data_Ca2Al
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.58
_cell_length_b   7.58
_cell_length_c   7.58
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca2Al
_chemical_formula_sum   'Ca8 Al4'
_cell_volume   435.99
_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
  Ca  Ca4  1  0.19  0.98  0.39  1.0
  Ca  Ca5  1  0.39  0.6  0.19  1.0
  Ca  Ca6  1  0.98  0.39  0.19  1.0
  Ca  Ca7  1  0.6  0.19  0.39  1.0
  Ca  Ca8  1  0.39  0.19  0.98  1.0
  Ca  Ca9  1  0.19  0.39  0.6  1.0
  Ca  Ca10  1  0.6  0.6  0.6  1.0
  Ca  Ca11  1  0.98  0.98  0.98  1.0
  Al  Al0  1  0.79  0.0  0.79  1.0
  Al  Al1  1  0.0  0.79  0.79  1.0
  Al  Al2  1  0.0  0.0  0.0  1.0
  Al  Al3  1  0.79  0.79  0.0  1.0

data_Ca2Al
_symmetry_space_group_name_H-M   R3
_cell_length_a   10.72
_cell_length_b   10.72
_cell_length_c   13.13
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Ca2Al
_chemical_formula_sum   'Ca24 Al12'
_cell_volume   1307.97
_cell_formula_units_Z   12
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+1/3, z+1/3'
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  9  0.0  0.8  0.19  1.0
  Ca  Ca1  9  0.13  0.46  0.06  1.0
  Ca  Ca2  3  0.0  0.0  0.6  1.0
  Ca  Ca3  3  0.0  0.0  0.98  1.0
  Al  Al4  9  0.14  0.07  0.86  1.0
  Al  Al5  3  0.0  0.0  0.0  1.0

Ca Ca Ca Ca Ca Ca Ca Ca Al Al Al Al
Ca2Al crystallizes in the trigonal R3 space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 1-coordinate geometry to three equivalent Ca(2) and one Al(2) atom. There are two shorter (3.48 Å) and one longer (3.61 Å) Ca(1)-Ca(2) bond length. The Ca(1)-Al(2) bond length is 3.31 Å. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one Ca(3), two equivalent Ca(2), three equivalent Ca(1), and one Al(1) atom. The Ca(2)-Ca(3) bond length is 3.48 Å. Both Ca(2)-Ca(2) bond lengths are 3.80 Å. The Ca(2)-Al(1) bond length is 3.66 Å. In the third Ca site, Ca(3) is bonded in a 6-coordinate geometry to three equivalent Ca(2) and three equivalent Al(1) atoms. All Ca(3)-Al(1) bond lengths are 3.66 Å. In the fourth Ca site, Ca(4) is bonded in a single-bond geometry to one Al(2) and three equivalent Al(1) atoms. The Ca(4)-Al(2) bond length is 0.23 Å. All Ca(4)-Al(1) bond lengths are 2.05 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a distorted single-bond geometry to one Ca(2), one Ca(3), and one Ca(4) atom. In the second Al site, Al(2) is bonded in a single-bond geometry to one Ca(4) and three equivalent Ca(1) atoms.