The structure described by Na4BaTi2(Si2O5)6 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms. In the second Na site, Na(2) is bonded to one O(8), one O(9), two equivalent O(4), and two equivalent O(7) atoms to form distorted NaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Si(3)O4 tetrahedra, and edges with two equivalent Ti(1)O6 octahedra. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(8), four equivalent O(4), and four equivalent O(6) atoms. Ti(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(8) atoms to form TiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ti(1)O6 octahedra, and edges with two equivalent Na(2)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-68°. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-71°. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Na(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 68-73°. There are nine inequivalent O sites. In the first O site, O(8) is bonded in a 3-coordinate geometry to one Na(2), one Ba(1), and two equivalent Ti(1) atoms. In the second O site, O(9) is bonded in a 3-coordinate geometry to one Na(2) and two equivalent Si(3) atoms. In the third O site, O(1) is bonded in a linear geometry to two equivalent Si(3) atoms. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Ti(1), and one Si(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Si(2), and one Si(3) atom. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), one Ba(1), one Ti(1), and one Si(2) atom. In the seventh O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the eighth O site, O(6) is bonded in a bent 150 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom. In the ninth O site, O(7) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaNa4Ti2(Si2O5)6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.105
_cell_length_b   10.105
_cell_length_c   7.385
_cell_angle_alpha   88.097
_cell_angle_beta   88.097
_cell_angle_gamma   119.352
_symmetry_Int_Tables_number   1
_cell_volume   655.887
_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
  Ba  Ba0  1  0.500  0.500  0.500  1.0
  Na  Na1  1  0.767  0.233  0.000  1.0
  Na  Na2  1  0.233  0.767  0.000  1.0
  Na  Na3  1  0.776  0.776  0.016  1.0
  Na  Na4  1  0.224  0.224  0.984  1.0
  Ti  Ti5  1  0.584  0.416  0.000  1.0
  Ti  Ti6  1  0.416  0.584  0.000  1.0
  Si  Si7  1  0.426  0.086  0.264  1.0
  Si  Si8  1  0.574  0.914  0.736  1.0
  Si  Si9  1  0.914  0.574  0.736  1.0
  Si  Si10  1  0.086  0.426  0.264  1.0
  Si  Si11  1  0.564  0.872  0.313  1.0
  Si  Si12  1  0.436  0.128  0.687  1.0
  Si  Si13  1  0.128  0.436  0.687  1.0
  Si  Si14  1  0.872  0.564  0.313  1.0
  Si  Si15  1  0.906  0.080  0.284  1.0
  Si  Si16  1  0.094  0.920  0.716  1.0
  Si  Si17  1  0.920  0.094  0.716  1.0
  Si  Si18  1  0.080  0.906  0.284  1.0
  O  O19  1  0.917  0.083  0.500  1.0
  O  O20  1  0.083  0.917  0.500  1.0
  O  O21  1  0.550  0.210  0.124  1.0
  O  O22  1  0.450  0.790  0.876  1.0
  O  O23  1  0.790  0.450  0.876  1.0
  O  O24  1  0.210  0.550  0.124  1.0
  O  O25  1  0.732  0.020  0.230  1.0
  O  O26  1  0.268  0.980  0.770  1.0
  O  O27  1  0.980  0.268  0.770  1.0
  O  O28  1  0.020  0.732  0.230  1.0
  O  O29  1  0.534  0.720  0.224  1.0
  O  O30  1  0.466  0.280  0.776  1.0
  O  O31  1  0.280  0.466  0.776  1.0
  O  O32  1  0.720  0.534  0.224  1.0
  O  O33  1  0.438  0.928  0.287  1.0
  O  O34  1  0.562  0.072  0.713  1.0
  O  O35  1  0.072  0.562  0.713  1.0
  O  O36  1  0.928  0.438  0.287  1.0
  O  O37  1  0.578  0.851  0.534  1.0
  O  O38  1  0.422  0.149  0.466  1.0
  O  O39  1  0.149  0.422  0.466  1.0
  O  O40  1  0.851  0.578  0.534  1.0
  O  O41  1  0.249  0.019  0.189  1.0
  O  O42  1  0.751  0.981  0.811  1.0
  O  O43  1  0.981  0.751  0.811  1.0
  O  O44  1  0.019  0.249  0.189  1.0
  O  O45  1  0.410  0.410  0.128  1.0
  O  O46  1  0.590  0.590  0.872  1.0
  O  O47  1  0.963  0.963  0.207  1.0
  O  O48  1  0.037  0.037  0.793  1.0
[/CIF]
.
