data_Mg3Ni
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.23
_cell_length_b   5.23
_cell_length_c   5.23
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg3Ni
_chemical_formula_sum   'Mg6 Ni2'
_cell_volume   143.06
_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
  Mg  Mg0  1  0.31  0.0  0.62  1.0
  Mg  Mg1  1  0.92  0.0  0.62  1.0
  Mg  Mg2  1  0.62  0.31  0.0  1.0
  Mg  Mg3  1  0.62  0.92  0.0  1.0
  Mg  Mg4  1  0.0  0.62  0.92  1.0
  Mg  Mg5  1  0.0  0.62  0.31  1.0
  Ni  Ni6  1  0.62  0.62  0.62  1.0
  Ni  Ni7  1  0.0  0.0  0.0  1.0

data_Mg3Ni
_symmetry_space_group_name_H-M   R3
_cell_length_a   7.4
_cell_length_b   7.4
_cell_length_c   9.06
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Mg3Ni
_chemical_formula_sum   'Mg18 Ni6'
_cell_volume   429.19
_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
  Mg  Mg0  9  0.03  0.67  0.97  1.0
  Mg  Mg1  9  0.08  0.23  0.85  1.0
  Ni  Ni2  3  0.0  0.0  0.0  1.0
  Ni  Ni3  3  0.0  0.0  0.62  1.0

Mg Mg Mg Mg Mg Mg Ni Ni
Mg Mg Mg Mg Mg Mg Ni Ni 0 1 - o o 0 6 o - o 1 7 + o + 1 6 o - o 2 3 o - o 2 6 o o - 3 7 + + o 3 6 o o - 4 7 o + + 4 5 o o + 4 6 - o o 5 6 - o o 
Mg3Ni crystallizes in the trigonal R3 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Mg(2), one Ni(1), and one Ni(2) atom. The Mg(1)-Mg(2) bond length is 2.01 Å. The Mg(1)-Ni(1) bond length is 2.58 Å. The Mg(1)-Ni(2) bond length is 2.58 Å. In the second Mg site, Mg(2) is bonded in a 1-coordinate geometry to one Mg(1), one Ni(1), and one Ni(2) atom. The Mg(2)-Ni(1) bond length is 2.58 Å. The Mg(2)-Ni(2) bond length is 2.05 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a distorted hexagonal planar geometry to three equivalent Mg(1) and three equivalent Mg(2) atoms. In the second Ni site, Ni(2) is bonded in a 3-coordinate geometry to three equivalent Mg(1) and three equivalent Mg(2) atoms.