The compound described by BaTbNbSnO6 crystallizes in the orthorhombic P222 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form BaO12 cuboctahedra that share faces with four equivalent Tb(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. In the second Ba site, Ba(2) is bonded to four equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form BaO12 cuboctahedra that share faces with four equivalent Tb(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(6) atoms. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(6) atoms. Tb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form TbO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-26°. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with six equivalent Tb(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-26°. There are four inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a square co-planar geometry to four equivalent O(5) atoms. In the second Sn site, Sn(2) is bonded in a square co-planar geometry to four equivalent O(4) atoms. In the third Sn site, Sn(3) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. In the fourth Sn site, Sn(4) is bonded in a rectangular see-saw-like geometry to four equivalent O(3) atoms. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 4-coordinate geometry to one Ba(2), one Tb(1), one Nb(1), and one Sn(1) atom. In the second O site, O(6) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ba(4), one Tb(1), and one Nb(1) atom. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(4), one Tb(1), and one Nb(1) atom. In the fourth O site, O(2) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Tb(1), one Nb(1), and one Sn(3) atom. In the fifth O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Tb(1), one Nb(1), and one Sn(4) atom. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Ba(2), one Tb(1), one Nb(1), and one Sn(2) atom. is represented by the CIF card [CIF]
data_BaTbNbSnO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.453
_cell_length_b   8.501
_cell_length_c   8.456
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   607.600
_cell_formula_units_Z   4
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
  Ba  Ba0  1  0.000  0.000  0.000  1.0
  Ba  Ba1  1  0.500  0.500  0.500  1.0
  Ba  Ba2  1  0.500  0.000  0.500  1.0
  Ba  Ba3  1  0.000  0.000  0.500  1.0
  Tb  Tb4  1  0.250  0.255  0.245  1.0
  Tb  Tb5  1  0.750  0.745  0.245  1.0
  Tb  Tb6  1  0.750  0.255  0.755  1.0
  Tb  Tb7  1  0.250  0.745  0.755  1.0
  Nb  Nb8  1  0.754  0.746  0.750  1.0
  Nb  Nb9  1  0.246  0.254  0.750  1.0
  Nb  Nb10  1  0.246  0.746  0.250  1.0
  Nb  Nb11  1  0.754  0.254  0.250  1.0
  Sn  Sn12  1  0.000  0.500  0.500  1.0
  Sn  Sn13  1  0.500  0.500  0.000  1.0
  Sn  Sn14  1  0.500  0.000  0.000  1.0
  Sn  Sn15  1  0.000  0.500  0.000  1.0
  O  O16  1  0.986  0.215  0.270  1.0
  O  O17  1  0.014  0.785  0.270  1.0
  O  O18  1  0.014  0.215  0.730  1.0
  O  O19  1  0.986  0.785  0.730  1.0
  O  O20  1  0.284  0.984  0.213  1.0
  O  O21  1  0.284  0.016  0.787  1.0
  O  O22  1  0.716  0.016  0.213  1.0
  O  O23  1  0.716  0.984  0.787  1.0
  O  O24  1  0.209  0.291  0.985  1.0
  O  O25  1  0.791  0.291  0.015  1.0
  O  O26  1  0.209  0.709  0.015  1.0
  O  O27  1  0.791  0.709  0.985  1.0
  O  O28  1  0.516  0.293  0.216  1.0
  O  O29  1  0.484  0.707  0.216  1.0
  O  O30  1  0.484  0.293  0.784  1.0
  O  O31  1  0.516  0.707  0.784  1.0
  O  O32  1  0.214  0.514  0.293  1.0
  O  O33  1  0.214  0.486  0.707  1.0
  O  O34  1  0.786  0.486  0.293  1.0
  O  O35  1  0.786  0.514  0.707  1.0
  O  O36  1  0.277  0.224  0.515  1.0
  O  O37  1  0.723  0.224  0.485  1.0
  O  O38  1  0.277  0.776  0.485  1.0
  O  O39  1  0.723  0.776  0.515  1.0
[/CIF]
.
