The crystal structure described by K2Ta4O11 crystallizes in the trigonal R-3c space group. K(1) is bonded in a 10-coordinate geometry to one O(2), three equivalent O(3), and six equivalent O(1) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent O(1) atoms to form corner-sharing TaO6 octahedra. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(2), and three equivalent O(3) atoms to form distorted TaO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids, and edges with four equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent K(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted corner and edge-sharing OK2Ta2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one K(1) and three equivalent Ta(2) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent K(1) and three equivalent Ta(2) atoms. is represented by the CIF file [CIF]
data_K2Ta4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.858
_cell_length_b   12.858
_cell_length_c   12.858
_cell_angle_alpha   28.327
_cell_angle_beta   28.327
_cell_angle_gamma   28.327
_symmetry_Int_Tables_number   1
_cell_volume   422.955
_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
  K  K0  1  0.826  0.826  0.826  1.0
  K  K1  1  0.326  0.326  0.326  1.0
  K  K2  1  0.174  0.174  0.174  1.0
  K  K3  1  0.674  0.674  0.674  1.0
  Ta  Ta4  1  0.500  0.500  0.500  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Ta  Ta6  1  0.250  0.615  0.885  1.0
  Ta  Ta7  1  0.885  0.250  0.615  1.0
  Ta  Ta8  1  0.615  0.885  0.250  1.0
  Ta  Ta9  1  0.385  0.115  0.750  1.0
  Ta  Ta10  1  0.750  0.385  0.115  1.0
  Ta  Ta11  1  0.115  0.750  0.385  1.0
  O  O12  1  0.260  0.570  0.765  1.0
  O  O13  1  0.765  0.260  0.570  1.0
  O  O14  1  0.570  0.765  0.260  1.0
  O  O15  1  0.265  0.070  0.760  1.0
  O  O16  1  0.760  0.265  0.070  1.0
  O  O17  1  0.070  0.760  0.265  1.0
  O  O18  1  0.740  0.430  0.235  1.0
  O  O19  1  0.235  0.740  0.430  1.0
  O  O20  1  0.430  0.235  0.740  1.0
  O  O21  1  0.735  0.930  0.240  1.0
  O  O22  1  0.240  0.735  0.930  1.0
  O  O23  1  0.930  0.240  0.735  1.0
  O  O24  1  0.906  0.906  0.906  1.0
  O  O25  1  0.406  0.406  0.406  1.0
  O  O26  1  0.094  0.094  0.094  1.0
  O  O27  1  0.594  0.594  0.594  1.0
  O  O28  1  0.005  0.495  0.250  1.0
  O  O29  1  0.250  0.005  0.495  1.0
  O  O30  1  0.495  0.250  0.005  1.0
  O  O31  1  0.750  0.995  0.505  1.0
  O  O32  1  0.505  0.750  0.995  1.0
  O  O33  1  0.995  0.505  0.750  1.0
[/CIF]
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The crystal structure described by K2Ta4O11 crystallizes in the trigonal R-3c space group. K(1) is bonded in a 10-coordinate geometry to one O(2), three equivalent O(3), and six equivalent O(1) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent O(1) atoms to form corner-sharing TaO6 octahedra. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(2), and three equivalent O(3) atoms to form distorted TaO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids, and edges with four equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent K(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted corner and edge-sharing OK2Ta2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one K(1) and three equivalent Ta(2) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent K(1) and three equivalent Ta(2) atoms. is represented by the CIF file [CIF]
data_K2Ta4O11
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.858
_cell_length_b   12.858
_cell_length_c   12.858
_cell_angle_alpha   28.327
_cell_angle_beta   28.327
_cell_angle_gamma   28.327
_symmetry_Int_Tables_number   1
_cell_volume   422.955
_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
  K  K0  1  0.826  0.826  0.826  1.0
  K  K1  1  0.326  0.326  0.326  1.0
  K  K2  1  0.174  0.174  0.174  1.0
  K  K3  1  0.674  0.674  0.674  1.0
  Ta  Ta4  1  0.500  0.500  0.500  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Ta  Ta6  1  0.250  0.615  0.885  1.0
  Ta  Ta7  1  0.885  0.250  0.615  1.0
  Ta  Ta8  1  0.615  0.885  0.250  1.0
  Ta  Ta9  1  0.385  0.115  0.750  1.0
  Ta  Ta10  1  0.750  0.385  0.115  1.0
  Ta  Ta11  1  0.115  0.750  0.385  1.0
  O  O12  1  0.260  0.570  0.765  1.0
  O  O13  1  0.765  0.260  0.570  1.0
  O  O14  1  0.570  0.765  0.260  1.0
  O  O15  1  0.265  0.070  0.760  1.0
  O  O16  1  0.760  0.265  0.070  1.0
  O  O17  1  0.070  0.760  0.265  1.0
  O  O18  1  0.740  0.430  0.235  1.0
  O  O19  1  0.235  0.740  0.430  1.0
  O  O20  1  0.430  0.235  0.740  1.0
  O  O21  1  0.735  0.930  0.240  1.0
  O  O22  1  0.240  0.735  0.930  1.0
  O  O23  1  0.930  0.240  0.735  1.0
  O  O24  1  0.906  0.906  0.906  1.0
  O  O25  1  0.406  0.406  0.406  1.0
  O  O26  1  0.094  0.094  0.094  1.0
  O  O27  1  0.594  0.594  0.594  1.0
  O  O28  1  0.005  0.495  0.250  1.0
  O  O29  1  0.250  0.005  0.495  1.0
  O  O30  1  0.495  0.250  0.005  1.0
  O  O31  1  0.750  0.995  0.505  1.0
  O  O32  1  0.505  0.750  0.995  1.0
  O  O33  1  0.995  0.505  0.750  1.0
[/CIF]
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