The crystal structure described by Mg5Er is beta-derived structured and crystallizes in the monoclinic Cm space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Mg(4), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(2), and two equivalent Er(1) atoms to form distorted MgEr2Mg10 cuboctahedra that share corners with six equivalent Mg(1)Er2Mg10 cuboctahedra, corners with six equivalent Mg(5)Er3Mg9 cuboctahedra, corners with six equivalent Mg(3)ErMg11 cuboctahedra, edges with two equivalent Mg(2)Er2Mg10 cuboctahedra, edges with three equivalent Mg(5)Er3Mg9 cuboctahedra, edges with three equivalent Mg(3)ErMg11 cuboctahedra, edges with four equivalent Mg(4)Er2Mg10 cuboctahedra, edges with six equivalent Er(1)Er2Mg10 cuboctahedra, faces with two equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(5)Er3Mg9 cuboctahedra, faces with three equivalent Mg(3)ErMg11 cuboctahedra, faces with three equivalent Er(1)Er2Mg10 cuboctahedra, faces with four equivalent Mg(4)Er2Mg10 cuboctahedra, and faces with five equivalent Mg(2)Er2Mg10 cuboctahedra. In the second Mg site, Mg(2) is bonded to one Mg(5), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), three equivalent Mg(1), and two equivalent Er(1) atoms to form distorted MgEr2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Er2Mg10 cuboctahedra, corners with six equivalent Mg(4)Er2Mg10 cuboctahedra, corners with six equivalent Er(1)Er2Mg10 cuboctahedra, edges with two equivalent Mg(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(4)Er2Mg10 cuboctahedra, edges with three equivalent Er(1)Er2Mg10 cuboctahedra, edges with four equivalent Mg(5)Er3Mg9 cuboctahedra, edges with six equivalent Mg(3)ErMg11 cuboctahedra, faces with two equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(4)Er2Mg10 cuboctahedra, faces with three equivalent Mg(3)ErMg11 cuboctahedra, faces with three equivalent Er(1)Er2Mg10 cuboctahedra, faces with four equivalent Mg(5)Er3Mg9 cuboctahedra, and faces with five equivalent Mg(1)Er2Mg10 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(4), and one Er(1) atom to form MgErMg11 cuboctahedra that share corners with six equivalent Mg(1)Er2Mg10 cuboctahedra, corners with six equivalent Mg(5)Er3Mg9 cuboctahedra, corners with six equivalent Mg(3)ErMg11 cuboctahedra, edges with two equivalent Mg(4)Er2Mg10 cuboctahedra, edges with three equivalent Mg(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(5)Er3Mg9 cuboctahedra, edges with four equivalent Er(1)Er2Mg10 cuboctahedra, edges with six equivalent Mg(2)Er2Mg10 cuboctahedra, faces with two equivalent Mg(3)ErMg11 cuboctahedra, faces with three equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(5)Er3Mg9 cuboctahedra, faces with four equivalent Er(1)Er2Mg10 cuboctahedra, and faces with five equivalent Mg(4)Er2Mg10 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(3), and two equivalent Er(1) atoms to form MgEr2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Er2Mg10 cuboctahedra, corners with six equivalent Mg(4)Er2Mg10 cuboctahedra, corners with six equivalent Er(1)Er2Mg10 cuboctahedra, edges with two equivalent Mg(3)ErMg11 cuboctahedra, edges with three equivalent Mg(2)Er2Mg10 cuboctahedra, edges with three equivalent Er(1)Er2Mg10 cuboctahedra, edges with four equivalent Mg(1)Er2Mg10 cuboctahedra, edges with six equivalent Mg(5)Er3Mg9 cuboctahedra, faces with two equivalent Mg(4)Er2Mg10 cuboctahedra, faces with three equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(5)Er3Mg9 cuboctahedra, faces with three equivalent Er(1)Er2Mg10 cuboctahedra, faces with four equivalent Mg(1)Er2Mg10 cuboctahedra, and faces with five equivalent Mg(3)ErMg11 cuboctahedra. In the fifth Mg site, Mg(5) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), and three equivalent Er(1) atoms to form MgEr3Mg9 cuboctahedra that share corners with six equivalent Mg(1)Er2Mg10 cuboctahedra, corners with six equivalent Mg(5)Er3Mg9 cuboctahedra, corners with six equivalent Mg(3)ErMg11 cuboctahedra, edges