The material structure described by TiNb2O7 crystallizes in the monoclinic Cm space group. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to one O(13), one O(15), one O(3), one O(7), and two equivalent O(11) atoms. In the second Ti site, Ti(2) is bonded to one O(1), one O(17), one O(21), one O(5), and two equivalent O(9) atoms to form TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-10°. In the third Ti site, Ti(3) is bonded in a 6-coordinate geometry to one O(12), one O(14), one O(4), one O(6), and two equivalent O(10) atoms. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(16), one O(7), and two equivalent O(4) atoms. In the second Nb site, Nb(2) is bonded to one O(19), one O(20), one O(5), one O(8), and two equivalent O(2) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and edges with two equivalent Nb(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-32°. In the third Nb site, Nb(3) is bonded to one O(11), one O(16), one O(18), one O(8), and two equivalent O(13) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 11-35°. In the fourth Nb site, Nb(4) is bonded to one O(10), one O(15), one O(19), one O(7), and two equivalent O(12) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 3-29°. In the fifth Nb site, Nb(5) is bonded to one O(14), one O(17), one O(2), one O(3), and two equivalent O(20) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-33°. In the sixth Nb site, Nb(6) is bonded in a 6-coordinate geometry to one O(13), one O(15), one O(21), one O(6), and two equivalent O(18) atoms. There are twenty-one inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Ti(2) and one Nb(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(5) and two equivalent Nb(2) atoms. In the third O site, O(3) is bonded in a linear geometry to one Ti(1) and one Nb(5) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ti(3) and two equivalent Nb(1) atoms. In the fifth O site, O(5) is bonded in a linear geometry to one Ti(2) and one Nb(2) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Ti(3) and one Nb(6) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ti(1), one Nb(1), and one Nb(4) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Nb(2) and one Nb(3) atom. In the ninth O site, O(9) is bonded in a linear geometry to two equivalent Ti(2) atoms. In the tenth O site, O(10) is bonded to two equivalent Ti(3), one Nb(1), and one Nb(4) atom to form distorted corner-sharing OTi2Nb2 tetrahedra. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to two equivalent Ti(1) and one Nb(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Ti(3) and two equivalent Nb(4) atoms. In the thirteenth O site, O(13) is bonded to one Ti(1), one Nb(6), and two equivalent Nb(3) atoms to form distorted corner-sharing OTiNb3 tetrahedra. In the fourteenth O site, O(14) is bonded in a linear geometry to one Ti(3) and one Nb(5) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Ti(1), one Nb(4), and one Nb(6) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Nb(1) and one Nb(3) atom. In the seventeenth O site, O(17) is bonded in a linear geometry to one Ti(2) and one Nb(5) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one Nb(3) and two equivalent Nb(6) atoms. In the nineteenth O site, O(19) is bonded in a linear geometry to one Nb(2) and one Nb(4) atom. In the twentieth O site, O(20) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Nb(5) atoms. In the twenty-first O site, O(21) is bonded in a linear geometry to one Ti(2) and one Nb(6) atom. is represented by the CIF file [CIF]
data_TiNb2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.568
_cell_length_b   10.568
_cell_length_c   12.164
_cell_angle_alpha   60.434
_cell_angle_beta   60.434
_cell_angle_gamma   20.869
_symmetry_Int_Tables_number   1
_cell_volume   418.619
_cell_formula_units_Z   3
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
  Ti  Ti0  1  0.921  0.921  0.641  1.0
  Ti  Ti1  1  0.000  0.000  0.998  1.0
  Ti  Ti2  1  0.709  0.709  0.363  1.0
  Nb  Nb3  1  0.107  0.107  0.632  1.0
  Nb  Nb4  1  0.181  0.181  0.000  1.0
  Nb  Nb5  1  0.294  0.294  0.634  1.0
  Nb  Nb6  1  0.077  0.077  0.368  1.0
  Nb  Nb7  1  0.818  0.818  0.004  1.0
  Nb  Nb8  1  0.890  0.890  0.363  1.0
  O  O9  1  0.050  0.050  0.803  1.0
  O  O10  1  0.708  0.708  0.997  1.0
  O  O11  1  0.875  0.875  0.810  1.0
  O  O12  1  0.628  0.628  0.580  1.0
  O  O13  1  0.099  0.099  0.984  1.0
  O  O14  1  0.792  0.792  0.382  1.0
  O  O15  1  0.024  0.024  0.583  1.0
  O  O16  1  0.249  0.249  0.808  1.0
  O  O17  1  0.500  0.500  1.000  1.0
  O  O18  1  0.173  0.173  0.402  1.0
  O  O19  1  0.403  0.403  0.624  1.0
  O  O20  1  0.598  0.598  0.378  1.0
  O  O21  1  0.827  0.827  0.596  1.0
  O  O22  1  0.750  0.750  0.196  1.0
  O  O23  1  0.975  0.975  0.415  1.0
  O  O24  1  0.210  0.210  0.617  1.0
  O  O25  1  0.902  0.902  0.015  1.0
  O  O26  1  0.373  0.373  0.420  1.0
  O  O27  1  0.125  0.125  0.191  1.0
  O  O28  1  0.291  0.291  0.004  1.0
  O  O29  1  0.952  0.952  0.194  1.0
[/CIF]
.
