The material described by Mg2Si3 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(1), one Si(10), two equivalent Si(11), two equivalent Si(3), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), one Si(9), two equivalent Si(12), and two equivalent Si(4) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), two equivalent Si(11), and two equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Si(2), one Si(4), two equivalent Si(1), and two equivalent Si(12) atoms. In the fifth Mg site, Mg(5) is bonded in a 7-coordinate geometry to one Si(4), two equivalent Si(12), two equivalent Si(5), and two equivalent Si(9) atoms. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(3), one Si(8), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 4-coordinate geometry to two equivalent Si(8), two equivalent Si(9), and three equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 6-coordinate geometry to one Si(10), one Si(8), two equivalent Si(6), and two equivalent Si(7) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(4), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(6), two equivalent Mg(1), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(4), one Mg(5), two equivalent Mg(2), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Mg(5), one Si(12), one Si(7), and two equivalent Si(9) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(11), and two equivalent Si(10) atoms. In the seventh Si site, Si(7) is bonded in a 7-coordinate geometry to two equivalent Mg(8), three equivalent Mg(7), one Si(5), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(7), one Si(7), and two equivalent Si(10) atoms. In the ninth Si site, Si(9) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(5), two equivalent Mg(7), and two equivalent Si(5) atoms. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(8), two equivalent Mg(6), two equivalent Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(6), and two equivalent Si(3) atoms. In the twelfth Si site, Si(12) is bonded in a 9-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(5), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   17.954
_cell_length_b   3.530
_cell_length_c   6.094
_cell_angle_alpha   72.935
_cell_angle_beta   96.379
_cell_angle_gamma   95.639
_symmetry_Int_Tables_number   1
_cell_volume   366.058
_cell_formula_units_Z   4
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  0.203  0.583  0.138  1.0
  Mg  Mg1  1  0.805  0.083  0.736  1.0
  Mg  Mg2  1  0.056  0.669  0.818  1.0
  Mg  Mg3  1  0.947  0.997  0.063  1.0
  Mg  Mg4  1  0.701  0.719  0.352  1.0
  Mg  Mg5  1  0.296  0.927  0.540  1.0
  Mg  Mg6  1  0.546  0.539  0.565  1.0
  Mg  Mg7  1  0.449  0.847  0.866  1.0
  Si  Si8  1  0.051  0.421  0.310  1.0
  Si  Si9  1  0.952  0.243  0.574  1.0
  Si  Si10  1  0.142  0.899  0.448  1.0
  Si  Si11  1  0.860  0.774  0.420  1.0
  Si  Si12  1  0.682  0.402  0.969  1.0
  Si  Si13  1  0.313  0.243  0.921  1.0
  Si  Si14  1  0.550  0.267  0.115  1.0
  Si  Si15  1  0.442  0.088  0.364  1.0
  Si  Si16  1  0.657  0.027  0.700  1.0
  Si  Si17  1  0.355  0.613  0.219  1.0
  Si  Si18  1  0.181  0.265  0.752  1.0
  Si  Si19  1  0.815  0.394  0.133  1.0
[/CIF]
.
The material described by Mg2Si3 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(1), one Si(10), two equivalent Si(11), two equivalent Si(3), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), one Si(9), two equivalent Si(12), and two equivalent Si(4) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), two equivalent Si(11), and two equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Si(2), one Si(4), two equivalent Si(1), and two equivalent Si(12) atoms. In the fifth Mg site, Mg(5) is bonded in a 7-coordinate geometry to one Si(4), two equivalent Si(12), two equivalent Si(5), and two equivalent Si(9) atoms. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(3), one Si(8), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 4-coordinate geometry to two equivalent Si(8), two equivalent Si(9), and three equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 6-coordinate geometry to one Si(10), one Si(8), two equivalent Si(6), and two equivalent Si(7) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(4), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(6), two equivalent Mg(1), two equivalent Si(1), and two equivalent Si(11) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(4), one Mg(5), two equivalent Mg(2), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to two equivalent Mg(5), one Si(12), one Si(7), and two equivalent Si(9) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(11), and two equivalent Si(10) atoms. In the seventh Si site, Si(7) is bonded in a 7-coordinate geometry to two equivalent Mg(8), three equivalent Mg(7), one Si(5), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(7), one Si(7), and two equivalent Si(10) atoms. In the ninth Si site, Si(9) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(5), two equivalent Mg(7), and two equivalent Si(5) atoms. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(8), two equivalent Mg(6), two equivalent Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 9-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(6), and two equivalent Si(3) atoms. In the twelfth Si site, Si(12) is bonded in a 9-coordinate geometry to two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(5), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   17.954
_cell_length_b   3.530
_cell_length_c   6.094
_cell_angle_alpha   72.935
_cell_angle_beta   96.379
_cell_angle_gamma   95.639
_symmetry_Int_Tables_number   1
_cell_volume   366.058
_cell_formula_units_Z   4
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  0.203  0.583  0.138  1.0
  Mg  Mg1  1  0.805  0.083  0.736  1.0
  Mg  Mg2  1  0.056  0.669  0.818  1.0
  Mg  Mg3  1  0.947  0.997  0.063  1.0
  Mg  Mg4  1  0.701  0.719  0.352  1.0
  Mg  Mg5  1  0.296  0.927  0.540  1.0
  Mg  Mg6  1  0.546  0.539  0.565  1.0
  Mg  Mg7  1  0.449  0.847  0.866  1.0
  Si  Si8  1  0.051  0.421  0.310  1.0
  Si  Si9  1  0.952  0.243  0.574  1.0
  Si  Si10  1  0.142  0.899  0.448  1.0
  Si  Si11  1  0.860  0.774  0.420  1.0
  Si  Si12  1  0.682  0.402  0.969  1.0
  Si  Si13  1  0.313  0.243  0.921  1.0
  Si  Si14  1  0.550  0.267  0.115  1.0
  Si  Si15  1  0.442  0.088  0.364  1.0
  Si  Si16  1  0.657  0.027  0.700  1.0
  Si  Si17  1  0.355  0.613  0.219  1.0
  Si  Si18  1  0.181  0.265  0.752  1.0
  Si  Si19  1  0.815  0.394  0.133  1.0
[/CIF]
.