data_Sr3Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.18
_cell_length_b   7.18
_cell_length_c   7.18
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sr3Mg
_chemical_formula_sum   'Sr6 Mg2'
_cell_volume   369.45
_cell_formula_units_Z   2
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  Sr2  1  0.79  0.0  0.59  1.0
  Sr  Sr3  1  0.38  0.0  0.59  1.0
  Sr  Sr4  1  0.59  0.79  0.0  1.0
  Sr  Sr5  1  0.59  0.38  0.0  1.0
  Sr  Sr6  1  0.0  0.59  0.38  1.0
  Sr  Sr7  1  0.0  0.59  0.79  1.0
  Mg  Mg0  1  0.59  0.59  0.59  1.0
  Mg  Mg1  1  0.0  0.0  0.0  1.0

data_Sr3Mg
_symmetry_space_group_name_H-M   R3
_cell_length_a   10.15
_cell_length_b   10.15
_cell_length_c   12.43
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Sr3Mg
_chemical_formula_sum   'Sr18 Mg6'
_cell_volume   1108.34
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+1/3, z+1/3'
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  9  0.01  0.61  0.99  1.0
  Sr  Sr1  9  0.13  0.46  0.46  1.0
  Mg  Mg2  3  0.0  0.0  0.0  1.0
  Mg  Mg3  3  0.0  0.0  0.59  1.0

Sr Sr Sr Sr Sr Sr Mg Mg
Sr Sr Sr Sr Sr Sr Mg Mg 0 2 o - + 0 6 o - o 0 1 o o o 0 4 + - o 0 5 + - o 0 7 + o + 1 2 o - + 1 6 o - o 2 6 o o - 2 5 + o - 2 3 o o o 2 7 + + o 3 6 o o - 3 5 + o - 4 6 - o o 4 5 o o o 5 6 - o o 5 7 o + + 
Sr3Mg crystallizes in the trigonal R3 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 3-coordinate geometry to one Sr(2), one Mg(1), and one Mg(2) atom. The Sr(1)-Sr(2) bond length is 2.96 Å. The Sr(1)-Mg(1) bond length is 3.31 Å. The Sr(1)-Mg(2) bond length is 3.31 Å. In the second Sr site, Sr(2) is bonded in a 2-coordinate geometry to one Sr(1), one Mg(1), and one Mg(2) atom. The Sr(2)-Mg(1) bond length is 3.31 Å. The Sr(2)-Mg(2) bond length is 4.03 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to three equivalent Sr(1) and three equivalent Sr(2) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to three equivalent Sr(1) and three equivalent Sr(2) atoms.