The structure described by Mg3Si4 is delta Molybdenum Boride-like structured and crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to two equivalent Si(1), two equivalent Si(2), and three equivalent Si(3) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), two equivalent Si(1), two equivalent Si(4), and three equivalent Si(3) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), two equivalent Si(2), and three equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), one Si(3), and three equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), one Si(4), and three equivalent Si(1) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to three equivalent Mg(1), three equivalent Mg(2), one Si(1), and two equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to two equivalent Mg(2), three equivalent Mg(3), one Si(2), and two equivalent Si(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.123
_cell_length_b   7.564
_cell_length_c   8.440
_cell_angle_alpha   72.763
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   251.435
_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  0.250  0.337  0.500  1.0
  Mg  Mg1  1  0.750  0.663  0.500  1.0
  Mg  Mg2  1  0.750  0.679  0.905  1.0
  Mg  Mg3  1  0.250  0.026  0.878  1.0
  Mg  Mg4  1  0.750  0.974  0.122  1.0
  Mg  Mg5  1  0.250  0.321  0.095  1.0
  Si  Si6  1  0.250  0.841  0.642  1.0
  Si  Si7  1  0.750  0.057  0.660  1.0
  Si  Si8  1  0.750  0.497  0.248  1.0
  Si  Si9  1  0.250  0.707  0.178  1.0
  Si  Si10  1  0.250  0.503  0.752  1.0
  Si  Si11  1  0.250  0.943  0.340  1.0
  Si  Si12  1  0.750  0.159  0.358  1.0
  Si  Si13  1  0.750  0.293  0.822  1.0
[/CIF]
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The structure described by Mg3Si4 is delta Molybdenum Boride-like structured and crystallizes in the monoclinic P2_1/m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to two equivalent Si(1), two equivalent Si(2), and three equivalent Si(3) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), two equivalent Si(1), two equivalent Si(4), and three equivalent Si(3) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), two equivalent Si(2), and three equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), one Si(3), and three equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), one Si(4), and three equivalent Si(1) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to three equivalent Mg(1), three equivalent Mg(2), one Si(1), and two equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to two equivalent Mg(2), three equivalent Mg(3), one Si(2), and two equivalent Si(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.123
_cell_length_b   7.564
_cell_length_c   8.440
_cell_angle_alpha   72.763
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   251.435
_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  0.250  0.337  0.500  1.0
  Mg  Mg1  1  0.750  0.663  0.500  1.0
  Mg  Mg2  1  0.750  0.679  0.905  1.0
  Mg  Mg3  1  0.250  0.026  0.878  1.0
  Mg  Mg4  1  0.750  0.974  0.122  1.0
  Mg  Mg5  1  0.250  0.321  0.095  1.0
  Si  Si6  1  0.250  0.841  0.642  1.0
  Si  Si7  1  0.750  0.057  0.660  1.0
  Si  Si8  1  0.750  0.497  0.248  1.0
  Si  Si9  1  0.250  0.707  0.178  1.0
  Si  Si10  1  0.250  0.503  0.752  1.0
  Si  Si11  1  0.250  0.943  0.340  1.0
  Si  Si12  1  0.750  0.159  0.358  1.0
  Si  Si13  1  0.750  0.293  0.822  1.0
[/CIF]
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