The compound described by UCr4Al8 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 20-coordinate geometry to eight equivalent Cr(1), four equivalent Al(1), and eight equivalent Al(2) atoms. Cr(1) is bonded to two equivalent U(1), two equivalent Cr(1), four equivalent Al(1), and four equivalent Al(2) atoms to form a mixture of distorted corner, edge, and face-sharing CrU2Al8Cr2 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to one U(1), four equivalent Cr(1), one Al(1), and four equivalent Al(2) atoms. In the second Al site, Al(2) is bonded in a 12-coordinate geometry to two equivalent U(1), four equivalent Cr(1), two equivalent Al(2), and four equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_U(Al2Cr)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.753
_cell_length_b   6.753
_cell_length_c   6.753
_cell_angle_alpha   97.873
_cell_angle_beta   97.873
_cell_angle_gamma   136.557
_symmetry_Int_Tables_number   1
_cell_volume   196.686
_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
  U  U0  1  0.000  0.000  0.000  1.0
  Al  Al1  1  0.342  0.000  0.342  1.0
  Al  Al2  1  0.000  0.342  0.342  1.0
  Al  Al3  1  0.000  0.658  0.658  1.0
  Al  Al4  1  0.658  0.000  0.658  1.0
  Al  Al5  1  0.283  0.500  0.783  1.0
  Al  Al6  1  0.500  0.283  0.783  1.0
  Al  Al7  1  0.500  0.717  0.217  1.0
  Al  Al8  1  0.717  0.500  0.217  1.0
  Cr  Cr9  1  0.500  0.500  0.500  1.0
  Cr  Cr10  1  0.000  0.500  0.000  1.0
  Cr  Cr11  1  0.500  0.000  0.000  1.0
  Cr  Cr12  1  0.000  0.000  0.500  1.0
[/CIF]
.
The compound described by UCr4Al8 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 20-coordinate geometry to eight equivalent Cr(1), four equivalent Al(1), and eight equivalent Al(2) atoms. Cr(1) is bonded to two equivalent U(1), two equivalent Cr(1), four equivalent Al(1), and four equivalent Al(2) atoms to form a mixture of distorted corner, edge, and face-sharing CrU2Al8Cr2 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 10-coordinate geometry to one U(1), four equivalent Cr(1), one Al(1), and four equivalent Al(2) atoms. In the second Al site, Al(2) is bonded in a 12-coordinate geometry to two equivalent U(1), four equivalent Cr(1), two equivalent Al(2), and four equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_U(Al2Cr)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.753
_cell_length_b   6.753
_cell_length_c   6.753
_cell_angle_alpha   97.873
_cell_angle_beta   97.873
_cell_angle_gamma   136.557
_symmetry_Int_Tables_number   1
_cell_volume   196.686
_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
  U  U0  1  0.000  0.000  0.000  1.0
  Al  Al1  1  0.342  0.000  0.342  1.0
  Al  Al2  1  0.000  0.342  0.342  1.0
  Al  Al3  1  0.000  0.658  0.658  1.0
  Al  Al4  1  0.658  0.000  0.658  1.0
  Al  Al5  1  0.283  0.500  0.783  1.0
  Al  Al6  1  0.500  0.283  0.783  1.0
  Al  Al7  1  0.500  0.717  0.217  1.0
  Al  Al8  1  0.717  0.500  0.217  1.0
  Cr  Cr9  1  0.500  0.500  0.500  1.0
  Cr  Cr10  1  0.000  0.500  0.000  1.0
  Cr  Cr11  1  0.500  0.000  0.000  1.0
  Cr  Cr12  1  0.000  0.000  0.500  1.0
[/CIF]
.