The material described by Na2Ti2O5 is Chalcostibite-like structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Ti(1)O4 tetrahedra, corners with three equivalent Ti(2)O4 tetrahedra, corners with two equivalent Na(2)O4 trigonal pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Ti(2)O4 tetrahedra, and  an edgeedge with one Na(2)O4 trigonal pyramid. In the second Na site, Na(2) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with four equivalent Ti(1)O4 tetrahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Na(2)O4 trigonal pyramid. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form TiO4 tetrahedra that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with two equivalent Ti(1)O4 tetrahedra, and corners with four equivalent Na(2)O4 trigonal pyramids. In the second Ti site, Ti(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with three equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, corners with two equivalent Ti(2)O4 tetrahedra,  a cornercorner with one Na(2)O4 trigonal pyramid, and  an edgeedge with one Na(1)O5 square pyramid. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Ti(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(2) and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Ti(1), and one Ti(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Ti2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.508
_cell_length_b   8.904
_cell_length_c   12.531
_cell_angle_alpha   75.816
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   595.810
_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
  Na  Na0  1  0.696  0.144  0.029  1.0
  Na  Na1  1  0.274  0.380  0.056  1.0
  Na  Na2  1  0.774  0.620  0.444  1.0
  Na  Na3  1  0.804  0.144  0.529  1.0
  Na  Na4  1  0.196  0.856  0.471  1.0
  Na  Na5  1  0.226  0.380  0.556  1.0
  Na  Na6  1  0.726  0.620  0.944  1.0
  Na  Na7  1  0.304  0.856  0.971  1.0
  Ti  Ti8  1  0.804  0.402  0.228  1.0
  Ti  Ti9  1  0.673  0.023  0.321  1.0
  Ti  Ti10  1  0.173  0.977  0.179  1.0
  Ti  Ti11  1  0.304  0.598  0.272  1.0
  Ti  Ti12  1  0.696  0.402  0.728  1.0
  Ti  Ti13  1  0.827  0.023  0.821  1.0
  Ti  Ti14  1  0.327  0.977  0.679  1.0
  Ti  Ti15  1  0.196  0.598  0.772  1.0
  O  O16  1  0.265  0.111  0.060  1.0
  O  O17  1  0.712  0.390  0.096  1.0
  O  O18  1  0.339  0.004  0.302  1.0
  O  O19  1  0.136  0.446  0.223  1.0
  O  O20  1  0.249  0.779  0.164  1.0
  O  O21  1  0.749  0.221  0.336  1.0
  O  O22  1  0.636  0.554  0.277  1.0
  O  O23  1  0.839  0.996  0.198  1.0
  O  O24  1  0.212  0.610  0.404  1.0
  O  O25  1  0.235  0.111  0.560  1.0
  O  O26  1  0.765  0.889  0.440  1.0
  O  O27  1  0.788  0.390  0.596  1.0
  O  O28  1  0.161  0.004  0.802  1.0
  O  O29  1  0.364  0.446  0.723  1.0
  O  O30  1  0.251  0.779  0.664  1.0
  O  O31  1  0.751  0.221  0.836  1.0
  O  O32  1  0.864  0.554  0.777  1.0
  O  O33  1  0.661  0.996  0.698  1.0
  O  O34  1  0.288  0.610  0.904  1.0
  O  O35  1  0.735  0.889  0.940  1.0
[/CIF]
.
The material described by Na2Ti2O5 is Chalcostibite-like structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Ti(1)O4 tetrahedra, corners with three equivalent Ti(2)O4 tetrahedra, corners with two equivalent Na(2)O4 trigonal pyramids,  an edgeedge with one Na(1)O5 square pyramid,  an edgeedge with one Ti(2)O4 tetrahedra, and  an edgeedge with one Na(2)O4 trigonal pyramid. In the second Na site, Na(2) is bonded to one O(1), one O(4), and two equivalent O(2) atoms to form NaO4 trigonal pyramids that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with four equivalent Ti(1)O4 tetrahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Na(2)O4 trigonal pyramid. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form TiO4 tetrahedra that share corners with two equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(2)O4 tetrahedra, corners with two equivalent Ti(1)O4 tetrahedra, and corners with four equivalent Na(2)O4 trigonal pyramids. In the second Ti site, Ti(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with three equivalent Na(1)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, corners with two equivalent Ti(2)O4 tetrahedra,  a cornercorner with one Na(2)O4 trigonal pyramid, and  an edgeedge with one Na(1)O5 square pyramid. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Ti(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(2) and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Na(1), one Ti(1), and one Ti(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Ti2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.508
_cell_length_b   8.904
_cell_length_c   12.531
_cell_angle_alpha   75.816
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   595.810
_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
  Na  Na0  1  0.696  0.144  0.029  1.0
  Na  Na1  1  0.274  0.380  0.056  1.0
  Na  Na2  1  0.774  0.620  0.444  1.0
  Na  Na3  1  0.804  0.144  0.529  1.0
  Na  Na4  1  0.196  0.856  0.471  1.0
  Na  Na5  1  0.226  0.380  0.556  1.0
  Na  Na6  1  0.726  0.620  0.944  1.0
  Na  Na7  1  0.304  0.856  0.971  1.0
  Ti  Ti8  1  0.804  0.402  0.228  1.0
  Ti  Ti9  1  0.673  0.023  0.321  1.0
  Ti  Ti10  1  0.173  0.977  0.179  1.0
  Ti  Ti11  1  0.304  0.598  0.272  1.0
  Ti  Ti12  1  0.696  0.402  0.728  1.0
  Ti  Ti13  1  0.827  0.023  0.821  1.0
  Ti  Ti14  1  0.327  0.977  0.679  1.0
  Ti  Ti15  1  0.196  0.598  0.772  1.0
  O  O16  1  0.265  0.111  0.060  1.0
  O  O17  1  0.712  0.390  0.096  1.0
  O  O18  1  0.339  0.004  0.302  1.0
  O  O19  1  0.136  0.446  0.223  1.0
  O  O20  1  0.249  0.779  0.164  1.0
  O  O21  1  0.749  0.221  0.336  1.0
  O  O22  1  0.636  0.554  0.277  1.0
  O  O23  1  0.839  0.996  0.198  1.0
  O  O24  1  0.212  0.610  0.404  1.0
  O  O25  1  0.235  0.111  0.560  1.0
  O  O26  1  0.765  0.889  0.440  1.0
  O  O27  1  0.788  0.390  0.596  1.0
  O  O28  1  0.161  0.004  0.802  1.0
  O  O29  1  0.364  0.446  0.723  1.0
  O  O30  1  0.251  0.779  0.664  1.0
  O  O31  1  0.751  0.221  0.836  1.0
  O  O32  1  0.864  0.554  0.777  1.0
  O  O33  1  0.661  0.996  0.698  1.0
  O  O34  1  0.288  0.610  0.904  1.0
  O  O35  1  0.735  0.889  0.940  1.0
[/CIF]
.