The crystal structure described by Y2SiO5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one O(1), two equivalent O(3), two equivalent O(4), and three equivalent O(5) atoms. In the second Y site, Y(2) is bonded to one O(3), three equivalent O(1), and three equivalent O(2) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Si(1)O4 tetrahedra, edges with six equivalent Y(2)O7 hexagonal pyramids, and  an edgeedge with one Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Y(2)O7 hexagonal pyramids and  an edgeedge with one Y(2)O7 hexagonal pyramid. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Y(1) and three equivalent Y(2) atoms to form a mixture of corner and edge-sharing OY4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Y(2) and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to three equivalent Y(1) and one Si(1) atom. is represented by the CIF card [CIF]
data_Y2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.676
_cell_length_b   6.855
_cell_length_c   9.037
_cell_angle_alpha   90.000
_cell_angle_beta   105.945
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   397.623
_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
  Y  Y0  1  0.060  0.639  0.876  1.0
  Y  Y1  1  0.940  0.361  0.124  1.0
  Y  Y2  1  0.440  0.139  0.124  1.0
  Y  Y3  1  0.560  0.861  0.876  1.0
  Y  Y4  1  0.267  0.125  0.474  1.0
  Y  Y5  1  0.233  0.625  0.526  1.0
  Y  Y6  1  0.767  0.375  0.474  1.0
  Y  Y7  1  0.733  0.875  0.526  1.0
  Si  Si8  1  0.527  0.411  0.800  1.0
  Si  Si9  1  0.973  0.911  0.200  1.0
  Si  Si10  1  0.473  0.589  0.200  1.0
  Si  Si11  1  0.027  0.089  0.800  1.0
  O  O12  1  0.439  0.881  0.614  1.0
  O  O13  1  0.993  0.135  0.616  1.0
  O  O14  1  0.339  0.571  0.792  1.0
  O  O15  1  0.981  0.717  0.105  1.0
  O  O16  1  0.561  0.119  0.386  1.0
  O  O17  1  0.774  0.049  0.124  1.0
  O  O18  1  0.061  0.381  0.386  1.0
  O  O19  1  0.661  0.429  0.208  1.0
  O  O20  1  0.519  0.217  0.895  1.0
  O  O21  1  0.019  0.283  0.895  1.0
  O  O22  1  0.726  0.549  0.876  1.0
  O  O23  1  0.839  0.929  0.792  1.0
  O  O24  1  0.939  0.619  0.614  1.0
  O  O25  1  0.226  0.951  0.876  1.0
  O  O26  1  0.161  0.071  0.208  1.0
  O  O27  1  0.493  0.365  0.616  1.0
  O  O28  1  0.507  0.635  0.384  1.0
  O  O29  1  0.481  0.783  0.105  1.0
  O  O30  1  0.007  0.865  0.384  1.0
  O  O31  1  0.274  0.451  0.124  1.0
[/CIF]
.
The crystal structure described by Y2SiO5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one O(1), two equivalent O(3), two equivalent O(4), and three equivalent O(5) atoms. In the second Y site, Y(2) is bonded to one O(3), three equivalent O(1), and three equivalent O(2) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Si(1)O4 tetrahedra, edges with six equivalent Y(2)O7 hexagonal pyramids, and  an edgeedge with one Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Y(2)O7 hexagonal pyramids and  an edgeedge with one Y(2)O7 hexagonal pyramid. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Y(1) and three equivalent Y(2) atoms to form a mixture of corner and edge-sharing OY4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Y(2) and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Y(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to three equivalent Y(1) and one Si(1) atom. is represented by the CIF card [CIF]
data_Y2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.676
_cell_length_b   6.855
_cell_length_c   9.037
_cell_angle_alpha   90.000
_cell_angle_beta   105.945
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   397.623
_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
  Y  Y0  1  0.060  0.639  0.876  1.0
  Y  Y1  1  0.940  0.361  0.124  1.0
  Y  Y2  1  0.440  0.139  0.124  1.0
  Y  Y3  1  0.560  0.861  0.876  1.0
  Y  Y4  1  0.267  0.125  0.474  1.0
  Y  Y5  1  0.233  0.625  0.526  1.0
  Y  Y6  1  0.767  0.375  0.474  1.0
  Y  Y7  1  0.733  0.875  0.526  1.0
  Si  Si8  1  0.527  0.411  0.800  1.0
  Si  Si9  1  0.973  0.911  0.200  1.0
  Si  Si10  1  0.473  0.589  0.200  1.0
  Si  Si11  1  0.027  0.089  0.800  1.0
  O  O12  1  0.439  0.881  0.614  1.0
  O  O13  1  0.993  0.135  0.616  1.0
  O  O14  1  0.339  0.571  0.792  1.0
  O  O15  1  0.981  0.717  0.105  1.0
  O  O16  1  0.561  0.119  0.386  1.0
  O  O17  1  0.774  0.049  0.124  1.0
  O  O18  1  0.061  0.381  0.386  1.0
  O  O19  1  0.661  0.429  0.208  1.0
  O  O20  1  0.519  0.217  0.895  1.0
  O  O21  1  0.019  0.283  0.895  1.0
  O  O22  1  0.726  0.549  0.876  1.0
  O  O23  1  0.839  0.929  0.792  1.0
  O  O24  1  0.939  0.619  0.614  1.0
  O  O25  1  0.226  0.951  0.876  1.0
  O  O26  1  0.161  0.071  0.208  1.0
  O  O27  1  0.493  0.365  0.616  1.0
  O  O28  1  0.507  0.635  0.384  1.0
  O  O29  1  0.481  0.783  0.105  1.0
  O  O30  1  0.007  0.865  0.384  1.0
  O  O31  1  0.274  0.451  0.124  1.0
[/CIF]
.