The material described by Mg2Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to one Mg(3), one Mg(8), three equivalent Mg(6), one Si(3), one Si(8), two equivalent Si(10), two equivalent Si(11), and three equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 13-coordinate geometry to one Mg(4), one Mg(7), three equivalent Mg(5), one Si(4), two equivalent Si(2), two equivalent Si(5), and three equivalent Si(12) atoms. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(6), two equivalent Mg(4), one Si(4), two equivalent Si(11), three equivalent Si(1), and three equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 14-coordinate geometry to one Mg(2), one Mg(5), two equivalent Mg(3), one Si(1), one Si(3), two equivalent Si(12), three equivalent Si(2), and three equivalent Si(4) atoms. In the fifth Mg site, Mg(5) is bonded in a 6-coordinate geometry to one Mg(4), one Mg(7), three equivalent Mg(2), one Si(2), one Si(7), two equivalent Si(12), and two equivalent Si(5) atoms. In the sixth Mg site, Mg(6) is bonded in a 14-coordinate geometry to one Mg(3), one Mg(8), three equivalent Mg(1), one Si(1), one Si(10), two equivalent Si(3), two equivalent Si(6), and three equivalent Si(11) atoms. In the seventh Mg site, Mg(7) is bonded in a 14-coordinate geometry to one Mg(2), one Mg(5), one Mg(8), one Si(10), two equivalent Si(5), two equivalent Si(8), three equivalent Si(7), and three equivalent Si(9) atoms. In the eighth Mg site, Mg(8) is bonded in a 14-coordinate geometry to one Mg(1), one Mg(6), one Mg(7), one Si(7), two equivalent Si(6), two equivalent Si(9), three equivalent Si(10), and three equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to one Mg(4), one Mg(6), three equivalent Mg(3), one Si(11), one Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Mg(5), two equivalent Mg(2), three equivalent Mg(4), one Si(1), one Si(12), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 11-coordinate geometry to one Mg(1), one Mg(4), two equivalent Mg(6), three equivalent Mg(3), one Si(11), one Si(4), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 11-coordinate geometry to one Mg(2), one Mg(3), three equivalent Mg(4), one Si(12), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(7), one Si(12), one Si(7), and one Si(9) atom. In the sixth Si site, Si(6) is bonded in a 10-coordinate geometry to two equivalent Mg(6), two equivalent Mg(8), three equivalent Mg(1), one Si(10), one Si(11), and one Si(8) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(5), one Mg(8), three equivalent Mg(7), one Si(5), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 10-coordinate geometry to one Mg(1), two equivalent Mg(7), three equivalent Mg(8), one Si(6), one Si(7), and two equivalent Si(10) atoms. In the ninth Si site, Si(9) is bonded in a 9-coordinate geometry to two equivalent Mg(8), three equivalent Mg(7), one Si(10), one Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 11-coordinate geometry to one Mg(6), one Mg(7), two equivalent Mg(1), three equivalent Mg(8), one Si(6), one Si(9), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), three equivalent Mg(6), one Si(1), one Si(3), and one Si(6) atom. In the twelfth Si site, Si(12) is bonded in a 10-coordinate geometry to two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(2), one Si(2), one Si(4), and one Si(5) atom. is represented by the CIF file [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.539
_cell_length_b   5.472
_cell_length_c   15.464
_cell_angle_alpha   91.594
_cell_angle_beta   97.486
_cell_angle_gamma   113.589
_symmetry_Int_Tables_number   1
_cell_volume   347.631
_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  0.724  0.609  0.738  1.0
  Mg  Mg1  1  0.855  0.379  0.235  1.0
  Mg  Mg2  1  0.983  0.937  0.932  1.0
  Mg  Mg3  1  0.581  0.992  0.063  1.0
  Mg  Mg4  1  0.568  0.786  0.254  1.0
  Mg  Mg5  1  0.047  0.233  0.764  1.0
  Mg  Mg6  1  0.868  0.220  0.426  1.0
  Mg  Mg7  1  0.794  0.906  0.574  1.0
  Si  Si8  1  0.285  0.524  0.942  1.0
  Si  Si9  1  0.305  0.391  0.105  1.0
  Si  Si10  1  0.670  0.320  0.898  1.0
  Si  Si11  1  0.868  0.563  0.057  1.0
  Si  Si12  1  0.267  0.110  0.327  1.0
  Si  Si13  1  0.390  0.000  0.675  1.0
  Si  Si14  1  0.534  0.560  0.411  1.0
  Si  Si15  1  0.494  0.322  0.556  1.0
  Si  Si16  1  0.154  0.790  0.440  1.0
  Si  Si17  1  0.109  0.532  0.603  1.0
  Si  Si18  1  0.390  0.861  0.830  1.0
  Si  Si19  1  0.114  0.965  0.168  1.0
[/CIF]
.