with two equivalent Er(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(3)ErMg11 cuboctahedra, edges with four equivalent Mg(2)Er2Mg10 cuboctahedra, edges with six equivalent Mg(4)Er2Mg10 cuboctahedra, faces with two equivalent Mg(5)Er3Mg9 cuboctahedra, faces with three equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(4)Er2Mg10 cuboctahedra, faces with three equivalent Mg(3)ErMg11 cuboctahedra, faces with four equivalent Mg(2)Er2Mg10 cuboctahedra, and faces with five equivalent Er(1)Er2Mg10 cuboctahedra. Er(1) is bonded to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), three equivalent Mg(5), and two equivalent Er(1) atoms to form ErEr2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Er2Mg10 cuboctahedra, corners with six equivalent Mg(4)Er2Mg10 cuboctahedra, corners with six equivalent Er(1)Er2Mg10 cuboctahedra, edges with two equivalent Mg(5)Er3Mg9 cuboctahedra, edges with three equivalent Mg(2)Er2Mg10 cuboctahedra, edges with three equivalent Mg(4)Er2Mg10 cuboctahedra, edges with four equivalent Mg(3)ErMg11 cuboctahedra, edges with six equivalent Mg(1)Er2Mg10 cuboctahedra, faces with two equivalent Er(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(4)Er2Mg10 cuboctahedra, faces with four equivalent Mg(3)ErMg11 cuboctahedra, and faces with five equivalent Mg(5)Er3Mg9 cuboctahedra. is represented by the CIF file [CIF]
data_ErMg5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.282
_cell_length_b   6.282
_cell_length_c   7.677
_cell_angle_alpha   74.489
_cell_angle_beta   74.489
_cell_angle_gamma   29.894
_symmetry_Int_Tables_number   1
_cell_volume   145.088
_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  0.617  0.617  0.267  1.0
  Mg  Mg1  1  0.991  0.991  0.002  1.0
  Mg  Mg2  1  0.282  0.282  0.932  1.0
  Mg  Mg3  1  0.662  0.662  0.672  1.0
  Mg  Mg4  1  0.943  0.943  0.616  1.0
  Mg  Mg5  1  0.337  0.337  0.344  1.0
[/CIF]
.
The crystal structure described by Mg5Er is beta-derived structured and crystallizes in the monoclinic Cm space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Mg(4), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(2), and two equivalent Er(1) atoms to form distorted MgEr2Mg10 cuboctahedra that share corners with six equivalent Mg(1)Er2Mg10 cuboctahedra, corners with six equivalent Mg(5)Er3Mg9 cuboctahedra, corners with six equivalent Mg(3)ErMg11 cuboctahedra, edges with two equivalent Mg(2)Er2Mg10 cuboctahedra, edges with three equivalent Mg(5)Er3Mg9 cuboctahedra, edges with three equivalent Mg(3)ErMg11 cuboctahedra, edges with four equivalent Mg(4)Er2Mg10 cuboctahedra, edges with six equivalent Er(1)Er2Mg10 cuboctahedra, faces with two equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(5)Er3Mg9 cuboctahedra, faces with three equivalent Mg(3)ErMg11 cuboctahedra, faces with three equivalent Er(1)Er2Mg10 cuboctahedra, faces with four equivalent Mg(4)Er2Mg10 cuboctahedra, and faces with five equivalent Mg(2)Er2Mg10 cuboctahedra. In the second Mg site, Mg(2) is bonded to one Mg(5), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), three equivalent Mg(1), and two equivalent Er(1) atoms to form distorted MgEr2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Er2Mg10 cuboctahedra, corners with six equivalent Mg(4)Er2Mg10 cuboctahedra, corners with six equivalent Er(1)Er2Mg10 cuboctahedra, edges with two equivalent Mg(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(4)Er2Mg10 cuboctahedra, edges with three equivalent Er(1)Er2Mg10 cuboctahedra, edges with four equivalent Mg(5)Er3Mg9 cuboctahedra, edges with six equivalent Mg(3)ErMg11 cuboctahedra, faces with two equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(4)Er2Mg10 cuboctahedra, faces with three equivalent Mg(3)ErMg11 cuboctahedra, faces with three equivalent Er(1)Er2Mg10 cuboctahedra, faces with four equivalent Mg(5)Er3Mg9 cuboctahedra, and faces with five equivalent Mg(1)Er2Mg10 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), three equivalent Mg(4), and one