The crystal structure described by CaAlSi crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Al(1), three equivalent Al(2), three equivalent Si(1), and three equivalent Si(2) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. In the second Ca site, Ca(2) is bonded to six equivalent Al(1) and six equivalent Si(1) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(2), and three equivalent Si(1) atoms. In the second Al site, Al(2) is bonded in a distorted trigonal planar geometry to six equivalent Ca(1) and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(2), and three equivalent Al(1) atoms. In the second Si site, Si(2) is bonded in a distorted trigonal planar geometry to six equivalent Ca(1) and three equivalent Al(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_CaAlSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.191
_cell_length_b   4.191
_cell_length_c   26.381
_cell_angle_alpha   90.001
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   401.274
_cell_formula_units_Z   6
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
  Ca  Ca0  1  0.000  0.000  0.332  1.0
  Ca  Ca1  1  0.000  0.000  0.832  1.0
  Ca  Ca2  1  0.000  0.000  0.168  1.0
  Ca  Ca3  1  0.000  0.000  1.000  1.0
  Ca  Ca4  1  1.000  1.000  0.668  1.0
  Ca  Ca5  1  0.000  0.000  0.500  1.0
  Al  Al6  1  0.333  0.667  0.411  1.0
  Al  Al7  1  0.333  0.667  0.250  1.0
  Al  Al8  1  0.333  0.667  0.090  1.0
  Al  Al9  1  0.667  0.333  0.910  1.0
  Al  Al10  1  0.667  0.333  0.750  1.0
  Al  Al11  1  0.667  0.333  0.589  1.0
  Si  Si12  1  0.333  0.667  0.579  1.0
  Si  Si13  1  0.333  0.667  0.921  1.0
  Si  Si14  1  0.333  0.667  0.750  1.0
  Si  Si15  1  0.667  0.333  0.250  1.0
  Si  Si16  1  0.667  0.333  0.079  1.0
  Si  Si17  1  0.667  0.333  0.421  1.0
[/CIF]
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The crystal structure described by CaAlSi crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Al(1), three equivalent Al(2), three equivalent Si(1), and three equivalent Si(2) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. In the second Ca site, Ca(2) is bonded to six equivalent Al(1) and six equivalent Si(1) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(2), and three equivalent Si(1) atoms. In the second Al site, Al(2) is bonded in a distorted trigonal planar geometry to six equivalent Ca(1) and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(2), and three equivalent Al(1) atoms. In the second Si site, Si(2) is bonded in a distorted trigonal planar geometry to six equivalent Ca(1) and three equivalent Al(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_CaAlSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.191
_cell_length_b   4.191
_cell_length_c   26.381
_cell_angle_alpha   90.001
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   401.274
_cell_formula_units_Z   6
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
  Ca  Ca0  1  0.000  0.000  0.332  1.0
  Ca  Ca1  1  0.000  0.000  0.832  1.0
  Ca  Ca2  1  0.000  0.000  0.168  1.0
  Ca  Ca3  1  0.000  0.000  1.000  1.0
  Ca  Ca4  1  1.000  1.000  0.668  1.0
  Ca  Ca5  1  0.000  0.000  0.500  1.0
  Al  Al6  1  0.333  0.667  0.411  1.0
  Al  Al7  1  0.333  0.667  0.250  1.0
  Al  Al8  1  0.333  0.667  0.090  1.0
  Al  Al9  1  0.667  0.333  0.910  1.0
  Al  Al10  1  0.667  0.333  0.750  1.0
  Al  Al11  1  0.667  0.333  0.589  1.0
  Si  Si12  1  0.333  0.667  0.579  1.0
  Si  Si13  1  0.333  0.667  0.921  1.0
  Si  Si14  1  0.333  0.667  0.750  1.0
  Si  Si15  1  0.667  0.333  0.250  1.0
  Si  Si16  1  0.667  0.333  0.079  1.0
  Si  Si17  1  0.667  0.333  0.421  1.0
[/CIF]
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