The structure described by MgSi2Sr crystallizes in the orthorhombic Pnma space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 14-coordinate geometry to one Mg(1), three equivalent Mg(2), two equivalent Si(1), two equivalent Si(4), three equivalent Si(2), and three equivalent Si(3) atoms. In the second Sr site, Sr(2) is bonded in a 14-coordinate geometry to two equivalent Mg(2), three equivalent Mg(1), two equivalent Si(1), two equivalent Si(3), two equivalent Si(4), and three equivalent Si(2) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Sr(1), three equivalent Sr(2), one Si(4), and three equivalent Si(1) atoms to form a mixture of edge and face-sharing MgSr4Si4 tetrahedra. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to two equivalent Sr(2), three equivalent Sr(1), one Si(1), two equivalent Si(3), and two 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 two equivalent Sr(1), two equivalent Sr(2), one Mg(2), three equivalent Mg(1), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Sr(1), three equivalent Sr(2), one Si(4), and two equivalent Si(2) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Sr(2), three equivalent Sr(1), two equivalent Mg(2), one Si(1), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Mg(1), two equivalent Mg(2), one Si(2), and one Si(3) atom. is represented by the CIF card [CIF]
data_SrMgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.461
_cell_length_b   11.370
_cell_length_c   14.377
_cell_angle_alpha   89.999
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   729.158
_cell_formula_units_Z   8
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
  Sr  Sr0  1  0.250  0.522  0.195  1.0
  Sr  Sr1  1  0.250  0.739  0.938  1.0
  Sr  Sr2  1  0.750  0.261  0.062  1.0
  Sr  Sr3  1  0.750  0.239  0.562  1.0
  Sr  Sr4  1  0.250  0.761  0.438  1.0
  Sr  Sr5  1  0.250  0.978  0.695  1.0
  Sr  Sr6  1  0.750  0.022  0.305  1.0
  Sr  Sr7  1  0.750  0.478  0.805  1.0
  Mg  Mg8  1  0.250  0.440  0.441  1.0
  Mg  Mg9  1  0.750  0.560  0.559  1.0
  Mg  Mg10  1  0.750  0.940  0.059  1.0
  Mg  Mg11  1  0.250  0.060  0.941  1.0
  Mg  Mg12  1  0.250  0.680  0.689  1.0
  Mg  Mg13  1  0.750  0.320  0.311  1.0
  Mg  Mg14  1  0.750  0.180  0.810  1.0
  Mg  Mg15  1  0.250  0.820  0.190  1.0
  Si  Si16  1  0.750  0.953  0.868  1.0
  Si  Si17  1  0.250  0.453  0.632  1.0
  Si  Si18  1  0.750  0.547  0.368  1.0
  Si  Si19  1  0.250  0.029  0.471  1.0
  Si  Si20  1  0.250  0.047  0.132  1.0
  Si  Si21  1  0.250  0.276  0.723  1.0
  Si  Si22  1  0.750  0.724  0.277  1.0
  Si  Si23  1  0.750  0.776  0.776  1.0
  Si  Si24  1  0.250  0.210  0.393  1.0
  Si  Si25  1  0.750  0.971  0.529  1.0
  Si  Si26  1  0.750  0.529  0.029  1.0
  Si  Si27  1  0.250  0.471  0.971  1.0
  Si  Si28  1  0.250  0.290  0.893  1.0
  Si  Si29  1  0.750  0.790  0.607  1.0
  Si  Si30  1  0.750  0.710  0.107  1.0
  Si  Si31  1  0.250  0.224  0.224  1.0
[/CIF]
.
The structure described by MgSi2Sr crystallizes in the orthorhombic Pnma space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 14-coordinate geometry to one Mg(1), three equivalent Mg(2), two equivalent Si(1), two equivalent Si(4), three equivalent Si(2), and three equivalent Si(3) atoms. In the second Sr site, Sr(2) is bonded in a 14-coordinate geometry to two equivalent Mg(2), three equivalent Mg(1), two equivalent Si(1), two equivalent Si(3), two equivalent Si(4), and three equivalent Si(2) atoms. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Sr(1), three equivalent Sr(2), one Si(4), and three equivalent Si(1) atoms to form a mixture of edge and face-sharing MgSr4Si4 tetrahedra. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to two equivalent Sr(2), three equivalent Sr(1), one Si(1), two equivalent Si(3), and two 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 two equivalent Sr(1), two equivalent Sr(2), one Mg(2), three equivalent Mg(1), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Sr(1), three equivalent Sr(2), one Si(4), and two equivalent Si(2) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Sr(2), three equivalent Sr(1), two equivalent Mg(2), one Si(1), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Mg(1), two equivalent Mg(2), one Si(2), and one Si(3) atom. is represented by the CIF card [CIF]
data_SrMgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.461
_cell_length_b   11.370
_cell_length_c   14.377
_cell_angle_alpha   89.999
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   729.158
_cell_formula_units_Z   8
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
  Sr  Sr0  1  0.250  0.522  0.195  1.0
  Sr  Sr1  1  0.250  0.739  0.938  1.0
  Sr  Sr2  1  0.750  0.261  0.062  1.0
  Sr  Sr3  1  0.750  0.239  0.562  1.0
  Sr  Sr4  1  0.250  0.761  0.438  1.0
  Sr  Sr5  1  0.250  0.978  0.695  1.0
  Sr  Sr6  1  0.750  0.022  0.305  1.0
  Sr  Sr7  1  0.750  0.478  0.805  1.0
  Mg  Mg8  1  0.250  0.440  0.441  1.0
  Mg  Mg9  1  0.750  0.560  0.559  1.0
  Mg  Mg10  1  0.750  0.940  0.059  1.0
  Mg  Mg11  1  0.250  0.060  0.941  1.0
  Mg  Mg12  1  0.250  0.680  0.689  1.0
  Mg  Mg13  1  0.750  0.320  0.311  1.0
  Mg  Mg14  1  0.750  0.180  0.810  1.0
  Mg  Mg15  1  0.250  0.820  0.190  1.0
  Si  Si16  1  0.750  0.953  0.868  1.0
  Si  Si17  1  0.250  0.453  0.632  1.0
  Si  Si18  1  0.750  0.547  0.368  1.0
  Si  Si19  1  0.250  0.029  0.471  1.0
  Si  Si20  1  0.250  0.047  0.132  1.0
  Si  Si21  1  0.250  0.276  0.723  1.0
  Si  Si22  1  0.750  0.724  0.277  1.0
  Si  Si23  1  0.750  0.776  0.776  1.0
  Si  Si24  1  0.250  0.210  0.393  1.0
  Si  Si25  1  0.750  0.971  0.529  1.0
  Si  Si26  1  0.750  0.529  0.029  1.0
  Si  Si27  1  0.250  0.471  0.971  1.0
  Si  Si28  1  0.250  0.290  0.893  1.0
  Si  Si29  1  0.750  0.790  0.607  1.0
  Si  Si30  1  0.750  0.710  0.107  1.0
  Si  Si31  1  0.250  0.224  0.224  1.0
[/CIF]
.