The material described by Mg2Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to one Mg(3), one Mg(8), three equivalent Mg(6), one Si(3), one Si(8), two equivalent Si(10), two equivalent Si(11), and three equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 13-coordinate geometry to one Mg(4), one Mg(7), three equivalent Mg(5), one Si(4), two equivalent Si(2), two equivalent Si(5), and three equivalent Si(12) atoms. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(6), two equivalent Mg(4), one Si(4), two equivalent Si(11), three equivalent Si(1), and three equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 14-coordinate geometry to one Mg(2), one Mg(5), two equivalent Mg(3), one Si(1), one Si(3), two equivalent Si(12), three equivalent Si(2), and three equivalent Si(4) atoms. In the fifth Mg site, Mg(5) is bonded in a 6-coordinate geometry to one Mg(4), one Mg(7), three equivalent Mg(2), one Si(2), one Si(7), two equivalent Si(12), and two equivalent Si(5) atoms. In the sixth Mg site, Mg(6) is bonded in a 14-coordinate geometry to one Mg(3), one Mg(8), three equivalent Mg(1), one Si(1), one Si(10), two equivalent Si(3), two equivalent Si(6), and three equivalent Si(11) atoms. In the seventh Mg site, Mg(7) is bonded in a 14-coordinate geometry to one Mg(2), one Mg(5), one Mg(8), one Si(10), two equivalent Si(5), two equivalent Si(8), three equivalent Si(7), and three equivalent Si(9) atoms. In the eighth Mg site, Mg(8) is bonded in a 14-coordinate geometry to one Mg(1), one Mg(6), one Mg(7), one Si(7), two equivalent Si(6), two equivalent Si(9), three equivalent Si(10), and three equivalent Si(8) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to one Mg(4), one Mg(6), three equivalent Mg(3), one Si(11), one Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Mg(5), two equivalent Mg(2), three equivalent Mg(4), one Si(1), one Si(12), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 11-coordinate geometry to one Mg(1), one Mg(4), two equivalent Mg(6), three equivalent Mg(3), one Si(11), one Si(4), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 11-coordinate geometry to one Mg(2), one Mg(3), three equivalent Mg(4), one Si(12), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(2), two equivalent Mg(5), two equivalent Mg(7), one Si(12), one Si(7), and one Si(9) atom. In the sixth Si site, Si(6) is bonded in a 10-coordinate geometry to two equivalent Mg(6), two equivalent Mg(8), three equivalent Mg(1), one Si(10), one Si(11), and one Si(8) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(5), one Mg(8), three equivalent Mg(7), one Si(5), one Si(8), and two equivalent Si(9) atoms. In the eighth Si site, Si(8) is bonded in a 10-coordinate geometry to one Mg(1), two equivalent Mg(7), three equivalent Mg(8), one Si(6), one Si(7), and two equivalent Si(10) atoms. In the ninth Si site, Si(9) is bonded in a 9-coordinate geometry to two equivalent Mg(8), three equivalent Mg(7), one Si(10), one Si(5), and two equivalent Si(7) atoms. In the tenth Si site, Si(10) is bonded in a 11-coordinate geometry to one Mg(6), one Mg(7), two equivalent Mg(1), three equivalent Mg(8), one Si(6), one Si(9), and two equivalent Si(8) atoms. In the eleventh Si site, Si(11) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), three equivalent Mg(6), one Si(1), one Si(3), and one Si(6) atom. In the twelfth Si site, Si(12) is bonded in a 10-coordinate geometry to two equivalent Mg(4), two equivalent Mg(5), three equivalent Mg(2), one Si(2), one Si(4), and one Si(5) atom. is represented by the CIF file [CIF]
data_Mg2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.539
_cell_length_b   5.472
_cell_length_c   15.464
_cell_angle_alpha   91.594
_cell_angle_beta   97.486
_cell_angle_gamma   113.589
_symmetry_Int_Tables_number   1
_cell_volume   347.631
_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  0.724  0.609  0.738  1.0
  Mg  Mg1  1  0.855  0.379  0.235  1.0
  Mg  Mg2  1  0.983  0.937  0.932  1.0
  Mg  Mg3  1  0.581  0.992  0.063  1.0
  Mg  Mg4  1  0.568  0.786  0.254  1.0
  Mg  Mg5  1  0.047  0.233  0.764  1.0
  Mg  Mg6  1  0.868  0.220  0.426  1.0
  Mg  Mg7  1  0.794  0.906  0.574  1.0
  Si  Si8  1  0.285  0.524  0.942  1.0
  Si  Si9  1  0.305  0.391  0.105  1.0
  Si  Si10  1  0.670  0.320  0.898  1.0
  Si  Si11  1  0.868  0.563  0.057  1.0
  Si  Si12  1  0.267  0.110  0.327  1.0
  Si  Si13  1  0.390  0.000  0.675  1.0
  Si  Si14  1  0.534  0.560  0.411  1.0
  Si  Si15  1  0.494  0.322  0.556  1.0
  Si  Si16  1  0.154  0.790  0.440  1.0
  Si  Si17  1  0.109  0.532  0.603  1.0
  Si  Si18  1  0.390  0.861  0.830  1.0
  Si  Si19  1  0.114  0.965  0.168  1.0
[/CIF]
.