data_HfMg2Al
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.24
_cell_length_b   5.24
_cell_length_c   5.57
_cell_angle_alpha   100.67
_cell_angle_beta   100.67
_cell_angle_gamma   33.31
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg2Al
_chemical_formula_sum   'Hf1 Mg2 Al1'
_cell_volume   82.55
_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
  Hf  Hf1  1  0.63  0.0  0.98  1.0
  Mg  Mg2  1  0.02  0.0  0.04  1.0
  Mg  Mg3  1  0.38  0.0  0.33  1.0
  Al  Al0  1  0.42  0.0  0.85  1.0

data_HfMg2Al
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.01
_cell_length_b   5.24
_cell_length_c   5.57
_cell_angle_alpha   100.67
_cell_angle_beta   90.0
_cell_angle_gamma   106.66
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg2Al
_chemical_formula_sum   'Hf1 Mg2 Al1'
_cell_volume   82.55
_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
  Hf  Hf0  1  0.0  0.37  0.02  1.0
  Mg  Mg1  1  0.0  0.62  0.67  1.0
  Mg  Mg2  1  0.0  0.98  0.96  1.0
  Al  Al3  1  0.0  0.58  0.15  1.0

Hf Mg Mg Al
Hf Mg Mg Al 0 3 o o o 0 1 + o + 0 2 o o + 1 2 o o o 2 3 o o - 2 3 o o o 
Mg2HfAl crystallizes in the triclinic P1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Mg(2), one Hf(1), and one Al(1) atom. The Mg(1)-Mg(2) bond length is 2.21 Å. The Mg(1)-Hf(1) bond length is 2.02 Å. The Mg(1)-Al(1) bond length is 2.52 Å. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Mg(1), two equivalent Mg(2), one Hf(1), and two equivalent Al(1) atoms. Both Mg(2)-Mg(2) bond lengths are 3.01 Å. The Mg(2)-Hf(1) bond length is 2.57 Å. There is one shorter (2.76 Å) and one longer (2.84 Å) Mg(2)-Al(1) bond length. Hf(1) is bonded in a single-bond geometry to one Mg(1), one Mg(2), and one Al(1) atom. The Hf(1)-Al(1) bond length is 1.21 Å. Al(1) is bonded in a single-bond geometry to one Mg(1), two equivalent Mg(2), and one Hf(1) atom.