The crystal 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 to one O(18), one O(21), one O(3), one O(9), and two equivalent O(12) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, edges with two equivalent Nb(3)O6 octahedra, and edges with two equivalent Nb(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-35°. In the second Ti site, Ti(2) is bonded to one O(10), one O(17), one O(20), one O(4), and two equivalent O(11) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Nb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-28°. In the third Ti site, Ti(3) is bonded to one O(11), one O(13), one O(14), one O(16), and two equivalent O(17) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra,  an edgeedge with one Nb(4)O6 octahedra,  an edgeedge with one Nb(6)O6 octahedra, and edges with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-29°. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(16), one O(6), one O(8), one O(9), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-31°. In the second Nb site, Nb(2) is bonded to one O(10), one O(15), one O(5), one O(7), and two equivalent O(6) atoms to form NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-30°. In the third Nb site, Nb(3) is bonded to one O(12), one O(14), one O(2), one O(20), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra,  an edgeedge with one Nb(6)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-30°. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(11), one O(13), one O(21), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(4)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, and edges with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-31°. In the fifth Nb site, Nb(5) is bonded to one O(1), one O(2), one O(7), one O(8), and two equivalent O(19) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 7-16°. In the sixth Nb site, Nb(6) is bonded to one O(12), one O(13), one O(14), one O(15), and two equivalent O(18) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(6)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra,  an edgeedge with one Nb(3)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-30°. There are twenty-one inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(4) and one Nb(5) atom. In the second O site, O(2) is bonded in a linear geometry to one Nb(3) and one Nb(5) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ti(1) and two equivalent Nb(3) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Ti(2) and two equivalent Nb(4) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Nb(1) atoms. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Nb(2) atoms. In the seventh O site, O(7) is bonded in a linear geometry to one Nb(2) and one Nb(5) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Nb(1) and one Nb(5) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Ti(1) and one Nb(1) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ti(2) and one Nb(2) atom. In the eleventh O site, O(11) is bonded to one Ti(3), two equivalent Ti(2), and one Nb(4) atom to form distorted corner-sharing OTi3Nb trigonal pyramids. In the twelfth O site, O(12) is bonded to two equivalent Ti(1), one Nb(3), and one Nb(6) atom to form distorted corner-sharing OTi2Nb2 tetrahedra. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Ti(3), one Nb(4), and one Nb(6) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Ti(3), one Nb(3), and one Nb(6) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one Nb(2) and one Nb(6) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Ti(3) and one Nb(1) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Ti(2) and two equivalent Ti(3) atoms. In the eighteenth O site, O(18) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Nb(6) atoms. In the nineteenth O site, O(19) is bonded in a linear geometry to two equivalent Nb(5) atoms. In the twentieth O site, O(20) is bonded in a linear geometry to one Ti(2) and one Nb(3) atom. In the twenty-first O site, O(21) is bonded in a linear geometry to one Ti(1) and one Nb(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_TiNb2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.536
_cell_length_b   10.536
_cell_length_c   11.993
_cell_angle_alpha   59.862
_cell_angle_beta   59.862
_cell_angle_gamma   21.003
_symmetry_Int_Tables_number   1
_cell_volume   410.226
_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  0.706  0.706  0.361  1.0
  Ti  Ti1  1  0.302  0.302  0.635  1.0
  Ti  Ti2  1  0.923  0.923  0.632  1.0
  Nb  Nb3  1  0.817  0.817  0.996  1.0
  Nb  Nb4  1  0.184  0.184  0.996  1.0
  Nb  Nb5  1  0.121  0.121  0.624  1.0
  Nb  Nb6  1  0.883  0.883  0.373  1.0
  Nb  Nb7  1  1.000  1.000  0.996  1.0
  Nb  Nb8  1  0.075  0.075  0.372  1.0
  O  O9  1  0.950  0.950  0.198  1.0
  O  O10  1  0.051  0.051  0.802  1.0
  O  O11  1  0.629  0.629  0.575  1.0
  O  O12  1  0.371  0.371  0.424  1.0
  O  O13  1  0.290  0.290  0.003  1.0
  O  O14  1  0.708  0.708  0.999  1.0
  O  O15  1  0.099  0.099  0.985  1.0
  O  O16  1  0.900  0.900  0.017  1.0
  O  O17  1  0.749  0.749  0.193  1.0
  O  O18  1  0.250  0.250  0.807  1.0
  O  O19  1  0.827  0.827  0.597  1.0
  O  O20  1  0.174  0.174  0.404  1.0
  O  O21  1  0.973  0.973  0.419  1.0
  O  O22  1  0.023  0.023  0.581  1.0
  O  O23  1  0.124  0.124  0.191  1.0
  O  O24  1  0.874  0.874  0.810  1.0
  O  O25  1  0.402  0.402  0.625  1.0
  O  O26  1  0.598  0.598  0.378  1.0
  O  O27  1  0.499  0.499  0.007  1.0
  O  O28  1  0.211  0.211  0.621  1.0
  O  O29  1  0.790  0.790  0.379  1.0
[/CIF]
.
