O site, O(9) is bonded to one Y(2), one Y(4), and two equivalent Ta(2) atoms to form distorted OY2Ta2 trigonal pyramids that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(10)YTa3 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(3)Y4 tetrahedra, edges with two equivalent O(7)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the tenth O site, O(10) is bonded to one Y(9), one Ta(3), and two equivalent Ta(2) atoms to form OYTa3 tetrahedra that share corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y2Ta2 trigonal pyramids,  an edgeedge with one O(16)Y3Ta tetrahedra, edges with two equivalent O(12)Y3Ta tetrahedra, and edges with two equivalent O(11)Y2Ta2 trigonal pyramids. In the eleventh O site, O(11) is bonded to one Y(6), one Y(7), one Ta(2), and one Ta(3) atom to form distorted OY2Ta2 trigonal pyramids that share  a cornercorner with one O(16)Y3Ta tetrahedra,  a cornercorner with one O(15)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra,  a cornercorner with one O(19)Y2Ta2 trigonal pyramid,  a cornercorner with one O(9)Y2Ta2 trigonal pyramid, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(14)Y3Ta tetrahedra,  an edgeedge with one O(7)Y3Ta tetrahedra,  an edgeedge with one O(13)Y4 tetrahedra, and  an edgeedge with one O(10)YTa3 tetrahedra. In the twelfth O site, O(12) is bonded to one Y(6), one Y(8), one Y(9), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(16)Y3Ta tetrahedra,  a cornercorner with one O(15)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra,  a cornercorner with one O(19)Y2Ta2 trigonal pyramid,  a cornercorner with one O(9)Y2Ta2 trigonal pyramid, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(14)Y3Ta tetrahedra,  an edgeedge with one O(17)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(13)Y4 tetrahedra, and  an edgeedge with one O(10)YTa3 tetrahedra. In the thirteenth O site, O(13) is bonded to one Y(7), one Y(8), and two equivalent Y(6) atoms to form OY4 tetrahedra that share corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(6)Y4 tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra, edges with two equivalent O(12)Y3Ta tetrahedra,  an edgeedge with one O(19)Y2Ta2 trigonal pyramid, and edges with two equivalent O(11)Y2Ta2 trigonal pyramids. In the fourteenth O site, O(14) is bonded to one Y(9), two equivalent Y(6), and one Ta(3) atom to form OY3Ta tetrahedra that share corners with two equivalent O(16)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(13)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(10)YTa3 tetrahedra,  an edgeedge with one O(6)Y4 tetrahedra, edges with two equivalent O(12)Y3Ta tetrahedra, and edges with two equivalent O(11)Y2Ta2 trigonal pyramids. In the fifteenth O site, O(15) is bonded to one Y(7), one Y(8), and two equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(16)Y3Ta tetrahedra, corners with two equivalent O(13)Y4 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids, corners with two equivalent O(19)Y2Ta2 trigonal pyramids,  an edgeedge with one O(3)Y4 tetrahedra, and edges with two equivalent O(17)Y3Ta tetrahedra. In the sixteenth O site, O(16) is bonded to one Y(9), two equivalent Y(1), and one Ta(3) atom to form distorted OY3Ta tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(3)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(4)Y4 tetrahedra,  an edgeedge with one O(10)YTa3 tetrahedra, and edges with two equivalent O(17)Y3Ta tetrahedra. In the seventeenth O site, O(17) is bonded to one Y(1), one Y(8), one Y(9), and one Ta(1) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(14)Y3Ta tetrahedra,  a cornercorner with one O(13)Y4 tetrahedra,  a cornercorner with one O(3)Y4 tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(10)YTa3 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra,  an edgeedge with one O(1)Y3Ta tetrahedra,  an edgeedge with one O(12)Y3Ta tetrahedra,  an edgeedge with one O(16)Y3Ta tetrahedra,  an edgeedge with one O(15)Y4 tetrahedra, and  an edgeedge with one O(19)Y2Ta2 trigonal pyramid. In the eighteenth O site, O(18) is bonded in a 2-coordinate geometry to one Y(7), one Ta(1), and one Ta(3) atom. In the nineteenth O site, O(19) is bonded to one Y(7), one Y(8), and two equivalent Ta(1) atoms to form distorted OY2Ta2 trigonal pyramids that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(13)Y4 tetrahedra, and edges with two equivalent O(17)Y3Ta tetrahedra. In the twentieth O site, O(20) is bonded in a 4-coordinate geometry to one Y(3), one Y(5), and two equivalent Ta(1) atoms. is represented by the CIF file [CIF]
data_Y11Ta5O28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.452
_cell_length_b   7.467
_cell_length_c   10.535
_cell_angle_alpha   89.562
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   586.164
_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
  Y  Y0  1  0.757  0.478  0.997  1.0
  Y  Y1  1  0.243  0.478  0.997  1.0
  Y  Y2  1  0.000  0.267  0.730  1.0
  Y  Y3  1  0.500  0.235  0.762  1.0
  Y  Y4  1  0.000  0.733  0.732  1.0
  Y  Y5  1  0.500  0.751  0.757  1.0
  Y  Y6  1  0.248  0.004  0.503  1.0
  Y  Y7  1  0.752  0.004  0.503  1.0
  Y  Y8  1  0.000  0.764  0.244  1.0
  Y  Y9  1  0.000  0.238  0.245  1.0
  Y  Y10  1  0.500  0.264  0.265  1.0
  Ta  Ta11  1  0.749  0.998  0.003  1.0
  Ta  Ta12  1  0.251  0.998  0.003  1.0
  Ta  Ta13  1  0.275  0.495  0.513  1.0
  Ta  Ta14  1  0.725  0.495  0.513  1.0
  Ta  Ta15  1  0.500  0.730  0.274  1.0
  O  O16  1  0.785  0.197  0.880  1.0
  O  O17  1  0.215  0.197  0.880  1.0
  O  O18  1  0.781  0.798  0.886  1.0
  O  O19  1  0.219  0.798  0.886  1.0
  O  O20  1  0.000  0.498  0.866  1.0
  O  O21  1  0.500  0.494  0.879  1.0
  O  O22  1  0.000  0.000  0.633  1.0
  O  O23  1  0.500  0.998  0.636  1.0
  O  O24  1  0.267  0.714  0.621  1.0
  O  O25  1  0.733  0.714  0.621  1.0
  O  O26  1  0.731  0.284  0.628  1.0
  O  O27  1  0.269  0.284  0.628  1.0
  O  O28  1  0.000  0.501  0.569  1.0
  O  O29  1  0.500  0.510  0.404  1.0
  O  O30  1  0.753  0.698  0.364  1.0
  O  O31  1  0.247  0.698  0.364  1.0
  O  O32  1  0.769  0.293  0.383  1.0
  O  O33  1  0.231  0.293  0.383  1.0
  O  O34  1  0.000  0.995  0.368  1.0
  O  O35  1  0.500  0.976  0.361  1.0
  O  O36  1  0.000  0.507  0.134  1.0
  O  O37  1  0.500  0.527  0.153  1.0
  O  O38  1  0.725  0.215  0.122  1.0
  O  O39  1  0.275  0.215  0.122  1.0
  O  O40  1  0.683  0.836  0.144  1.0
  O  O41  1  0.317  0.836  0.144  1.0
  O  O42  1  0.000  0.983  0.076  1.0
  O  O43  1  0.500  0.008  0.935  1.0
[/CIF]
.
