The structure described by Na6Zr2Si4O17 crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(3), one O(5), and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with three equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O5 tetrahedra,  an edgeedge with one Zr(1)O6 octahedra, and  an edgeedge with one Zr(2)O6 octahedra. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(6), one O(7), and four equivalent O(4) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form ZrO6 octahedra that share corners with six equivalent Si(2)O4 tetrahedra and edges with two equivalent Na(2)O6 octahedra. In the second Zr site, Zr(2) is bonded to two equivalent O(6) and four equivalent O(4) atoms to form distorted ZrO6 octahedra that share corners with six equivalent Si(1)O5 tetrahedra and edges with two equivalent Na(2)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(6), one O(7), and two equivalent O(4) atoms to form distorted SiO5 tetrahedra that share corners with three equivalent Na(2)O6 octahedra, corners with three equivalent Zr(2)O6 octahedra, and  a cornercorner with one Si(1)O5 tetrahedra. The corner-sharing octahedral tilt angles range from 22-58°. In the second Si site, Si(2) is bonded to one O(1), one O(5), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Na(2)O6 octahedra and corners with three equivalent Zr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-62°. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(3), one Zr(2), and one Si(1) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Zr(1), and one Si(2) atom. In the third O site, O(6) is bonded in a 2-coordinate geometry to one Na(3), one Zr(2), and one Si(1) atom. In the fourth O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Na(3) and two equivalent Si(1) atoms. In the fifth O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Na(3), and one Si(2) atom. In the sixth O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Zr(1), and one Si(2) atom. In the seventh O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_Na6Zr2Si4O17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.389
_cell_length_b   5.389
_cell_length_c   14.260
_cell_angle_alpha   89.124
_cell_angle_beta   89.124
_cell_angle_gamma   62.286
_symmetry_Int_Tables_number   1
_cell_volume   366.506
_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  0.174  0.174  0.119  1.0
  Na  Na1  1  0.826  0.826  0.881  1.0
  Na  Na2  1  0.493  0.493  0.245  1.0
  Na  Na3  1  0.507  0.507  0.755  1.0
  Na  Na4  1  0.817  0.817  0.376  1.0
  Na  Na5  1  0.183  0.183  0.624  1.0
  Zr  Zr6  1  0.500  0.500  0.000  1.0
  Zr  Zr7  1  0.500  0.500  0.500  1.0
  Si  Si8  1  0.159  0.159  0.377  1.0
  Si  Si9  1  0.841  0.841  0.623  1.0
  Si  Si10  1  0.844  0.844  0.118  1.0
  Si  Si11  1  0.156  0.156  0.882  1.0
  O  O12  1  0.767  0.767  0.223  1.0
  O  O13  1  0.233  0.233  0.777  1.0
  O  O14  1  0.711  0.187  0.104  1.0
  O  O15  1  0.187  0.711  0.104  1.0
  O  O16  1  0.289  0.813  0.896  1.0
  O  O17  1  0.813  0.289  0.896  1.0
  O  O18  1  0.232  0.232  0.272  1.0
  O  O19  1  0.768  0.768  0.728  1.0
  O  O20  1  0.809  0.318  0.385  1.0
  O  O21  1  0.318  0.809  0.385  1.0
  O  O22  1  0.191  0.682  0.615  1.0
  O  O23  1  0.682  0.191  0.615  1.0
  O  O24  1  0.717  0.717  0.038  1.0
  O  O25  1  0.283  0.283  0.962  1.0
  O  O26  1  0.293  0.293  0.453  1.0
  O  O27  1  0.707  0.707  0.547  1.0
  O  O28  1  0.000  0.000  0.500  1.0
[/CIF]
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The structure described by Na6Zr2Si4O17 crystallizes in the monoclinic C2/m space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(3), one O(5), and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(3), two equivalent O(2), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with three equivalent Si(2)O4 tetrahedra, corners with three equivalent Si(1)O5 tetrahedra,  an edgeedge with one Zr(1)O6 octahedra, and  an edgeedge with one Zr(2)O6 octahedra. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one O(1), one O(6), one O(7), and four equivalent O(4) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to two equivalent O(5) and four equivalent O(2) atoms to form ZrO6 octahedra that share corners with six equivalent Si(2)O4 tetrahedra and edges with two equivalent Na(2)O6 octahedra. In the second Zr site, Zr(2) is bonded to two equivalent O(6) and four equivalent O(4) atoms to form distorted ZrO6 octahedra that share corners with six equivalent Si(1)O5 tetrahedra and edges with two equivalent Na(2)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(6), one O(7), and two equivalent O(4) atoms to form distorted SiO5 tetrahedra that share corners with three equivalent Na(2)O6 octahedra, corners with three equivalent Zr(2)O6 octahedra, and  a cornercorner with one Si(1)O5 tetrahedra. The corner-sharing octahedral tilt angles range from 22-58°. In the second Si site, Si(2) is bonded to one O(1), one O(5), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Na(2)O6 octahedra and corners with three equivalent Zr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-62°. There are seven inequivalent O sites. In the first O site, O(4) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(3), one Zr(2), and one Si(1) atom. In the second O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Zr(1), and one Si(2) atom. In the third O site, O(6) is bonded in a 2-coordinate geometry to one Na(3), one Zr(2), and one Si(1) atom. In the fourth O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Na(3) and two equivalent Si(1) atoms. In the fifth O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Na(3), and one Si(2) atom. In the sixth O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Zr(1), and one Si(2) atom. In the seventh O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_Na6Zr2Si4O17
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.389
_cell_length_b   5.389
_cell_length_c   14.260
_cell_angle_alpha   89.124
_cell_angle_beta   89.124
_cell_angle_gamma   62.286
_symmetry_Int_Tables_number   1
_cell_volume   366.506
_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  0.174  0.174  0.119  1.0
  Na  Na1  1  0.826  0.826  0.881  1.0
  Na  Na2  1  0.493  0.493  0.245  1.0
  Na  Na3  1  0.507  0.507  0.755  1.0
  Na  Na4  1  0.817  0.817  0.376  1.0
  Na  Na5  1  0.183  0.183  0.624  1.0
  Zr  Zr6  1  0.500  0.500  0.000  1.0
  Zr  Zr7  1  0.500  0.500  0.500  1.0
  Si  Si8  1  0.159  0.159  0.377  1.0
  Si  Si9  1  0.841  0.841  0.623  1.0
  Si  Si10  1  0.844  0.844  0.118  1.0
  Si  Si11  1  0.156  0.156  0.882  1.0
  O  O12  1  0.767  0.767  0.223  1.0
  O  O13  1  0.233  0.233  0.777  1.0
  O  O14  1  0.711  0.187  0.104  1.0
  O  O15  1  0.187  0.711  0.104  1.0
  O  O16  1  0.289  0.813  0.896  1.0
  O  O17  1  0.813  0.289  0.896  1.0
  O  O18  1  0.232  0.232  0.272  1.0
  O  O19  1  0.768  0.768  0.728  1.0
  O  O20  1  0.809  0.318  0.385  1.0
  O  O21  1  0.318  0.809  0.385  1.0
  O  O22  1  0.191  0.682  0.615  1.0
  O  O23  1  0.682  0.191  0.615  1.0
  O  O24  1  0.717  0.717  0.038  1.0
  O  O25  1  0.283  0.283  0.962  1.0
  O  O26  1  0.293  0.293  0.453  1.0
  O  O27  1  0.707  0.707  0.547  1.0
  O  O28  1  0.000  0.000  0.500  1.0
[/CIF]
.