The structure described by Al4Si crystallizes in the trigonal R-3m space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to three equivalent Al(2), six equivalent Al(1), and three equivalent Si(1) atoms to form distorted AlAl9Si3 cuboctahedra that share corners with three equivalent Al(2)Al12 cuboctahedra, corners with six equivalent Si(1)Al6 cuboctahedra, corners with nine equivalent Al(1)Al9Si3 cuboctahedra, edges with six equivalent Si(1)Al6 cuboctahedra, edges with nine equivalent Al(2)Al12 cuboctahedra, edges with nine equivalent Al(1)Al9Si3 cuboctahedra, faces with six equivalent Al(2)Al12 cuboctahedra, and faces with six equivalent Al(1)Al9Si3 cuboctahedra. In the second Al site, Al(2) is bonded to three equivalent Al(1) and nine equivalent Al(2) atoms to form AlAl12 cuboctahedra that share corners with three equivalent Al(1)Al9Si3 cuboctahedra, corners with three equivalent Si(1)Al6 cuboctahedra, corners with six equivalent Al(2)Al12 cuboctahedra, edges with three equivalent Si(1)Al6 cuboctahedra, edges with nine equivalent Al(1)Al9Si3 cuboctahedra, edges with twelve equivalent Al(2)Al12 cuboctahedra, faces with six equivalent Al(1)Al9Si3 cuboctahedra, and faces with twelve equivalent Al(2)Al12 cuboctahedra. In the third Al site, Al(2) is bonded to three equivalent Al(1) and nine Al(2,2) atoms to form AlAl12 cuboctahedra that share corners with three equivalent Al(1)Al9Si3 cuboctahedra; corners with three equivalent Si(1)Al6 cuboctahedra; corners with six equivalent Al(2)Al12 cuboctahedra; edges with three equivalent Si(1)Al6 cuboctahedra; edges with nine equivalent Al(1)Al9Si3 cuboctahedra; edges with twelve Al(2,2)Al12 cuboctahedra; faces with six equivalent Al(1)Al9Si3 cuboctahedra; and faces with twelve Al(2,2)Al12 cuboctahedra. In the fourth Al site, Al(2) is bonded to three equivalent Al(1) and nine Al(2,2) atoms to form AlAl12 cuboctahedra that share corners with three equivalent Al(1)Al9Si3 cuboctahedra; corners with three equivalent Si(1)Al6 cuboctahedra; corners with six equivalent Al(2)Al12 cuboctahedra; edges with three equivalent Si(1)Al6 cuboctahedra; edges with nine equivalent Al(1)Al9Si3 cuboctahedra; edges with twelve Al(2,2)Al12 cuboctahedra; faces with six equivalent Al(1)Al9Si3 cuboctahedra; and faces with twelve Al(2,2)Al12 cuboctahedra. Si(1) is bonded to six equivalent Al(1) atoms to form distorted SiAl6 cuboctahedra that share corners with six Al(2,2)Al12 cuboctahedra; corners with twelve equivalent Al(1)Al9Si3 cuboctahedra; edges with six Al(2,2)Al12 cuboctahedra; edges with six equivalent Si(1)Al6 cuboctahedra; and edges with twelve equivalent Al(1)Al9Si3 cuboctahedra. is represented by the CIF card [CIF]
data_Al4Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.480
_cell_length_b   11.480
_cell_length_c   11.480
_cell_angle_alpha   14.237
_cell_angle_beta   14.237
_cell_angle_gamma   14.237
_symmetry_Int_Tables_number   1
_cell_volume   79.659
_cell_formula_units_Z   1
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  0.603  0.603  0.603  1.0
  Al  Al1  1  0.201  0.201  0.201  1.0
  Al  Al2  1  0.799  0.799  0.799  1.0
  Al  Al3  1  0.397  0.397  0.397  1.0
  Si  Si4  1  0.000  0.000  0.000  1.0
[/CIF]
