The material structure described by Mg7Si4 crystallizes in the triclinic P1 space group. There are fourteen inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 2-coordinate geometry to one Si(2) and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Si(2), one Si(7), and two equivalent Si(3) atoms. In the third Mg site, Mg(3) is bonded in a 2-coordinate geometry to one Si(3) and one Si(7) atom. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to one Si(3), one Si(6), and two equivalent Si(7) atoms. In the fifth Mg site, Mg(5) is bonded in a 3-coordinate geometry to one Si(3) and two equivalent Si(2) atoms. In the sixth Mg site, Mg(6) is bonded in a 3-coordinate geometry to one Si(1), one Si(4), and one Si(8) atom. In the seventh Mg site, Mg(7) is bonded in a 4-coordinate geometry to one Si(5), one Si(8), and two equivalent Si(4) atoms. In the eighth Mg site, Mg(8) is bonded in a 2-coordinate geometry to one Si(3) and one Si(7) atom. In the ninth Mg site, Mg(9) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(5), and one Si(6) atom. In the tenth Mg site, Mg(10) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(5), and one Si(6) atom. In the eleventh Mg site, Mg(11) is bonded in a 3-coordinate geometry to one Si(1), one Si(5), and one Si(8) atom. In the twelfth Mg site, Mg(12) is bonded in a 3-coordinate geometry to one Si(4) and two equivalent Si(5) atoms. In the thirteenth Mg site, Mg(13) is bonded in a distorted L-shaped geometry to one Si(4) and one Si(8) atom. In the fourteenth Mg site, Mg(14) is bonded in a 2-coordinate geometry to one Si(7) and one Si(8) atom. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to one Mg(10), one Mg(11), one Mg(6), one Mg(9), one Si(5), and one Si(8) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(2), one Mg(9), two equivalent Mg(5), one Si(3), and one Si(6) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), one Mg(8), two equivalent Mg(2), one Si(2), and one Si(7) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(12), one Mg(13), one Mg(6), two equivalent Mg(7), one Si(5), and one Si(8) atom. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(10), one Mg(11), one Mg(7), one Mg(9), two equivalent Mg(12), one Si(1), and one Si(4) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(10), one Mg(4), one Mg(9), two equivalent Mg(1), one Si(2), and one Si(7) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(14), one Mg(2), one Mg(3), one Mg(8), two equivalent Mg(4), one Si(3), and one Si(6) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(11), one Mg(13), one Mg(14), one Mg(6), one Mg(7), one Si(1), and one Si(4) atom. is represented by the CIF card [CIF]
data_Mg7Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.279
_cell_length_b   5.986
_cell_length_c   14.301
_cell_angle_alpha   81.668
_cell_angle_beta   87.008
_cell_angle_gamma   82.626
_symmetry_Int_Tables_number   1
_cell_volume   443.167
_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  0.369  0.101  0.908  1.0
  Mg  Mg1  1  0.725  0.579  0.634  1.0
  Mg  Mg2  1  0.192  0.382  0.525  1.0
  Mg  Mg3  1  0.423  0.078  0.695  1.0
  Mg  Mg4  1  0.483  0.611  0.847  1.0
  Mg  Mg5  1  0.237  0.761  0.286  1.0
  Mg  Mg6  1  0.135  0.263  0.319  1.0
  Mg  Mg7  1  0.241  0.882  0.491  1.0
  Mg  Mg8  1  0.822  0.279  0.998  1.0
  Mg  Mg9  1  0.949  0.770  0.949  1.0
  Mg  Mg10  1  0.350  0.171  0.121  1.0
  Mg  Mg11  1  0.453  0.675  0.079  1.0
  Mg  Mg12  1  0.747  0.647  0.411  1.0
  Mg  Mg13  1  0.707  0.141  0.474  1.0
  Si  Si14  1  0.920  0.929  0.138  1.0
  Si  Si15  1  0.003  0.478  0.818  1.0
  Si  Si16  1  0.214  0.645  0.676  1.0
  Si  Si17  1  0.636  0.424  0.263  1.0
  Si  Si18  1  0.959  0.522  0.139  1.0
  Si  Si19  1  0.846  0.121  0.808  1.0
  Si  Si20  1  0.938  0.022  0.648  1.0
  Si  Si21  1  0.656  0.017  0.276  1.0
[/CIF]
.
