The structure described by SrMg6Hf crystallizes in the orthorhombic Amm2 space group. Sr(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Hf(1) atoms to form SrHf2Mg10 cuboctahedra that share corners with four equivalent Mg(2)Sr2Mg10 cuboctahedra, corners with six equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(2)Sr2Mg10 cuboctahedra, edges with four equivalent Hf(1)Sr2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Mg(4)Hf2Mg10 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms. In the second Mg site, Mg(2) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form distorted MgSr2Mg10 cuboctahedra that share corners with four equivalent Sr(1)Hf2Mg10 cuboctahedra, corners with six equivalent Mg(2)Sr2Mg10 cuboctahedra, edges with two equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Hf(1)Sr2Mg10 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgSr2Hf2Mg8 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with four equivalent Hf(1)Sr2Mg10 cuboctahedra, corners with ten equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Hf(1)Sr2Mg10 cuboctahedra, edges with four equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with four equivalent Hf(1)Sr2Mg10 cuboctahedra, corners with six equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Hf(1)Sr2Mg10 cuboctahedra, edges with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with four equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Sr(1)Hf2Mg10 cuboctahedra. Hf(1) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form HfSr2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with six equivalent Hf(1)Sr2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with four equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Mg(2)Sr2Mg10 cuboctahedra. is represented by the CIF file [CIF]
data_SrHfMg6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.657
_cell_length_b   6.657
_cell_length_c   5.338
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.055
_symmetry_Int_Tables_number   1
_cell_volume   204.769
_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
  Sr  Sr0  1  0.665  0.335  0.500  1.0
  Hf  Hf1  1  0.844  0.156  0.000  1.0
  Mg  Mg2  1  0.152  0.324  0.500  1.0
  Mg  Mg3  1  0.676  0.848  0.500  1.0
  Mg  Mg4  1  0.166  0.834  0.500  1.0
  Mg  Mg5  1  0.324  0.163  0.000  1.0
  Mg  Mg6  1  0.837  0.676  0.000  1.0
  Mg  Mg7  1  0.335  0.665  0.000  1.0
[/CIF]
.
The structure described by SrMg6Hf crystallizes in the orthorhombic Amm2 space group. Sr(1) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Hf(1) atoms to form SrHf2Mg10 cuboctahedra that share corners with four equivalent Mg(2)Sr2Mg10 cuboctahedra, corners with six equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(2)Sr2Mg10 cuboctahedra, edges with four equivalent Hf(1)Sr2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Mg(4)Hf2Mg10 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms. In the second Mg site, Mg(2) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form distorted MgSr2Mg10 cuboctahedra that share corners with four equivalent Sr(1)Hf2Mg10 cuboctahedra, corners with six equivalent Mg(2)Sr2Mg10 cuboctahedra, edges with two equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Hf(1)Sr2Mg10 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Hf(1) atoms to form distorted MgSr2Hf2Mg8 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with four equivalent Hf(1)Sr2Mg10 cuboctahedra, corners with ten equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with two equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Hf(1)Sr2Mg10 cuboctahedra, edges with four equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Hf(1) atoms to form MgHf2Mg10 cuboctahedra that share corners with four equivalent Hf(1)Sr2Mg10 cuboctahedra, corners with six equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Hf(1)Sr2Mg10 cuboctahedra, edges with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with four equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(2)Sr2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Sr(1)Hf2Mg10 cuboctahedra. Hf(1) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(3) atoms to form HfSr2Mg10 cuboctahedra that share corners with four equivalent Mg(4)Hf2Mg10 cuboctahedra, corners with six equivalent Hf(1)Sr2Mg10 cuboctahedra, corners with eight equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, edges with two equivalent Mg(4)Hf2Mg10 cuboctahedra, edges with four equivalent Sr(1)Hf2Mg10 cuboctahedra, edges with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, faces with two equivalent Sr(1)Hf2Mg10 cuboctahedra, faces with two equivalent Mg(4)Hf2Mg10 cuboctahedra, faces with two equivalent Hf(1)Sr2Mg10 cuboctahedra, faces with four equivalent Mg(3)Sr2Hf2Mg8 cuboctahedra, and faces with six equivalent Mg(2)Sr2Mg10 cuboctahedra. is represented by the CIF file [CIF]
data_SrHfMg6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.657
_cell_length_b   6.657
_cell_length_c   5.338
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.055
_symmetry_Int_Tables_number   1
_cell_volume   204.769
_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
  Sr  Sr0  1  0.665  0.335  0.500  1.0
  Hf  Hf1  1  0.844  0.156  0.000  1.0
  Mg  Mg2  1  0.152  0.324  0.500  1.0
  Mg  Mg3  1  0.676  0.848  0.500  1.0
  Mg  Mg4  1  0.166  0.834  0.500  1.0
  Mg  Mg5  1  0.324  0.163  0.000  1.0
  Mg  Mg6  1  0.837  0.676  0.000  1.0
  Mg  Mg7  1  0.335  0.665  0.000  1.0
[/CIF]
.