The crystal structure described by HfCuAl crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 12-coordinate geometry to three equivalent Hf(2), one Cu(3), two equivalent Cu(1), two equivalent Cu(2), three equivalent Al(1), and four equivalent Al(2) atoms. In the second Hf site, Hf(2) is bonded in a 16-coordinate geometry to one Hf(2), three equivalent Hf(1), one Cu(1), two equivalent Cu(3), four equivalent Cu(2), two equivalent Al(2), and three equivalent Al(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent Hf(2), four equivalent Hf(1), two equivalent Al(1), and four equivalent Al(2) atoms to form CuHf6Al6 cuboctahedra that share corners with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with eight equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, edges with two equivalent Cu(1)Hf6Al6 cuboctahedra, edges with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, faces with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra, and faces with eight equivalent Al(2)Hf6Al4Cu2 cuboctahedra. In the second Cu site, Cu(2) is bonded to two equivalent Hf(1), four equivalent Hf(2), two equivalent Cu(2), two equivalent Cu(3), and two equivalent Al(1) atoms to form distorted CuHf6Al2Cu4 cuboctahedra that share corners with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with six equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with two equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, edges with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, faces with two equivalent Cu(1)Hf6Al6 cuboctahedra, faces with two equivalent Al(2)Hf6Al4Cu2 cuboctahedra, faces with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, and faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra. In the third Cu site, Cu(3) is bonded to two equivalent Hf(1), four equivalent Hf(2), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuHf6Al2Cu4 cuboctahedra that share corners with two equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with eight equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, edges with four equivalent Cu(1)Hf6Al6 cuboctahedra, faces with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra, and faces with eight equivalent Cu(2)Hf6Al2Cu4 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to three equivalent Hf(1), three equivalent Hf(2), one Cu(1), one Cu(3), two equivalent Cu(2), and two equivalent Al(2) atoms to form distorted AlHf6Al2Cu4 cuboctahedra that share corners with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with two equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra, faces with two equivalent Al(1)Hf6Al2Cu4 cuboctahedra, faces with three equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, faces with three equivalent Cu(1)Hf6Al6 cuboctahedra, faces with six equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, and faces with six equivalent Al(2)Hf6Al4Cu2 cuboctahedra. In the second Al site, Al(2) is bonded to two equivalent Hf(2), four equivalent Hf(1), two equivalent Cu(1), two equivalent Al(1), and two equivalent Al(2) atoms to form distorted AlHf6Al4Cu2 cuboctahedra that share corners with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, corners with six equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, edges with two equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with two equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, faces with four equivalent Cu(1)Hf6Al6 cuboctahedra, faces with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, and faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra. is represented by the CIF file [CIF]
data_HfAlCu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.155
_cell_length_b   5.155
_cell_length_c   8.325
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   118.879
_symmetry_Int_Tables_number   1
_cell_volume   193.758
_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
  Hf  Hf0  1  0.667  0.333  0.304  1.0
  Hf  Hf1  1  0.335  0.665  0.182  1.0
  Hf  Hf2  1  0.335  0.665  0.818  1.0
  Hf  Hf3  1  0.667  0.333  0.696  1.0
  Al  Al4  1  0.005  0.995  0.238  1.0
  Al  Al5  1  0.005  0.995  0.762  1.0
  Al  Al6  1  0.652  0.833  0.500  1.0
  Al  Al7  1  0.167  0.348  0.500  1.0
  Cu  Cu8  1  0.166  0.834  0.500  1.0
  Cu  Cu9  1  0.346  0.173  0.000  1.0
  Cu  Cu10  1  0.827  0.654  0.000  1.0
  Cu  Cu11  1  0.829  0.171  0.000  1.0
[/CIF]
.
