The crystal structure described by NbCr4Al is Hexagonal Laves-derived structured and crystallizes in the trigonal P-3m1 space group. Nb(1) is bonded in a 16-coordinate geometry to three equivalent Nb(1), three equivalent Cr(2), nine equivalent Cr(3), and one Al(1) atom. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to six equivalent Cr(3) and six equivalent Al(1) atoms to form CrAl6Cr6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, edges with six equivalent Cr(1)Al6Cr6 cuboctahedra, faces with two equivalent Cr(2)Nb6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Al3Cr6 cuboctahedra. In the second Cr site, Cr(2) is bonded to six equivalent Nb(1) and six equivalent Cr(3) atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, edges with six equivalent Cr(2)Nb6Cr6 cuboctahedra, faces with two equivalent Cr(1)Al6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Al3Cr6 cuboctahedra. In the third Cr site, Cr(3) is bonded to three equivalent Nb(1), one Cr(1), one Cr(2), four equivalent Cr(3), and three equivalent Al(1) atoms to form CrNb3Al3Cr6 cuboctahedra that share corners with two equivalent Cr(1)Al6Cr6 cuboctahedra, corners with two equivalent Cr(2)Nb6Cr6 cuboctahedra, corners with fourteen equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, edges with six equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, faces with three equivalent Cr(1)Al6Cr6 cuboctahedra, faces with three equivalent Cr(2)Nb6Cr6 cuboctahedra, and faces with twelve equivalent Cr(3)Nb3Al3Cr6 cuboctahedra. Al(1) is bonded in a 16-coordinate geometry to one Nb(1), three equivalent Cr(1), nine equivalent Cr(3), and three equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_NbAlCr4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.901
_cell_length_b   4.901
_cell_length_c   7.802
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   162.277
_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
  Nb  Nb0  1  0.667  0.333  0.938  1.0
  Nb  Nb1  1  0.333  0.667  0.062  1.0
  Al  Al2  1  0.333  0.667  0.436  1.0
  Al  Al3  1  0.667  0.333  0.564  1.0
  Cr  Cr4  1  0.000  0.000  0.500  1.0
  Cr  Cr5  1  0.000  0.000  0.000  1.0
  Cr  Cr6  1  0.829  0.171  0.256  1.0
  Cr  Cr7  1  0.829  0.658  0.256  1.0
  Cr  Cr8  1  0.342  0.171  0.256  1.0
  Cr  Cr9  1  0.171  0.829  0.744  1.0
  Cr  Cr10  1  0.171  0.342  0.744  1.0
  Cr  Cr11  1  0.658  0.829  0.744  1.0
[/CIF]
.
The crystal structure described by NbCr4Al is Hexagonal Laves-derived structured and crystallizes in the trigonal P-3m1 space group. Nb(1) is bonded in a 16-coordinate geometry to three equivalent Nb(1), three equivalent Cr(2), nine equivalent Cr(3), and one Al(1) atom. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to six equivalent Cr(3) and six equivalent Al(1) atoms to form CrAl6Cr6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, edges with six equivalent Cr(1)Al6Cr6 cuboctahedra, faces with two equivalent Cr(2)Nb6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Al3Cr6 cuboctahedra. In the second Cr site, Cr(2) is bonded to six equivalent Nb(1) and six equivalent Cr(3) atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, edges with six equivalent Cr(2)Nb6Cr6 cuboctahedra, faces with two equivalent Cr(1)Al6Cr6 cuboctahedra, and faces with eighteen equivalent Cr(3)Nb3Al3Cr6 cuboctahedra. In the third Cr site, Cr(3) is bonded to three equivalent Nb(1), one Cr(1), one Cr(2), four equivalent Cr(3), and three equivalent Al(1) atoms to form CrNb3Al3Cr6 cuboctahedra that share corners with two equivalent Cr(1)Al6Cr6 cuboctahedra, corners with two equivalent Cr(2)Nb6Cr6 cuboctahedra, corners with fourteen equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, edges with six equivalent Cr(3)Nb3Al3Cr6 cuboctahedra, faces with three equivalent Cr(1)Al6Cr6 cuboctahedra, faces with three equivalent Cr(2)Nb6Cr6 cuboctahedra, and faces with twelve equivalent Cr(3)Nb3Al3Cr6 cuboctahedra. Al(1) is bonded in a 16-coordinate geometry to one Nb(1), three equivalent Cr(1), nine equivalent Cr(3), and three equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_NbAlCr4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.901
_cell_length_b   4.901
_cell_length_c   7.802
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   162.277
_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
  Nb  Nb0  1  0.667  0.333  0.938  1.0
  Nb  Nb1  1  0.333  0.667  0.062  1.0
  Al  Al2  1  0.333  0.667  0.436  1.0
  Al  Al3  1  0.667  0.333  0.564  1.0
  Cr  Cr4  1  0.000  0.000  0.500  1.0
  Cr  Cr5  1  0.000  0.000  0.000  1.0
  Cr  Cr6  1  0.829  0.171  0.256  1.0
  Cr  Cr7  1  0.829  0.658  0.256  1.0
  Cr  Cr8  1  0.342  0.171  0.256  1.0
  Cr  Cr9  1  0.171  0.829  0.744  1.0
  Cr  Cr10  1  0.171  0.342  0.744  1.0
  Cr  Cr11  1  0.658  0.829  0.744  1.0
[/CIF]
.