The structure described by K4Ta3NbO12 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal R-3m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to three equivalent O(2) and nine equivalent O(1) atoms to form KO12 cuboctahedra that share corners with six equivalent K(1)O12 cuboctahedra, corners with six equivalent K(2)O12 cuboctahedra, faces with three equivalent K(1)O12 cuboctahedra, faces with three equivalent K(2)O12 cuboctahedra,  a faceface with one Nb(1)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with four equivalent Ta(1)O6 octahedra. In the second K site, K(2) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form KO12 cuboctahedra that share corners with six equivalent K(1)O12 cuboctahedra, corners with six equivalent K(2)O12 cuboctahedra, faces with three equivalent K(1)O12 cuboctahedra, faces with three equivalent K(2)O12 cuboctahedra,  a faceface with one Ta(2)O6 octahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with four equivalent Ta(1)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form TaO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, faces with four equivalent K(1)O12 cuboctahedra, and faces with four equivalent K(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. In the second Ta site, Ta(2) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with six equivalent Ta(1)O6 octahedra, faces with two equivalent K(2)O12 cuboctahedra, and faces with six equivalent K(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Nb(1) is bonded to six equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Ta(1)O6 octahedra, faces with two equivalent K(1)O12 cuboctahedra, and faces with six equivalent K(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one K(2), three equivalent K(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one K(1), three equivalent K(2), one Ta(1), and one Nb(1) atom. is represented by the CIF file [CIF]
data_K4Ta3NbO12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.880
_cell_length_b   9.880
_cell_length_c   9.880
_cell_angle_alpha   33.557
_cell_angle_beta   33.557
_cell_angle_gamma   33.557
_symmetry_Int_Tables_number   1
_cell_volume   262.475
_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
  K  K0  1  0.375  0.375  0.375  1.0
  K  K1  1  0.125  0.125  0.125  1.0
  K  K2  1  0.875  0.875  0.875  1.0
  K  K3  1  0.625  0.625  0.625  1.0
  Ta  Ta4  1  0.250  0.250  0.250  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Ta  Ta6  1  0.750  0.750  0.750  1.0
  Nb  Nb7  1  0.500  0.500  0.500  1.0
  O  O8  1  0.125  0.625  0.125  1.0
  O  O9  1  0.875  0.375  0.875  1.0
  O  O10  1  0.626  0.123  0.626  1.0
  O  O11  1  0.374  0.877  0.374  1.0
  O  O12  1  0.875  0.875  0.375  1.0
  O  O13  1  0.626  0.626  0.123  1.0
  O  O14  1  0.374  0.374  0.877  1.0
  O  O15  1  0.125  0.125  0.625  1.0
  O  O16  1  0.375  0.875  0.875  1.0
  O  O17  1  0.123  0.626  0.626  1.0
  O  O18  1  0.877  0.374  0.374  1.0
  O  O19  1  0.625  0.125  0.125  1.0
[/CIF]
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The structure described by K4Ta3NbO12 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal R-3m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to three equivalent O(2) and nine equivalent O(1) atoms to form KO12 cuboctahedra that share corners with six equivalent K(1)O12 cuboctahedra, corners with six equivalent K(2)O12 cuboctahedra, faces with three equivalent K(1)O12 cuboctahedra, faces with three equivalent K(2)O12 cuboctahedra,  a faceface with one Nb(1)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with four equivalent Ta(1)O6 octahedra. In the second K site, K(2) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form KO12 cuboctahedra that share corners with six equivalent K(1)O12 cuboctahedra, corners with six equivalent K(2)O12 cuboctahedra, faces with three equivalent K(1)O12 cuboctahedra, faces with three equivalent K(2)O12 cuboctahedra,  a faceface with one Ta(2)O6 octahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with four equivalent Ta(1)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form TaO6 octahedra that share corners with three equivalent Ta(2)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, faces with four equivalent K(1)O12 cuboctahedra, and faces with four equivalent K(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. In the second Ta site, Ta(2) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with six equivalent Ta(1)O6 octahedra, faces with two equivalent K(2)O12 cuboctahedra, and faces with six equivalent K(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Nb(1) is bonded to six equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Ta(1)O6 octahedra, faces with two equivalent K(1)O12 cuboctahedra, and faces with six equivalent K(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one K(2), three equivalent K(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one K(1), three equivalent K(2), one Ta(1), and one Nb(1) atom. is represented by the CIF file [CIF]
data_K4Ta3NbO12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.880
_cell_length_b   9.880
_cell_length_c   9.880
_cell_angle_alpha   33.557
_cell_angle_beta   33.557
_cell_angle_gamma   33.557
_symmetry_Int_Tables_number   1
_cell_volume   262.475
_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
  K  K0  1  0.375  0.375  0.375  1.0
  K  K1  1  0.125  0.125  0.125  1.0
  K  K2  1  0.875  0.875  0.875  1.0
  K  K3  1  0.625  0.625  0.625  1.0
  Ta  Ta4  1  0.250  0.250  0.250  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Ta  Ta6  1  0.750  0.750  0.750  1.0
  Nb  Nb7  1  0.500  0.500  0.500  1.0
  O  O8  1  0.125  0.625  0.125  1.0
  O  O9  1  0.875  0.375  0.875  1.0
  O  O10  1  0.626  0.123  0.626  1.0
  O  O11  1  0.374  0.877  0.374  1.0
  O  O12  1  0.875  0.875  0.375  1.0
  O  O13  1  0.626  0.626  0.123  1.0
  O  O14  1  0.374  0.374  0.877  1.0
  O  O15  1  0.125  0.125  0.625  1.0
  O  O16  1  0.375  0.875  0.875  1.0
  O  O17  1  0.123  0.626  0.626  1.0
  O  O18  1  0.877  0.374  0.374  1.0
  O  O19  1  0.625  0.125  0.125  1.0
[/CIF]
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