The material structure described by TiNb2O7 crystallizes in the monoclinic Cm space group. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to one O(13), one O(15), one O(3), one O(7), and two equivalent O(11) atoms. In the second Ti site, Ti(2) is bonded to one O(1), one O(17), one O(21), one O(5), and two equivalent O(9) atoms to form TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, and corners with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-10°. In the third Ti site, Ti(3) is bonded in a 6-coordinate geometry to one O(12), one O(14), one O(4), one O(6), and two equivalent O(10) atoms. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(16), one O(7), and two equivalent O(4) atoms. In the second Nb site, Nb(2) is bonded to one O(19), one O(20), one O(5), one O(8), and two equivalent O(2) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and edges with two equivalent Nb(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-32°. In the third Nb site, Nb(3) is bonded to one O(11), one O(16), one O(18), one O(8), and two equivalent O(13) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 11-35°. In the fourth Nb site, Nb(4) is bonded to one O(10), one O(15), one O(19), one O(7), and two equivalent O(12) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 3-29°. In the fifth Nb site, Nb(5) is bonded to one O(14), one O(17), one O(2), one O(3), and two equivalent O(20) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 9-33°. In the sixth Nb site, Nb(6) is bonded in a 6-coordinate geometry to one O(13), one O(15), one O(21), one O(6), and two equivalent O(18) atoms. There are twenty-one inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Ti(2) and one Nb(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(5) and two equivalent Nb(2) atoms. In the third O site, O(3) is bonded in a linear geometry to one Ti(1) and one Nb(5) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ti(3) and two equivalent Nb(1) atoms. In the fifth O site, O(5) is bonded in a linear geometry to one Ti(2) and one Nb(2) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Ti(3) and one Nb(6) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Ti(1), one Nb(1), and one Nb(4) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Nb(2) and one Nb(3) atom. In the ninth O site, O(9) is bonded in a linear geometry to two equivalent Ti(2) atoms. In the tenth O site, O(10) is bonded to two equivalent Ti(3), one Nb(1), and one Nb(4) atom to form distorted corner-sharing OTi2Nb2 tetrahedra. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to two equivalent Ti(1) and one Nb(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Ti(3) and two equivalent Nb(4) atoms. In the thirteenth O site, O(13) is bonded to one Ti(1), one Nb(6), and two equivalent Nb(3) atoms to form distorted corner-sharing OTiNb3 tetrahedra. In the fourteenth O site, O(14) is bonded in a linear geometry to one Ti(3) and one Nb(5) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Ti(1), one Nb(4), and one Nb(6) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Nb(1) and one Nb(3) atom. In the seventeenth O site, O(17) is bonded in a linear geometry to one Ti(2) and one Nb(5) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one Nb(3) and two equivalent Nb(6) atoms. In the nineteenth O site, O(19) is bonded in a linear geometry to one Nb(2) and one Nb(4) atom. In the twentieth O site, O(20) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Nb(5) atoms. In the twenty-first O site, O(21) is bonded in a linear geometry to one Ti(2) and one Nb(6) atom. is represented by the CIF file [CIF]
data_TiNb2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.568
_cell_length_b   10.568
_cell_length_c   12.164
_cell_angle_alpha   60.434
_cell_angle_beta   60.434
_cell_angle_gamma   20.869
_symmetry_Int_Tables_number   1
_cell_volume   418.619
_cell_formula_units_Z   3
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
  Ti  Ti0  1  0.921  0.921  0.641  1.0
  Ti  Ti1  1  0.000  0.000  0.998  1.0
  Ti  Ti2  1  0.709  0.709  0.363  1.0
  Nb  Nb3  1  0.107  0.107  0.632  1.0
  Nb  Nb4  1  0.181  0.181  0.000  1.0
  Nb  Nb5  1  0.294  0.294  0.634  1.0
  Nb  Nb6  1  0.077  0.077  0.368  1.0
  Nb  Nb7  1  0.818  0.818  0.004  1.0
  Nb  Nb8  1  0.890  0.890  0.363  1.0
  O  O9  1  0.050  0.050  0.803  1.0
  O  O10  1  0.708  0.708  0.997  1.0
  O  O11  1  0.875  0.875  0.810  1.0
  O  O12  1  0.628  0.628  0.580  1.0
  O  O13  1  0.099  0.099  0.984  1.0
  O  O14  1  0.792  0.792  0.382  1.0
  O  O15  1  0.024  0.024  0.583  1.0
  O  O16  1  0.249  0.249  0.808  1.0
  O  O17  1  0.500  0.500  1.000  1.0
  O  O18  1  0.173  0.173  0.402  1.0
  O  O19  1  0.403  0.403  0.624  1.0
  O  O20  1  0.598  0.598  0.378  1.0
  O  O21  1  0.827  0.827  0.596  1.0
  O  O22  1  0.750  0.750  0.196  1.0
  O  O23  1  0.975  0.975  0.415  1.0
  O  O24  1  0.210  0.210  0.617  1.0
  O  O25  1  0.902  0.902  0.015  1.0
  O  O26  1  0.373  0.373  0.420  1.0
  O  O27  1  0.125  0.125  0.191  1.0
  O  O28  1  0.291  0.291  0.004  1.0
  O  O29  1  0.952  0.952  0.194  1.0
[/CIF]
.