The material structure described by Mg4Si7 crystallizes in the monoclinic Cm space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to two equivalent Mg(5), one Si(13), one Si(3), one Si(4), one Si(9), two equivalent Si(1), two equivalent Si(12), two equivalent Si(2), and two equivalent Si(8) atoms. In the second Mg site, Mg(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), two equivalent Mg(8), one Si(10), one Si(9), and two equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 13-coordinate geometry to one Mg(8), two equivalent Mg(2), two equivalent Mg(7), one Si(11), one Si(7), two equivalent Si(10), two equivalent Si(5), and two equivalent Si(6) atoms. In the fourth Mg site, Mg(4) is bonded in a 13-coordinate geometry to one Mg(7), two equivalent Mg(2), two equivalent Mg(8), one Si(12), one Si(8), two equivalent Si(13), two equivalent Si(5), and two equivalent Si(9) atoms. In the fifth Mg site, Mg(5) is bonded in a 14-coordinate geometry to two equivalent Mg(1), one Si(13), one Si(3), one Si(4), one Si(9), two equivalent Si(1), two equivalent Si(12), two equivalent Si(2), and two equivalent Si(8) atoms. In the sixth Mg site, Mg(6) is bonded in a 14-coordinate geometry to one Si(1), one Si(10), one Si(2), one Si(6), two equivalent Si(11), two equivalent Si(14), two equivalent Si(3), two equivalent Si(4), and two equivalent Si(7) atoms. In the seventh Mg site, Mg(7) is bonded in a 13-coordinate geometry to one Mg(4), two equivalent Mg(2), two equivalent Mg(3), one Si(11), one Si(7), two equivalent Si(10), two equivalent Si(5), and two equivalent Si(6) atoms. In the eighth Mg site, Mg(8) is bonded in a 13-coordinate geometry to one Mg(3), two equivalent Mg(2), two equivalent Mg(4), one Si(12), one Si(8), two equivalent Si(13), two equivalent Si(5), and two equivalent Si(9) atoms. There are fourteen inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(6), two equivalent Mg(1), two equivalent Mg(5), one Si(12), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(6), two equivalent Mg(1), two equivalent Mg(5), one Si(1), one Si(8), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(6), one Si(11), one Si(4), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(6), one Si(3), one Si(7), two equivalent Si(14), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), two equivalent Mg(8), one Si(13), and one Si(6) atom to form a mixture of distorted corner and face-sharing SiMg10Si2 cuboctahedra. In the sixth Si site, Si(6) is bonded in a 11-coordinate geometry to one Mg(6), two equivalent Mg(3), two equivalent Mg(7), one Si(14), one Si(5), two equivalent Si(10), and two equivalent Si(7) atoms. In the seventh Si site, Si(7) is bonded in a 10-coordinate geometry to one Mg(3), one Mg(7), two equivalent Mg(6), one Si(11), one Si(4), two equivalent Si(14), and two equivalent Si(6) atoms. In the eighth Si site, Si(8) is bonded in a 10-coordinate geometry to one Mg(4), one Mg(8), two equivalent Mg(1), two equivalent Mg(5), one Si(12), one Si(2), and two equivalent Si(13) atoms. In the ninth Si site, Si(9) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(2), one Mg(5), two equivalent Mg(4), two equivalent Mg(8), one Si(13), and two equivalent Si(12) atoms. In the tenth Si site, Si(10) is bonded in a 9-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(3), two equivalent Mg(7), two equivalent Si(11), and two equivalent Si(6) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(7), two equivalent Mg(6), one Si(3), one Si(7), and two equivalent Si(10) atoms. In