data_HfMgNb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   4.76
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMgNb
_chemical_formula_sum   'Hf1 Mg1 Nb1'
_cell_volume   76.16
_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  0.68  0.68  0.68  1.0
  Mg  Mg1  1  0.0  0.0  0.0  1.0
  Nb  Nb2  1  0.36  0.36  0.36  1.0

data_HfMgNb
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.76
_cell_length_b   4.76
_cell_length_c   11.65
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   HfMgNb
_chemical_formula_sum   'Hf3 Mg3 Nb3'
_cell_volume   228.47
_cell_formula_units_Z   3
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  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+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
  Hf  Hf0  3  0.0  0.0  0.32  1.0
  Mg  Mg1  3  0.0  0.0  0.0  1.0
  Nb  Nb2  3  0.0  0.0  0.64  1.0

Hf Mg Nb
Hf Mg Nb 0 2 o o + 0 2 o + o 0 2 + o o 0 1 o + + 0 1 + o + 0 1 + + o 1 2 - o o 1 2 o - o 1 2 o o - 
MgHfNb is half-Heusler structured and crystallizes in the trigonal R3m space group. Mg(1) is bonded to four equivalent Hf(1) and three equivalent Nb(1) atoms to form distorted MgHf4Nb3 hexagonal pyramids that share corners with six equivalent Hf(1)Mg4Nb4 hexagonal bipyramids, corners with four equivalent Nb(1)Hf4Mg3 hexagonal pyramids, corners with six equivalent Mg(1)Hf4Nb3 hexagonal pyramids, edges with three equivalent Hf(1)Mg4Nb4 hexagonal bipyramids, edges with six equivalent Mg(1)Hf4Nb3 hexagonal pyramids, and edges with six equivalent Nb(1)Hf4Mg3 hexagonal pyramids. There are three shorter (2.75 Å) and one longer (3.70 Å) Mg(1)-Hf(1) bond length. All Mg(1)-Nb(1) bond lengths are 2.77 Å. Hf(1) is bonded to four equivalent Mg(1) and four equivalent Nb(1) atoms to form distorted HfMg4Nb4 hexagonal bipyramids that share corners with six equivalent Mg(1)Hf4Nb3 hexagonal pyramids, corners with six equivalent Nb(1)Hf4Mg3 hexagonal pyramids, edges with twelve equivalent Hf(1)Mg4Nb4 hexagonal bipyramids, edges with three equivalent Mg(1)Hf4Nb3 hexagonal pyramids, and edges with three equivalent Nb(1)Hf4Mg3 hexagonal pyramids. There are three shorter (2.75 Å) and one longer (3.70 Å) Hf(1)-Nb(1) bond length. Nb(1) is bonded to three equivalent Mg(1) and four equivalent Hf(1) atoms to form NbHf4Mg3 hexagonal pyramids that share corners with six equivalent Hf(1)Mg4Nb4 hexagonal bipyramids, corners with four equivalent Mg(1)Hf4Nb3 hexagonal pyramids, corners with six equivalent Nb(1)Hf4Mg3 hexagonal pyramids, edges with three equivalent Hf(1)Mg4Nb4 hexagonal bipyramids, edges with six equivalent Mg(1)Hf4Nb3 hexagonal pyramids, and edges with six equivalent Nb(1)Hf4Mg3 hexagonal pyramids.