The crystal structure described by Na2Ti2O5 is Chalcostibite-like structured and crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded to one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Na(2)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, corners with four equivalent Ti(2)O4 tetrahedra, and  an edgeedge with one Ti(1)O4 tetrahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(5), and two equivalent O(2) atoms to form TiO4 tetrahedra that share  a cornercorner with one Na(2)O5 square pyramid,  a cornercorner with one Ti(2)O4 tetrahedra, corners with two equivalent Ti(1)O4 tetrahedra, and  an edgeedge with one Na(2)O5 square pyramid. In the second Ti site, Ti(2) is bonded to one O(4), one O(5), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with four equivalent Na(2)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, and corners with two equivalent Ti(2)O4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Na(1) and two equivalent Ti(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2) and two equivalent Ti(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Ti(1), and one Ti(2) atom. is represented by the CIF file [CIF]
data_Na2Ti2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.427
_cell_length_b   8.865
_cell_length_c   11.955
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   575.204
_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  0.458  0.934  0.773  1.0
  Na  Na1  1  0.376  0.810  0.305  1.0
  Na  Na2  1  0.876  0.690  0.805  1.0
  Na  Na3  1  0.958  0.566  0.273  1.0
  Na  Na4  1  0.458  0.434  0.727  1.0
  Na  Na5  1  0.376  0.310  0.195  1.0
  Na  Na6  1  0.876  0.190  0.695  1.0
  Na  Na7  1  0.958  0.066  0.227  1.0
  Ti  Ti8  1  0.487  0.952  0.071  1.0
  Ti  Ti9  1  0.849  0.893  0.482  1.0
  Ti  Ti10  1  0.349  0.607  0.982  1.0
  Ti  Ti11  1  0.987  0.548  0.571  1.0
  Ti  Ti12  1  0.487  0.452  0.429  1.0
  Ti  Ti13  1  0.849  0.393  0.018  1.0
  Ti  Ti14  1  0.349  0.107  0.518  1.0
  Ti  Ti15  1  0.987  0.048  0.929  1.0
  O  O16  1  0.889  0.955  0.808  1.0
  O  O17  1  0.826  0.977  0.056  1.0
  O  O18  1  0.510  0.929  0.477  1.0
  O  O19  1  0.942  0.837  0.347  1.0
  O  O20  1  0.913  0.750  0.592  1.0
  O  O21  1  0.413  0.750  0.092  1.0
  O  O22  1  0.442  0.663  0.847  1.0
  O  O23  1  0.010  0.571  0.977  1.0
  O  O24  1  0.326  0.523  0.556  1.0
  O  O25  1  0.389  0.545  0.308  1.0
  O  O26  1  0.889  0.455  0.692  1.0
  O  O27  1  0.826  0.477  0.444  1.0
  O  O28  1  0.510  0.429  0.023  1.0
  O  O29  1  0.942  0.337  0.153  1.0
  O  O30  1  0.913  0.250  0.908  1.0
  O  O31  1  0.413  0.250  0.408  1.0
  O  O32  1  0.442  0.163  0.653  1.0
  O  O33  1  0.010  0.071  0.523  1.0
  O  O34  1  0.326  0.023  0.944  1.0
  O  O35  1  0.389  0.045  0.192  1.0
[/CIF]
.
The crystal structure described by Na2Ti2O5 is Chalcostibite-like structured and crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded to one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Na(2)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, corners with four equivalent Ti(2)O4 tetrahedra, and  an edgeedge with one Ti(1)O4 tetrahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(5), and two equivalent O(2) atoms to form TiO4 tetrahedra that share  a cornercorner with one Na(2)O5 square pyramid,  a cornercorner with one Ti(2)O4 tetrahedra, corners with two equivalent Ti(1)O4 tetrahedra, and  an edgeedge with one Na(2)O5 square pyramid. In the second Ti site, Ti(2) is bonded to one O(4), one O(5), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with four equivalent Na(2)O5 square pyramids,  a cornercorner with one Ti(1)O4 tetrahedra, and corners with two equivalent Ti(2)O4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Na(1) and two equivalent Ti(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2) and two equivalent Ti(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Ti(1), and one Ti(2) atom. is represented by the CIF file [CIF]
data_Na2Ti2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.427
_cell_length_b   8.865
_cell_length_c   11.955
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   575.204
_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  0.458  0.934  0.773  1.0
  Na  Na1  1  0.376  0.810  0.305  1.0
  Na  Na2  1  0.876  0.690  0.805  1.0
  Na  Na3  1  0.958  0.566  0.273  1.0
  Na  Na4  1  0.458  0.434  0.727  1.0
  Na  Na5  1  0.376  0.310  0.195  1.0
  Na  Na6  1  0.876  0.190  0.695  1.0
  Na  Na7  1  0.958  0.066  0.227  1.0
  Ti  Ti8  1  0.487  0.952  0.071  1.0
  Ti  Ti9  1  0.849  0.893  0.482  1.0
  Ti  Ti10  1  0.349  0.607  0.982  1.0
  Ti  Ti11  1  0.987  0.548  0.571  1.0
  Ti  Ti12  1  0.487  0.452  0.429  1.0
  Ti  Ti13  1  0.849  0.393  0.018  1.0
  Ti  Ti14  1  0.349  0.107  0.518  1.0
  Ti  Ti15  1  0.987  0.048  0.929  1.0
  O  O16  1  0.889  0.955  0.808  1.0
  O  O17  1  0.826  0.977  0.056  1.0
  O  O18  1  0.510  0.929  0.477  1.0
  O  O19  1  0.942  0.837  0.347  1.0
  O  O20  1  0.913  0.750  0.592  1.0
  O  O21  1  0.413  0.750  0.092  1.0
  O  O22  1  0.442  0.663  0.847  1.0
  O  O23  1  0.010  0.571  0.977  1.0
  O  O24  1  0.326  0.523  0.556  1.0
  O  O25  1  0.389  0.545  0.308  1.0
  O  O26  1  0.889  0.455  0.692  1.0
  O  O27  1  0.826  0.477  0.444  1.0
  O  O28  1  0.510  0.429  0.023  1.0
  O  O29  1  0.942  0.337  0.153  1.0
  O  O30  1  0.913  0.250  0.908  1.0
  O  O31  1  0.413  0.250  0.408  1.0
  O  O32  1  0.442  0.163  0.653  1.0
  O  O33  1  0.010  0.071  0.523  1.0
  O  O34  1  0.326  0.023  0.944  1.0
  O  O35  1  0.389  0.045  0.192  1.0
[/CIF]
.