The material structure described by Y11Ta5O28 crystallizes in the monoclinic Pm space group. There are nine inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(1), one O(15), one O(16), one O(17), one O(2), one O(3), and one O(4) atom. In the second Y site, Y(2) is bonded to one O(3), one O(5), one O(9), two equivalent O(1), and two equivalent O(8) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(4)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Y(4)O7 pentagonal bipyramid, and edges with two equivalent Y(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. In the third Y site, Y(3) is bonded to one O(20), one O(4), one O(6), two equivalent O(1), and two equivalent O(8) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Y(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 61°. In the fourth Y site, Y(4) is bonded to one O(3), one O(5), one O(9), two equivalent O(2), and two equivalent O(7) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(2)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra, and  an edgeedge with one Y(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 47°. In the fifth Y site, Y(5) is bonded in a 7-coordinate geometry to one O(20), one O(4), one O(6), two equivalent O(2), and two equivalent O(7) atoms. In the sixth Y site, Y(6) is bonded in a distorted body-centered cubic geometry to one O(11), one O(12), one O(13), one O(14), one O(5), one O(6), one O(7), and one O(8) atom. In the seventh Y site, Y(7) is bonded to one O(13), one O(15), one O(19), two equivalent O(11), and two equivalent O(18) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Ta(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Ta(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 51°. In the eighth Y site, Y(8) is bonded in a 7-coordinate geometry to one O(13), one O(15), one O(19), two equivalent O(12), and two equivalent O(17) atoms. In the ninth Y site, Y(9) is bonded to one O(10), one O(14), one O(16), two equivalent O(12), and two equivalent O(17) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Ta(3)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra, and  an edgeedge with one Ta(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 54°. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(17), one O(18), one O(19), one O(2), and one O(20) atom to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(2)O7 pentagonal bipyramid,  a cornercorner with one Y(4)O7 pentagonal bipyramid,  a cornercorner with one Y(9)O7 pentagonal bipyramid,  a cornercorner with one Ta(3)O7 pentagonal bipyramid,  an edgeedge with one Y(7)O7 hexagonal pyramid, and  an edgeedge with one Y(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 42-45°. In the second Ta site, Ta(2) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form distorted TaO6 octahedra that share  a cornercorner with one Y(7)O7 hexagonal pyramid, corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(3)O7 pentagonal bipyramid,  an edgeedge with one Y(2)O7 pentagonal bipyramid,  an edgeedge with one Y(4)O7 pentagonal bipyramid,  an edgeedge with one Y(9)O7 pentagonal bipyramid, and  an edgeedge with one Ta(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 32-69°. In the third Ta site, Ta(3) is bonded to one O(10), one O(14), one O(16), two equivalent O(11), and two equivalent O(18) atoms to form TaO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one Y(9)O7 pentagonal bipyramid, edges with two equivalent Y(7)O7 hexagonal pyramids, edges with two equivalent Ta(2)O6 octahedra, and  an edgeedge with one Y(9)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 28°. There are twenty inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), one Y(3), and one Ta(1) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(16)Y3Ta tetrahedra,  a cornercorner with one O(15)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4 tetrahedra, corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra,  a cornercorner with one O(19)Y2Ta2 trigonal pyramid,  a cornercorner with one O(9)Y2Ta2 trigonal pyramid,  an edgeedge with one O(17)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(3)Y4 tetrahedra, and  an edgeedge with one O(4)Y4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(1), one Y(4), one Y(5), and one Ta(1) atom. In the third O site, O(3) is bonded to one Y(2), one Y(4), and two equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(16)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra,  an edgeedge with one O(15)Y4 tetrahedra, edges with two equivalent O(1)Y3Ta