The crystal structure described by Hf2Al3C4 crystallizes in the hexagonal P6_3/mmc space group. Hf(1) is bonded to three equivalent C(1) and three equivalent C(3) 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(2) and three equivalent C(1) atoms to form AlC4 tetrahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with seven equivalent Al(1)C4 tetrahedra, and edges with three equivalent Hf(1)C6 octahedra. The corner-sharing octahedral tilt angles are 19°. In the second Al site, Al(2) is bonded in a trigonal planar geometry to three equivalent C(2) atoms. There are three inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to three equivalent Hf(1) and three equivalent Al(1) atoms. In the second C site, C(2) is bonded to two equivalent Al(1) and three equivalent Al(2) atoms to form corner-sharing CAl5 trigonal bipyramids. In the third C site, C(3) is bonded to six equivalent Hf(1) atoms to form edge-sharing CHf6 octahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Hf2Al3C4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.318
_cell_length_b   3.318
_cell_length_c   22.031
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   210.036
_cell_formula_units_Z   2
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  0.667  0.333  0.058  1.0
  Hf  Hf1  1  0.333  0.667  0.942  1.0
  Hf  Hf2  1  0.333  0.667  0.558  1.0
  Hf  Hf3  1  0.667  0.333  0.442  1.0
  Al  Al4  1  0.000  0.000  0.159  1.0
  Al  Al5  1  0.000  0.000  0.341  1.0
  Al  Al6  1  0.000  0.000  0.841  1.0
  Al  Al7  1  0.000  0.000  0.659  1.0
  Al  Al8  1  0.667  0.333  0.750  1.0
  Al  Al9  1  0.333  0.667  0.250  1.0
  C  C10  1  0.667  0.333  0.627  1.0
  C  C11  1  0.333  0.667  0.373  1.0
  C  C12  1  0.000  0.000  0.250  1.0
  C  C13  1  0.333  0.667  0.127  1.0
  C  C14  1  0.000  0.000  0.000  1.0
  C  C15  1  0.667  0.333  0.873  1.0
  C  C16  1  0.000  0.000  0.500  1.0
  C  C17  1  0.000  0.000  0.750  1.0
[/CIF]
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The crystal structure described by Hf2Al3C4 crystallizes in the hexagonal P6_3/mmc space group. Hf(1) is bonded to three equivalent C(1) and three equivalent C(3) 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(2) and three equivalent C(1) atoms to form AlC4 tetrahedra that share corners with three equivalent Hf(1)C6 octahedra, corners with seven equivalent Al(1)C4 tetrahedra, and edges with three equivalent Hf(1)C6 octahedra. The corner-sharing octahedral tilt angles are 19°. In the second Al site, Al(2) is bonded in a trigonal planar geometry to three equivalent C(2) atoms. There are three inequivalent C sites. In the first C site, C(1) is bonded in a 6-coordinate geometry to three equivalent Hf(1) and three equivalent Al(1) atoms. In the second C site, C(2) is bonded to two equivalent Al(1) and three equivalent Al(2) atoms to form corner-sharing CAl5 trigonal bipyramids. In the third C site, C(3) is bonded to six equivalent Hf(1) atoms to form edge-sharing CHf6 octahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Hf2Al3C4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.318
_cell_length_b   3.318
_cell_length_c   22.031
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   210.036
_cell_formula_units_Z   2
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  0.667  0.333  0.058  1.0
  Hf  Hf1  1  0.333  0.667  0.942  1.0
  Hf  Hf2  1  0.333  0.667  0.558  1.0
  Hf  Hf3  1  0.667  0.333  0.442  1.0
  Al  Al4  1  0.000  0.000  0.159  1.0
  Al  Al5  1  0.000  0.000  0.341  1.0
  Al  Al6  1  0.000  0.000  0.841  1.0
  Al  Al7  1  0.000  0.000  0.659  1.0
  Al  Al8  1  0.667  0.333  0.750  1.0
  Al  Al9  1  0.333  0.667  0.250  1.0
  C  C10  1  0.667  0.333  0.627  1.0
  C  C11  1  0.333  0.667  0.373  1.0
  C  C12  1  0.000  0.000  0.250  1.0
  C  C13  1  0.333  0.667  0.127  1.0
  C  C14  1  0.000  0.000  0.000  1.0
  C  C15  1  0.667  0.333  0.873  1.0
  C  C16  1  0.000  0.000  0.500  1.0
  C  C17  1  0.000  0.000  0.750  1.0
[/CIF]
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