The material described by Ta3AlC2 is MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent C(1) atoms. In the second Ta site, Ta(2) is bonded to six equivalent C(1) atoms to form edge-sharing TaC6 octahedra. Al(1) is bonded to six equivalent Ta(1) atoms to form distorted AlTa6 cuboctahedra that share corners with six equivalent C(1)Ta6 octahedra, edges with six equivalent Al(1)Ta6 cuboctahedra, and edges with six equivalent C(1)Ta6 octahedra. The corner-sharing octahedral tilt angles are 16°. C(1) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form CTa6 octahedra that share corners with three equivalent Al(1)Ta6 cuboctahedra, corners with three equivalent C(1)Ta6 octahedra, edges with three equivalent Al(1)Ta6 cuboctahedra, and edges with nine equivalent C(1)Ta6 octahedra. The corner-sharing octahedra are not tilted. is represented by the CIF file [CIF]
data_Ta3AlC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.089
_cell_length_b   3.089
_cell_length_c   19.220
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   158.792
_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
  Ta  Ta0  1  0.333  0.667  0.134  1.0
  Ta  Ta1  1  0.667  0.333  0.634  1.0
  Ta  Ta2  1  0.333  0.667  0.366  1.0
  Ta  Ta3  1  0.667  0.333  0.866  1.0
  Ta  Ta4  1  0.000  0.000  0.500  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Al  Al6  1  0.000  0.000  0.250  1.0
  Al  Al7  1  0.000  0.000  0.750  1.0
  C  C8  1  0.667  0.333  0.432  1.0
  C  C9  1  0.667  0.333  0.068  1.0
  C  C10  1  0.333  0.667  0.568  1.0
  C  C11  1  0.333  0.667  0.932  1.0
[/CIF]
.
The material described by Ta3AlC2 is MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent C(1) atoms. In the second Ta site, Ta(2) is bonded to six equivalent C(1) atoms to form edge-sharing TaC6 octahedra. Al(1) is bonded to six equivalent Ta(1) atoms to form distorted AlTa6 cuboctahedra that share corners with six equivalent C(1)Ta6 octahedra, edges with six equivalent Al(1)Ta6 cuboctahedra, and edges with six equivalent C(1)Ta6 octahedra. The corner-sharing octahedral tilt angles are 16°. C(1) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form CTa6 octahedra that share corners with three equivalent Al(1)Ta6 cuboctahedra, corners with three equivalent C(1)Ta6 octahedra, edges with three equivalent Al(1)Ta6 cuboctahedra, and edges with nine equivalent C(1)Ta6 octahedra. The corner-sharing octahedra are not tilted. is represented by the CIF file [CIF]
data_Ta3AlC2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.089
_cell_length_b   3.089
_cell_length_c   19.220
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   158.792
_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
  Ta  Ta0  1  0.333  0.667  0.134  1.0
  Ta  Ta1  1  0.667  0.333  0.634  1.0
  Ta  Ta2  1  0.333  0.667  0.366  1.0
  Ta  Ta3  1  0.667  0.333  0.866  1.0
  Ta  Ta4  1  0.000  0.000  0.500  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Al  Al6  1  0.000  0.000  0.250  1.0
  Al  Al7  1  0.000  0.000  0.750  1.0
  C  C8  1  0.667  0.333  0.432  1.0
  C  C9  1  0.667  0.333  0.068  1.0
  C  C10  1  0.333  0.667  0.568  1.0
  C  C11  1  0.333  0.667  0.932  1.0
[/CIF]
.