The structure described by Mg3Si4 crystallizes in the monoclinic Cm space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one Si(2), one Si(6), two equivalent Si(1), and two equivalent Si(7) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to two equivalent Si(1), two equivalent Si(5), two equivalent Si(6), and two equivalent Si(7) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(7), two equivalent Si(2), two equivalent Si(4), and two equivalent Si(5) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(4), two equivalent Si(7), and two equivalent Si(8) atoms. In the fifth Mg site, Mg(5) is bonded in a 10-coordinate geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), two equivalent Si(5), and two equivalent Si(8) atoms. In the sixth Mg site, Mg(6) is bonded to two equivalent Si(2), two equivalent Si(6), and two equivalent Si(8) atoms to form distorted face-sharing MgSi6 octahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(5), one Si(3), one Si(5), and one Si(7) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), one Si(5), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent Mg(5), one Si(1), one Si(8), and two equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(5), one Si(6), and two equivalent Si(3) atoms. In the fifth Si site, Si(5) is bonded in a 10-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), one Si(1), one Si(2), one Si(4), and one Si(6) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(1), two equivalent Mg(2), two equivalent Mg(6), one Si(4), and one Si(5) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), and one Si(1) atom. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), one Si(2), and one Si(3) atom. is represented by the CIF card [CIF]
data_Mg3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.421
_cell_length_b   8.421
_cell_length_c   8.794
_cell_angle_alpha   63.741
_cell_angle_beta   63.741
_cell_angle_gamma   28.128
_symmetry_Int_Tables_number   1
_cell_volume   261.607
_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  0.002  0.002  0.946  1.0
  Mg  Mg1  1  0.231  0.231  0.836  1.0
  Mg  Mg2  1  0.434  0.434  0.353  1.0
  Mg  Mg3  1  0.101  0.101  0.228  1.0
  Mg  Mg4  1  0.211  0.211  0.483  1.0
  Mg  Mg5  1  0.332  0.332  0.069  1.0
  Si  Si6  1  0.634  0.634  0.734  1.0
  Si  Si7  1  0.842  0.842  0.281  1.0
  Si  Si8  1  0.568  0.568  0.535  1.0
  Si  Si9  1  0.978  0.978  0.567  1.0
  Si  Si10  1  0.812  0.812  0.587  1.0
  Si  Si11  1  0.847  0.847  0.845  1.0
  Si  Si12  1  0.597  0.597  0.029  1.0
  Si  Si13  1  0.702  0.702  0.254  1.0
[/CIF]
.
The structure described by Mg3Si4 crystallizes in the monoclinic Cm space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one Si(2), one Si(6), two equivalent Si(1), and two equivalent Si(7) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to two equivalent Si(1), two equivalent Si(5), two equivalent Si(6), and two equivalent Si(7) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(7), two equivalent Si(2), two equivalent Si(4), and two equivalent Si(5) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(4), two equivalent Si(7), and two equivalent Si(8) atoms. In the fifth Mg site, Mg(5) is bonded in a 10-coordinate geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), two equivalent Si(5), and two equivalent Si(8) atoms. In the sixth Mg site, Mg(6) is bonded to two equivalent Si(2), two equivalent Si(6), and two equivalent Si(8) atoms to form distorted face-sharing MgSi6 octahedra. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(5), one Si(3), one Si(5), and one Si(7) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), one Si(5), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent Mg(5), one Si(1), one Si(8), and two equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(5), one Si(6), and two equivalent Si(3) atoms. In the fifth Si site, Si(5) is bonded in a 10-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), one Si(1), one Si(2), one Si(4), and one Si(6) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(1), two equivalent Mg(2), two equivalent Mg(6), one Si(4), and one Si(5) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), and one Si(1) atom. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), one Si(2), and one Si(3) atom. is represented by the CIF card [CIF]
data_Mg3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.421
_cell_length_b   8.421
_cell_length_c   8.794
_cell_angle_alpha   63.741
_cell_angle_beta   63.741
_cell_angle_gamma   28.128
_symmetry_Int_Tables_number   1
_cell_volume   261.607
_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  0.002  0.002  0.946  1.0
  Mg  Mg1  1  0.231  0.231  0.836  1.0
  Mg  Mg2  1  0.434  0.434  0.353  1.0
  Mg  Mg3  1  0.101  0.101  0.228  1.0
  Mg  Mg4  1  0.211  0.211  0.483  1.0
  Mg  Mg5  1  0.332  0.332  0.069  1.0
  Si  Si6  1  0.634  0.634  0.734  1.0
  Si  Si7  1  0.842  0.842  0.281  1.0
  Si  Si8  1  0.568  0.568  0.535  1.0
  Si  Si9  1  0.978  0.978  0.567  1.0
  Si  Si10  1  0.812  0.812  0.587  1.0
  Si  Si11  1  0.847  0.847  0.845  1.0
  Si  Si12  1  0.597  0.597  0.029  1.0
  Si  Si13  1  0.702  0.702  0.254  1.0
[/CIF]
.