The structure described by Na3Sr2Ti3(Si2O9)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, and edges with two equivalent Ti(2)O6 octahedra. In the second Na site, Na(2) is bonded to two equivalent O(4) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Ti(2)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. Sr(1) is bonded in a 11-coordinate geometry to one O(5), two equivalent O(6), four equivalent O(1), and four equivalent O(3) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Na(1)O6 octahedra, and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-58°. In the second Ti site, Ti(2) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form TiO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-64°. There are six inequivalent O sites. In the first O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Sr(1), one Ti(1), and one Si(1) atom. In the second O site, O(4) is bonded to one Na(2), two equivalent Na(1), and one Ti(1) atom to form a mixture of distorted edge and corner-sharing ONa3Ti trigonal pyramids. In the third O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Na(1), one Sr(1), and one Ti(2) atom. In the fourth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Si(1) atoms. In the fifth O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Sr(1), one Ti(1), and one Si(1) atom. In the sixth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Ti(2), and one Si(1) atom. is represented by the CIF card [CIF]
data_Na3Sr2Ti3(Si2O9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.560
_cell_length_b   10.560
_cell_length_c   5.433
_cell_angle_alpha   83.529
_cell_angle_beta   83.529
_cell_angle_gamma   39.652
_symmetry_Int_Tables_number   1
_cell_volume   383.766
_cell_formula_units_Z   1
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  0.758  0.242  0.500  1.0
  Na  Na1  1  0.242  0.758  0.500  1.0
  Na  Na2  1  0.500  0.500  0.000  1.0
  Sr  Sr3  1  0.784  0.784  0.739  1.0
  Sr  Sr4  1  0.216  0.216  0.261  1.0
  Ti  Ti5  1  0.649  0.649  0.294  1.0
  Ti  Ti6  1  0.351  0.351  0.706  1.0
  Ti  Ti7  1  0.000  0.000  0.000  1.0
  Si  Si8  1  0.642  0.074  0.201  1.0
  Si  Si9  1  0.358  0.926  0.799  1.0
  Si  Si10  1  0.926  0.358  0.799  1.0
  Si  Si11  1  0.074  0.642  0.201  1.0
  O  O12  1  0.516  0.134  0.466  1.0
  O  O13  1  0.484  0.866  0.534  1.0
  O  O14  1  0.866  0.484  0.534  1.0
  O  O15  1  0.134  0.516  0.466  1.0
  O  O16  1  0.730  0.149  0.170  1.0
  O  O17  1  0.270  0.851  0.830  1.0
  O  O18  1  0.851  0.270  0.830  1.0
  O  O19  1  0.149  0.730  0.170  1.0
  O  O20  1  0.488  0.866  0.029  1.0
  O  O21  1  0.512  0.134  0.971  1.0
  O  O22  1  0.134  0.512  0.971  1.0
  O  O23  1  0.866  0.488  0.029  1.0
  O  O24  1  0.564  0.564  0.327  1.0
  O  O25  1  0.436  0.436  0.673  1.0
  O  O26  1  0.944  0.944  0.752  1.0
  O  O27  1  0.056  0.056  0.248  1.0
  O  O28  1  0.824  0.824  0.219  1.0
  O  O29  1  0.176  0.176  0.781  1.0
[/CIF]
.
The structure described by Na3Sr2Ti3(Si2O9)2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form NaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, and edges with two equivalent Ti(2)O6 octahedra. In the second Na site, Na(2) is bonded to two equivalent O(4) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, corners with two equivalent Ti(1)O5 trigonal bipyramids, edges with two equivalent Ti(2)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. Sr(1) is bonded in a 11-coordinate geometry to one O(5), two equivalent O(6), four equivalent O(1), and four equivalent O(3) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted TiO5 trigonal bipyramids that share  a cornercorner with one Na(2)O6 octahedra, corners with two equivalent Na(1)O6 octahedra, and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-58°. In the second Ti site, Ti(2) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form TiO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Na(2)O6 octahedra, and edges with four equivalent Na(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Ti(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 54-64°. There are six inequivalent O sites. In the first O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Sr(1), one Ti(1), and one Si(1) atom. In the second O site, O(4) is bonded to one Na(2), two equivalent Na(1), and one Ti(1) atom to form a mixture of distorted edge and corner-sharing ONa3Ti trigonal pyramids. In the third O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Na(1), one Sr(1), and one Ti(2) atom. In the fourth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Si(1) atoms. In the fifth O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Sr(1), one Ti(1), and one Si(1) atom. In the sixth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Ti(2), and one Si(1) atom. is represented by the CIF card [CIF]
data_Na3Sr2Ti3(Si2O9)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.560
_cell_length_b   10.560
_cell_length_c   5.433
_cell_angle_alpha   83.529
_cell_angle_beta   83.529
_cell_angle_gamma   39.652
_symmetry_Int_Tables_number   1
_cell_volume   383.766
_cell_formula_units_Z   1
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  0.758  0.242  0.500  1.0
  Na  Na1  1  0.242  0.758  0.500  1.0
  Na  Na2  1  0.500  0.500  0.000  1.0
  Sr  Sr3  1  0.784  0.784  0.739  1.0
  Sr  Sr4  1  0.216  0.216  0.261  1.0
  Ti  Ti5  1  0.649  0.649  0.294  1.0
  Ti  Ti6  1  0.351  0.351  0.706  1.0
  Ti  Ti7  1  0.000  0.000  0.000  1.0
  Si  Si8  1  0.642  0.074  0.201  1.0
  Si  Si9  1  0.358  0.926  0.799  1.0
  Si  Si10  1  0.926  0.358  0.799  1.0
  Si  Si11  1  0.074  0.642  0.201  1.0
  O  O12  1  0.516  0.134  0.466  1.0
  O  O13  1  0.484  0.866  0.534  1.0
  O  O14  1  0.866  0.484  0.534  1.0
  O  O15  1  0.134  0.516  0.466  1.0
  O  O16  1  0.730  0.149  0.170  1.0
  O  O17  1  0.270  0.851  0.830  1.0
  O  O18  1  0.851  0.270  0.830  1.0
  O  O19  1  0.149  0.730  0.170  1.0
  O  O20  1  0.488  0.866  0.029  1.0
  O  O21  1  0.512  0.134  0.971  1.0
  O  O22  1  0.134  0.512  0.971  1.0
  O  O23  1  0.866  0.488  0.029  1.0
  O  O24  1  0.564  0.564  0.327  1.0
  O  O25  1  0.436  0.436  0.673  1.0
  O  O26  1  0.944  0.944  0.752  1.0
  O  O27  1  0.056  0.056  0.248  1.0
  O  O28  1  0.824  0.824  0.219  1.0
  O  O29  1  0.176  0.176  0.781  1.0
[/CIF]
.