The structure described by Si3N4 is Hausmannite structured and crystallizes in the cubic Fd-3m space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to six equivalent N(1) atoms to form SiN6 octahedra that share corners with six equivalent Si(2)N4 tetrahedra and edges with six equivalent Si(1)N6 octahedra. In the second Si site, Si(2) is bonded to four equivalent N(1) atoms to form corner-sharing SiN4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. N(1) is bonded in a distorted rectangular see-saw-like geometry to one Si(2) and three equivalent Si(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Si3N4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.507
_cell_length_b   5.507
_cell_length_c   5.507
_cell_angle_alpha   60.000
_cell_angle_beta   60.000
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   118.066
_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
  Si  Si0  1  0.625  0.625  0.125  1.0
  Si  Si1  1  0.625  0.125  0.625  1.0
  Si  Si2  1  0.125  0.625  0.625  1.0
  Si  Si3  1  0.625  0.625  0.625  1.0
  Si  Si4  1  0.250  0.250  0.250  1.0
  Si  Si5  1  0.000  0.000  0.000  1.0
  N  N6  1  0.868  0.868  0.868  1.0
  N  N7  1  0.853  0.382  0.382  1.0
  N  N8  1  0.382  0.382  0.853  1.0
  N  N9  1  0.382  0.853  0.382  1.0
  N  N10  1  0.868  0.868  0.397  1.0
  N  N11  1  0.868  0.397  0.868  1.0
  N  N12  1  0.382  0.382  0.382  1.0
  N  N13  1  0.397  0.868  0.868  1.0
[/CIF]
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The structure described by Si3N4 is Hausmannite structured and crystallizes in the cubic Fd-3m space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to six equivalent N(1) atoms to form SiN6 octahedra that share corners with six equivalent Si(2)N4 tetrahedra and edges with six equivalent Si(1)N6 octahedra. In the second Si site, Si(2) is bonded to four equivalent N(1) atoms to form corner-sharing SiN4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. N(1) is bonded in a distorted rectangular see-saw-like geometry to one Si(2) and three equivalent Si(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Si3N4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.507
_cell_length_b   5.507
_cell_length_c   5.507
_cell_angle_alpha   60.000
_cell_angle_beta   60.000
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   118.066
_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
  Si  Si0  1  0.625  0.625  0.125  1.0
  Si  Si1  1  0.625  0.125  0.625  1.0
  Si  Si2  1  0.125  0.625  0.625  1.0
  Si  Si3  1  0.625  0.625  0.625  1.0
  Si  Si4  1  0.250  0.250  0.250  1.0
  Si  Si5  1  0.000  0.000  0.000  1.0
  N  N6  1  0.868  0.868  0.868  1.0
  N  N7  1  0.853  0.382  0.382  1.0
  N  N8  1  0.382  0.382  0.853  1.0
  N  N9  1  0.382  0.853  0.382  1.0
  N  N10  1  0.868  0.868  0.397  1.0
  N  N11  1  0.868  0.397  0.868  1.0
  N  N12  1  0.382  0.382  0.382  1.0
  N  N13  1  0.397  0.868  0.868  1.0
[/CIF]
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