The structure described by Al4Ca crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded in a 16-coordinate geometry to eight equivalent Al(1) and eight equivalent Al(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Ca(1), four equivalent Al(1), and four equivalent Al(2) atoms to form a mixture of distorted corner, edge, and face-sharing AlCa4Al8 cuboctahedra. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to four equivalent Ca(1), one Al(2), and four equivalent Al(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_CaAl4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.318
_cell_length_b   4.318
_cell_length_c   6.393
_cell_angle_alpha   109.738
_cell_angle_beta   109.738
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   104.717
_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
  Ca  Ca0  1  0.000  0.000  0.000  1.0
  Al  Al1  1  0.250  0.750  0.500  1.0
  Al  Al2  1  0.387  0.387  0.773  1.0
  Al  Al3  1  0.613  0.613  0.227  1.0
  Al  Al4  1  0.750  0.250  0.500  1.0
[/CIF]
.
The structure described by Al4Ca crystallizes in the tetragonal I4/mmm space group. Ca(1) is bonded in a 16-coordinate geometry to eight equivalent Al(1) and eight equivalent Al(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Ca(1), four equivalent Al(1), and four equivalent Al(2) atoms to form a mixture of distorted corner, edge, and face-sharing AlCa4Al8 cuboctahedra. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to four equivalent Ca(1), one Al(2), and four equivalent Al(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_CaAl4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.318
_cell_length_b   4.318
_cell_length_c   6.393
_cell_angle_alpha   109.738
_cell_angle_beta   109.738
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   104.717
_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
  Ca  Ca0  1  0.000  0.000  0.000  1.0
  Al  Al1  1  0.250  0.750  0.500  1.0
  Al  Al2  1  0.387  0.387  0.773  1.0
  Al  Al3  1  0.613  0.613  0.227  1.0
  Al  Al4  1  0.750  0.250  0.500  1.0
[/CIF]
.