The material structure described by Mg7Si4 crystallizes in the triclinic P1 space group. There are fourteen inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 2-coordinate geometry to one Si(2) and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Si(2), one Si(7), and two equivalent Si(3) atoms. In the third Mg site, Mg(3) is bonded in a 2-coordinate geometry to one Si(3) and one Si(7) atom. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to one Si(3), one Si(6), and two equivalent Si(7) atoms. In the fifth Mg site, Mg(5) is bonded in a 3-coordinate geometry to one Si(3) and two equivalent Si(2) atoms. In the sixth Mg site, Mg(6) is bonded in a 3-coordinate geometry to one Si(1), one Si(4), and one Si(8) atom. In the seventh Mg site, Mg(7) is bonded in a 4-coordinate geometry to one Si(5), one Si(8), and two equivalent Si(4) atoms. In the eighth Mg site, Mg(8) is bonded in a 2-coordinate geometry to one Si(3) and one Si(7) atom. In the ninth Mg site, Mg(9) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(5), and one Si(6) atom. In the tenth Mg site, Mg(10) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(5), and one Si(6) atom. In the eleventh Mg site, Mg(11) is bonded in a 3-coordinate geometry to one Si(1), one Si(5), and one Si(8) atom. In the twelfth Mg site, Mg(12) is bonded in a 3-coordinate geometry to one Si(4) and two equivalent Si(5) atoms. In the thirteenth Mg site, Mg(13) is bonded in a distorted L-shaped geometry to one Si(4) and one Si(8) atom. In the fourteenth Mg site, Mg(14) is bonded in a 2-coordinate geometry to one Si(7) and one Si(8) atom. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 6-coordinate geometry to one Mg(10), one Mg(11), one Mg(6), one Mg(9), one Si(5), and one Si(8) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(2), one Mg(9), two equivalent Mg(5), one Si(3), and one Si(6) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), one Mg(8), two equivalent Mg(2), one Si(2), and one Si(7) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(12), one Mg(13), one Mg(6), two equivalent Mg(7), one Si(5), and one Si(8) atom. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(10), one Mg(11), one Mg(7), one Mg(9), two equivalent Mg(12), one Si(1), and one Si(4) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(10), one Mg(4), one Mg(9), two equivalent Mg(1), one Si(2), and one Si(7) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(14), one Mg(2), one Mg(3), one Mg(8), two equivalent Mg(4), one Si(3), and one Si(6) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(11), one Mg(13), one Mg(14), one Mg(6), one Mg(7), one Si(1), and one Si(4) atom. is represented by the CIF card [CIF]
data_Mg7Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.279
_cell_length_b   5.986
_cell_length_c   14.301
_cell_angle_alpha   81.668
_cell_angle_beta   87.008
_cell_angle_gamma   82.626
_symmetry_Int_Tables_number   1
_cell_volume   443.167
_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  0.369  0.101  0.908  1.0
  Mg  Mg1  1  0.725  0.579  0.634  1.0
  Mg  Mg2  1  0.192  0.382  0.525  1.0
  Mg  Mg3  1  0.423  0.078  0.695  1.0
  Mg  Mg4  1  0.483  0.611  0.847  1.0
  Mg  Mg5  1  0.237  0.761  0.286  1.0
  Mg  Mg6  1  0.135  0.263  0.319  1.0
  Mg  Mg7  1  0.241  0.882  0.491  1.0
  Mg  Mg8  1  0.822  0.279  0.998  1.0
  Mg  Mg9  1  0.949  0.770  0.949  1.0
  Mg  Mg10  1  0.350  0.171  0.121  1.0
  Mg  Mg11  1  0.453  0.675  0.079  1.0
  Mg  Mg12  1  0.747  0.647  0.411  1.0
  Mg  Mg13  1  0.707  0.141  0.474  1.0
  Si  Si14  1  0.920  0.929  0.138  1.0
  Si  Si15  1  0.003  0.478  0.818  1.0
  Si  Si16  1  0.214  0.645  0.676  1.0
  Si  Si17  1  0.636  0.424  0.263  1.0
  Si  Si18  1  0.959  0.522  0.139  1.0
  Si  Si19  1  0.846  0.121  0.808  1.0
  Si  Si20  1  0.938  0.022  0.648  1.0
  Si  Si21  1  0.656  0.017  0.276  1.0
[/CIF]
.