The structure described by Na4BaTi2(Si2O5)6 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms. In the second Na site, Na(2) is bonded to one O(8), one O(9), two equivalent O(4), and two equivalent O(7) atoms to form distorted NaO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with four equivalent Si(3)O4 tetrahedra, and edges with two equivalent Ti(1)O6 octahedra. Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(8), four equivalent O(4), and four equivalent O(6) atoms. Ti(1) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(8) atoms to form TiO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ti(1)O6 octahedra, and edges with two equivalent Na(2)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-68°. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Na(2)O6 octahedra,  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 41-71°. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(7), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Na(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 68-73°. There are nine inequivalent O sites. In the first O site, O(8) is bonded in a 3-coordinate geometry to one Na(2), one Ba(1), and two equivalent Ti(1) atoms. In the second O site, O(9) is bonded in a 3-coordinate geometry to one Na(2) and two equivalent Si(3) atoms. In the third O site, O(1) is bonded in a linear geometry to two equivalent Si(3) atoms. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Ti(1), and one Si(1) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Si(2), and one Si(3) atom. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), one Ba(1), one Ti(1), and one Si(2) atom. In the seventh O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(2) atom. In the eighth O site, O(6) is bonded in a bent 150 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom. In the ninth O site, O(7) is bonded in a 2-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaNa4Ti2(Si2O5)6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.105
_cell_length_b   10.105
_cell_length_c   7.385
_cell_angle_alpha   88.097
_cell_angle_beta   88.097
_cell_angle_gamma   119.352
_symmetry_Int_Tables_number   1
_cell_volume   655.887
_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
  Ba  Ba0  1  0.500  0.500  0.500  1.0
  Na  Na1  1  0.767  0.233  0.000  1.0
  Na  Na2  1  0.233  0.767  0.000  1.0
  Na  Na3  1  0.776  0.776  0.016  1.0
  Na  Na4  1  0.224  0.224  0.984  1.0
  Ti  Ti5  1  0.584  0.416  0.000  1.0
  Ti  Ti6  1  0.416  0.584  0.000  1.0
  Si  Si7  1  0.426  0.086  0.264  1.0
  Si  Si8  1  0.574  0.914  0.736  1.0
  Si  Si9  1  0.914  0.574  0.736  1.0
  Si  Si10  1  0.086  0.426  0.264  1.0
  Si  Si11  1  0.564  0.872  0.313  1.0
  Si  Si12  1  0.436  0.128  0.687  1.0
  Si  Si13  1  0.128  0.436  0.687  1.0
  Si  Si14  1  0.872  0.564  0.313  1.0
  Si  Si15  1  0.906  0.080  0.284  1.0
  Si  Si16  1  0.094  0.920  0.716  1.0
  Si  Si17  1  0.920  0.094  0.716  1.0
  Si  Si18  1  0.080  0.906  0.284  1.0
  O  O19  1  0.917  0.083  0.500  1.0
  O  O20  1  0.083  0.917  0.500  1.0
  O  O21  1  0.550  0.210  0.124  1.0
  O  O22  1  0.450  0.790  0.876  1.0
  O  O23  1  0.790  0.450  0.876  1.0
  O  O24  1  0.210  0.550  0.124  1.0
  O  O25  1  0.732  0.020  0.230  1.0
  O  O26  1  0.268  0.980  0.770  1.0
  O  O27  1  0.980  0.268  0.770  1.0
  O  O28  1  0.020  0.732  0.230  1.0
  O  O29  1  0.534  0.720  0.224  1.0
  O  O30  1  0.466  0.280  0.776  1.0
  O  O31  1  0.280  0.466  0.776  1.0
  O  O32  1  0.720  0.534  0.224  1.0
  O  O33  1  0.438  0.928  0.287  1.0
  O  O34  1  0.562  0.072  0.713  1.0
  O  O35  1  0.072  0.562  0.713  1.0
  O  O36  1  0.928  0.438  0.287  1.0
  O  O37  1  0.578  0.851  0.534  1.0
  O  O38  1  0.422  0.149  0.466  1.0
  O  O39  1  0.149  0.422  0.466  1.0
  O  O40  1  0.851  0.578  0.534  1.0
  O  O41  1  0.249  0.019  0.189  1.0
  O  O42  1  0.751  0.981  0.811  1.0
  O  O43  1  0.981  0.751  0.811  1.0
  O  O44  1  0.019  0.249  0.189  1.0
  O  O45  1  0.410  0.410  0.128  1.0
  O  O46  1  0.590  0.590  0.872  1.0
  O  O47  1  0.963  0.963  0.207  1.0
  O  O48  1  0.037  0.037  0.793  1.0
[/CIF]
.