Er(1) atom to form MgErMg11 cuboctahedra that share corners with six equivalent Mg(1)Er2Mg10 cuboctahedra, corners with six equivalent Mg(5)Er3Mg9 cuboctahedra, corners with six equivalent Mg(3)ErMg11 cuboctahedra, edges with two equivalent Mg(4)Er2Mg10 cuboctahedra, edges with three equivalent Mg(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(5)Er3Mg9 cuboctahedra, edges with four equivalent Er(1)Er2Mg10 cuboctahedra, edges with six equivalent Mg(2)Er2Mg10 cuboctahedra, faces with two equivalent Mg(3)ErMg11 cuboctahedra, faces with three equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(5)Er3Mg9 cuboctahedra, faces with four equivalent Er(1)Er2Mg10 cuboctahedra, and faces with five equivalent Mg(4)Er2Mg10 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(3), and two equivalent Er(1) atoms to form MgEr2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Er2Mg10 cuboctahedra, corners with six equivalent Mg(4)Er2Mg10 cuboctahedra, corners with six equivalent Er(1)Er2Mg10 cuboctahedra, edges with two equivalent Mg(3)ErMg11 cuboctahedra, edges with three equivalent Mg(2)Er2Mg10 cuboctahedra, edges with three equivalent Er(1)Er2Mg10 cuboctahedra, edges with four equivalent Mg(1)Er2Mg10 cuboctahedra, edges with six equivalent Mg(5)Er3Mg9 cuboctahedra, faces with two equivalent Mg(4)Er2Mg10 cuboctahedra, faces with three equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(5)Er3Mg9 cuboctahedra, faces with three equivalent Er(1)Er2Mg10 cuboctahedra, faces with four equivalent Mg(1)Er2Mg10 cuboctahedra, and faces with five equivalent Mg(3)ErMg11 cuboctahedra. In the fifth Mg site, Mg(5) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), and three equivalent Er(1) atoms to form MgEr3Mg9 cuboctahedra that share corners with six equivalent Mg(1)Er2Mg10 cuboctahedra, corners with six equivalent Mg(5)Er3Mg9 cuboctahedra, corners with six equivalent Mg(3)ErMg11 cuboctahedra, edges with two equivalent Er(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(1)Er2Mg10 cuboctahedra, edges with three equivalent Mg(3)ErMg11 cuboctahedra, edges with four equivalent Mg(2)Er2Mg10 cuboctahedra, edges with six equivalent Mg(4)Er2Mg10 cuboctahedra, faces with two equivalent Mg(5)Er3Mg9 cuboctahedra, faces with three equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(4)Er2Mg10 cuboctahedra, faces with three equivalent Mg(3)ErMg11 cuboctahedra, faces with four equivalent Mg(2)Er2Mg10 cuboctahedra, and faces with five equivalent Er(1)Er2Mg10 cuboctahedra. Er(1) is bonded to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), three equivalent Mg(5), and two equivalent Er(1) atoms to form ErEr2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Er2Mg10 cuboctahedra, corners with six equivalent Mg(4)Er2Mg10 cuboctahedra, corners with six equivalent Er(1)Er2Mg10 cuboctahedra, edges with two equivalent Mg(5)Er3Mg9 cuboctahedra, edges with three equivalent Mg(2)Er2Mg10 cuboctahedra, edges with three equivalent Mg(4)Er2Mg10 cuboctahedra, edges with four equivalent Mg(3)ErMg11 cuboctahedra, edges with six equivalent Mg(1)Er2Mg10 cuboctahedra, faces with two equivalent Er(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(1)Er2Mg10 cuboctahedra, faces with three equivalent Mg(2)Er2Mg10 cuboctahedra, faces with three equivalent Mg(4)Er2Mg10 cuboctahedra, faces with four equivalent Mg(3)ErMg11 cuboctahedra, and faces with five equivalent Mg(5)Er3Mg9 cuboctahedra. is represented by the CIF file [CIF]
data_ErMg5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.282
_cell_length_b   6.282
_cell_length_c   7.677
_cell_angle_alpha   74.489
_cell_angle_beta   74.489
_cell_angle_gamma   29.894
_symmetry_Int_Tables_number   1
_cell_volume   145.088
_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  0.617  0.617  0.267  1.0
  Mg  Mg1  1  0.991  0.991  0.002  1.0
  Mg  Mg2  1  0.282  0.282  0.932  1.0
  Mg  Mg3  1  0.662  0.662  0.672  1.0
  Mg  Mg4  1  0.943  0.943  0.616  1.0
  Mg  Mg5  1  0.337  0.337  0.344  1.0
[/CIF]
.