The crystal structure described by Y2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(13), one O(14), one O(5), one O(7), and two equivalent O(4) atoms. In the second Y site, Y(2) is bonded in a 8-coordinate geometry to one O(12), one O(14), one O(2), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the third Y site, Y(3) is bonded to one O(11), one O(13), one O(14), one O(3), one O(4), and one O(6) atom to form distorted YO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and corners with three equivalent Si(4)O4 tetrahedra. In the fourth Y site, Y(4) is bonded in a 7-coordinate geometry to one O(10), one O(12), one O(2), one O(7), one O(9), and two equivalent O(8) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Y(3)O6 octahedra and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. In the second Si site, Si(2) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Y(3)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(14), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Y(3)O6 octahedra and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-67°. In the fourth Si site, Si(4) is bonded to one O(1), one O(11), one O(13), and one O(3) atom to form SiO4 tetrahedra that share corners with three equivalent Y(3)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 64-66°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(3) and one Si(4) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Y(2), one Y(4), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Y(3), one Si(1), and one Si(4) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Y(3), two equivalent Y(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a 1-coordinate geometry to one Y(1), one Y(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Y(2), one Y(3), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Y(1), one Y(2), one Y(4), and one Si(2) atom. In the eighth O site, O(8) is bonded to one Y(2), two equivalent Y(4), and one Si(2) atom to form distorted edge-sharing OY3Si tetrahedra. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Y(2), one Y(4), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Y(1), one Y(4), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(3), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Y(2), one Y(4), and one Si(1) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(3), and one Si(4) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Y(1), one Y(2), one Y(3), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.672
_cell_length_b   6.713
_cell_length_c   12.187
_cell_angle_alpha   94.488
_cell_angle_beta   91.215
_cell_angle_gamma   91.882
_symmetry_Int_Tables_number   1
_cell_volume   543.725
_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  0.116  0.092  0.357  1.0
  Y  Y1  1  0.329  0.828  0.108  1.0
  Y  Y2  1  0.630  0.783  0.366  1.0
  Y  Y3  1  0.884  0.908  0.643  1.0
  Y  Y4  1  0.671  0.172  0.892  1.0
  Y  Y5  1  0.370  0.217  0.634  1.0
  Y  Y6  1  0.948  0.670  0.885  1.0
  Y  Y7  1  0.052  0.330  0.115  1.0
  Si  Si8  1  0.486  0.665  0.824  1.0
  Si  Si9  1  0.846  0.853  0.115  1.0
  Si  Si10  1  0.514  0.335  0.176  1.0
  Si  Si11  1  0.154  0.147  0.885  1.0
  Si  Si12  1  0.144  0.628  0.380  1.0
  Si  Si13  1  0.856  0.372  0.620  1.0
  Si  Si14  1  0.622  0.275  0.406  1.0
  Si  Si15  1  0.378  0.725  0.594  1.0
  O  O16  1  0.286  0.577  0.488  1.0
  O  O17  1  0.235  0.085  0.004  1.0
  O  O18  1  0.401  0.568  0.694  1.0
  O  O19  1  0.038  0.228  0.578  1.0
  O  O20  1  0.384  0.138  0.211  1.0
  O  O21  1  0.654  0.790  0.186  1.0
  O  O22  1  0.002  0.983  0.816  1.0
  O  O23  1  0.001  0.669  0.081  1.0
  O  O24  1  0.701  0.297  0.095  1.0
  O  O25  1  0.346  0.210  0.814  1.0
  O  O26  1  0.076  0.418  0.311  1.0
  O  O27  1  0.228  0.904  0.623  1.0
  O  O28  1  0.644  0.510  0.873  1.0
  O  O29  1  0.587  0.826  0.553  1.0
  O  O30  1  0.765  0.915  0.996  1.0
  O  O31  1  0.998  0.017  0.184  1.0
  O  O32  1  0.924  0.582  0.689  1.0
  O  O33  1  0.962  0.772  0.422  1.0
  O  O34  1  0.772  0.096  0.377  1.0
  O  O35  1  0.599  0.432  0.306  1.0
  O  O36  1  0.413  0.174  0.447  1.0
  O  O37  1  0.616  0.862  0.789  1.0
  O  O38  1  0.712  0.216  0.687  1.0
  O  O39  1  0.714  0.423  0.512  1.0
  O  O40  1  0.288  0.784  0.313  1.0
  O  O41  1  0.356  0.490  0.127  1.0
  O  O42  1  0.299  0.703  0.905  1.0
  O  O43  1  0.999  0.331  0.919  1.0
[/CIF]
.
