The crystal structure described by Ta3NbV4O20 crystallizes in the monoclinic Pm space group. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(11), one O(2), two equivalent O(10), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent Ta(3)O6 octahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra, and corners with two equivalent V(3)O4 tetrahedra. The corner-sharing octahedra are not tilted. In the second Ta site, Ta(2) is bonded to one O(14), one O(3), two equivalent O(7), and two equivalent O(9) atoms to form TaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and corners with two equivalent V(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. In the third Ta site, Ta(3) is bonded to one O(13), one O(4), two equivalent O(10), and two equivalent O(8) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and corners with two equivalent V(1)O4 tetrahedra. The corner-sharing octahedra are not tilted. Nb(1) is bonded to one O(1), one O(12), two equivalent O(5), and two equivalent O(9) atoms to form NbO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra, and corners with two equivalent V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. There are four inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(11), and two equivalent O(8) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Nb(1)O6 octahedra, and corners with two equivalent Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-21°. In the second V site, V(2) is bonded to one O(12), one O(2), and two equivalent O(7) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Nb(1)O6 octahedra, and corners with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-20°. In the third V site, V(3) is bonded to one O(13), one O(3), and two equivalent O(6) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(2)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra, and corners with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-20°. In the fourth V site, V(4) is bonded to one O(14), one O(4), and two equivalent O(5) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(2)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra, and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-21°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(1) and one V(1) atom. In the second O site, O(2) is bonded in a linear geometry to one Ta(1) and one V(2) atom. In the third O site, O(3) is bonded in a linear geometry to one Ta(2) and one V(3) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Ta(3) and one V(4) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Nb(1) and one V(4) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Ta(1) and one V(3) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ta(2) and one V(2) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Ta(3) and one V(1) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Ta(2) and one Nb(1) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Ta(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ta(1) and one V(1) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Nb(1) and one V(2) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Ta(3) and one V(3) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Ta(2) and one V(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ta3NbV4O20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.628
_cell_length_b   7.071
_cell_length_c   12.061
_cell_angle_alpha   89.922
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   479.996
_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
  Ta  Ta0  1  0.000  0.658  0.943  1.0
  Ta  Ta1  1  0.500  0.161  0.559  1.0
  Ta  Ta2  1  0.500  0.343  0.057  1.0
  Nb  Nb3  1  0.000  0.846  0.443  1.0
  V  V4  1  0.000  0.032  0.155  1.0
  V  V5  1  0.000  0.468  0.656  1.0
  V  V6  1  0.500  0.968  0.845  1.0
  V  V7  1  0.500  0.531  0.344  1.0
  O  O8  1  0.000  0.974  0.296  1.0
  O  O9  1  0.000  0.527  0.798  1.0
  O  O10  1  0.500  0.027  0.703  1.0
  O  O11  1  0.500  0.472  0.202  1.0
  O  O12  1  0.249  0.658  0.374  1.0
  O  O13  1  0.752  0.840  0.875  1.0
  O  O14  1  0.748  0.340  0.625  1.0
  O  O15  1  0.252  0.160  0.124  1.0
  O  O16  1  0.252  0.340  0.625  1.0
  O  O17  1  0.748  0.160  0.124  1.0
  O  O18  1  0.751  0.658  0.374  1.0
  O  O19  1  0.248  0.840  0.875  1.0
  O  O20  1  0.251  0.000  0.501  1.0
  O  O21  1  0.750  0.500  1.000  1.0
  O  O22  1  0.749  0.000  0.501  1.0
  O  O23  1  0.250  0.500  1.000  1.0
  O  O24  1  0.000  0.824  0.076  1.0
  O  O25  1  0.000  0.675  0.577  1.0
  O  O26  1  0.500  0.175  0.924  1.0
  O  O27  1  0.500  0.323  0.424  1.0
[/CIF]
.
