The crystal structure described by Mg9Sn5 crystallizes in the trigonal R3 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Sn(4), one Sn(5), and two equivalent Sn(6) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. In the second Mg site, Mg(2) is bonded to one Sn(3), one Sn(6), and two equivalent Sn(5) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Sn(2), one Sn(4), one Sn(6), and two equivalent Sn(5) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Sn(1), one Sn(3), one Sn(5), and two equivalent Sn(6) atoms. In the fifth Mg site, Mg(5) is bonded to one Sn(2), one Sn(5), and two equivalent Sn(6) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. In the sixth Mg site, Mg(6) is bonded to one Sn(1), one Sn(6), and two equivalent Sn(5) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. There are six inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 6-coordinate geometry to three equivalent Mg(4) and three equivalent Mg(6) atoms. In the second Sn site, Sn(2) is bonded in a 6-coordinate geometry to three equivalent Mg(3) and three equivalent Mg(5) atoms. In the third Sn site, Sn(3) is bonded in a 6-coordinate geometry to three equivalent Mg(2) and three equivalent Mg(4) atoms. In the fourth Sn site, Sn(4) is bonded in a 6-coordinate geometry to three equivalent Mg(1) and three equivalent Mg(3) atoms. In the fifth Sn site, Sn(5) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(4), one Mg(5), two equivalent Mg(2), two equivalent Mg(3), and two equivalent Mg(6) atoms. In the sixth Sn site, Sn(6) is bonded in a 9-coordinate geometry to one Mg(2), one Mg(3), one Mg(6), two equivalent Mg(1), two equivalent Mg(4), and two equivalent Mg(5) atoms. is represented by the CIF card [CIF]
data_Mg9Sn5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.888
_cell_length_b   8.888
_cell_length_c   8.888
_cell_angle_alpha   96.875
_cell_angle_beta   96.875
_cell_angle_gamma   96.875
_symmetry_Int_Tables_number   1
_cell_volume   685.724
_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  0.752  0.349  0.660  1.0
  Mg  Mg1  1  0.349  0.660  0.752  1.0
  Mg  Mg2  1  0.660  0.752  0.349  1.0
  Mg  Mg3  1  0.257  0.662  0.349  1.0
  Mg  Mg4  1  0.662  0.349  0.257  1.0
  Mg  Mg5  1  0.349  0.257  0.662  1.0
  Mg  Mg6  1  0.606  0.979  0.676  1.0
  Mg  Mg7  1  0.979  0.676  0.606  1.0
  Mg  Mg8  1  0.676  0.606  0.979  1.0
  Mg  Mg9  1  0.404  0.031  0.334  1.0
  Mg  Mg10  1  0.082  0.680  0.999  1.0
  Mg  Mg11  1  0.999  0.082  0.680  1.0
  Mg  Mg12  1  0.680  0.999  0.082  1.0
  Mg  Mg13  1  0.928  0.328  0.010  1.0
  Mg  Mg14  1  0.010  0.928  0.328  1.0
  Mg  Mg15  1  0.328  0.010  0.928  1.0
  Mg  Mg16  1  0.334  0.404  0.031  1.0
  Mg  Mg17  1  0.031  0.334  0.404  1.0
  Sn  Sn18  1  0.139  0.139  0.139  1.0
  Sn  Sn19  1  0.875  0.875  0.875  1.0
  Sn  Sn20  1  0.375  0.375  0.375  1.0
  Sn  Sn21  1  0.638  0.638  0.638  1.0
  Sn  Sn22  1  0.593  0.255  0.917  1.0
  Sn  Sn23  1  0.255  0.917  0.593  1.0
  Sn  Sn24  1  0.917  0.593  0.255  1.0
  Sn  Sn25  1  0.417  0.755  0.093  1.0
  Sn  Sn26  1  0.755  0.093  0.417  1.0
  Sn  Sn27  1  0.093  0.417  0.755  1.0
[/CIF]
