The material described by Y4Ti2Nb2O15 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(3), one O(6), two equivalent O(5), and two equivalent O(8) atoms. In the second Y site, Y(2) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(4), one O(7), two equivalent O(5), and two equivalent O(8) atoms. Ti(1) is bonded to one O(4), one O(7), one O(9), two equivalent O(5), and two equivalent O(8) atoms to form distorted TiO7 pentagonal bipyramids that share  a cornercorner with one Ti(1)O7 pentagonal bipyramid, corners with two equivalent Nb(1)O7 pentagonal bipyramids,  an edgeedge with one Ti(1)O7 pentagonal bipyramid, and edges with two equivalent Nb(1)O7 pentagonal bipyramids. Nb(1) is bonded to one O(3), one O(6), one O(9), two equivalent O(5), and two equivalent O(8) atoms to form distorted NbO7 pentagonal bipyramids that share  a cornercorner with one Nb(1)O7 pentagonal bipyramid, corners with two equivalent Ti(1)O7 pentagonal bipyramids,  an edgeedge with one Nb(1)O7 pentagonal bipyramid, and edges with two equivalent Ti(1)O7 pentagonal bipyramids. There are nine inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(3)Y2Nb2 tetrahedra, corners with two equivalent O(4)Y2Ti2 tetrahedra, corners with four equivalent O(2)Y4 tetrahedra, corners with eight equivalent O(5)Y2TiNb tetrahedra, and  an edgeedge with one O(6)Y2Nb2 trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with four equivalent O(1)Y4 tetrahedra, corners with two equivalent O(6)Y2Nb2 trigonal pyramids,  an edgeedge with one O(3)Y2Nb2 tetrahedra,  an edgeedge with one O(4)Y2Ti2 tetrahedra, and edges with four equivalent O(5)Y2TiNb tetrahedra. In the third O site, O(3) is bonded to two equivalent Y(1) and two equivalent Nb(1) atoms to form OY2Nb2 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with eight equivalent O(5)Y2TiNb tetrahedra, corners with four equivalent O(6)Y2Nb2 trigonal pyramids,  an edgeedge with one O(9)Ti2Nb2 tetrahedra, and  an edgeedge with one O(2)Y4 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Y(2) and two equivalent Ti(1) atoms to form OY2Ti2 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with eight equivalent O(5)Y2TiNb tetrahedra,  an edgeedge with one O(9)Ti2Nb2 tetrahedra, and  an edgeedge with one O(2)Y4 tetrahedra. In the fifth O site, O(5) is bonded to one Y(1), one Y(2), one Ti(1), and one Nb(1) atom to form OY2TiNb tetrahedra that share corners with two equivalent O(3)Y2Nb2 tetrahedra, corners with two equivalent O(4)Y2Ti2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(5)Y2TiNb tetrahedra,  an edgeedge with one O(9)Ti2Nb2 tetrahedra,  an edgeedge with one O(2)Y4 tetrahedra, and  an edgeedge with one O(6)Y2Nb2 trigonal pyramid. In the sixth O site, O(6) is bonded to two equivalent Y(1) and two equivalent Nb(1) atoms to form distorted OY2Nb2 trigonal pyramids that share corners with two equivalent O(9)Ti2Nb2 tetrahedra, corners with two equivalent O(2)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra,  an edgeedge with one O(1)Y4 tetrahedra, and edges with four equivalent O(5)Y2TiNb tetrahedra. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Y(2) and two equivalent Ti(1) atoms. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Y(1), one Y(2), one Ti(1), and one Nb(1) atom. In the ninth O site, O(9) is bonded to two equivalent Ti(1) and two equivalent Nb(1) atoms to form OTi2Nb2 tetrahedra that share corners with two equivalent O(6)Y2Nb2 trigonal pyramids,  an edgeedge with one O(3)Y2Nb2 tetrahedra,  an edgeedge with one O(4)Y2Ti2 tetrahedra, and edges with four equivalent O(5)Y2TiNb tetrahedra. is represented by the CIF file [CIF]