the twelfth Si site, Si(12) is bonded in a 10-coordinate geometry to one Mg(4), one Mg(8), two equivalent Mg(1), two equivalent Mg(5), one Si(1), one Si(8), and two equivalent Si(9) atoms. In the thirteenth Si site, Si(13) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(4), two equivalent Mg(8), one Si(5), one Si(9), and two equivalent Si(8) atoms. In the fourteenth Si site, Si(14) is bonded in a distorted linear geometry to two equivalent Mg(6), one Si(6), two equivalent Si(4), and two equivalent Si(7) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg4Si7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.769
_cell_length_b   14.769
_cell_length_c   5.688
_cell_angle_alpha   89.578
_cell_angle_beta   89.578
_cell_angle_gamma   17.227
_symmetry_Int_Tables_number   1
_cell_volume   367.454
_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  0.585  0.585  0.201  1.0
  Mg  Mg1  1  0.772  0.772  0.451  1.0
  Mg  Mg2  1  0.328  0.328  0.204  1.0
  Mg  Mg3  1  0.216  0.216  0.701  1.0
  Mg  Mg4  1  0.591  0.591  0.703  1.0
  Mg  Mg5  1  0.955  0.955  0.215  1.0
  Mg  Mg6  1  0.322  0.322  0.710  1.0
  Mg  Mg7  1  0.221  0.221  0.195  1.0
  Si  Si8  1  0.044  0.044  0.463  1.0
  Si  Si9  1  0.042  0.042  0.944  1.0
  Si  Si10  1  0.499  0.499  0.493  1.0
  Si  Si11  1  0.500  0.500  0.927  1.0
  Si  Si12  1  0.771  0.771  0.952  1.0
  Si  Si13  1  0.868  0.868  0.944  1.0
  Si  Si14  1  0.411  0.411  0.928  1.0
  Si  Si15  1  0.132  0.132  0.961  1.0
  Si  Si16  1  0.674  0.674  0.424  1.0
  Si  Si17  1  0.870  0.870  0.465  1.0
  Si  Si18  1  0.411  0.411  0.485  1.0
  Si  Si19  1  0.132  0.132  0.440  1.0
  Si  Si20  1  0.676  0.676  0.977  1.0
  Si  Si21  1  0.953  0.953  0.720  1.0
[/CIF]
.
The material structure described by Mg4Si7 crystallizes in the monoclinic Cm space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to two equivalent Mg(5), one Si(13), one Si(3), one Si(4), one Si(9), two equivalent Si(1), two equivalent Si(12), two equivalent Si(2), and two equivalent Si(8) atoms. In the second Mg site, Mg(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), two equivalent Mg(8), one Si(10), one Si(9), and two equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 13-coordinate geometry to one Mg(8), two equivalent Mg(2), two equivalent Mg(7), one Si(11), one Si(7), two equivalent Si(10), two equivalent Si(5), and two equivalent Si(6) atoms. In the fourth Mg site, Mg(4) is bonded in a 13-coordinate geometry to one Mg(7), two equivalent Mg(2), two equivalent Mg(8), one Si(12), one Si(8), two equivalent Si(13), two equivalent Si(5), and two equivalent Si(9) atoms. In the fifth Mg site, Mg(5) is bonded in a 14-coordinate geometry to two equivalent Mg(1), one Si(13), one Si(3), one Si(4), one Si(9), two equivalent Si(1), two equivalent Si(12), two equivalent Si(2), and two equivalent Si(8) atoms. In the sixth Mg site, Mg(6) is bonded in a 14-coordinate geometry to one Si(1), one Si(10), one Si(2), one Si(6), two equivalent Si(11), two equivalent Si(14), two equivalent Si(3), two equivalent Si(4), and two equivalent Si(7) atoms. In the seventh Mg site, Mg(7) is bonded in a 13-coordinate geometry to one Mg(4), two equivalent Mg(2), two equivalent Mg(3), one Si(11), one Si(7), two equivalent Si(10), two equivalent Si(5), and two equivalent Si(6) atoms. In the eighth Mg site, Mg(8) is bonded in a 13-coordinate geometry to one Mg(3), two equivalent Mg(2), two equivalent Mg(4), one Si(12), one Si(8), two equivalent Si(13), two equivalent Si(5), and two