The structure described by Cr3N4 is Corundum-like structured and crystallizes in the orthorhombic Pnma space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent N(1), two equivalent N(2), and two equivalent N(3) atoms to form CrN6 octahedra that share corners with four equivalent Cr(2)N6 octahedra, corners with two equivalent Cr(3)N4 tetrahedra, edges with two equivalent Cr(1)N6 octahedra, edges with two equivalent Cr(2)N6 octahedra, and edges with two equivalent Cr(3)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-55°. In the second Cr site, Cr(2) is bonded to one N(1), one N(2), and four equivalent N(3) atoms to form CrN6 octahedra that share corners with four equivalent Cr(1)N6 octahedra, corners with four equivalent Cr(2)N6 octahedra, corners with four equivalent Cr(3)N4 tetrahedra, edges with two equivalent Cr(1)N6 octahedra, and  an edgeedge with one Cr(3)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-55°. In the third Cr site, Cr(3) is bonded to one N(1), one N(2), and two equivalent N(3) atoms to form a mixture of corner and edge-sharing CrN4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-62°. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Cr(2), one Cr(3), and two equivalent Cr(1) atoms to form distorted corner-sharing NCr4 trigonal pyramids. In the second N site, N(2) is bonded in a rectangular see-saw-like geometry to one Cr(2), one Cr(3), and two equivalent Cr(1) atoms. In the third N site, N(3) is bonded in a rectangular see-saw-like geometry to one Cr(1), one Cr(3), and two equivalent Cr(2) atoms. is represented by the CIF file [CIF]
data_Cr3N4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.812
_cell_length_b   5.892
_cell_length_c   9.948
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   282.087
_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
  Cr  Cr0  1  0.000  0.500  0.000  1.0
  Cr  Cr1  1  0.500  0.000  0.500  1.0
  Cr  Cr2  1  0.000  0.000  0.000  1.0
  Cr  Cr3  1  0.500  0.500  0.500  1.0
  Cr  Cr4  1  0.010  0.750  0.262  1.0
  Cr  Cr5  1  0.490  0.750  0.762  1.0
  Cr  Cr6  1  0.990  0.250  0.738  1.0
  Cr  Cr7  1  0.510  0.250  0.238  1.0
  Cr  Cr8  1  0.586  0.750  0.091  1.0
  Cr  Cr9  1  0.914  0.750  0.591  1.0
  Cr  Cr10  1  0.414  0.250  0.909  1.0
  Cr  Cr11  1  0.086  0.250  0.409  1.0
  N  N12  1  0.221  0.750  0.085  1.0
  N  N13  1  0.279  0.750  0.585  1.0
  N  N14  1  0.779  0.250  0.915  1.0
  N  N15  1  0.721  0.250  0.415  1.0
  N  N16  1  0.756  0.750  0.429  1.0
  N  N17  1  0.744  0.750  0.929  1.0
  N  N18  1  0.244  0.250  0.571  1.0
  N  N19  1  0.256  0.250  0.071  1.0
  N  N20  1  0.750  0.514  0.167  1.0
  N  N21  1  0.750  0.986  0.667  1.0
  N  N22  1  0.250  0.014  0.833  1.0
  N  N23  1  0.250  0.486  0.333  1.0
  N  N24  1  0.250  0.486  0.833  1.0
  N  N25  1  0.250  0.014  0.333  1.0
  N  N26  1  0.750  0.986  0.167  1.0
  N  N27  1  0.750  0.514  0.667  1.0
[/CIF]
.
The structure described by Cr3N4 is Corundum-like structured and crystallizes in the orthorhombic Pnma space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent N(1), two equivalent N(2), and two equivalent N(3) atoms to form CrN6 octahedra that share corners with four equivalent Cr(2)N6 octahedra, corners with two equivalent Cr(3)N4 tetrahedra, edges with two equivalent Cr(1)N6 octahedra, edges with two equivalent Cr(2)N6 octahedra, and edges with two equivalent Cr(3)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-55°. In the second Cr site, Cr(2) is bonded to one N(1), one N(2), and four equivalent N(3) atoms to form CrN6 octahedra that share corners with four equivalent Cr(1)N6 octahedra, corners with four equivalent Cr(2)N6 octahedra, corners with four equivalent Cr(3)N4 tetrahedra, edges with two equivalent Cr(1)N6 octahedra, and  an edgeedge with one Cr(3)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-55°. In the third Cr site, Cr(3) is bonded to one N(1), one N(2), and two equivalent N(3) atoms to form a mixture of corner and edge-sharing CrN4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-62°. There are three inequivalent N sites. In the first N site, N(1) is bonded to one Cr(2), one Cr(3), and two equivalent Cr(1) atoms to form distorted corner-sharing NCr4 trigonal pyramids. In the second N site, N(2) is bonded in a rectangular see-saw-like geometry to one Cr(2), one Cr(3), and two equivalent Cr(1) atoms. In the third N site, N(3) is bonded in a rectangular see-saw-like geometry to one Cr(1), one Cr(3), and two equivalent Cr(2) atoms. is represented by the CIF file [CIF]
data_Cr3N4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.812
_cell_length_b   5.892
_cell_length_c   9.948
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   282.087
_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
  Cr  Cr0  1  0.000  0.500  0.000  1.0
  Cr  Cr1  1  0.500  0.000  0.500  1.0
  Cr  Cr2  1  0.000  0.000  0.000  1.0
  Cr  Cr3  1  0.500  0.500  0.500  1.0
  Cr  Cr4  1  0.010  0.750  0.262  1.0
  Cr  Cr5  1  0.490  0.750  0.762  1.0
  Cr  Cr6  1  0.990  0.250  0.738  1.0
  Cr  Cr7  1  0.510  0.250  0.238  1.0
  Cr  Cr8  1  0.586  0.750  0.091  1.0
  Cr  Cr9  1  0.914  0.750  0.591  1.0
  Cr  Cr10  1  0.414  0.250  0.909  1.0
  Cr  Cr11  1  0.086  0.250  0.409  1.0
  N  N12  1  0.221  0.750  0.085  1.0
  N  N13  1  0.279  0.750  0.585  1.0
  N  N14  1  0.779  0.250  0.915  1.0
  N  N15  1  0.721  0.250  0.415  1.0
  N  N16  1  0.756  0.750  0.429  1.0
  N  N17  1  0.744  0.750  0.929  1.0
  N  N18  1  0.244  0.250  0.571  1.0
  N  N19  1  0.256  0.250  0.071  1.0
  N  N20  1  0.750  0.514  0.167  1.0
  N  N21  1  0.750  0.986  0.667  1.0
  N  N22  1  0.250  0.014  0.833  1.0
  N  N23  1  0.250  0.486  0.333  1.0
  N  N24  1  0.250  0.486  0.833  1.0
  N  N25  1  0.250  0.014  0.333  1.0
  N  N26  1  0.750  0.986  0.167  1.0
  N  N27  1  0.750  0.514  0.667  1.0
[/CIF]
.