The crystal structure described by NaYSi2O6 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms. Y(1) is bonded to one O(2), one O(3), one O(4), two equivalent O(5), and two equivalent O(6) atoms to form YO7 pentagonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, 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 corners with two equivalent Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Y(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Y(1), and one Si(1) atom. is represented by the CIF file [CIF]
data_NaY(SiO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.859
_cell_length_b   5.481
_cell_length_c   7.694
_cell_angle_alpha   70.028
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   549.265
_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  0.231  0.863  0.546  1.0
  Na  Na1  1  0.731  0.137  0.954  1.0
  Na  Na2  1  0.769  0.137  0.454  1.0
  Na  Na3  1  0.269  0.863  0.046  1.0
  Y  Y4  1  0.994  0.983  0.752  1.0
  Y  Y5  1  0.006  0.017  0.248  1.0
  Y  Y6  1  0.494  0.017  0.748  1.0
  Y  Y7  1  0.506  0.983  0.252  1.0
  Si  Si8  1  0.640  0.571  0.144  1.0
  Si  Si9  1  0.138  0.418  0.933  1.0
  Si  Si10  1  0.362  0.418  0.433  1.0
  Si  Si11  1  0.862  0.582  0.067  1.0
  Si  Si12  1  0.638  0.582  0.567  1.0
  Si  Si13  1  0.860  0.571  0.644  1.0
  Si  Si14  1  0.360  0.429  0.856  1.0
  Si  Si15  1  0.140  0.429  0.356  1.0
  O  O16  1  0.749  0.684  0.580  1.0
  O  O17  1  0.878  0.619  0.845  1.0
  O  O18  1  0.134  0.733  0.329  1.0
  O  O19  1  0.751  0.684  0.080  1.0
  O  O20  1  0.375  0.716  0.304  1.0
  O  O21  1  0.866  0.267  0.671  1.0
  O  O22  1  0.437  0.200  0.418  1.0
  O  O23  1  0.566  0.788  0.016  1.0
  O  O24  1  0.625  0.284  0.696  1.0
  O  O25  1  0.366  0.733  0.829  1.0
  O  O26  1  0.122  0.381  0.155  1.0
  O  O27  1  0.434  0.212  0.984  1.0
  O  O28  1  0.937  0.800  0.082  1.0
  O  O29  1  0.249  0.316  0.920  1.0
  O  O30  1  0.125  0.716  0.804  1.0
  O  O31  1  0.934  0.788  0.516  1.0
  O  O32  1  0.563  0.800  0.582  1.0
  O  O33  1  0.378  0.381  0.655  1.0
  O  O34  1  0.251  0.316  0.420  1.0
  O  O35  1  0.875  0.284  0.196  1.0
  O  O36  1  0.622  0.619  0.345  1.0
  O  O37  1  0.634  0.267  0.171  1.0
  O  O38  1  0.066  0.212  0.484  1.0
  O  O39  1  0.063  0.200  0.918  1.0
[/CIF]
.
The crystal structure described by NaYSi2O6 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms. Y(1) is bonded to one O(2), one O(3), one O(4), two equivalent O(5), and two equivalent O(6) atoms to form YO7 pentagonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Y(1)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, 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 corners with two equivalent Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Y(1)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Y(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Na(1), one Y(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Y(1), and one Si(1) atom. is represented by the CIF file [CIF]
data_NaY(SiO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.859
_cell_length_b   5.481
_cell_length_c   7.694
_cell_angle_alpha   70.028
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   549.265
_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  0.231  0.863  0.546  1.0
  Na  Na1  1  0.731  0.137  0.954  1.0
  Na  Na2  1  0.769  0.137  0.454  1.0
  Na  Na3  1  0.269  0.863  0.046  1.0
  Y  Y4  1  0.994  0.983  0.752  1.0
  Y  Y5  1  0.006  0.017  0.248  1.0
  Y  Y6  1  0.494  0.017  0.748  1.0
  Y  Y7  1  0.506  0.983  0.252  1.0
  Si  Si8  1  0.640  0.571  0.144  1.0
  Si  Si9  1  0.138  0.418  0.933  1.0
  Si  Si10  1  0.362  0.418  0.433  1.0
  Si  Si11  1  0.862  0.582  0.067  1.0
  Si  Si12  1  0.638  0.582  0.567  1.0
  Si  Si13  1  0.860  0.571  0.644  1.0
  Si  Si14  1  0.360  0.429  0.856  1.0
  Si  Si15  1  0.140  0.429  0.356  1.0
  O  O16  1  0.749  0.684  0.580  1.0
  O  O17  1  0.878  0.619  0.845  1.0
  O  O18  1  0.134  0.733  0.329  1.0
  O  O19  1  0.751  0.684  0.080  1.0
  O  O20  1  0.375  0.716  0.304  1.0
  O  O21  1  0.866  0.267  0.671  1.0
  O  O22  1  0.437  0.200  0.418  1.0
  O  O23  1  0.566  0.788  0.016  1.0
  O  O24  1  0.625  0.284  0.696  1.0
  O  O25  1  0.366  0.733  0.829  1.0
  O  O26  1  0.122  0.381  0.155  1.0
  O  O27  1  0.434  0.212  0.984  1.0
  O  O28  1  0.937  0.800  0.082  1.0
  O  O29  1  0.249  0.316  0.920  1.0
  O  O30  1  0.125  0.716  0.804  1.0
  O  O31  1  0.934  0.788  0.516  1.0
  O  O32  1  0.563  0.800  0.582  1.0
  O  O33  1  0.378  0.381  0.655  1.0
  O  O34  1  0.251  0.316  0.420  1.0
  O  O35  1  0.875  0.284  0.196  1.0
  O  O36  1  0.622  0.619  0.345  1.0
  O  O37  1  0.634  0.267  0.171  1.0
  O  O38  1  0.066  0.212  0.484  1.0
  O  O39  1  0.063  0.200  0.918  1.0
[/CIF]
.