The structure described by Al4SiC4 is Aluminum carbonitride-like structured and crystallizes in the hexagonal P6_3mc space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(1) and three equivalent C(2) atoms to form distorted AlC4 tetrahedra that share  a cornercorner with one Si(1)C4 tetrahedra, corners with three equivalent Al(3)C4 tetrahedra, corners with six equivalent Al(1)C4 tetrahedra, and edges with three equivalent Al(2)C4 trigonal pyramids. In the second Al site, Al(2) is bonded to one C(2) and three equivalent C(1) atoms to form distorted AlC4 trigonal pyramids that share  a cornercorner with one Al(3)C4 tetrahedra, corners with three equivalent Si(1)C4 tetrahedra, corners with six equivalent Al(2)C4 trigonal pyramids, and edges with three equivalent Al(1)C4 tetrahedra. In the third Al site, Al(3) is bonded to one C(2) and three equivalent C(4) atoms to form a mixture of distorted edge and corner-sharing AlC4 tetrahedra. In the fourth Al site, Al(4) is bonded to one C(3) and three equivalent C(4) atoms to form AlC4 tetrahedra that share corners with three equivalent Al(3)C4 tetrahedra, corners with three equivalent Si(1)C4 tetrahedra, corners with six equivalent Al(4)C4 tetrahedra, and edges with three equivalent Al(3)C4 tetrahedra. Si(1) is bonded to one C(1) and three equivalent C(3) atoms to form SiC4 tetrahedra that share  a cornercorner with one Al(1)C4 tetrahedra, corners with three equivalent Al(4)C4 tetrahedra, corners with six equivalent Si(1)C4 tetrahedra, and corners with three equivalent Al(2)C4 trigonal pyramids. There are four inequivalent C sites. In the first C site, C(1) is bonded to one Al(1), three equivalent Al(2), and one Si(1) atom to form CAl4Si trigonal bipyramids that share corners with three equivalent C(3)AlSi3 tetrahedra, corners with six equivalent C(1)Al4Si trigonal bipyramids, and edges with three equivalent C(2)Al5 trigonal bipyramids. In the second C site, C(2) is bonded to one Al(2), one Al(3), and three equivalent Al(1) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent C(4)Al6 octahedra, corners with six equivalent C(2)Al5 trigonal bipyramids, and edges with three equivalent C(1)Al4Si trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. In the third C site, C(3) is bonded to one Al(4) and three equivalent Si(1) atoms to form CAlSi3 tetrahedra that share corners with three equivalent C(4)Al6 octahedra, corners with six equivalent C(3)AlSi3 tetrahedra, and corners with three equivalent C(1)Al4Si trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. In the fourth C site, C(4) is bonded to three equivalent Al(3) and three equivalent Al(4) atoms to form CAl6 octahedra that share corners with three equivalent C(3)AlSi3 tetrahedra, corners with three equivalent C(2)Al5 trigonal bipyramids, and edges with six equivalent C(4)Al6 octahedra. is represented by the CIF file [CIF]
data_Al4SiC4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.292
_cell_length_b   3.292
_cell_length_c   21.837
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   204.943
_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
  Al  Al0  1  0.000  0.000  0.848  1.0
  Al  Al1  1  0.000  0.000  0.348  1.0
  Al  Al2  1  0.667  0.333  0.763  1.0
  Al  Al3  1  0.333  0.667  0.263  1.0
  Al  Al4  1  0.667  0.333  0.952  1.0
  Al  Al5  1  0.333  0.667  0.452  1.0
  Al  Al6  1  0.667  0.333  0.544  1.0
  Al  Al7  1  0.333  0.667  0.044  1.0
  Si  Si8  1  0.000  0.000  0.662  1.0
  Si  Si9  1  0.000  0.000  0.162  1.0
  C  C10  1  0.000  0.000  0.748  1.0
  C  C11  1  0.000  0.000  0.248  1.0
  C  C12  1  0.667  0.333  0.864  1.0
  C  C13  1  0.333  0.667  0.364  1.0
  C  C14  1  0.667  0.333  0.634  1.0
  C  C15  1  0.333  0.667  0.134  1.0
  C  C16  1  0.000  0.000  0.999  1.0
  C  C17  1  0.000  0.000  0.499  1.0
[/CIF]