The crystal 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 to one O(18), one O(21), one O(3), one O(9), and two equivalent O(12) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, edges with two equivalent Nb(3)O6 octahedra, and edges with two equivalent Nb(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-35°. In the second Ti site, Ti(2) is bonded to one O(10), one O(17), one O(20), one O(4), and two equivalent O(11) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Ti(2)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Nb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-28°. In the third Ti site, Ti(3) is bonded to one O(11), one O(13), one O(14), one O(16), and two equivalent O(17) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra,  an edgeedge with one Nb(4)O6 octahedra,  an edgeedge with one Nb(6)O6 octahedra, and edges with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-29°. There are six inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(16), one O(6), one O(8), one O(9), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-31°. In the second Nb site, Nb(2) is bonded to one O(10), one O(15), one O(5), one O(7), and two equivalent O(6) atoms to form NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-30°. In the third Nb site, Nb(3) is bonded to one O(12), one O(14), one O(2), one O(20), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Ti(3)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra,  an edgeedge with one Nb(6)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-30°. In the fourth Nb site, Nb(4) is bonded to one O(1), one O(11), one O(13), one O(21), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Nb(5)O6 octahedra,  a cornercorner with one Nb(6)O6 octahedra, corners with two equivalent Nb(4)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, and edges with two equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-31°. In the fifth Nb site, Nb(5) is bonded to one O(1), one O(2), one O(7), one O(8), and two equivalent O(19) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 7-16°. In the sixth Nb site, Nb(6) is bonded to one O(12), one O(13), one O(14), one O(15), and two equivalent O(18) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(6)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra,  an edgeedge with one Nb(3)O6 octahedra, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-30°. There are twenty-one inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Nb(4) and one Nb(5) atom. In the second O site, O(2) is bonded in a linear geometry to one Nb(3) and one Nb(5) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ti(1) and two equivalent Nb(3) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Ti(2) and two equivalent Nb(4) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Nb(1) atoms. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Nb(2) atoms. In the seventh O site, O(7) is bonded in a linear geometry to one Nb(2) and one Nb(5) atom. In the eighth O site, O(8) is bonded in a linear geometry to one Nb(1) and one Nb(5) atom. In the ninth O site, O(9) is bonded in a linear geometry to one Ti(1) and one Nb(1) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ti(2) and one Nb(2) atom. In the eleventh O site, O(11) is bonded to one Ti(3), two equivalent Ti(2), and one Nb(4) atom to form distorted corner-sharing OTi3Nb trigonal pyramids. In the twelfth O site, O(12) is bonded to two equivalent Ti(1), one Nb(3), and one Nb(6) atom to form distorted corner-sharing OTi2Nb2 tetrahedra. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one Ti(3), one Nb(4), and one Nb(6) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Ti(3), one Nb(3), and one Nb(6) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one Nb(2) and one Nb(6) atom. In the sixteenth O site, O(16) is bonded in a linear geometry to one Ti(3) and one Nb(1) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Ti(2) and two equivalent Ti(3) atoms. In the eighteenth O site, O(18) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Nb(6) atoms. In the nineteenth O site, O(19) is bonded in a linear geometry to two equivalent Nb(5) atoms. In the twentieth O site, O(20) is bonded in a linear geometry to one Ti(2) and one Nb(3) atom. In the twenty-first O site, O(21) is bonded in a linear geometry to one Ti(1) and one Nb(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_TiNb2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.536
_cell_length_b   10.536
_cell_length_c   11.993
_cell_angle_alpha   59.862
_cell_angle_beta   59.862
_cell_angle_gamma   21.003
_symmetry_Int_Tables_number   1
_cell_volume   410.226
_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  0.706  0.706  0.361  1.0
  Ti  Ti1  1  0.302  0.302  0.635  1.0
  Ti  Ti2  1  0.923  0.923  0.632  1.0
  Nb  Nb3  1  0.817  0.817  0.996  1.0
  Nb  Nb4  1  0.184  0.184  0.996  1.0
  Nb  Nb5  1  0.121  0.121  0.624  1.0
  Nb  Nb6  1  0.883  0.883  0.373  1.0
  Nb  Nb7  1  1.000  1.000  0.996  1.0
  Nb  Nb8  1  0.075  0.075  0.372  1.0
  O  O9  1  0.950  0.950  0.198  1.0
  O  O10  1  0.051  0.051  0.802  1.0
  O  O11  1  0.629  0.629  0.575  1.0
  O  O12  1  0.371  0.371  0.424  1.0
  O  O13  1  0.290  0.290  0.003  1.0
  O  O14  1  0.708  0.708  0.999  1.0
  O  O15  1  0.099  0.099  0.985  1.0
  O  O16  1  0.900  0.900  0.017  1.0
  O  O17  1  0.749  0.749  0.193  1.0
  O  O18  1  0.250  0.250  0.807  1.0
  O  O19  1  0.827  0.827  0.597  1.0
  O  O20  1  0.174  0.174  0.404  1.0
  O  O21  1  0.973  0.973  0.419  1.0
  O  O22  1  0.023  0.023  0.581  1.0
  O  O23  1  0.124  0.124  0.191  1.0
  O  O24  1  0.874  0.874  0.810  1.0
  O  O25  1  0.402  0.402  0.625  1.0
  O  O26  1  0.598  0.598  0.378  1.0
  O  O27  1  0.499  0.499  0.007  1.0
  O  O28  1  0.211  0.211  0.621  1.0
  O  O29  1  0.790  0.790  0.379  1.0
[/CIF]
.