The structure described by Y11Ta5O28 crystallizes in the monoclinic C2/m space group. There are six inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(1), one O(5), one O(7), two equivalent O(8), and two equivalent O(9) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(6)O7 pentagonal bipyramid,  an edgeedge with one Y(2)O8 hexagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra, and edges with two equivalent Y(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 57°. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(7), and four equivalent O(3) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Ta(1)O6 octahedra, edges with four equivalent Ta(2)O6 octahedra, and edges with two equivalent Y(1)O7 pentagonal bipyramids. In the third Y site, Y(3) is bonded to one O(2), one O(4), one O(6), two equivalent O(8), and two equivalent O(9) atoms to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Y(6)O7 pentagonal bipyramid, and edges with two equivalent Y(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 46-54°. In the fourth Y site, Y(4) is bonded in a body-centered cubic geometry to two equivalent O(10), two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms. In the fifth Y site, Y(5) is bonded in a distorted body-centered cubic geometry to two equivalent O(3), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms. In the sixth Y site, Y(6) is bonded to one O(2), one O(4), one O(5), and four equivalent O(10) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(1)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Y(3)O7 pentagonal bipyramid, and edges with two equivalent Y(6)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 51°. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(6) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with four equivalent Ta(2)O6 octahedra, corners with two equivalent Y(3)O7 pentagonal bipyramids, and edges with two equivalent Y(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. In the second Ta site, Ta(2) is bonded to one O(1), one O(10), one O(2), one O(3), one O(8), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(1)O7 pentagonal bipyramid,  a cornercorner with one Y(3)O7 pentagonal bipyramid,  a cornercorner with one Y(6)O7 pentagonal bipyramid,  an edgeedge with one Y(2)O8 hexagonal bipyramid,  an edgeedge with one Y(1)O7 pentagonal bipyramid,  an edgeedge with one Y(3)O7 pentagonal bipyramid, and  an edgeedge with one Y(6)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 39-63°. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), and two equivalent Ta(2) atoms to form OY2Ta2 tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(10)Y3Ta tetrahedra, corners with four equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(2)Y2Ta2 trigonal pyramids,  an edgeedge with one O(7)Y4 tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the second O site, O(2) is bonded to one Y(3), one Y(6), and two equivalent Ta(2) atoms to form distorted OY2Ta2 trigonal pyramids that share  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra, corners with two equivalent O(1)Y2Ta2 tetrahedra, corners with two equivalent O(10)Y3Ta tetrahedra, corners with four equivalent O(8)Y3Ta tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(10)Y3Ta tetrahedra, and edges with two equivalent O(9)Y3Ta tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Y(2), one Y(5), one Ta(1), and one Ta(2) atom. In the fourth O site, O(4) is bonded to one Y(3), one Y(6), and two equivalent Y(4) atoms to form OY4 tetrahedra that share  a cornercorner with one O(6)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with three equivalent O(5)Y4 tetrahedra, corners with four equivalent O(10)Y3Ta tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra, edges with two equivalent O(10)Y3Ta tetrahedra, edges with two equivalent O(8)Y3Ta tetrahedra, and  an edgeedge with one O(2)Y2Ta2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Y(1), one Y(6), and two equivalent Y(4) atoms to form OY4 tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with three equivalent O(4)Y4 tetrahedra, corners with four equivalent O(10)Y3Ta tetrahedra,  a cornercorner with one O(2)Y2Ta2 trigonal