The structure described by Na6Ti2O7 crystallizes in the monoclinic C2/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Ti(1)O4 tetrahedra, edges with two equivalent Ti(1)O4 tetrahedra, and edges with two equivalent Na(4)O4 trigonal pyramids. In the fourth Na site, Na(4) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted NaO4 trigonal pyramids that share corners with four equivalent Ti(1)O4 tetrahedra and edges with two equivalent Na(3)O6 octahedra. Ti(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form TiO4 tetrahedra that share  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Ti(1)O4 tetrahedra, corners with two equivalent Na(4)O4 trigonal pyramids, and  an edgeedge with one Na(3)O6 octahedra. The corner-sharing octahedral tilt angles are 21°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(2), one Na(3), one Na(4), two equivalent Na(1), and one Ti(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Ti(1) atom to form distorted ONa4Ti trigonal bipyramids that share corners with five equivalent O(3)Na5Ti octahedra, corners with two equivalent O(2)Na4Ti trigonal bipyramids, and  an edgeedge with one O(3)Na5Ti octahedra. The corner-sharing octahedral tilt angles range from 33-75°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ti(1) atom to form distorted ONa5Ti octahedra that share  a cornercorner with one O(3)Na5Ti octahedra, corners with five equivalent O(2)Na4Ti trigonal bipyramids, edges with two equivalent O(3)Na5Ti octahedra, and  an edgeedge with one O(2)Na4Ti trigonal bipyramid. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Na(1) and two equivalent Ti(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na6Ti2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.973
_cell_length_b   5.973
_cell_length_c   12.481
_cell_angle_alpha   79.639
_cell_angle_beta   79.639
_cell_angle_gamma   94.387
_symmetry_Int_Tables_number   1
_cell_volume   428.124
_cell_formula_units_Z   2
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  0.759  0.049  0.581  1.0
  Na  Na1  1  0.489  0.049  0.866  1.0
  Na  Na2  1  0.500  0.500  0.500  1.0
  Na  Na3  1  0.436  0.564  0.750  1.0
  Na  Na4  1  0.049  0.759  0.081  1.0
  Na  Na5  1  0.049  0.489  0.366  1.0
  Na  Na6  1  0.951  0.511  0.634  1.0
  Na  Na7  1  0.951  0.241  0.919  1.0
  Na  Na8  1  0.564  0.436  0.250  1.0
  Na  Na9  1  0.511  0.951  0.134  1.0
  Na  Na10  1  0.241  0.951  0.419  1.0
  Na  Na11  1  0.500  0.500  0.000  1.0
  Ti  Ti12  1  0.927  0.765  0.860  1.0
  Ti  Ti13  1  0.235  0.073  0.640  1.0
  Ti  Ti14  1  0.765  0.927  0.360  1.0
  Ti  Ti15  1  0.073  0.235  0.140  1.0
  O  O16  1  0.201  0.696  0.893  1.0
  O  O17  1  0.696  0.201  0.393  1.0
  O  O18  1  0.474  0.230  0.677  1.0
  O  O19  1  0.749  0.847  0.979  1.0
  O  O20  1  0.962  0.038  0.750  1.0
  O  O21  1  0.153  0.251  0.521  1.0
  O  O22  1  0.230  0.474  0.177  1.0
  O  O23  1  0.770  0.526  0.823  1.0
  O  O24  1  0.847  0.749  0.479  1.0
  O  O25  1  0.038  0.962  0.250  1.0
  O  O26  1  0.251  0.153  0.021  1.0
  O  O27  1  0.526  0.770  0.323  1.0
  O  O28  1  0.304  0.799  0.607  1.0
  O  O29  1  0.799  0.304  0.107  1.0
[/CIF]
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The structure described by Na6Ti2O7 crystallizes in the monoclinic C2/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Ti(1)O4 tetrahedra, edges with two equivalent Ti(1)O4 tetrahedra, and edges with two equivalent Na(4)O4 trigonal pyramids. In the fourth Na site, Na(4) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted NaO4 trigonal pyramids that share corners with four equivalent Ti(1)O4 tetrahedra and edges with two equivalent Na(3)O6 octahedra. Ti(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form TiO4 tetrahedra that share  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Ti(1)O4 tetrahedra, corners with two equivalent Na(4)O4 trigonal pyramids, and  an edgeedge with one Na(3)O6 octahedra. The corner-sharing octahedral tilt angles are 21°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(2), one Na(3), one Na(4), two equivalent Na(1), and one Ti(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Ti(1) atom to form distorted ONa4Ti trigonal bipyramids that share corners with five equivalent O(3)Na5Ti octahedra, corners with two equivalent O(2)Na4Ti trigonal bipyramids, and  an edgeedge with one O(3)Na5Ti octahedra. The corner-sharing octahedral tilt angles range from 33-75°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ti(1) atom to form distorted ONa5Ti octahedra that share  a cornercorner with one O(3)Na5Ti octahedra, corners with five equivalent O(2)Na4Ti trigonal bipyramids, edges with two equivalent O(3)Na5Ti octahedra, and  an edgeedge with one O(2)Na4Ti trigonal bipyramid. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Na(1) and two equivalent Ti(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na6Ti2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.973
_cell_length_b   5.973
_cell_length_c   12.481
_cell_angle_alpha   79.639
_cell_angle_beta   79.639
_cell_angle_gamma   94.387
_symmetry_Int_Tables_number   1
_cell_volume   428.124
_cell_formula_units_Z   2
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  0.759  0.049  0.581  1.0
  Na  Na1  1  0.489  0.049  0.866  1.0
  Na  Na2  1  0.500  0.500  0.500  1.0
  Na  Na3  1  0.436  0.564  0.750  1.0
  Na  Na4  1  0.049  0.759  0.081  1.0
  Na  Na5  1  0.049  0.489  0.366  1.0
  Na  Na6  1  0.951  0.511  0.634  1.0
  Na  Na7  1  0.951  0.241  0.919  1.0
  Na  Na8  1  0.564  0.436  0.250  1.0
  Na  Na9  1  0.511  0.951  0.134  1.0
  Na  Na10  1  0.241  0.951  0.419  1.0
  Na  Na11  1  0.500  0.500  0.000  1.0
  Ti  Ti12  1  0.927  0.765  0.860  1.0
  Ti  Ti13  1  0.235  0.073  0.640  1.0
  Ti  Ti14  1  0.765  0.927  0.360  1.0
  Ti  Ti15  1  0.073  0.235  0.140  1.0
  O  O16  1  0.201  0.696  0.893  1.0
  O  O17  1  0.696  0.201  0.393  1.0
  O  O18  1  0.474  0.230  0.677  1.0
  O  O19  1  0.749  0.847  0.979  1.0
  O  O20  1  0.962  0.038  0.750  1.0
  O  O21  1  0.153  0.251  0.521  1.0
  O  O22  1  0.230  0.474  0.177  1.0
  O  O23  1  0.770  0.526  0.823  1.0
  O  O24  1  0.847  0.749  0.479  1.0
  O  O25  1  0.038  0.962  0.250  1.0
  O  O26  1  0.251  0.153  0.021  1.0
  O  O27  1  0.526  0.770  0.323  1.0
  O  O28  1  0.304  0.799  0.607  1.0
  O  O29  1  0.799  0.304  0.107  1.0
[/CIF]
.