data_Y4Ti2Nb2O15
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.292
_cell_length_b   7.292
_cell_length_c   7.292
_cell_angle_alpha   120.515
_cell_angle_beta   119.516
_cell_angle_gamma   89.975
_symmetry_Int_Tables_number   1
_cell_volume   274.074
_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
  Y  Y0  1  0.254  0.502  0.247  1.0
  Y  Y1  1  0.254  0.007  0.753  1.0
  Y  Y2  1  0.256  0.499  0.756  1.0
  Y  Y3  1  0.743  0.499  0.244  1.0
  Ti  Ti4  1  0.758  0.997  0.238  1.0
  Ti  Ti5  1  0.758  0.520  0.762  1.0
  Nb  Nb6  1  0.758  0.995  0.764  1.0
  Nb  Nb7  1  0.231  0.995  0.236  1.0
  O  O8  1  0.124  0.624  0.500  1.0
  O  O9  1  0.377  0.377  0.000  1.0
  O  O10  1  0.110  0.110  0.000  1.0
  O  O11  1  0.649  0.649  0.000  1.0
  O  O12  1  0.102  0.640  1.000  1.0
  O  O13  1  0.641  0.102  0.000  1.0
  O  O14  1  0.102  0.102  0.462  1.0
  O  O15  1  0.641  0.640  0.538  1.0
  O  O16  1  0.423  0.923  0.500  1.0
  O  O17  1  0.821  0.321  0.500  1.0
  O  O18  1  0.425  0.323  0.501  1.0
  O  O19  1  0.821  0.923  0.499  1.0
  O  O20  1  0.425  0.923  0.102  1.0
  O  O21  1  0.821  0.323  0.898  1.0
  O  O22  1  0.880  0.880  0.000  1.0
[/CIF]
.
The material described by Y4Ti2Nb2O15 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(3), one O(6), two equivalent O(5), and two equivalent O(8) atoms. In the second Y site, Y(2) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(4), one O(7), two equivalent O(5), and two equivalent O(8) atoms. Ti(1) is bonded to one O(4), one O(7), one O(9), two equivalent O(5), and two equivalent O(8) atoms to form distorted TiO7 pentagonal bipyramids that share  a cornercorner with one Ti(1)O7 pentagonal bipyramid, corners with two equivalent Nb(1)O7 pentagonal bipyramids,  an edgeedge with one Ti(1)O7 pentagonal bipyramid, and edges with two equivalent Nb(1)O7 pentagonal bipyramids. Nb(1) is bonded to one O(3), one O(6), one O(9), two equivalent O(5), and two equivalent O(8) atoms to form distorted NbO7 pentagonal bipyramids that share  a cornercorner with one Nb(1)O7 pentagonal bipyramid, corners with two equivalent Ti(1)O7 pentagonal bipyramids,  an edgeedge with one Nb(1)O7 pentagonal bipyramid, and edges with two equivalent Ti(1)O7 pentagonal bipyramids. There are nine inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(3)Y2Nb2 tetrahedra, corners with two equivalent O(4)Y2Ti2 tetrahedra, corners with four equivalent O(2)Y4 tetrahedra, corners with eight equivalent O(5)Y2TiNb tetrahedra, and  an edgeedge with one O(6)Y2Nb2 trigonal pyramid. In the second O site, O(2) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with four equivalent O(1)Y4 tetrahedra, corners with two equivalent O(6)Y2Nb2 trigonal pyramids,  an edgeedge with one O(3)Y2Nb2 tetrahedra,  an edgeedge with one O(4)Y2Ti2 tetrahedra, and edges with four equivalent