tetrahedra, and  an edgeedge with one O(9)Y2Ta2 trigonal pyramid. In the fourth O site, O(4) is bonded to one Y(3), one Y(5), and two equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(3)Y4 tetrahedra, corners with two equivalent O(6)Y4 tetrahedra,  an edgeedge with one O(16)Y3Ta tetrahedra, and edges with two equivalent O(1)Y3Ta tetrahedra. In the fifth O site, O(5) is bonded to one Y(2), one Y(4), and two equivalent Y(6) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(3)Y4 tetrahedra, corners with two equivalent O(6)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids, corners with two equivalent O(9)Y2Ta2 trigonal pyramids,  an edgeedge with one O(13)Y4 tetrahedra, edges with two equivalent O(7)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the sixth O site, O(6) is bonded to one Y(3), one Y(5), and two equivalent Y(6) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(13)Y4 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(14)Y3Ta tetrahedra, edges with two equivalent O(7)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the seventh O site, O(7) is bonded to one Y(4), one Y(5), one Y(6), and one Ta(2) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(14)Y3Ta tetrahedra,  a cornercorner with one O(13)Y4 tetrahedra,  a cornercorner with one O(3)Y4 tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(10)YTa3 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(6)Y4 tetrahedra,  an edgeedge with one O(11)Y2Ta2 trigonal pyramid, and  an edgeedge with one O(9)Y2Ta2 trigonal pyramid. In the eighth O site, O(8) is bonded to one Y(2), one Y(3), one Y(6), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(14)Y3Ta tetrahedra,  a cornercorner with one O(13)Y4 tetrahedra,  a cornercorner with one O(3)Y4 tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(10)YTa3 tetrahedra, corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(1)Y3Ta tetrahedra,  an edgeedge with one O(12)Y3Ta tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra,  an edgeedge with one O(6)Y4 tetrahedra, and  an edgeedge with one O(9)Y2Ta2 trigonal pyramid. In the ninth O site, O(9) is bonded to one Y(2), one Y(4), and two equivalent Ta(2) atoms to form distorted OY2Ta2 trigonal pyramids that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(10)YTa3 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(3)Y4 tetrahedra, edges with two equivalent O(7)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the tenth O site, O(10) is bonded to one Y(9), one Ta(3), and two equivalent Ta(2) atoms to form OYTa3 tetrahedra that share corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y2Ta2 trigonal pyramids,  an edgeedge with one O(16)Y3Ta tetrahedra, edges with two equivalent O(12)Y3Ta tetrahedra, and edges with two equivalent O(11)Y2Ta2 trigonal pyramids. In the eleventh O site, O(11) is bonded to one Y(6), one Y(7), one Ta(2), and one Ta(3) atom to form distorted OY2Ta2 trigonal pyramids that share  a cornercorner with one O(16)Y3Ta tetrahedra,  a cornercorner with one O(15)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra,  a cornercorner with one O(19)Y2Ta2 trigonal pyramid,  a cornercorner with one O(9)Y2Ta2 trigonal pyramid, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(14)Y3Ta tetrahedra,  an edgeedge with one O(7)Y3Ta tetrahedra,  an edgeedge with one O(13)Y4 tetrahedra, and  an edgeedge with one O(10)YTa3 tetrahedra. In the twelfth O site, O(12) is bonded to one Y(6), one Y(8), one Y(9), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(16)Y3Ta tetrahedra,  a cornercorner with one O(15)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(6)Y4 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra,  a cornercorner with one O(19)Y2Ta2 trigonal pyramid,  a cornercorner with one O(9)Y2Ta2 trigonal pyramid, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(14)Y3Ta tetrahedra,  an edgeedge with one O(17)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(13)Y4 tetrahedra, and  an edgeedge with one O(10)YTa3 tetrahedra. In the thirteenth O site, O(13) is bonded to one Y(7), one Y(8), and two equivalent Y(6) atoms to form OY4 tetrahedra that share corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(6)Y4 tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra, edges with two equivalent O(12)Y3Ta tetrahedra,  an edgeedge with one O(19)Y2Ta2 trigonal pyramid, and edges with two equivalent O(11)Y2Ta2 trigonal pyramids. In the fourteenth O site, O(14) is bonded to one Y(9), two equivalent Y(6), and one Ta(3) atom to form OY3Ta tetrahedra