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The structure described by Al4SiC4 is Aluminum carbonitride-like structured and crystallizes in the hexagonal P6_3mc space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(1) and three equivalent C(2) atoms to form distorted AlC4 tetrahedra that share  a cornercorner with one Si(1)C4 tetrahedra, corners with three equivalent Al(3)C4 tetrahedra, corners with six equivalent Al(1)C4 tetrahedra, and edges with three equivalent Al(2)C4 trigonal pyramids. In the second Al site, Al(2) is bonded to one C(2) and three equivalent C(1) atoms to form distorted AlC4 trigonal pyramids that share  a cornercorner with one Al(3)C4 tetrahedra, corners with three equivalent Si(1)C4 tetrahedra, corners with six equivalent Al(2)C4 trigonal pyramids, and edges with three equivalent Al(1)C4 tetrahedra. In the third Al site, Al(3) is bonded to one C(2) and three equivalent C(4) atoms to form a mixture of distorted edge and corner-sharing AlC4 tetrahedra. In the fourth Al site, Al(4) is bonded to one C(3) and three equivalent C(4) atoms to form AlC4 tetrahedra that share corners with three equivalent Al(3)C4 tetrahedra, corners with three equivalent Si(1)C4 tetrahedra, corners with six equivalent Al(4)C4 tetrahedra, and edges with three equivalent Al(3)C4 tetrahedra. Si(1) is bonded to one C(1) and three equivalent C(3) atoms to form SiC4 tetrahedra that share  a cornercorner with one Al(1)C4 tetrahedra, corners with three equivalent Al(4)C4 tetrahedra, corners with six equivalent Si(1)C4 tetrahedra, and corners with three equivalent Al(2)C4 trigonal pyramids. There are four inequivalent C sites. In the first C site, C(1) is bonded to one Al(1), three equivalent Al(2), and one Si(1) atom to form CAl4Si trigonal bipyramids that share corners with three equivalent C(3)AlSi3 tetrahedra, corners with six equivalent C(1)Al4Si trigonal bipyramids, and edges with three equivalent C(2)Al5 trigonal bipyramids. In the second C site, C(2) is bonded to one Al(2), one Al(3), and three equivalent Al(1) atoms to form distorted CAl5 trigonal bipyramids that share corners with three equivalent C(4)Al6 octahedra, corners with six equivalent C(2)Al5 trigonal bipyramids, and edges with three equivalent C(1)Al4Si trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. In the third C site, C(3) is bonded to one Al(4) and three equivalent Si(1) atoms to form CAlSi3 tetrahedra that share corners with three equivalent C(4)Al6 octahedra, corners with six equivalent C(3)AlSi3 tetrahedra, and corners with three equivalent C(1)Al4Si trigonal bipyramids. The corner-sharing octahedral tilt angles are 62°. In the fourth C site, C(4) is bonded to three equivalent Al(3) and three equivalent Al(4) atoms to form CAl6 octahedra that share corners with three equivalent C(3)AlSi3 tetrahedra, corners with three equivalent C(2)Al5 trigonal bipyramids, and edges with six equivalent C(4)Al6 octahedra. is represented by the CIF file [CIF]
data_Al4SiC4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.292
_cell_length_b   3.292
_cell_length_c   21.837
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   204.943
_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
  Al  Al0  1  0.000  0.000  0.848  1.0
  Al  Al1  1  0.000  0.000  0.348  1.0
  Al  Al2  1  0.667  0.333  0.763  1.0
  Al  Al3  1  0.333  0.667  0.263  1.0
  Al  Al4  1  0.667  0.333  0.952  1.0
  Al  Al5  1  0.333  0.667  0.452  1.0
  Al  Al6  1  0.667  0.333  0.544  1.0
  Al  Al7  1  0.333  0.667  0.044  1.0
  Si  Si8  1  0.000  0.000  0.662  1.0
  Si  Si9  1  0.000  0.000  0.162  1.0
  C  C10  1  0.000  0.000  0.748  1.0
  C  C11  1  0.000  0.000  0.248  1.0
  C  C12  1  0.667  0.333  0.864  1.0
  C  C13  1  0.333  0.667  0.364  1.0
  C  C14  1  0.667  0.333  0.634  1.0
  C  C15  1  0.333  0.667  0.134  1.0
  C  C16  1  0.000  0.000  0.999  1.0
  C  C17  1  0.000  0.000  0.499  1.0
[/CIF]
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