The compound described by BaTbNbSnO6 crystallizes in the orthorhombic P222 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form BaO12 cuboctahedra that share faces with four equivalent Tb(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. In the second Ba site, Ba(2) is bonded to four equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form BaO12 cuboctahedra that share faces with four equivalent Tb(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(6) atoms. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(6) atoms. Tb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form TbO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-26°. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with six equivalent Tb(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-26°. There are four inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a square co-planar geometry to four equivalent O(5) atoms. In the second Sn site, Sn(2) is bonded in a square co-planar geometry to four equivalent O(4) atoms. In the third Sn site, Sn(3) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. In the fourth Sn site, Sn(4) is bonded in a rectangular see-saw-like geometry to four equivalent O(3) atoms. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 4-coordinate geometry to one Ba(2), one Tb(1), one Nb(1), and one Sn(1) atom. In the second O site, O(6) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ba(4), one Tb(1), and one Nb(1) atom. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(4), one Tb(1), and one Nb(1) atom. In the fourth O site, O(2) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Tb(1), one Nb(1), and one Sn(3) atom. In the fifth O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Tb(1), one Nb(1), and one Sn(4) atom. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Ba(2), one Tb(1), one Nb(1), and one Sn(2) atom. is represented by the CIF card [CIF]
data_BaTbNbSnO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.453
_cell_length_b   8.501
_cell_length_c   8.456
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   607.600
_cell_formula_units_Z   4
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
  Ba  Ba0  1  0.000  0.000  0.000  1.0
  Ba  Ba1  1  0.500  0.500  0.500  1.0
  Ba  Ba2  1  0.500  0.000  0.500  1.0
  Ba  Ba3  1  0.000  0.000  0.500  1.0
  Tb  Tb4  1  0.250  0.255  0.245  1.0
  Tb  Tb5  1  0.750  0.745  0.245  1.0
  Tb  Tb6  1  0.750  0.255  0.755  1.0
  Tb  Tb7  1  0.250  0.745  0.755  1.0
  Nb  Nb8  1  0.754  0.746  0.750  1.0
  Nb  Nb9  1  0.246  0.254  0.750  1.0
  Nb  Nb10  1  0.246  0.746  0.250  1.0
  Nb  Nb11  1  0.754  0.254  0.250  1.0
  Sn  Sn12  1  0.000  0.500  0.500  1.0
  Sn  Sn13  1  0.500  0.500  0.000  1.0
  Sn  Sn14  1  0.500  0.000  0.000  1.0
  Sn  Sn15  1  0.000  0.500  0.000  1.0
  O  O16  1  0.986  0.215  0.270  1.0
  O  O17  1  0.014  0.785  0.270  1.0
  O  O18  1  0.014  0.215  0.730  1.0
  O  O19  1  0.986  0.785  0.730  1.0
  O  O20  1  0.284  0.984  0.213  1.0
  O  O21  1  0.284  0.016  0.787  1.0
  O  O22  1  0.716  0.016  0.213  1.0
  O  O23  1  0.716  0.984  0.787  1.0
  O  O24  1  0.209  0.291  0.985  1.0
  O  O25  1  0.791  0.291  0.015  1.0
  O  O26  1  0.209  0.709  0.015  1.0
  O  O27  1  0.791  0.709  0.985  1.0
  O  O28  1  0.516  0.293  0.216  1.0
  O  O29  1  0.484  0.707  0.216  1.0
  O  O30  1  0.484  0.293  0.784  1.0
  O  O31  1  0.516  0.707  0.784  1.0
  O  O32  1  0.214  0.514  0.293  1.0
  O  O33  1  0.214  0.486  0.707  1.0
  O  O34  1  0.786  0.486  0.293  1.0
  O  O35  1  0.786  0.514  0.707  1.0
  O  O36  1  0.277  0.224  0.515  1.0
  O  O37  1  0.723  0.224  0.485  1.0
  O  O38  1  0.277  0.776  0.485  1.0
  O  O39  1  0.723  0.776  0.515  1.0
[/CIF]
.