The crystal structure described by Y2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(13), one O(14), one O(5), one O(7), and two equivalent O(4) atoms. In the second Y site, Y(2) is bonded in a 8-coordinate geometry to one O(12), one O(14), one O(2), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the third Y site, Y(3) is bonded to one O(11), one O(13), one O(14), one O(3), one O(4), and one O(6) atom to form distorted YO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and corners with three equivalent Si(4)O4 tetrahedra. In the fourth Y site, Y(4) is bonded in a 7-coordinate geometry to one O(10), one O(12), one O(2), one O(7), one O(9), and two equivalent O(8) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Y(3)O6 octahedra and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. In the second Si site, Si(2) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Y(3)O6 octahedra. The corner-sharing octahedral tilt angles are 51°. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(14), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Y(3)O6 octahedra and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-67°. In the fourth Si site, Si(4) is bonded to one O(1), one O(11), one O(13), and one O(3) atom to form SiO4 tetrahedra that share corners with three equivalent Y(3)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 64-66°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(3) and one Si(4) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Y(2), one Y(4), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Y(3), one Si(1), and one Si(4) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Y(3), two equivalent Y(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a 1-coordinate geometry to one Y(1), one Y(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Y(2), one Y(3), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Y(1), one Y(2), one Y(4), and one Si(2) atom. In the eighth O site, O(8) is bonded to one Y(2), two equivalent Y(4), and one Si(2) atom to form distorted edge-sharing OY3Si tetrahedra. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Y(2), one Y(4), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Y(1), one Y(4), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(3), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Y(2), one Y(4), and one Si(1) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Y(1), one Y(3), and one Si(4) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Y(1), one Y(2), one Y(3), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.672
_cell_length_b   6.713
_cell_length_c   12.187
_cell_angle_alpha   94.488
_cell_angle_beta   91.215
_cell_angle_gamma   91.882
_symmetry_Int_Tables_number   1
_cell_volume   543.725
_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  0.116  0.092  0.357  1.0
  Y  Y1  1  0.329  0.828  0.108  1.0
  Y  Y2  1  0.630  0.783  0.366  1.0
  Y  Y3  1  0.884  0.908  0.643  1.0
  Y  Y4  1  0.671  0.172  0.892  1.0
  Y  Y5  1  0.370  0.217  0.634  1.0
  Y  Y6  1  0.948  0.670  0.885  1.0
  Y  Y7  1  0.052  0.330  0.115  1.0
  Si  Si8  1  0.486  0.665  0.824  1.0
  Si  Si9  1  0.846  0.853  0.115  1.0
  Si  Si10  1  0.514  0.335  0.176  1.0
  Si  Si11  1  0.154  0.147  0.885  1.0
  Si  Si12  1  0.144  0.628  0.380  1.0
  Si  Si13  1  0.856  0.372  0.620  1.0
  Si  Si14  1  0.622  0.275  0.406  1.0
  Si  Si15  1  0.378  0.725  0.594  1.0
  O  O16  1  0.286  0.577  0.488  1.0
  O  O17  1  0.235  0.085  0.004  1.0
  O  O18  1  0.401  0.568  0.694  1.0
  O  O19  1  0.038  0.228  0.578  1.0
  O  O20  1  0.384  0.138  0.211  1.0
  O  O21  1  0.654  0.790  0.186  1.0
  O  O22  1  0.002  0.983  0.816  1.0
  O  O23  1  0.001  0.669  0.081  1.0
  O  O24  1  0.701  0.297  0.095  1.0
  O  O25  1  0.346  0.210  0.814  1.0
  O  O26  1  0.076  0.418  0.311  1.0
  O  O27  1  0.228  0.904  0.623  1.0
  O  O28  1  0.644  0.510  0.873  1.0
  O  O29  1  0.587  0.826  0.553  1.0
  O  O30  1  0.765  0.915  0.996  1.0
  O  O31  1  0.998  0.017  0.184  1.0
  O  O32  1  0.924  0.582  0.689  1.0
  O  O33  1  0.962  0.772  0.422  1.0
  O  O34  1  0.772  0.096  0.377  1.0
  O  O35  1  0.599  0.432  0.306  1.0
  O  O36  1  0.413  0.174  0.447  1.0
  O  O37  1  0.616  0.862  0.789  1.0
  O  O38  1  0.712  0.216  0.687  1.0
  O  O39  1  0.714  0.423  0.512  1.0
  O  O40  1  0.288  0.784  0.313  1.0
  O  O41  1  0.356  0.490  0.127  1.0
  O  O42  1  0.299  0.703  0.905  1.0
  O  O43  1  0.999  0.331  0.919  1.0
[/CIF]
.