The crystal structure described by Mg2CuSi3 crystallizes in the trigonal R-3m space group. Mg(1) is bonded in a 16-coordinate geometry to four equivalent Mg(1), three equivalent Cu(1), and nine equivalent Si(1) atoms. Cu(1) is bonded to six equivalent Mg(1) and six equivalent Si(1) atoms to form CuMg6Si6 cuboctahedra that share corners with six equivalent Cu(1)Mg6Si6 cuboctahedra, corners with twelve equivalent Si(1)Mg6Cu2Si4 cuboctahedra, edges with six equivalent Cu(1)Mg6Si6 cuboctahedra, and faces with eighteen equivalent Si(1)Mg6Cu2Si4 cuboctahedra. Si(1) is bonded to six equivalent Mg(1), two equivalent Cu(1), and four equivalent Si(1) atoms to form SiMg6Cu2Si4 cuboctahedra that share corners with four equivalent Cu(1)Mg6Si6 cuboctahedra, corners with fourteen equivalent Si(1)Mg6Cu2Si4 cuboctahedra, edges with six equivalent Si(1)Mg6Cu2Si4 cuboctahedra, faces with six equivalent Cu(1)Mg6Si6 cuboctahedra, and faces with twelve equivalent Si(1)Mg6Cu2Si4 cuboctahedra. is represented by the CIF file [CIF]
data_Mg2CuSi3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.940
_cell_length_b   4.940
_cell_length_c   4.940
_cell_angle_alpha   65.383
_cell_angle_beta   65.383
_cell_angle_gamma   65.383
_symmetry_Int_Tables_number   1
_cell_volume   95.214
_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  0.627  0.627  0.627  1.0
  Mg  Mg1  1  0.373  0.373  0.373  1.0
  Cu  Cu2  1  0.000  0.000  0.000  1.0
  Si  Si3  1  0.000  0.500  0.000  1.0
  Si  Si4  1  0.500  0.000  0.000  1.0
  Si  Si5  1  0.000  0.000  0.500  1.0
[/CIF]
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The crystal structure described by Mg2CuSi3 crystallizes in the trigonal R-3m space group. Mg(1) is bonded in a 16-coordinate geometry to four equivalent Mg(1), three equivalent Cu(1), and nine equivalent Si(1) atoms. Cu(1) is bonded to six equivalent Mg(1) and six equivalent Si(1) atoms to form CuMg6Si6 cuboctahedra that share corners with six equivalent Cu(1)Mg6Si6 cuboctahedra, corners with twelve equivalent Si(1)Mg6Cu2Si4 cuboctahedra, edges with six equivalent Cu(1)Mg6Si6 cuboctahedra, and faces with eighteen equivalent Si(1)Mg6Cu2Si4 cuboctahedra. Si(1) is bonded to six equivalent Mg(1), two equivalent Cu(1), and four equivalent Si(1) atoms to form SiMg6Cu2Si4 cuboctahedra that share corners with four equivalent Cu(1)Mg6Si6 cuboctahedra, corners with fourteen equivalent Si(1)Mg6Cu2Si4 cuboctahedra, edges with six equivalent Si(1)Mg6Cu2Si4 cuboctahedra, faces with six equivalent Cu(1)Mg6Si6 cuboctahedra, and faces with twelve equivalent Si(1)Mg6Cu2Si4 cuboctahedra. is represented by the CIF file [CIF]
data_Mg2CuSi3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.940
_cell_length_b   4.940
_cell_length_c   4.940
_cell_angle_alpha   65.383
_cell_angle_beta   65.383
_cell_angle_gamma   65.383
_symmetry_Int_Tables_number   1
_cell_volume   95.214
_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  0.627  0.627  0.627  1.0
  Mg  Mg1  1  0.373  0.373  0.373  1.0
  Cu  Cu2  1  0.000  0.000  0.000  1.0
  Si  Si3  1  0.000  0.500  0.000  1.0
  Si  Si4  1  0.500  0.000  0.000  1.0
  Si  Si5  1  0.000  0.000  0.500  1.0
[/CIF]
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