The crystal structure described by Mg5Eu is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted hexagonal planar geometry to six equivalent Mg(5) atoms. In the second Mg site, Mg(2) is bonded in a distorted q6 geometry to three equivalent Mg(3), three equivalent Mg(4), three equivalent Mg(5), and three equivalent Eu(1) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Mg(2), two equivalent Mg(4), four equivalent Mg(5), and four equivalent Eu(1) atoms to form distorted MgEu4Mg8 cuboctahedra that share corners with four equivalent Mg(4)Eu2Mg10 cuboctahedra, corners with four equivalent Mg(3)Eu4Mg8 cuboctahedra, faces with six equivalent Mg(4)Eu2Mg10 cuboctahedra, and faces with six equivalent Mg(3)Eu4Mg8 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), four equivalent Mg(5), and two equivalent Eu(1) atoms to form distorted MgEu2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Eu2Mg10 cuboctahedra, corners with four equivalent Mg(3)Eu4Mg8 cuboctahedra, faces with two equivalent Mg(4)Eu2Mg10 cuboctahedra, and faces with six equivalent Mg(3)Eu4Mg8 cuboctahedra. In the fifth Mg site, Mg(5) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), two equivalent Mg(4), three equivalent Mg(5), and three equivalent Eu(1) atoms. Eu(1) is bonded in a 14-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), four equivalent Mg(3), and six equivalent Mg(5) atoms. is represented by the CIF card [CIF]
data_EuMg5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.517
_cell_length_b   10.517
_cell_length_c   10.844
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   1038.723
_cell_formula_units_Z   6
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
  Eu  Eu0  1  0.195  0.805  0.250  1.0
  Eu  Eu1  1  0.195  0.390  0.250  1.0
  Eu  Eu2  1  0.610  0.805  0.250  1.0
  Eu  Eu3  1  0.805  0.195  0.750  1.0
  Eu  Eu4  1  0.805  0.610  0.750  1.0
  Eu  Eu5  1  0.390  0.195  0.750  1.0
  Mg  Mg6  1  0.000  0.000  0.500  1.0
  Mg  Mg7  1  0.000  0.000  0.000  1.0
  Mg  Mg8  1  0.333  0.667  0.503  1.0
  Mg  Mg9  1  0.667  0.333  0.497  1.0
  Mg  Mg10  1  0.667  0.333  0.003  1.0
  Mg  Mg11  1  0.333  0.667  0.997  1.0
  Mg  Mg12  1  0.500  0.500  0.500  1.0
  Mg  Mg13  1  0.500  0.000  0.500  1.0
  Mg  Mg14  1  0.000  0.500  0.500  1.0
  Mg  Mg15  1  0.500  0.500  0.000  1.0
  Mg  Mg16  1  0.500  0.000  0.000  1.0
  Mg  Mg17  1  0.000  0.500  0.000  1.0
  Mg  Mg18  1  0.568  0.432  0.250  1.0
  Mg  Mg19  1  0.568  0.137  0.250  1.0
  Mg  Mg20  1  0.863  0.432  0.250  1.0
  Mg  Mg21  1  0.432  0.568  0.750  1.0
  Mg  Mg22  1  0.432  0.863  0.750  1.0
  Mg  Mg23  1  0.137  0.568  0.750  1.0
  Mg  Mg24  1  0.838  0.162  0.410  1.0
  Mg  Mg25  1  0.838  0.677  0.410  1.0
  Mg  Mg26  1  0.323  0.162  0.410  1.0
  Mg  Mg27  1  0.162  0.838  0.590  1.0
  Mg  Mg28  1  0.162  0.323  0.590  1.0
  Mg  Mg29  1  0.677  0.838  0.590  1.0
  Mg  Mg30  1  0.162  0.838  0.910  1.0
  Mg  Mg31  1  0.162  0.323  0.910  1.0
  Mg  Mg32  1  0.677  0.838  0.910  1.0
  Mg  Mg33  1  0.838  0.162  0.090  1.0
  Mg  Mg34  1  0.838  0.677  0.090  1.0
  Mg  Mg35  1  0.323  0.162  0.090  1.0
[/CIF]