that share corners with two equivalent O(16)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra, corners with two equivalent O(7)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(13)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with two equivalent O(10)YTa3 tetrahedra,  an edgeedge with one O(6)Y4 tetrahedra, edges with two equivalent O(12)Y3Ta tetrahedra, and edges with two equivalent O(11)Y2Ta2 trigonal pyramids. In the fifteenth O site, O(15) is bonded to one Y(7), one Y(8), and two equivalent Y(1) atoms to form OY4 tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(16)Y3Ta tetrahedra, corners with two equivalent O(13)Y4 tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids, corners with two equivalent O(19)Y2Ta2 trigonal pyramids,  an edgeedge with one O(3)Y4 tetrahedra, and edges with two equivalent O(17)Y3Ta tetrahedra. In the sixteenth O site, O(16) is bonded to one Y(9), two equivalent Y(1), and one Ta(3) atom to form distorted OY3Ta tetrahedra that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(14)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(3)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(4)Y4 tetrahedra,  an edgeedge with one O(10)YTa3 tetrahedra, and edges with two equivalent O(17)Y3Ta tetrahedra. In the seventeenth O site, O(17) is bonded to one Y(1), one Y(8), one Y(9), and one Ta(1) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(14)Y3Ta tetrahedra,  a cornercorner with one O(13)Y4 tetrahedra,  a cornercorner with one O(3)Y4 tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(10)YTa3 tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(17)Y3Ta tetrahedra,  an edgeedge with one O(1)Y3Ta tetrahedra,  an edgeedge with one O(12)Y3Ta tetrahedra,  an edgeedge with one O(16)Y3Ta tetrahedra,  an edgeedge with one O(15)Y4 tetrahedra, and  an edgeedge with one O(19)Y2Ta2 trigonal pyramid. In the eighteenth O site, O(18) is bonded in a 2-coordinate geometry to one Y(7), one Ta(1), and one Ta(3) atom. In the nineteenth O site, O(19) is bonded to one Y(7), one Y(8), and two equivalent Ta(1) atoms to form distorted OY2Ta2 trigonal pyramids that share corners with two equivalent O(1)Y3Ta tetrahedra, corners with two equivalent O(12)Y3Ta tetrahedra, corners with two equivalent O(15)Y4 tetrahedra, corners with two equivalent O(11)Y2Ta2 trigonal pyramids,  an edgeedge with one O(13)Y4 tetrahedra, and edges with two equivalent O(17)Y3Ta tetrahedra. In the twentieth O site, O(20) is bonded in a 4-coordinate geometry to one Y(3), one Y(5), and two equivalent Ta(1) atoms. is represented by the CIF file [CIF]
data_Y11Ta5O28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.452
_cell_length_b   7.467
_cell_length_c   10.535
_cell_angle_alpha   89.562
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   586.164
_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
  Y  Y0  1  0.757  0.478  0.997  1.0
  Y  Y1  1  0.243  0.478  0.997  1.0
  Y  Y2  1  0.000  0.267  0.730  1.0
  Y  Y3  1  0.500  0.235  0.762  1.0
  Y  Y4  1  0.000  0.733  0.732  1.0
  Y  Y5  1  0.500  0.751  0.757  1.0
  Y  Y6  1  0.248  0.004  0.503  1.0
  Y  Y7  1  0.752  0.004  0.503  1.0
  Y  Y8  1  0.000  0.764  0.244  1.0
  Y  Y9  1  0.000  0.238  0.245  1.0
  Y  Y10  1  0.500  0.264  0.265  1.0
  Ta  Ta11  1  0.749  0.998  0.003  1.0
  Ta  Ta12  1  0.251  0.998  0.003  1.0
  Ta  Ta13  1  0.275  0.495  0.513  1.0
  Ta  Ta14  1  0.725  0.495  0.513  1.0
  Ta  Ta15  1  0.500  0.730  0.274  1.0
  O  O16  1  0.785  0.197  0.880  1.0
  O  O17  1  0.215  0.197  0.880  1.0
  O  O18  1  0.781  0.798  0.886  1.0
  O  O19  1  0.219  0.798  0.886  1.0
  O  O20  1  0.000  0.498  0.866  1.0
  O  O21  1  0.500  0.494  0.879  1.0
  O  O22  1  0.000  0.000  0.633  1.0
  O  O23  1  0.500  0.998  0.636  1.0
  O  O24  1  0.267  0.714  0.621  1.0
  O  O25  1  0.733  0.714  0.621  1.0
  O  O26  1  0.731  0.284  0.628  1.0
  O  O27  1  0.269  0.284  0.628  1.0
  O  O28  1  0.000  0.501  0.569  1.0
  O  O29  1  0.500  0.510  0.404  1.0
  O  O30  1  0.753  0.698  0.364  1.0
  O  O31  1  0.247  0.698  0.364  1.0
  O  O32  1  0.769  0.293  0.383  1.0
  O  O33  1  0.231  0.293  0.383  1.0
  O  O34  1  0.000  0.995  0.368  1.0
  O  O35  1  0.500  0.976  0.361  1.0
  O  O36  1  0.000  0.507  0.134  1.0
  O  O37  1  0.500  0.527  0.153  1.0
  O  O38  1  0.725  0.215  0.122  1.0
  O  O39  1  0.275  0.215  0.122  1.0
  O  O40  1  0.683  0.836  0.144  1.0
  O  O41  1  0.317  0.836  0.144  1.0
  O  O42  1  0.000  0.983  0.076  1.0
  O  O43  1  0.500  0.008  0.935  1.0
[/CIF]
.