The material described by Hf2Al4C5 crystallizes in the trigonal R-3m space group. Hf(1) is bonded to three equivalent C(1) and three equivalent C(2) atoms to form HfC6 octahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with three equivalent Al(1)C4 tetrahedra, edges with nine equivalent Hf(1)C6 octahedra, and edges with three equivalent Al(1)C4 tetrahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(3) and three equivalent C(1) atoms to form AlC4 tetrahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with six equivalent Al(1)C4 tetrahedra, corners with four equivalent Al(2)C4 trigonal pyramids, and edges with three equivalent Hf(1)C6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the second Al site, Al(2) is bonded to four equivalent C(3) atoms to form a mixture of distorted corner and edge-sharing AlC4 trigonal pyramids. There are three inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Hf(1) and three equivalent Al(1) atoms to form CHf3Al3 octahedra that share corners with three equivalent C(2)Hf6 octahedra, corners with three equivalent C(3)Al5 trigonal bipyramids, edges with three equivalent C(2)Hf6 octahedra, and edges with six equivalent C(1)Hf3Al3 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second C site, C(2) is bonded to six equivalent Hf(1) atoms to form CHf6 octahedra that share corners with six equivalent C(1)Hf3Al3 octahedra, edges with six equivalent C(1)Hf3Al3 octahedra, and edges with six equivalent C(2)Hf6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the third C site, C(3) is bonded to one Al(1) and four equivalent Al(2) atoms to form CAl5 trigonal bipyramids that share corners with three equivalent C(1)Hf3Al3 octahedra, corners with six equivalent C(3)Al5 trigonal bipyramids, and edges with three equivalent C(3)Al5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 64°. is represented by the CIF file [CIF]
data_Hf2Al4C5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.751
_cell_length_b   13.751
_cell_length_c   13.751
_cell_angle_alpha   13.945
_cell_angle_beta   13.945
_cell_angle_gamma   13.945
_symmetry_Int_Tables_number   1
_cell_volume   131.430
_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  0.366  0.366  0.366  1.0
  Hf  Hf1  1  0.634  0.634  0.634  1.0
  Al  Al2  1  0.912  0.912  0.912  1.0
  Al  Al3  1  0.189  0.189  0.189  1.0
  Al  Al4  1  0.811  0.811  0.811  1.0
  Al  Al5  1  0.088  0.088  0.088  1.0
  C  C6  1  0.267  0.267  0.267  1.0
  C  C7  1  0.733  0.733  0.733  1.0
  C  C8  1  0.000  0.000  0.000  1.0
  C  C9  1  0.136  0.136  0.136  1.0
  C  C10  1  0.864  0.864  0.864  1.0
[/CIF]
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The material described by Hf2Al4C5 crystallizes in the trigonal R-3m space group. Hf(1) is bonded to three equivalent C(1) and three equivalent C(2) atoms to form HfC6 octahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with three equivalent Al(1)C4 tetrahedra, edges with nine equivalent Hf(1)C6 octahedra, and edges with three equivalent Al(1)C4 tetrahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one C(3) and three equivalent C(1) atoms to form AlC4 tetrahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with six equivalent Al(1)C4 tetrahedra, corners with four equivalent Al(2)C4 trigonal pyramids, and edges with three equivalent Hf(1)C6 octahedra. The corner-sharing octahedral tilt angles are 10°. In the second Al site, Al(2) is bonded to four equivalent C(3) atoms to form a mixture of distorted corner and edge-sharing AlC4 trigonal pyramids. There are three inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Hf(1) and three equivalent Al(1) atoms to form CHf3Al3 octahedra that share corners with three equivalent C(2)Hf6 octahedra, corners with three equivalent C(3)Al5 trigonal bipyramids, edges with three equivalent C(2)Hf6 octahedra, and edges with six equivalent C(1)Hf3Al3 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second C site, C(2) is bonded to six equivalent Hf(1) atoms to form CHf6 octahedra that share corners with six equivalent C(1)Hf3Al3 octahedra, edges with six equivalent C(1)Hf3Al3 octahedra, and edges with six equivalent C(2)Hf6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the third C site, C(3) is bonded to one Al(1) and four equivalent Al(2) atoms to form CAl5 trigonal bipyramids that share corners with three equivalent C(1)Hf3Al3 octahedra, corners with six equivalent C(3)Al5 trigonal bipyramids, and edges with three equivalent C(3)Al5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 64°. is represented by the CIF file [CIF]
data_Hf2Al4C5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.751
_cell_length_b   13.751
_cell_length_c   13.751
_cell_angle_alpha   13.945
_cell_angle_beta   13.945
_cell_angle_gamma   13.945
_symmetry_Int_Tables_number   1
_cell_volume   131.430
_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  0.366  0.366  0.366  1.0
  Hf  Hf1  1  0.634  0.634  0.634  1.0
  Al  Al2  1  0.912  0.912  0.912  1.0
  Al  Al3  1  0.189  0.189  0.189  1.0
  Al  Al4  1  0.811  0.811  0.811  1.0
  Al  Al5  1  0.088  0.088  0.088  1.0
  C  C6  1  0.267  0.267  0.267  1.0
  C  C7  1  0.733  0.733  0.733  1.0
  C  C8  1  0.000  0.000  0.000  1.0
  C  C9  1  0.136  0.136  0.136  1.0
  C  C10  1  0.864  0.864  0.864  1.0
[/CIF]
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