The crystal structure described by MgNi3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Mg(1) is bonded to four equivalent Ni(1) and eight equivalent Ni(2) atoms to form MgNi12 cuboctahedra that share corners with four equivalent Mg(1)Ni12 cuboctahedra, corners with eight equivalent Ni(1)Mg4Ni8 cuboctahedra, edges with eight equivalent Mg(1)Ni12 cuboctahedra, edges with sixteen equivalent Ni(2)Mg4Ni8 cuboctahedra, faces with four equivalent Mg(1)Ni12 cuboctahedra, faces with six equivalent Ni(1)Mg4Ni8 cuboctahedra, and faces with eight equivalent Ni(2)Mg4Ni8 cuboctahedra. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent Mg(1) and eight equivalent Ni(2) atoms to form distorted NiMg4Ni8 cuboctahedra that share corners with four equivalent Ni(1)Mg4Ni8 cuboctahedra, corners with eight equivalent Mg(1)Ni12 cuboctahedra, edges with eight equivalent Ni(1)Mg4Ni8 cuboctahedra, edges with sixteen equivalent Ni(2)Mg4Ni8 cuboctahedra, faces with four equivalent Ni(1)Mg4Ni8 cuboctahedra, faces with six equivalent Mg(1)Ni12 cuboctahedra, and faces with eight equivalent Ni(2)Mg4Ni8 cuboctahedra. In the second Ni site, Ni(2) is bonded to four equivalent Mg(1), four equivalent Ni(1), and four equivalent Ni(2) atoms to form distorted NiMg4Ni8 cuboctahedra that share corners with twelve equivalent Ni(2)Mg4Ni8 cuboctahedra, edges with eight equivalent Mg(1)Ni12 cuboctahedra, edges with eight equivalent Ni(1)Mg4Ni8 cuboctahedra, edges with eight equivalent Ni(2)Mg4Ni8 cuboctahedra, faces with four equivalent Mg(1)Ni12 cuboctahedra, faces with four equivalent Ni(1)Mg4Ni8 cuboctahedra, and faces with ten equivalent Ni(2)Mg4Ni8 cuboctahedra. is represented by the CIF file [CIF]
data_MgNi3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.449
_cell_length_b   4.449
_cell_length_c   4.449
_cell_angle_alpha   131.360
_cell_angle_beta   131.360
_cell_angle_gamma   71.242
_symmetry_Int_Tables_number   1
_cell_volume   48.576
_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
  Mg  Mg0  1  0.000  0.000  0.000  1.0
  Ni  Ni1  1  0.500  0.500  0.000  1.0
  Ni  Ni2  1  0.750  0.250  0.500  1.0
  Ni  Ni3  1  0.250  0.750  0.500  1.0
[/CIF]
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The crystal structure described by MgNi3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Mg(1) is bonded to four equivalent Ni(1) and eight equivalent Ni(2) atoms to form MgNi12 cuboctahedra that share corners with four equivalent Mg(1)Ni12 cuboctahedra, corners with eight equivalent Ni(1)Mg4Ni8 cuboctahedra, edges with eight equivalent Mg(1)Ni12 cuboctahedra, edges with sixteen equivalent Ni(2)Mg4Ni8 cuboctahedra, faces with four equivalent Mg(1)Ni12 cuboctahedra, faces with six equivalent Ni(1)Mg4Ni8 cuboctahedra, and faces with eight equivalent Ni(2)Mg4Ni8 cuboctahedra. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent Mg(1) and eight equivalent Ni(2) atoms to form distorted NiMg4Ni8 cuboctahedra that share corners with four equivalent Ni(1)Mg4Ni8 cuboctahedra, corners with eight equivalent Mg(1)Ni12 cuboctahedra, edges with eight equivalent Ni(1)Mg4Ni8 cuboctahedra, edges with sixteen equivalent Ni(2)Mg4Ni8 cuboctahedra, faces with four equivalent Ni(1)Mg4Ni8 cuboctahedra, faces with six equivalent Mg(1)Ni12 cuboctahedra, and faces with eight equivalent Ni(2)Mg4Ni8 cuboctahedra. In the second Ni site, Ni(2) is bonded to four equivalent Mg(1), four equivalent Ni(1), and four equivalent Ni(2) atoms to form distorted NiMg4Ni8 cuboctahedra that share corners with twelve equivalent Ni(2)Mg4Ni8 cuboctahedra, edges with eight equivalent Mg(1)Ni12 cuboctahedra, edges with eight equivalent Ni(1)Mg4Ni8 cuboctahedra, edges with eight equivalent Ni(2)Mg4Ni8 cuboctahedra, faces with four equivalent Mg(1)Ni12 cuboctahedra, faces with four equivalent Ni(1)Mg4Ni8 cuboctahedra, and faces with ten equivalent Ni(2)Mg4Ni8 cuboctahedra. is represented by the CIF file [CIF]
data_MgNi3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.449
_cell_length_b   4.449
_cell_length_c   4.449
_cell_angle_alpha   131.360
_cell_angle_beta   131.360
_cell_angle_gamma   71.242
_symmetry_Int_Tables_number   1
_cell_volume   48.576
_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
  Mg  Mg0  1  0.000  0.000  0.000  1.0
  Ni  Ni1  1  0.500  0.500  0.000  1.0
  Ni  Ni2  1  0.750  0.250  0.500  1.0
  Ni  Ni3  1  0.250  0.750  0.500  1.0
[/CIF]
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