The structure described by ErCu4Al crystallizes in the hexagonal P-6m2 space group. Er(1) is bonded in a 18-coordinate geometry to three equivalent Cu(1), twelve equivalent Cu(2), and three equivalent Al(1) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to three equivalent Er(1), six equivalent Cu(2), and three equivalent Al(1) atoms to form CuEr3Al3Cu6 cuboctahedra that share corners with nine equivalent Al(1)Er3Cu9 cuboctahedra, corners with twelve equivalent Cu(2)Er4Al2Cu6 cuboctahedra, edges with six equivalent Cu(1)Er3Al3Cu6 cuboctahedra, faces with two equivalent Cu(1)Er3Al3Cu6 cuboctahedra, faces with three equivalent Al(1)Er3Cu9 cuboctahedra, and faces with eighteen equivalent Cu(2)Er4Al2Cu6 cuboctahedra. In the second Cu site, Cu(2) is bonded to four equivalent Er(1), two equivalent Cu(1), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuEr4Al2Cu6 cuboctahedra that share corners with four equivalent Cu(1)Er3Al3Cu6 cuboctahedra, corners with four equivalent Al(1)Er3Cu9 cuboctahedra, corners with sixteen equivalent Cu(2)Er4Al2Cu6 cuboctahedra, edges with ten equivalent Cu(2)Er4Al2Cu6 cuboctahedra, faces with six equivalent Cu(1)Er3Al3Cu6 cuboctahedra, faces with six equivalent Al(1)Er3Cu9 cuboctahedra, and faces with ten equivalent Cu(2)Er4Al2Cu6 cuboctahedra. Al(1) is bonded to three equivalent Er(1), three equivalent Cu(1), and six equivalent Cu(2) atoms to form distorted AlEr3Cu9 cuboctahedra that share corners with nine equivalent Cu(1)Er3Al3Cu6 cuboctahedra, corners with twelve equivalent Cu(2)Er4Al2Cu6 cuboctahedra, edges with six equivalent Al(1)Er3Cu9 cuboctahedra, faces with two equivalent Al(1)Er3Cu9 cuboctahedra, faces with three equivalent Cu(1)Er3Al3Cu6 cuboctahedra, and faces with eighteen equivalent Cu(2)Er4Al2Cu6 cuboctahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_ErAlCu4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.153
_cell_length_b   5.153
_cell_length_c   4.013
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   92.280
_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
  Er  Er0  1  0.667  0.333  0.000  1.0
  Al  Al1  1  0.000  0.000  0.000  1.0
  Cu  Cu2  1  0.333  0.667  0.000  1.0
  Cu  Cu3  1  0.665  0.833  0.500  1.0
  Cu  Cu4  1  0.167  0.833  0.500  1.0
  Cu  Cu5  1  0.167  0.335  0.500  1.0
[/CIF]
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The structure described by ErCu4Al crystallizes in the hexagonal P-6m2 space group. Er(1) is bonded in a 18-coordinate geometry to three equivalent Cu(1), twelve equivalent Cu(2), and three equivalent Al(1) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to three equivalent Er(1), six equivalent Cu(2), and three equivalent Al(1) atoms to form CuEr3Al3Cu6 cuboctahedra that share corners with nine equivalent Al(1)Er3Cu9 cuboctahedra, corners with twelve equivalent Cu(2)Er4Al2Cu6 cuboctahedra, edges with six equivalent Cu(1)Er3Al3Cu6 cuboctahedra, faces with two equivalent Cu(1)Er3Al3Cu6 cuboctahedra, faces with three equivalent Al(1)Er3Cu9 cuboctahedra, and faces with eighteen equivalent Cu(2)Er4Al2Cu6 cuboctahedra. In the second Cu site, Cu(2) is bonded to four equivalent Er(1), two equivalent Cu(1), four equivalent Cu(2), and two equivalent Al(1) atoms to form distorted CuEr4Al2Cu6 cuboctahedra that share corners with four equivalent Cu(1)Er3Al3Cu6 cuboctahedra, corners with four equivalent Al(1)Er3Cu9 cuboctahedra, corners with sixteen equivalent Cu(2)Er4Al2Cu6 cuboctahedra, edges with ten equivalent Cu(2)Er4Al2Cu6 cuboctahedra, faces with six equivalent Cu(1)Er3Al3Cu6 cuboctahedra, faces with six equivalent Al(1)Er3Cu9 cuboctahedra, and faces with ten equivalent Cu(2)Er4Al2Cu6 cuboctahedra. Al(1) is bonded to three equivalent Er(1), three equivalent Cu(1), and six equivalent Cu(2) atoms to form distorted AlEr3Cu9 cuboctahedra that share corners with nine equivalent Cu(1)Er3Al3Cu6 cuboctahedra, corners with twelve equivalent Cu(2)Er4Al2Cu6 cuboctahedra, edges with six equivalent Al(1)Er3Cu9 cuboctahedra, faces with two equivalent Al(1)Er3Cu9 cuboctahedra, faces with three equivalent Cu(1)Er3Al3Cu6 cuboctahedra, and faces with eighteen equivalent Cu(2)Er4Al2Cu6 cuboctahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_ErAlCu4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.153
_cell_length_b   5.153
_cell_length_c   4.013
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   92.280
_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
  Er  Er0  1  0.667  0.333  0.000  1.0
  Al  Al1  1  0.000  0.000  0.000  1.0
  Cu  Cu2  1  0.333  0.667  0.000  1.0
  Cu  Cu3  1  0.665  0.833  0.500  1.0
  Cu  Cu4  1  0.167  0.833  0.500  1.0
  Cu  Cu5  1  0.167  0.335  0.500  1.0
[/CIF]
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