pyramid,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(10)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the sixth O site, O(6) is bonded to one Y(3), two equivalent Y(5), and one Ta(1) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with four equivalent O(7)Y4 tetrahedra,  a cornercorner with one O(2)Y2Ta2 trigonal pyramid,  an edgeedge with one O(6)Y3Ta tetrahedra, and edges with two equivalent O(9)Y3Ta tetrahedra. In the seventh O site, O(7) is bonded to one Y(1), one Y(2), and two equivalent Y(5) atoms to form OY4 tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with four equivalent O(6)Y3Ta tetrahedra,  an edgeedge with one O(1)Y2Ta2 tetrahedra,  an edgeedge with one O(7)Y4 tetrahedra, and edges with two equivalent O(9)Y3Ta tetrahedra. In the eighth O site, O(8) is bonded to one Y(1), one Y(3), one Y(4), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(10)Y3Ta tetrahedra,  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with three equivalent O(8)Y3Ta tetrahedra, corners with three equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(2)Y2Ta2 trigonal pyramids,  an edgeedge with one O(1)Y2Ta2 tetrahedra,  an edgeedge with one O(10)Y3Ta tetrahedra,  an edgeedge with one O(9)Y3Ta tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, and  an edgeedge with one O(5)Y4 tetrahedra. In the ninth O site, O(9) is bonded to one Y(1), one Y(3), one Y(5), and one Ta(2) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(10)Y3Ta tetrahedra,  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(1)Y2Ta2 tetrahedra, corners with three equivalent O(8)Y3Ta tetrahedra, corners with three equivalent O(9)Y3Ta tetrahedra,  an edgeedge with one O(6)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(7)Y4 tetrahedra, and  an edgeedge with one O(2)Y2Ta2 trigonal pyramid. In the tenth O site, O(10) is bonded to one Y(4), two equivalent Y(6), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(8)Y3Ta tetrahedra,  a cornercorner with one O(9)Y3Ta tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with five equivalent O(10)Y3Ta tetrahedra,  a cornercorner with one O(2)Y2Ta2 trigonal pyramid,  an edgeedge with one O(10)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra, and  an edgeedge with one O(2)Y2Ta2 trigonal pyramid. is represented by the CIF file [CIF]
data_Y11Ta5O28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.002
_cell_length_b   13.002
_cell_length_c   6.445
_cell_angle_alpha   80.560
_cell_angle_beta   80.560
_cell_angle_gamma   32.950
_symmetry_Int_Tables_number   1
_cell_volume   583.829
_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  0.123  0.123  0.720  1.0
  Y  Y1  1  0.000  0.000  0.500  1.0
  Y  Y2  1  0.626  0.626  0.778  1.0
  Y  Y3  1  0.500  0.000  0.500  1.0
  Y  Y4  1  0.246  0.754  0.000  1.0
  Y  Y5  1  0.754  0.246  0.000  1.0
  Y  Y6  1  0.000  0.500  0.500  1.0
  Y  Y7  1  0.374  0.374  0.222  1.0
  Y  Y8  1  0.259  0.259  0.980  1.0
  Y  Y9  1  0.877  0.877  0.280  1.0
  Y  Y10  1  0.741  0.741  0.020  1.0
  Ta  Ta11  1  0.500  0.500  0.500  1.0
  Ta  Ta12  1  0.108  0.637  0.758  1.0
  Ta  Ta13  1  0.363  0.892  0.242  1.0
  Ta  Ta14  1  0.892  0.363  0.242  1.0
  Ta  Ta15  1  0.637  0.108  0.758  1.0
  O  O16  1  0.904  0.904  0.622  1.0
  O  O17  1  0.357  0.357  0.859  1.0
  O  O18  1  0.256  0.653  0.643  1.0
  O  O19  1  0.653  0.256  0.643  1.0
  O  O20  1  0.716  0.716  0.705  1.0
  O  O21  1  0.215  0.215  0.697  1.0
  O  O22  1  0.465  0.465  0.231  1.0
  O  O23  1  0.973  0.973  0.200  1.0
  O  O24  1  0.872  0.417  0.533  1.0
  O  O25  1  0.125  0.678  0.031  1.0
  O  O26  1  0.744  0.347  0.357  1.0
  O  O27  1  0.347  0.744  0.357  1.0
  O  O28  1  0.678  0.125  0.031  1.0
  O  O29  1  0.417  0.872  0.533  1.0
  O  O30  1  0.643  0.643  0.141  1.0
  O  O31  1  0.096  0.096  0.378  1.0
  O  O32  1  0.875  0.322  0.969  1.0
  O  O33  1  0.128  0.583  0.467  1.0
  O  O34  1  0.583  0.128  0.467  1.0
  O  O35  1  0.986  0.428  0.162  1.0
  O  O36  1  0.322  0.875  0.969  1.0
  O  O37  1  0.428  0.986  0.162  1.0
  O  O38  1  0.027  0.027  0.800  1.0
  O  O39  1  0.284  0.284  0.295  1.0
  O  O40  1  0.785  0.785  0.303  1.0
  O  O41  1  0.535  0.535  0.769  1.0
  O  O42  1  0.572  0.014  0.838  1.0
  O  O43  1  0.014  0.572  0.838  1.0
[/CIF]
.