equivalent Si(9) atoms. There are fourteen inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(6), two equivalent Mg(1), two equivalent Mg(5), one Si(12), one Si(2), and two equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(6), two equivalent Mg(1), two equivalent Mg(5), one Si(1), one Si(8), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(6), one Si(11), one Si(4), and two equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(6), one Si(3), one Si(7), two equivalent Si(14), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(7), two equivalent Mg(8), one Si(13), and one Si(6) atom to form a mixture of distorted corner and face-sharing SiMg10Si2 cuboctahedra. In the sixth Si site, Si(6) is bonded in a 11-coordinate geometry to one Mg(6), two equivalent Mg(3), two equivalent Mg(7), one Si(14), one Si(5), two equivalent Si(10), and two equivalent Si(7) atoms. In the seventh Si site, Si(7) is bonded in a 10-coordinate geometry to one Mg(3), one Mg(7), two equivalent Mg(6), one Si(11), one Si(4), two equivalent Si(14), and two equivalent Si(6) atoms. In the eighth Si site, Si(8) is bonded in a 10-coordinate geometry to one Mg(4), one Mg(8), two equivalent Mg(1), two equivalent Mg(5), one Si(12), one Si(2), and two equivalent Si(13) atoms. In the ninth Si site, Si(9) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(2), one Mg(5), two equivalent Mg(4), two equivalent Mg(8), one Si(13), and two equivalent Si(12) atoms. In the tenth Si site, Si(10) is bonded in a 9-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(3), two equivalent Mg(7), two equivalent Si(11), and two equivalent Si(6) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(7), two equivalent Mg(6), one Si(3), one Si(7), and two equivalent Si(10) atoms. In the twelfth Si site, Si(12) is bonded in a 10-coordinate geometry to one Mg(4), one Mg(8), two equivalent Mg(1), two equivalent Mg(5), one Si(1), one Si(8), and two equivalent Si(9) atoms. In the thirteenth Si site, Si(13) is bonded in a 10-coordinate geometry to one Mg(1), one Mg(5), two equivalent Mg(4), two equivalent Mg(8), one Si(5), one Si(9), and two equivalent Si(8) atoms. In the fourteenth Si site, Si(14) is bonded in a distorted linear geometry to two equivalent Mg(6), one Si(6), two equivalent Si(4), and two equivalent Si(7) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg4Si7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   14.769
_cell_length_b   14.769
_cell_length_c   5.688
_cell_angle_alpha   89.578
_cell_angle_beta   89.578
_cell_angle_gamma   17.227
_symmetry_Int_Tables_number   1
_cell_volume   367.454
_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  0.585  0.585  0.201  1.0
  Mg  Mg1  1  0.772  0.772  0.451  1.0
  Mg  Mg2  1  0.328  0.328  0.204  1.0
  Mg  Mg3  1  0.216  0.216  0.701  1.0
  Mg  Mg4  1  0.591  0.591  0.703  1.0
  Mg  Mg5  1  0.955  0.955  0.215  1.0
  Mg  Mg6  1  0.322  0.322  0.710  1.0
  Mg  Mg7  1  0.221  0.221  0.195  1.0
  Si  Si8  1  0.044  0.044  0.463  1.0
  Si  Si9  1  0.042  0.042  0.944  1.0
  Si  Si10  1  0.499  0.499  0.493  1.0
  Si  Si11  1  0.500  0.500  0.927  1.0
  Si  Si12  1  0.771  0.771  0.952  1.0
  Si  Si13  1  0.868  0.868  0.944  1.0
  Si  Si14  1  0.411  0.411  0.928  1.0
  Si  Si15  1  0.132  0.132  0.961  1.0
  Si  Si16  1  0.674  0.674  0.424  1.0
  Si  Si17  1  0.870  0.870  0.465  1.0
  Si  Si18  1  0.411  0.411  0.485  1.0
  Si  Si19  1  0.132  0.132  0.440  1.0
  Si  Si20  1  0.676  0.676  0.977  1.0
  Si  Si21  1  0.953  0.953  0.720  1.0
[/CIF]
.