data_Hf3NbSi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.86
_cell_length_b   4.86
_cell_length_c   4.86
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Hf3NbSi
_chemical_formula_sum   'Hf3 Nb1 Si1'
_cell_volume   114.85
_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  0.0  0.43  0.0  1.0
  Hf  Hf2  1  0.0  0.0  0.43  1.0
  Hf  Hf3  1  0.43  0.0  0.0  1.0
  Nb  Nb0  1  0.43  0.43  0.43  1.0
  Si  Si4  1  0.0  0.0  0.0  1.0

data_Hf3NbSi
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.87
_cell_length_b   6.87
_cell_length_c   8.42
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Hf3NbSi
_chemical_formula_sum   'Hf9 Nb3 Si3'
_cell_volume   344.56
_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  9  0.19  0.38  0.81  1.0
  Nb  Nb1  3  0.0  0.0  0.43  1.0
  Si  Si2  3  0.0  0.0  0.0  1.0

Hf Hf Hf Nb Si
Nb(Hf)3Si crystallizes in the trigonal R3m space group. Hf(1) is bonded in a 1-coordinate geometry to four equivalent Nb(1) and two equivalent Si(1) atoms. There are a spread of Hf(1)-Nb(1) bond distances ranging from 2.96-3.92 Å. There is one shorter (2.09 Å) and one longer (2.77 Å) Hf(1)-Si(1) bond length. Nb(1) is bonded to twelve equivalent Hf(1) atoms to form distorted NbHf12 cuboctahedra that share corners with twelve equivalent Nb(1)Hf12 cuboctahedra, faces with six equivalent Nb(1)Hf12 cuboctahedra, and faces with eight equivalent Si(1)Hf6 octahedra. Si(1) is bonded to six equivalent Hf(1) atoms to form SiHf6 octahedra that share corners with six equivalent Si(1)Hf6 octahedra and faces with eight equivalent Nb(1)Hf12 cuboctahedra. The corner-sharing octahedra are not tilted.