The compound described by TiTa6Tl2O18 crystallizes in the monoclinic C2 space group. Ti(1) is bonded to two equivalent O(7), two equivalent O(8), and two equivalent O(9) atoms to form TiO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and corners with two equivalent Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-35°. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(2), one O(3), one O(6), one O(7), and two equivalent O(5) atoms to form distorted TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra, and  an edgeedge with one Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-49°. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(6), one O(8), and two equivalent O(4) atoms to form distorted TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, and  an edgeedge with one Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-50°. In the third Ta site, Ta(3) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(9) atom to form distorted TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra, and  an edgeedge with one Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-50°. Tl(1) is bonded in a distorted single-bond geometry to one O(2) atom. There are nine inequivalent O sites. In the first O site, O(9) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ta(3) atom. In the second O site, O(1) is bonded in a bent 150 degrees geometry to one Ta(2) and one Ta(3) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Ta(1), one Ta(3), and one Tl(1) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom. In the fifth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Ta(3) and two equivalent Ta(2) atoms. In the sixth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Ta(3) and two equivalent Ta(1) atoms. In the seventh O site, O(6) is bonded in a trigonal non-coplanar geometry to one Ta(1), one Ta(2), and one Ta(3) atom. In the eighth O site, O(7) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ta(1) atom. In the ninth O site, O(8) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ta(2) atom. is represented by the CIF file [CIF]
data_Ta6TiTl2O18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.618
_cell_length_b   7.618
_cell_length_c   8.348
_cell_angle_alpha   89.845
_cell_angle_beta   89.845
_cell_angle_gamma   60.103
_symmetry_Int_Tables_number   1
_cell_volume   420.018
_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  0.664  0.172  0.849  1.0
  Ta  Ta1  1  0.167  0.666  0.848  1.0
  Ta  Ta2  1  0.164  0.171  0.849  1.0
  Ta  Ta3  1  0.334  0.833  0.152  1.0
  Ta  Ta4  1  0.828  0.336  0.151  1.0
  Ta  Ta5  1  0.829  0.836  0.151  1.0
  Ti  Ti6  1  0.999  0.001  0.500  1.0
  Tl  Tl7  1  0.277  0.362  0.307  1.0
  Tl  Tl8  1  0.638  0.723  0.693  1.0
  O  O9  1  0.102  0.450  0.841  1.0
  O  O10  1  0.449  0.102  0.839  1.0
  O  O11  1  0.448  0.450  0.840  1.0
  O  O12  1  0.898  0.551  0.161  1.0
  O  O13  1  0.550  0.898  0.159  1.0
  O  O14  1  0.550  0.552  0.160  1.0
  O  O15  1  0.284  0.859  0.899  1.0
  O  O16  1  0.858  0.283  0.899  1.0
  O  O17  1  0.857  0.858  0.899  1.0
  O  O18  1  0.717  0.142  0.101  1.0
  O  O19  1  0.141  0.716  0.101  1.0
  O  O20  1  0.142  0.143  0.101  1.0
  O  O21  1  0.759  0.119  0.639  1.0
  O  O22  1  0.121  0.758  0.638  1.0
  O  O23  1  0.123  0.120  0.638  1.0
  O  O24  1  0.242  0.879  0.362  1.0
  O  O25  1  0.881  0.241  0.361  1.0
  O  O26  1  0.880  0.877  0.362  1.0
[/CIF]
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The compound described by TiTa6Tl2O18 crystallizes in the monoclinic C2 space group. Ti(1) is bonded to two equivalent O(7), two equivalent O(8), and two equivalent O(9) atoms to form TiO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and corners with two equivalent Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-35°. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(2), one O(3), one O(6), one O(7), and two equivalent O(5) atoms to form distorted TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra, and  an edgeedge with one Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 26-49°. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(6), one O(8), and two equivalent O(4) atoms to form distorted TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, and  an edgeedge with one Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-50°. In the third Ta site, Ta(3) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(9) atom to form distorted TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra, and  an edgeedge with one Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-50°. Tl(1) is bonded in a distorted single-bond geometry to one O(2) atom. There are nine inequivalent O sites. In the first O site, O(9) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ta(3) atom. In the second O site, O(1) is bonded in a bent 150 degrees geometry to one Ta(2) and one Ta(3) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Ta(1), one Ta(3), and one Tl(1) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom. In the fifth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Ta(3) and two equivalent Ta(2) atoms. In the sixth O site, O(5) is bonded in a trigonal non-coplanar geometry to one Ta(3) and two equivalent Ta(1) atoms. In the seventh O site, O(6) is bonded in a trigonal non-coplanar geometry to one Ta(1), one Ta(2), and one Ta(3) atom. In the eighth O site, O(7) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ta(1) atom. In the ninth O site, O(8) is bonded in a bent 150 degrees geometry to one Ti(1) and one Ta(2) atom. is represented by the CIF file [CIF]
data_Ta6TiTl2O18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.618
_cell_length_b   7.618
_cell_length_c   8.348
_cell_angle_alpha   89.845
_cell_angle_beta   89.845
_cell_angle_gamma   60.103
_symmetry_Int_Tables_number   1
_cell_volume   420.018
_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  0.664  0.172  0.849  1.0
  Ta  Ta1  1  0.167  0.666  0.848  1.0
  Ta  Ta2  1  0.164  0.171  0.849  1.0
  Ta  Ta3  1  0.334  0.833  0.152  1.0
  Ta  Ta4  1  0.828  0.336  0.151  1.0
  Ta  Ta5  1  0.829  0.836  0.151  1.0
  Ti  Ti6  1  0.999  0.001  0.500  1.0
  Tl  Tl7  1  0.277  0.362  0.307  1.0
  Tl  Tl8  1  0.638  0.723  0.693  1.0
  O  O9  1  0.102  0.450  0.841  1.0
  O  O10  1  0.449  0.102  0.839  1.0
  O  O11  1  0.448  0.450  0.840  1.0
  O  O12  1  0.898  0.551  0.161  1.0
  O  O13  1  0.550  0.898  0.159  1.0
  O  O14  1  0.550  0.552  0.160  1.0
  O  O15  1  0.284  0.859  0.899  1.0
  O  O16  1  0.858  0.283  0.899  1.0
  O  O17  1  0.857  0.858  0.899  1.0
  O  O18  1  0.717  0.142  0.101  1.0
  O  O19  1  0.141  0.716  0.101  1.0
  O  O20  1  0.142  0.143  0.101  1.0
  O  O21  1  0.759  0.119  0.639  1.0
  O  O22  1  0.121  0.758  0.638  1.0
  O  O23  1  0.123  0.120  0.638  1.0
  O  O24  1  0.242  0.879  0.362  1.0
  O  O25  1  0.881  0.241  0.361  1.0
  O  O26  1  0.880  0.877  0.362  1.0
[/CIF]
.