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 7-coordinate geometry to one Si(3), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Si(12), two equivalent Si(4), two equivalent Si(5), and two equivalent Si(9) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), one Si(4), two equivalent Si(11), and two equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), two equivalent Si(12), and two equivalent Si(4) atoms. In the fifth Mg site, Mg(5) is bonded to one Si(9), two equivalent Si(12), and two equivalent Si(5) atoms to form distorted edge-sharing MgSi5 trigonal bipyramids. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Si(10), two equivalent Si(11), two equivalent Si(3), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to one Si(8), one Si(9), two equivalent Si(5), and two equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 6-coordinate geometry to one Si(10), one Si(7), two equivalent Si(6), and two equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 1-coordinate geometry to one Mg(3), one Mg(4), two equivalent Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(12), two equivalent Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(6), one Si(11), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(3), two equivalent Mg(2), two equivalent Mg(4), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(7), and one Si(9) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(10), and one Si(11) atom. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to one Mg(8), two equivalent Mg(7), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 6-coordinate geometry to one Mg(7), two equivalent Mg(8), 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(5), one Mg(7), two equivalent Mg(2), one Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(1), one Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(3), and one Si(6) atom. In the twelfth Si site, Si(12) is bonded in a 8-coordinate geometry to one Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(2), and two equivalent Si(4) atoms. is represented by the CIF card [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.769
_cell_length_b   6.159
_cell_length_c   17.408
_cell_angle_alpha   83.288
_cell_angle_beta   83.923
_cell_angle_gamma   72.810
_symmetry_Int_Tables_number   1
_cell_volume   382.341
_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  0.293  0.993  0.241  1.0
  Mg  Mg1  1  0.043  0.924  0.757  1.0
  Mg  Mg2  1  0.393  0.939  0.058  1.0
  Mg  Mg3  1  0.865  0.162  0.912  1.0
  Mg  Mg4  1  0.780  0.466  0.745  1.0
  Mg  Mg5  1  0.571  0.435  0.249  1.0
  Mg  Mg6  1  0.920  0.391  0.566  1.0
  Mg  Mg7  1  0.429  0.521  0.419  1.0
  Si  Si8  1  0.721  0.367  0.046  1.0
  Si  Si9  1  0.041  0.656  0.986  1.0
  Si  Si10  1  0.184  0.360  0.133  1.0
  Si  Si11  1  0.550  0.804  0.887  1.0
  Si  Si12  1  0.457  0.204  0.670  1.0
  Si  Si13  1  0.896  0.704  0.314  1.0
  Si  Si14  1  0.228  0.789  0.543  1.0
  Si  Si15  1  0.122  0.112  0.447  1.0
  Si  Si16  1  0.667  0.827  0.628  1.0
  Si  Si17  1  0.682  0.076  0.364  1.0
  Si  Si18  1  0.951  0.744  0.171  1.0
  Si  Si19  1  0.207  0.524  0.861  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 7-coordinate geometry to one Si(3), two equivalent Si(10), two equivalent Si(11), and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Si(12), two equivalent Si(4), two equivalent Si(5), and two equivalent Si(9) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(1), one Si(3), one Si(4), two equivalent Si(11), and two equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), two equivalent Si(12), and two equivalent Si(4) atoms. In the fifth Mg site, Mg(5) is bonded to one Si(9), two equivalent Si(12), and two equivalent Si(5) atoms to form distorted edge-sharing MgSi5 trigonal bipyramids. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Si(10), two equivalent Si(11), two equivalent Si(3), and two equivalent Si(6) atoms. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to one Si(8), one Si(9), two equivalent Si(5), and two equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 6-coordinate geometry to one Si(10), one Si(7), two equivalent Si(6), and two equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 1-coordinate geometry to one Mg(3), one Mg(4), two equivalent Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(12), two equivalent Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(6), one Si(11), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(3), two equivalent Mg(2), two equivalent Mg(4), two equivalent Si(12), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(7), and one Si(9) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(6), two equivalent Mg(8), one Si(10), and one Si(11) atom. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to one Mg(8), two equivalent Mg(7), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 6-coordinate geometry to one Mg(7), two equivalent Mg(8), 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(5), one Mg(7), two equivalent Mg(2), one Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 7-coordinate geometry to one Mg(6), one Mg(8), two equivalent Mg(1), one Si(6), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(6), one Si(3), and one Si(6) atom. In the twelfth Si site, Si(12) is bonded in a 8-coordinate geometry to one Mg(2), two equivalent Mg(4), two equivalent Mg(5), one Si(2), and two equivalent Si(4) atoms. is represented by the CIF card [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.769
_cell_length_b   6.159
_cell_length_c   17.408
_cell_angle_alpha   83.288
_cell_angle_beta   83.923
_cell_angle_gamma   72.810
_symmetry_Int_Tables_number   1
_cell_volume   382.341
_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  0.293  0.993  0.241  1.0
  Mg  Mg1  1  0.043  0.924  0.757  1.0
  Mg  Mg2  1  0.393  0.939  0.058  1.0
  Mg  Mg3  1  0.865  0.162  0.912  1.0
  Mg  Mg4  1  0.780  0.466  0.745  1.0
  Mg  Mg5  1  0.571  0.435  0.249  1.0
  Mg  Mg6  1  0.920  0.391  0.566  1.0
  Mg  Mg7  1  0.429  0.521  0.419  1.0
  Si  Si8  1  0.721  0.367  0.046  1.0
  Si  Si9  1  0.041  0.656  0.986  1.0
  Si  Si10  1  0.184  0.360  0.133  1.0
  Si  Si11  1  0.550  0.804  0.887  1.0
  Si  Si12  1  0.457  0.204  0.670  1.0
  Si  Si13  1  0.896  0.704  0.314  1.0
  Si  Si14  1  0.228  0.789  0.543  1.0
  Si  Si15  1  0.122  0.112  0.447  1.0
  Si  Si16  1  0.667  0.827  0.628  1.0
  Si  Si17  1  0.682  0.076  0.364  1.0
  Si  Si18  1  0.951  0.744  0.171  1.0
  Si  Si19  1  0.207  0.524  0.861  1.0
[/CIF]
.