The structure described by Y11Ta5O28 crystallizes in the monoclinic C2/m space group. There are six inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(1), one O(5), one O(7), two equivalent O(8), and two equivalent O(9) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(6)O7 pentagonal bipyramid,  an edgeedge with one Y(2)O8 hexagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra, and edges with two equivalent Y(3)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 57°. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(7), and four equivalent O(3) atoms to form distorted YO8 hexagonal bipyramids that share edges with two equivalent Ta(1)O6 octahedra, edges with four equivalent Ta(2)O6 octahedra, and edges with two equivalent Y(1)O7 pentagonal bipyramids. In the third Y site, Y(3) is bonded to one O(2), one O(4), one O(6), two equivalent O(8), and two equivalent O(9) atoms to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Y(6)O7 pentagonal bipyramid, and edges with two equivalent Y(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 46-54°. In the fourth Y site, Y(4) is bonded in a body-centered cubic geometry to two equivalent O(10), two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms. In the fifth Y site, Y(5) is bonded in a distorted body-centered cubic geometry to two equivalent O(3), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms. In the sixth Y site, Y(6) is bonded to one O(2), one O(4), one O(5), and four equivalent O(10) atoms to form distorted YO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(1)O7 pentagonal bipyramid, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Y(3)O7 pentagonal bipyramid, and edges with two equivalent Y(6)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 51°. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(6) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with four equivalent Ta(2)O6 octahedra, corners with two equivalent Y(3)O7 pentagonal bipyramids, and edges with two equivalent Y(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. In the second Ta site, Ta(2) is bonded to one O(1), one O(10), one O(2), one O(3), one O(8), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Y(1)O7 pentagonal bipyramid,  a cornercorner with one Y(3)O7 pentagonal bipyramid,  a cornercorner with one Y(6)O7 pentagonal bipyramid,  an edgeedge with one Y(2)O8 hexagonal bipyramid,  an edgeedge with one Y(1)O7 pentagonal bipyramid,  an edgeedge with one Y(3)O7 pentagonal bipyramid, and  an edgeedge with one Y(6)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 39-63°. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), and two equivalent Ta(2) atoms to form OY2Ta2 tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(10)Y3Ta tetrahedra, corners with four equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(2)Y2Ta2 trigonal pyramids,  an edgeedge with one O(7)Y4 tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the second O site, O(2) is bonded to one Y(3), one Y(6), and two equivalent Ta(2) atoms to form distorted OY2Ta2 trigonal pyramids that share  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra, corners with two equivalent O(1)Y2Ta2 tetrahedra, corners with two equivalent O(10)Y3Ta tetrahedra, corners with four equivalent O(8)Y3Ta tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(10)Y3Ta tetrahedra, and edges with two equivalent O(9)Y3Ta tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Y(2), one Y(5), one Ta(1), and one Ta(2) atom. In the fourth O site, O(4) is bonded to one Y(3), one Y(6), and two equivalent Y(4) atoms to form OY4 tetrahedra that share  a cornercorner with one O(6)Y3Ta tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with three equivalent O(5)Y4 tetrahedra, corners with four equivalent O(10)Y3Ta tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra, edges with two equivalent O(10)Y3Ta tetrahedra, edges with two equivalent O(8)Y3Ta tetrahedra, and  an edgeedge with one O(2)Y2Ta2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Y(1), one Y(6), and two equivalent Y(4) atoms to form OY4 tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with three equivalent O(4)Y4 tetrahedra, corners with four equivalent O(10)Y3Ta tetrahedra,  a cornercorner with one O(2)Y2Ta2 trigonal pyramid,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(10)Y3Ta tetrahedra, and edges with two equivalent O(8)Y3Ta tetrahedra. In the sixth O site, O(6) is bonded to one Y(3), two equivalent Y(5), and one Ta(1) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with