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The crystal structure described by Mg9Sn5 crystallizes in the trigonal R3 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Sn(4), one Sn(5), and two equivalent Sn(6) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. In the second Mg site, Mg(2) is bonded to one Sn(3), one Sn(6), and two equivalent Sn(5) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Sn(2), one Sn(4), one Sn(6), and two equivalent Sn(5) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Sn(1), one Sn(3), one Sn(5), and two equivalent Sn(6) atoms. In the fifth Mg site, Mg(5) is bonded to one Sn(2), one Sn(5), and two equivalent Sn(6) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. In the sixth Mg site, Mg(6) is bonded to one Sn(1), one Sn(6), and two equivalent Sn(5) atoms to form a mixture of distorted corner and edge-sharing MgSn4 tetrahedra. There are six inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 6-coordinate geometry to three equivalent Mg(4) and three equivalent Mg(6) atoms. In the second Sn site, Sn(2) is bonded in a 6-coordinate geometry to three equivalent Mg(3) and three equivalent Mg(5) atoms. In the third Sn site, Sn(3) is bonded in a 6-coordinate geometry to three equivalent Mg(2) and three equivalent Mg(4) atoms. In the fourth Sn site, Sn(4) is bonded in a 6-coordinate geometry to three equivalent Mg(1) and three equivalent Mg(3) atoms. In the fifth Sn site, Sn(5) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(4), one Mg(5), two equivalent Mg(2), two equivalent Mg(3), and two equivalent Mg(6) atoms. In the sixth Sn site, Sn(6) is bonded in a 9-coordinate geometry to one Mg(2), one Mg(3), one Mg(6), two equivalent Mg(1), two equivalent Mg(4), and two equivalent Mg(5) atoms. is represented by the CIF card [CIF]
data_Mg9Sn5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.888
_cell_length_b   8.888
_cell_length_c   8.888
_cell_angle_alpha   96.875
_cell_angle_beta   96.875
_cell_angle_gamma   96.875
_symmetry_Int_Tables_number   1
_cell_volume   685.724
_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  0.752  0.349  0.660  1.0
  Mg  Mg1  1  0.349  0.660  0.752  1.0
  Mg  Mg2  1  0.660  0.752  0.349  1.0
  Mg  Mg3  1  0.257  0.662  0.349  1.0
  Mg  Mg4  1  0.662  0.349  0.257  1.0
  Mg  Mg5  1  0.349  0.257  0.662  1.0
  Mg  Mg6  1  0.606  0.979  0.676  1.0
  Mg  Mg7  1  0.979  0.676  0.606  1.0
  Mg  Mg8  1  0.676  0.606  0.979  1.0
  Mg  Mg9  1  0.404  0.031  0.334  1.0
  Mg  Mg10  1  0.082  0.680  0.999  1.0
  Mg  Mg11  1  0.999  0.082  0.680  1.0
  Mg  Mg12  1  0.680  0.999  0.082  1.0
  Mg  Mg13  1  0.928  0.328  0.010  1.0
  Mg  Mg14  1  0.010  0.928  0.328  1.0
  Mg  Mg15  1  0.328  0.010  0.928  1.0
  Mg  Mg16  1  0.334  0.404  0.031  1.0
  Mg  Mg17  1  0.031  0.334  0.404  1.0
  Sn  Sn18  1  0.139  0.139  0.139  1.0
  Sn  Sn19  1  0.875  0.875  0.875  1.0
  Sn  Sn20  1  0.375  0.375  0.375  1.0
  Sn  Sn21  1  0.638  0.638  0.638  1.0
  Sn  Sn22  1  0.593  0.255  0.917  1.0
  Sn  Sn23  1  0.255  0.917  0.593  1.0
  Sn  Sn24  1  0.917  0.593  0.255  1.0
  Sn  Sn25  1  0.417  0.755  0.093  1.0
  Sn  Sn26  1  0.755  0.093  0.417  1.0
  Sn  Sn27  1  0.093  0.417  0.755  1.0
[/CIF]
.