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The structure described by Al4Si crystallizes in the trigonal R-3m space group. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to three equivalent Al(2), six equivalent Al(1), and three equivalent Si(1) atoms to form distorted AlAl9Si3 cuboctahedra that share corners with three equivalent Al(2)Al12 cuboctahedra, corners with six equivalent Si(1)Al6 cuboctahedra, corners with nine equivalent Al(1)Al9Si3 cuboctahedra, edges with six equivalent Si(1)Al6 cuboctahedra, edges with nine equivalent Al(2)Al12 cuboctahedra, edges with nine equivalent Al(1)Al9Si3 cuboctahedra, faces with six equivalent Al(2)Al12 cuboctahedra, and faces with six equivalent Al(1)Al9Si3 cuboctahedra. In the second Al site, Al(2) is bonded to three equivalent Al(1) and nine equivalent Al(2) atoms to form AlAl12 cuboctahedra that share corners with three equivalent Al(1)Al9Si3 cuboctahedra, corners with three equivalent Si(1)Al6 cuboctahedra, corners with six equivalent Al(2)Al12 cuboctahedra, edges with three equivalent Si(1)Al6 cuboctahedra, edges with nine equivalent Al(1)Al9Si3 cuboctahedra, edges with twelve equivalent Al(2)Al12 cuboctahedra, faces with six equivalent Al(1)Al9Si3 cuboctahedra, and faces with twelve equivalent Al(2)Al12 cuboctahedra. In the third Al site, Al(2) is bonded to three equivalent Al(1) and nine Al(2,2) atoms to form AlAl12 cuboctahedra that share corners with three equivalent Al(1)Al9Si3 cuboctahedra; corners with three equivalent Si(1)Al6 cuboctahedra; corners with six equivalent Al(2)Al12 cuboctahedra; edges with three equivalent Si(1)Al6 cuboctahedra; edges with nine equivalent Al(1)Al9Si3 cuboctahedra; edges with twelve Al(2,2)Al12 cuboctahedra; faces with six equivalent Al(1)Al9Si3 cuboctahedra; and faces with twelve Al(2,2)Al12 cuboctahedra. In the fourth Al site, Al(2) is bonded to three equivalent Al(1) and nine Al(2,2) atoms to form AlAl12 cuboctahedra that share corners with three equivalent Al(1)Al9Si3 cuboctahedra; corners with three equivalent Si(1)Al6 cuboctahedra; corners with six equivalent Al(2)Al12 cuboctahedra; edges with three equivalent Si(1)Al6 cuboctahedra; edges with nine equivalent Al(1)Al9Si3 cuboctahedra; edges with twelve Al(2,2)Al12 cuboctahedra; faces with six equivalent Al(1)Al9Si3 cuboctahedra; and faces with twelve Al(2,2)Al12 cuboctahedra. Si(1) is bonded to six equivalent Al(1) atoms to form distorted SiAl6 cuboctahedra that share corners with six Al(2,2)Al12 cuboctahedra; corners with twelve equivalent Al(1)Al9Si3 cuboctahedra; edges with six Al(2,2)Al12 cuboctahedra; edges with six equivalent Si(1)Al6 cuboctahedra; and edges with twelve equivalent Al(1)Al9Si3 cuboctahedra. is represented by the CIF card [CIF]
data_Al4Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.480
_cell_length_b   11.480
_cell_length_c   11.480
_cell_angle_alpha   14.237
_cell_angle_beta   14.237
_cell_angle_gamma   14.237
_symmetry_Int_Tables_number   1
_cell_volume   79.659
_cell_formula_units_Z   1
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  0.603  0.603  0.603  1.0
  Al  Al1  1  0.201  0.201  0.201  1.0
  Al  Al2  1  0.799  0.799  0.799  1.0
  Al  Al3  1  0.397  0.397  0.397  1.0
  Si  Si4  1  0.000  0.000  0.000  1.0
[/CIF]
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