The crystal structure described by HfCuAl crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 12-coordinate geometry to three equivalent Hf(2), one Cu(3), two equivalent Cu(1), two equivalent Cu(2), three equivalent Al(1), and four equivalent Al(2) atoms. In the second Hf site, Hf(2) is bonded in a 16-coordinate geometry to one Hf(2), three equivalent Hf(1), one Cu(1), two equivalent Cu(3), four equivalent Cu(2), two equivalent Al(2), and three equivalent Al(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent Hf(2), four equivalent Hf(1), two equivalent Al(1), and four equivalent Al(2) atoms to form CuHf6Al6 cuboctahedra that share corners with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with eight equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, edges with two equivalent Cu(1)Hf6Al6 cuboctahedra, edges with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, faces with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra, and faces with eight equivalent Al(2)Hf6Al4Cu2 cuboctahedra. In the second Cu site, Cu(2) is bonded to two equivalent Hf(1), four equivalent Hf(2), two equivalent Cu(2), two equivalent Cu(3), and two equivalent Al(1) atoms to form distorted CuHf6Al2Cu4 cuboctahedra that share corners with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with six equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with two equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, edges with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, faces with two equivalent Cu(1)Hf6Al6 cuboctahedra, faces with two equivalent Al(2)Hf6Al4Cu2 cuboctahedra, faces with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, and faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra. In the third Cu site, Cu(3) is bonded to two equivalent Hf(1), four equivalent Hf(2), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuHf6Al2Cu4 cuboctahedra that share corners with two equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with eight equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, edges with four equivalent Cu(1)Hf6Al6 cuboctahedra, faces with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra, and faces with eight equivalent Cu(2)Hf6Al2Cu4 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to three equivalent Hf(1), three equivalent Hf(2), one Cu(1), one Cu(3), two equivalent Cu(2), and two equivalent Al(2) atoms to form distorted AlHf6Al2Cu4 cuboctahedra that share corners with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with two equivalent Cu(1)Hf6Al6 cuboctahedra, corners with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra, faces with two equivalent Al(1)Hf6Al2Cu4 cuboctahedra, faces with three equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, faces with three equivalent Cu(1)Hf6Al6 cuboctahedra, faces with six equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, and faces with six equivalent Al(2)Hf6Al4Cu2 cuboctahedra. In the second Al site, Al(2) is bonded to two equivalent Hf(2), four equivalent Hf(1), two equivalent Cu(1), two equivalent Al(1), and two equivalent Al(2) atoms to form distorted AlHf6Al4Cu2 cuboctahedra that share corners with four equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(1)Hf6Al2Cu4 cuboctahedra, corners with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, corners with six equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, edges with two equivalent Al(2)Hf6Al4Cu2 cuboctahedra, edges with four equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with two equivalent Cu(2)Hf6Al2Cu4 cuboctahedra, faces with two equivalent Cu(3)Hf6Al2Cu4 cuboctahedra, faces with four equivalent Cu(1)Hf6Al6 cuboctahedra, faces with four equivalent Al(2)Hf6Al4Cu2 cuboctahedra, and faces with six equivalent Al(1)Hf6Al2Cu4 cuboctahedra. is represented by the CIF file [CIF]
data_HfAlCu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.155
_cell_length_b   5.155
_cell_length_c   8.325
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   118.879
_symmetry_Int_Tables_number   1
_cell_volume   193.758
_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
  Hf  Hf0  1  0.667  0.333  0.304  1.0
  Hf  Hf1  1  0.335  0.665  0.182  1.0
  Hf  Hf2  1  0.335  0.665  0.818  1.0
  Hf  Hf3  1  0.667  0.333  0.696  1.0
  Al  Al4  1  0.005  0.995  0.238  1.0
  Al  Al5  1  0.005  0.995  0.762  1.0
  Al  Al6  1  0.652  0.833  0.500  1.0
  Al  Al7  1  0.167  0.348  0.500  1.0
  Cu  Cu8  1  0.166  0.834  0.500  1.0
  Cu  Cu9  1  0.346  0.173  0.000  1.0
  Cu  Cu10  1  0.827  0.654  0.000  1.0
  Cu  Cu11  1  0.829  0.171  0.000  1.0
[/CIF]
.