The structure described by HfTa3C4 is Caswellsilverite-like structured and crystallizes in the trigonal P-3m1 space group. Hf(1) is bonded to six equivalent C(1) atoms to form HfC6 octahedra that share corners with twelve equivalent Ta(2)C6 octahedra, edges with six equivalent Hf(1)C6 octahedra, and faces with two equivalent Ta(2)C6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent C(2) atoms to form a mixture of face, corner, and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 47°. In the second Ta site, Ta(2) is bonded to three equivalent C(1) and three equivalent C(2) atoms to form TaC6 octahedra that share corners with six equivalent Hf(1)C6 octahedra, corners with six equivalent Ta(1)C6 octahedra, edges with six equivalent Ta(2)C6 octahedra,  a faceface with one Hf(1)C6 octahedra, and  a faceface with one Ta(1)C6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are two inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Hf(1) and three equivalent Ta(2) atoms to form distorted CHf3Ta3 pentagonal pyramids that share corners with three equivalent C(1)Hf3Ta3 pentagonal pyramids, corners with three equivalent C(2)Ta6 pentagonal pyramids, edges with three equivalent C(2)Ta6 pentagonal pyramids, and edges with nine equivalent C(1)Hf3Ta3 pentagonal pyramids. In the second C site, C(2) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form distorted CTa6 pentagonal pyramids that share corners with three equivalent C(1)Hf3Ta3 pentagonal pyramids, corners with three equivalent C(2)Ta6 pentagonal pyramids, edges with three equivalent C(1)Hf3Ta3 pentagonal pyramids, and edges with nine equivalent C(2)Ta6 pentagonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_HfTa3C4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.178
_cell_length_b   3.178
_cell_length_c   11.150
_cell_angle_alpha   89.990
_cell_angle_beta   90.010
_cell_angle_gamma   120.013
_symmetry_Int_Tables_number   1
_cell_volume   97.538
_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  0.000  0.000  0.250  1.0
  Ta  Ta1  1  0.000  0.000  0.750  1.0
  Ta  Ta2  1  1.000  0.000  0.998  1.0
  Ta  Ta3  1  0.000  1.000  0.502  1.0
  C  C4  1  0.667  0.333  0.382  1.0
  C  C5  1  0.667  0.333  0.872  1.0
  C  C6  1  0.333  0.667  0.118  1.0
  C  C7  1  0.333  0.667  0.628  1.0
[/CIF]
.
The structure described by HfTa3C4 is Caswellsilverite-like structured and crystallizes in the trigonal P-3m1 space group. Hf(1) is bonded to six equivalent C(1) atoms to form HfC6 octahedra that share corners with twelve equivalent Ta(2)C6 octahedra, edges with six equivalent Hf(1)C6 octahedra, and faces with two equivalent Ta(2)C6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to six equivalent C(2) atoms to form a mixture of face, corner, and edge-sharing TaC6 octahedra. The corner-sharing octahedral tilt angles are 47°. In the second Ta site, Ta(2) is bonded to three equivalent C(1) and three equivalent C(2) atoms to form TaC6 octahedra that share corners with six equivalent Hf(1)C6 octahedra, corners with six equivalent Ta(1)C6 octahedra, edges with six equivalent Ta(2)C6 octahedra,  a faceface with one Hf(1)C6 octahedra, and  a faceface with one Ta(1)C6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are two inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Hf(1) and three equivalent Ta(2) atoms to form distorted CHf3Ta3 pentagonal pyramids that share corners with three equivalent C(1)Hf3Ta3 pentagonal pyramids, corners with three equivalent C(2)Ta6 pentagonal pyramids, edges with three equivalent C(2)Ta6 pentagonal pyramids, and edges with nine equivalent C(1)Hf3Ta3 pentagonal pyramids. In the second C site, C(2) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form distorted CTa6 pentagonal pyramids that share corners with three equivalent C(1)Hf3Ta3 pentagonal pyramids, corners with three equivalent C(2)Ta6 pentagonal pyramids, edges with three equivalent C(1)Hf3Ta3 pentagonal pyramids, and edges with nine equivalent C(2)Ta6 pentagonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_HfTa3C4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.178
_cell_length_b   3.178
_cell_length_c   11.150
_cell_angle_alpha   89.990
_cell_angle_beta   90.010
_cell_angle_gamma   120.013
_symmetry_Int_Tables_number   1
_cell_volume   97.538
_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  0.000  0.000  0.250  1.0
  Ta  Ta1  1  0.000  0.000  0.750  1.0
  Ta  Ta2  1  1.000  0.000  0.998  1.0
  Ta  Ta3  1  0.000  1.000  0.502  1.0
  C  C4  1  0.667  0.333  0.382  1.0
  C  C5  1  0.667  0.333  0.872  1.0
  C  C6  1  0.333  0.667  0.118  1.0
  C  C7  1  0.333  0.667  0.628  1.0
[/CIF]
.