The structure described by Y2Si3O3N4 crystallizes in the tetragonal P-42_1m space group. Y(1) is bonded in a 8-coordinate geometry to four equivalent N(1), one O(2), and three equivalent O(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent N(1), one O(1), and one O(2) atom to form SiN2O2 tetrahedra that share  a cornercorner with one Si(1)N2O2 tetrahedra and corners with two equivalent Si(2)N4 tetrahedra. In the second Si site, Si(2) is bonded to four equivalent N(1) atoms to form corner-sharing SiN4 tetrahedra. N(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Y(1), one Si(1), and one Si(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Y(1) and one Si(1) atom to form distorted OY3Si tetrahedra that share corners with two equivalent O(2)Y2Si2 tetrahedra, corners with four equivalent O(1)Y3Si tetrahedra,  an edgeedge with one O(2)Y2Si2 tetrahedra, and  an edgeedge with one O(1)Y3Si tetrahedra. In the second O site, O(2) is bonded to two equivalent Y(1) and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing OY2Si2 tetrahedra. is represented by the CIF file [CIF]
data_Y2Si3N4O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.649
_cell_length_b   7.649
_cell_length_c   4.950
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   289.586
_cell_formula_units_Z   2
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  0.670  0.170  0.504  1.0
  Y  Y1  1  0.830  0.670  0.496  1.0
  Y  Y2  1  0.170  0.330  0.496  1.0
  Y  Y3  1  0.330  0.830  0.504  1.0
  Si  Si4  1  0.855  0.355  0.945  1.0
  Si  Si5  1  0.645  0.855  0.055  1.0
  Si  Si6  1  0.355  0.145  0.055  1.0
  Si  Si7  1  0.145  0.645  0.945  1.0
  Si  Si8  1  0.500  0.500  0.000  1.0
  Si  Si9  1  0.000  0.000  0.000  1.0
  N  N10  1  0.667  0.423  0.793  1.0
  N  N11  1  0.333  0.577  0.793  1.0
  N  N12  1  0.423  0.333  0.207  1.0
  N  N13  1  0.577  0.667  0.207  1.0
  N  N14  1  0.923  0.167  0.793  1.0
  N  N15  1  0.833  0.923  0.207  1.0
  N  N16  1  0.167  0.077  0.207  1.0
  N  N17  1  0.077  0.833  0.793  1.0
  O  O18  1  0.869  0.369  0.279  1.0
  O  O19  1  0.631  0.869  0.721  1.0
  O  O20  1  0.500  0.000  0.184  1.0
  O  O21  1  0.000  0.500  0.816  1.0
  O  O22  1  0.131  0.631  0.279  1.0
  O  O23  1  0.369  0.131  0.721  1.0
[/CIF]
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The structure described by Y2Si3O3N4 crystallizes in the tetragonal P-42_1m space group. Y(1) is bonded in a 8-coordinate geometry to four equivalent N(1), one O(2), and three equivalent O(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent N(1), one O(1), and one O(2) atom to form SiN2O2 tetrahedra that share  a cornercorner with one Si(1)N2O2 tetrahedra and corners with two equivalent Si(2)N4 tetrahedra. In the second Si site, Si(2) is bonded to four equivalent N(1) atoms to form corner-sharing SiN4 tetrahedra. N(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Y(1), one Si(1), and one Si(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Y(1) and one Si(1) atom to form distorted OY3Si tetrahedra that share corners with two equivalent O(2)Y2Si2 tetrahedra, corners with four equivalent O(1)Y3Si tetrahedra,  an edgeedge with one O(2)Y2Si2 tetrahedra, and  an edgeedge with one O(1)Y3Si tetrahedra. In the second O site, O(2) is bonded to two equivalent Y(1) and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing OY2Si2 tetrahedra. is represented by the CIF file [CIF]
data_Y2Si3N4O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.649
_cell_length_b   7.649
_cell_length_c   4.950
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   289.586
_cell_formula_units_Z   2
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  0.670  0.170  0.504  1.0
  Y  Y1  1  0.830  0.670  0.496  1.0
  Y  Y2  1  0.170  0.330  0.496  1.0
  Y  Y3  1  0.330  0.830  0.504  1.0
  Si  Si4  1  0.855  0.355  0.945  1.0
  Si  Si5  1  0.645  0.855  0.055  1.0
  Si  Si6  1  0.355  0.145  0.055  1.0
  Si  Si7  1  0.145  0.645  0.945  1.0
  Si  Si8  1  0.500  0.500  0.000  1.0
  Si  Si9  1  0.000  0.000  0.000  1.0
  N  N10  1  0.667  0.423  0.793  1.0
  N  N11  1  0.333  0.577  0.793  1.0
  N  N12  1  0.423  0.333  0.207  1.0
  N  N13  1  0.577  0.667  0.207  1.0
  N  N14  1  0.923  0.167  0.793  1.0
  N  N15  1  0.833  0.923  0.207  1.0
  N  N16  1  0.167  0.077  0.207  1.0
  N  N17  1  0.077  0.833  0.793  1.0
  O  O18  1  0.869  0.369  0.279  1.0
  O  O19  1  0.631  0.869  0.721  1.0
  O  O20  1  0.500  0.000  0.184  1.0
  O  O21  1  0.000  0.500  0.816  1.0
  O  O22  1  0.131  0.631  0.279  1.0
  O  O23  1  0.369  0.131  0.721  1.0
[/CIF]
.