The material described by Cr2Nb is Hexagonal Laves-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 16-coordinate geometry to one Nb(1), three equivalent Nb(2), three equivalent Cr(1), three equivalent Cr(3), and six equivalent Cr(2) atoms. In the second Nb site, Nb(2) is bonded in a 16-coordinate geometry to one Nb(2), three equivalent Nb(1), three equivalent Cr(1), three equivalent Cr(2), and six equivalent Cr(3) atoms. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to three equivalent Nb(1), three equivalent Nb(2), three equivalent Cr(2), and three equivalent Cr(3) atoms to form a mixture of face, corner, and edge-sharing CrNb6Cr6 cuboctahedra. In the second Cr site, Cr(2) is bonded to two equivalent Nb(2), four equivalent Nb(1), two equivalent Cr(1), and four equivalent Cr(2) atoms to form a mixture of face, corner, and edge-sharing CrNb6Cr6 cuboctahedra. In the third Cr site, Cr(3) is bonded to two equivalent Nb(1), four equivalent Nb(2), two equivalent Cr(1), and four equivalent Cr(3) atoms to form a mixture of face, corner, and edge-sharing CrNb6Cr6 cuboctahedra. is represented by the CIF file [CIF]
data_NbCr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.898
_cell_length_b   4.898
_cell_length_c   16.010
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   332.605
_cell_formula_units_Z   8
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  0.000  1.000  0.595  1.0
  Nb  Nb1  1  1.000  0.000  0.405  1.0
  Nb  Nb2  1  1.000  0.000  0.095  1.0
  Nb  Nb3  1  0.000  1.000  0.905  1.0
  Nb  Nb4  1  0.667  0.333  0.344  1.0
  Nb  Nb5  1  0.333  0.667  0.656  1.0
  Nb  Nb6  1  0.333  0.667  0.844  1.0
  Nb  Nb7  1  0.667  0.333  0.156  1.0
  Cr  Cr8  1  0.667  0.333  0.623  1.0
  Cr  Cr9  1  0.333  0.667  0.377  1.0
  Cr  Cr10  1  0.333  0.667  0.123  1.0
  Cr  Cr11  1  0.667  0.333  0.877  1.0
  Cr  Cr12  1  0.500  0.000  0.500  1.0
  Cr  Cr13  1  0.500  0.500  0.500  1.0
  Cr  Cr14  1  0.000  0.500  0.500  1.0
  Cr  Cr15  1  0.500  0.000  0.000  1.0
  Cr  Cr16  1  0.500  0.500  0.000  1.0
  Cr  Cr17  1  0.000  0.500  0.000  1.0
  Cr  Cr18  1  0.836  0.671  0.750  1.0
  Cr  Cr19  1  0.836  0.164  0.750  1.0
  Cr  Cr20  1  0.329  0.164  0.750  1.0
  Cr  Cr21  1  0.164  0.329  0.250  1.0
  Cr  Cr22  1  0.164  0.836  0.250  1.0
  Cr  Cr23  1  0.671  0.836  0.250  1.0
[/CIF]
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The material described by Cr2Nb is Hexagonal Laves-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 16-coordinate geometry to one Nb(1), three equivalent Nb(2), three equivalent Cr(1), three equivalent Cr(3), and six equivalent Cr(2) atoms. In the second Nb site, Nb(2) is bonded in a 16-coordinate geometry to one Nb(2), three equivalent Nb(1), three equivalent Cr(1), three equivalent Cr(2), and six equivalent Cr(3) atoms. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to three equivalent Nb(1), three equivalent Nb(2), three equivalent Cr(2), and three equivalent Cr(3) atoms to form a mixture of face, corner, and edge-sharing CrNb6Cr6 cuboctahedra. In the second Cr site, Cr(2) is bonded to two equivalent Nb(2), four equivalent Nb(1), two equivalent Cr(1), and four equivalent Cr(2) atoms to form a mixture of face, corner, and edge-sharing CrNb6Cr6 cuboctahedra. In the third Cr site, Cr(3) is bonded to two equivalent Nb(1), four equivalent Nb(2), two equivalent Cr(1), and four equivalent Cr(3) atoms to form a mixture of face, corner, and edge-sharing CrNb6Cr6 cuboctahedra. is represented by the CIF file [CIF]
data_NbCr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.898
_cell_length_b   4.898
_cell_length_c   16.010
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   332.605
_cell_formula_units_Z   8
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  0.000  1.000  0.595  1.0
  Nb  Nb1  1  1.000  0.000  0.405  1.0
  Nb  Nb2  1  1.000  0.000  0.095  1.0
  Nb  Nb3  1  0.000  1.000  0.905  1.0
  Nb  Nb4  1  0.667  0.333  0.344  1.0
  Nb  Nb5  1  0.333  0.667  0.656  1.0
  Nb  Nb6  1  0.333  0.667  0.844  1.0
  Nb  Nb7  1  0.667  0.333  0.156  1.0
  Cr  Cr8  1  0.667  0.333  0.623  1.0
  Cr  Cr9  1  0.333  0.667  0.377  1.0
  Cr  Cr10  1  0.333  0.667  0.123  1.0
  Cr  Cr11  1  0.667  0.333  0.877  1.0
  Cr  Cr12  1  0.500  0.000  0.500  1.0
  Cr  Cr13  1  0.500  0.500  0.500  1.0
  Cr  Cr14  1  0.000  0.500  0.500  1.0
  Cr  Cr15  1  0.500  0.000  0.000  1.0
  Cr  Cr16  1  0.500  0.500  0.000  1.0
  Cr  Cr17  1  0.000  0.500  0.000  1.0
  Cr  Cr18  1  0.836  0.671  0.750  1.0
  Cr  Cr19  1  0.836  0.164  0.750  1.0
  Cr  Cr20  1  0.329  0.164  0.750  1.0
  Cr  Cr21  1  0.164  0.329  0.250  1.0
  Cr  Cr22  1  0.164  0.836  0.250  1.0
  Cr  Cr23  1  0.671  0.836  0.250  1.0
[/CIF]
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