four equivalent O(7)Y4 tetrahedra,  a cornercorner with one O(2)Y2Ta2 trigonal pyramid,  an edgeedge with one O(6)Y3Ta tetrahedra, and edges with two equivalent O(9)Y3Ta tetrahedra. In the seventh O site, O(7) is bonded to one Y(1), one Y(2), and two equivalent Y(5) atoms to form OY4 tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(8)Y3Ta tetrahedra, corners with two equivalent O(9)Y3Ta tetrahedra, corners with four equivalent O(6)Y3Ta tetrahedra,  an edgeedge with one O(1)Y2Ta2 tetrahedra,  an edgeedge with one O(7)Y4 tetrahedra, and edges with two equivalent O(9)Y3Ta tetrahedra. In the eighth O site, O(8) is bonded to one Y(1), one Y(3), one Y(4), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(10)Y3Ta tetrahedra,  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with three equivalent O(8)Y3Ta tetrahedra, corners with three equivalent O(9)Y3Ta tetrahedra, corners with two equivalent O(2)Y2Ta2 trigonal pyramids,  an edgeedge with one O(1)Y2Ta2 tetrahedra,  an edgeedge with one O(10)Y3Ta tetrahedra,  an edgeedge with one O(9)Y3Ta tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, and  an edgeedge with one O(5)Y4 tetrahedra. In the ninth O site, O(9) is bonded to one Y(1), one Y(3), one Y(5), and one Ta(2) atom to form OY3Ta tetrahedra that share  a cornercorner with one O(10)Y3Ta tetrahedra,  a cornercorner with one O(6)Y3Ta tetrahedra,  a cornercorner with one O(4)Y4 tetrahedra,  a cornercorner with one O(5)Y4 tetrahedra,  a cornercorner with one O(7)Y4 tetrahedra, corners with two equivalent O(1)Y2Ta2 tetrahedra, corners with three equivalent O(8)Y3Ta tetrahedra, corners with three equivalent O(9)Y3Ta tetrahedra,  an edgeedge with one O(6)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(7)Y4 tetrahedra, and  an edgeedge with one O(2)Y2Ta2 trigonal pyramid. In the tenth O site, O(10) is bonded to one Y(4), two equivalent Y(6), and one Ta(2) atom to form distorted OY3Ta tetrahedra that share  a cornercorner with one O(1)Y2Ta2 tetrahedra,  a cornercorner with one O(8)Y3Ta tetrahedra,  a cornercorner with one O(9)Y3Ta tetrahedra, corners with two equivalent O(4)Y4 tetrahedra, corners with two equivalent O(5)Y4 tetrahedra, corners with five equivalent O(10)Y3Ta tetrahedra,  a cornercorner with one O(2)Y2Ta2 trigonal pyramid,  an edgeedge with one O(10)Y3Ta tetrahedra,  an edgeedge with one O(8)Y3Ta tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra,  an edgeedge with one O(5)Y4 tetrahedra, and  an edgeedge with one O(2)Y2Ta2 trigonal pyramid. is represented by the CIF file [CIF]
data_Y11Ta5O28
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.002
_cell_length_b   13.002
_cell_length_c   6.445
_cell_angle_alpha   80.560
_cell_angle_beta   80.560
_cell_angle_gamma   32.950
_symmetry_Int_Tables_number   1
_cell_volume   583.829
_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  0.123  0.123  0.720  1.0
  Y  Y1  1  0.000  0.000  0.500  1.0
  Y  Y2  1  0.626  0.626  0.778  1.0
  Y  Y3  1  0.500  0.000  0.500  1.0
  Y  Y4  1  0.246  0.754  0.000  1.0
  Y  Y5  1  0.754  0.246  0.000  1.0
  Y  Y6  1  0.000  0.500  0.500  1.0
  Y  Y7  1  0.374  0.374  0.222  1.0
  Y  Y8  1  0.259  0.259  0.980  1.0
  Y  Y9  1  0.877  0.877  0.280  1.0
  Y  Y10  1  0.741  0.741  0.020  1.0
  Ta  Ta11  1  0.500  0.500  0.500  1.0
  Ta  Ta12  1  0.108  0.637  0.758  1.0
  Ta  Ta13  1  0.363  0.892  0.242  1.0
  Ta  Ta14  1  0.892  0.363  0.242  1.0
  Ta  Ta15  1  0.637  0.108  0.758  1.0
  O  O16  1  0.904  0.904  0.622  1.0
  O  O17  1  0.357  0.357  0.859  1.0
  O  O18  1  0.256  0.653  0.643  1.0
  O  O19  1  0.653  0.256  0.643  1.0
  O  O20  1  0.716  0.716  0.705  1.0
  O  O21  1  0.215  0.215  0.697  1.0
  O  O22  1  0.465  0.465  0.231  1.0
  O  O23  1  0.973  0.973  0.200  1.0
  O  O24  1  0.872  0.417  0.533  1.0
  O  O25  1  0.125  0.678  0.031  1.0
  O  O26  1  0.744  0.347  0.357  1.0
  O  O27  1  0.347  0.744  0.357  1.0
  O  O28  1  0.678  0.125  0.031  1.0
  O  O29  1  0.417  0.872  0.533  1.0
  O  O30  1  0.643  0.643  0.141  1.0
  O  O31  1  0.096  0.096  0.378  1.0
  O  O32  1  0.875  0.322  0.969  1.0
  O  O33  1  0.128  0.583  0.467  1.0
  O  O34  1  0.583  0.128  0.467  1.0
  O  O35  1  0.986  0.428  0.162  1.0
  O  O36  1  0.322  0.875  0.969  1.0
  O  O37  1  0.428  0.986  0.162  1.0
  O  O38  1  0.027  0.027  0.800  1.0
  O  O39  1  0.284  0.284  0.295  1.0
  O  O40  1  0.785  0.785  0.303  1.0
  O  O41  1  0.535  0.535  0.769  1.0
  O  O42  1  0.572  0.014  0.838  1.0
  O  O43  1  0.014  0.572  0.838  1.0
[/CIF]
.