The crystal structure described by Ta3NbV4O20 crystallizes in the monoclinic Pm space group. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(11), one O(2), two equivalent O(10), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent Ta(3)O6 octahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra, and corners with two equivalent V(3)O4 tetrahedra. The corner-sharing octahedra are not tilted. In the second Ta site, Ta(2) is bonded to one O(14), one O(3), two equivalent O(7), and two equivalent O(9) atoms to form TaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and corners with two equivalent V(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. In the third Ta site, Ta(3) is bonded to one O(13), one O(4), two equivalent O(10), and two equivalent O(8) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra,  a cornercorner with one V(3)O4 tetrahedra,  a cornercorner with one V(4)O4 tetrahedra, and corners with two equivalent V(1)O4 tetrahedra. The corner-sharing octahedra are not tilted. Nb(1) is bonded to one O(1), one O(12), two equivalent O(5), and two equivalent O(9) atoms to form NbO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one V(1)O4 tetrahedra,  a cornercorner with one V(2)O4 tetrahedra, and corners with two equivalent V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 1°. There are four inequivalent V sites. In the first V site, V(1) is bonded to one O(1), one O(11), and two equivalent O(8) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Nb(1)O6 octahedra, and corners with two equivalent Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-21°. In the second V site, V(2) is bonded to one O(12), one O(2), and two equivalent O(7) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Nb(1)O6 octahedra, and corners with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-20°. In the third V site, V(3) is bonded to one O(13), one O(3), and two equivalent O(6) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(2)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra, and corners with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-20°. In the fourth V site, V(4) is bonded to one O(14), one O(4), and two equivalent O(5) atoms to form VO4 tetrahedra that share  a cornercorner with one Ta(2)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra, and corners with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-21°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(1) and one V(1) atom. In the second O site, O(2) is bonded in a linear geometry to one Ta(1) and one V(2) atom. In the third O site, O(3) is bonded in a linear geometry to one Ta(2) and one V(3) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Ta(3) and one V(4) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Nb(1) and one V(4) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Ta(1) and one V(3) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ta(2) and one V(2) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Ta(3) and one V(1) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Ta(2) and one Nb(1) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Ta(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ta(1) and one V(1) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Nb(1) and one V(2) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Ta(3) and one V(3) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Ta(2) and one V(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ta3NbV4O20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.628
_cell_length_b   7.071
_cell_length_c   12.061
_cell_angle_alpha   89.922
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   479.996
_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
  Ta  Ta0  1  0.000  0.658  0.943  1.0
  Ta  Ta1  1  0.500  0.161  0.559  1.0
  Ta  Ta2  1  0.500  0.343  0.057  1.0
  Nb  Nb3  1  0.000  0.846  0.443  1.0
  V  V4  1  0.000  0.032  0.155  1.0
  V  V5  1  0.000  0.468  0.656  1.0
  V  V6  1  0.500  0.968  0.845  1.0
  V  V7  1  0.500  0.531  0.344  1.0
  O  O8  1  0.000  0.974  0.296  1.0
  O  O9  1  0.000  0.527  0.798  1.0
  O  O10  1  0.500  0.027  0.703  1.0
  O  O11  1  0.500  0.472  0.202  1.0
  O  O12  1  0.249  0.658  0.374  1.0
  O  O13  1  0.752  0.840  0.875  1.0
  O  O14  1  0.748  0.340  0.625  1.0
  O  O15  1  0.252  0.160  0.124  1.0
  O  O16  1  0.252  0.340  0.625  1.0
  O  O17  1  0.748  0.160  0.124  1.0
  O  O18  1  0.751  0.658  0.374  1.0
  O  O19  1  0.248  0.840  0.875  1.0
  O  O20  1  0.251  0.000  0.501  1.0
  O  O21  1  0.750  0.500  1.000  1.0
  O  O22  1  0.749  0.000  0.501  1.0
  O  O23  1  0.250  0.500  1.000  1.0
  O  O24  1  0.000  0.824  0.076  1.0
  O  O25  1  0.000  0.675  0.577  1.0
  O  O26  1  0.500  0.175  0.924  1.0
  O  O27  1  0.500  0.323  0.424  1.0
[/CIF]
.