O(5)Y2TiNb tetrahedra. In the third O site, O(3) is bonded to two equivalent Y(1) and two equivalent Nb(1) atoms to form OY2Nb2 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with eight equivalent O(5)Y2TiNb tetrahedra, corners with four equivalent O(6)Y2Nb2 trigonal pyramids,  an edgeedge with one O(9)Ti2Nb2 tetrahedra, and  an edgeedge with one O(2)Y4 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Y(2) and two equivalent Ti(1) atoms to form OY2Ti2 tetrahedra that share corners with two equivalent O(1)Y4 tetrahedra, corners with eight equivalent O(5)Y2TiNb tetrahedra,  an edgeedge with one O(9)Ti2Nb2 tetrahedra, and  an edgeedge with one O(2)Y4 tetrahedra. In the fifth O site, O(5) is bonded to one Y(1), one Y(2), one Ti(1), and one Nb(1) atom to form OY2TiNb tetrahedra that share corners with two equivalent O(3)Y2Nb2 tetrahedra, corners with two equivalent O(4)Y2Ti2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(5)Y2TiNb tetrahedra,  an edgeedge with one O(9)Ti2Nb2 tetrahedra,  an edgeedge with one O(2)Y4 tetrahedra, and  an edgeedge with one O(6)Y2Nb2 trigonal pyramid. In the sixth O site, O(6) is bonded to two equivalent Y(1) and two equivalent Nb(1) atoms to form distorted OY2Nb2 trigonal pyramids that share corners with two equivalent O(9)Ti2Nb2 tetrahedra, corners with two equivalent O(2)Y4 tetrahedra, corners with four equivalent O(3)Y2Nb2 tetrahedra,  an edgeedge with one O(1)Y4 tetrahedra, and edges with four equivalent O(5)Y2TiNb tetrahedra. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Y(2) and two equivalent Ti(1) atoms. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Y(1), one Y(2), one Ti(1), and one Nb(1) atom. In the ninth O site, O(9) is bonded to two equivalent Ti(1) and two equivalent Nb(1) atoms to form OTi2Nb2 tetrahedra that share corners with two equivalent O(6)Y2Nb2 trigonal pyramids,  an edgeedge with one O(3)Y2Nb2 tetrahedra,  an edgeedge with one O(4)Y2Ti2 tetrahedra, and edges with four equivalent O(5)Y2TiNb tetrahedra. is represented by the CIF file [CIF]
data_Y4Ti2Nb2O15
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.292
_cell_length_b   7.292
_cell_length_c   7.292
_cell_angle_alpha   120.515
_cell_angle_beta   119.516
_cell_angle_gamma   89.975
_symmetry_Int_Tables_number   1
_cell_volume   274.074
_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
  Y  Y0  1  0.254  0.502  0.247  1.0
  Y  Y1  1  0.254  0.007  0.753  1.0
  Y  Y2  1  0.256  0.499  0.756  1.0
  Y  Y3  1  0.743  0.499  0.244  1.0
  Ti  Ti4  1  0.758  0.997  0.238  1.0
  Ti  Ti5  1  0.758  0.520  0.762  1.0
  Nb  Nb6  1  0.758  0.995  0.764  1.0
  Nb  Nb7  1  0.231  0.995  0.236  1.0
  O  O8  1  0.124  0.624  0.500  1.0
  O  O9  1  0.377  0.377  0.000  1.0
  O  O10  1  0.110  0.110  0.000  1.0
  O  O11  1  0.649  0.649  0.000  1.0
  O  O12  1  0.102  0.640  1.000  1.0
  O  O13  1  0.641  0.102  0.000  1.0
  O  O14  1  0.102  0.102  0.462  1.0
  O  O15  1  0.641  0.640  0.538  1.0
  O  O16  1  0.423  0.923  0.500  1.0
  O  O17  1  0.821  0.321  0.500  1.0
  O  O18  1  0.425  0.323  0.501  1.0
  O  O19  1  0.821  0.923  0.499  1.0
  O  O20  1  0.425  0.923  0.102  1.0
  O  O21  1  0.821  0.323  0.898  1.0
  O  O22  1  0.880  0.880  0.000  1.0
[/CIF]
.