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The crystal structure described by Mg5Eu is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a distorted hexagonal planar geometry to six equivalent Mg(5) atoms. In the second Mg site, Mg(2) is bonded in a distorted q6 geometry to three equivalent Mg(3), three equivalent Mg(4), three equivalent Mg(5), and three equivalent Eu(1) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Mg(2), two equivalent Mg(4), four equivalent Mg(5), and four equivalent Eu(1) atoms to form distorted MgEu4Mg8 cuboctahedra that share corners with four equivalent Mg(4)Eu2Mg10 cuboctahedra, corners with four equivalent Mg(3)Eu4Mg8 cuboctahedra, faces with six equivalent Mg(4)Eu2Mg10 cuboctahedra, and faces with six equivalent Mg(3)Eu4Mg8 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), four equivalent Mg(5), and two equivalent Eu(1) atoms to form distorted MgEu2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Eu2Mg10 cuboctahedra, corners with four equivalent Mg(3)Eu4Mg8 cuboctahedra, faces with two equivalent Mg(4)Eu2Mg10 cuboctahedra, and faces with six equivalent Mg(3)Eu4Mg8 cuboctahedra. In the fifth Mg site, Mg(5) is bonded in a 12-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), two equivalent Mg(4), three equivalent Mg(5), and three equivalent Eu(1) atoms. Eu(1) is bonded in a 14-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), four equivalent Mg(3), and six equivalent Mg(5) atoms. is represented by the CIF card [CIF]
data_EuMg5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.517
_cell_length_b   10.517
_cell_length_c   10.844
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   1038.723
_cell_formula_units_Z   6
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
  Eu  Eu0  1  0.195  0.805  0.250  1.0
  Eu  Eu1  1  0.195  0.390  0.250  1.0
  Eu  Eu2  1  0.610  0.805  0.250  1.0
  Eu  Eu3  1  0.805  0.195  0.750  1.0
  Eu  Eu4  1  0.805  0.610  0.750  1.0
  Eu  Eu5  1  0.390  0.195  0.750  1.0
  Mg  Mg6  1  0.000  0.000  0.500  1.0
  Mg  Mg7  1  0.000  0.000  0.000  1.0
  Mg  Mg8  1  0.333  0.667  0.503  1.0
  Mg  Mg9  1  0.667  0.333  0.497  1.0
  Mg  Mg10  1  0.667  0.333  0.003  1.0
  Mg  Mg11  1  0.333  0.667  0.997  1.0
  Mg  Mg12  1  0.500  0.500  0.500  1.0
  Mg  Mg13  1  0.500  0.000  0.500  1.0
  Mg  Mg14  1  0.000  0.500  0.500  1.0
  Mg  Mg15  1  0.500  0.500  0.000  1.0
  Mg  Mg16  1  0.500  0.000  0.000  1.0
  Mg  Mg17  1  0.000  0.500  0.000  1.0
  Mg  Mg18  1  0.568  0.432  0.250  1.0
  Mg  Mg19  1  0.568  0.137  0.250  1.0
  Mg  Mg20  1  0.863  0.432  0.250  1.0
  Mg  Mg21  1  0.432  0.568  0.750  1.0
  Mg  Mg22  1  0.432  0.863  0.750  1.0
  Mg  Mg23  1  0.137  0.568  0.750  1.0
  Mg  Mg24  1  0.838  0.162  0.410  1.0
  Mg  Mg25  1  0.838  0.677  0.410  1.0
  Mg  Mg26  1  0.323  0.162  0.410  1.0
  Mg  Mg27  1  0.162  0.838  0.590  1.0
  Mg  Mg28  1  0.162  0.323  0.590  1.0
  Mg  Mg29  1  0.677  0.838  0.590  1.0
  Mg  Mg30  1  0.162  0.838  0.910  1.0
  Mg  Mg31  1  0.162  0.323  0.910  1.0
  Mg  Mg32  1  0.677  0.838  0.910  1.0
  Mg  Mg33  1  0.838  0.162  0.090  1.0
  Mg  Mg34  1  0.838  0.677  0.090  1.0
  Mg  Mg35  1  0.323  0.162  0.090  1.0
[/CIF]
.