The crystal structure described by Na2Si2Se5 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(5), two equivalent Se(2), and two equivalent Se(4) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one Se(1), one Se(5), and two equivalent Se(4) atoms to form corner-sharing SiSe4 tetrahedra. In the second Si site, Si(2) is bonded to one Se(2), one Se(3), and two equivalent Se(4) atoms to form corner-sharing SiSe4 tetrahedra. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), two equivalent Na(2), and one Si(1) atom to form distorted SeNa3Si tetrahedra that share corners with six equivalent Se(2)Na4Si square pyramids and corners with two equivalent Se(1)Na3Si tetrahedra. In the second Se site, Se(2) is bonded to two equivalent Na(1), two equivalent Na(2), and one Si(2) atom to form distorted SeNa4Si square pyramids that share corners with six equivalent Se(1)Na3Si tetrahedra and edges with two equivalent Se(2)Na4Si square pyramids. In the third Se site, Se(3) is bonded in a water-like geometry to two equivalent Si(2) atoms. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the fifth Se site, Se(5) is bonded in a distorted water-like geometry to two equivalent Na(1) and two equivalent Si(1) atoms. is represented by the CIF file [CIF]
data_Na2Si2Se5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.430
_cell_length_b   9.430
_cell_length_c   10.962
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   89.800
_symmetry_Int_Tables_number   1
_cell_volume   974.827
_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
  Na  Na0  1  0.579  0.079  0.750  1.0
  Na  Na1  1  0.421  0.921  0.250  1.0
  Na  Na2  1  0.921  0.421  0.750  1.0
  Na  Na3  1  0.079  0.579  0.250  1.0
  Na  Na4  1  0.148  0.148  0.500  1.0
  Na  Na5  1  0.852  0.852  0.000  1.0
  Na  Na6  1  0.852  0.852  0.500  1.0
  Na  Na7  1  0.148  0.148  0.000  1.0
  Si  Si8  1  0.585  0.686  0.750  1.0
  Si  Si9  1  0.415  0.314  0.250  1.0
  Si  Si10  1  0.314  0.415  0.750  1.0
  Si  Si11  1  0.686  0.585  0.250  1.0
  Si  Si12  1  0.254  0.746  0.917  1.0
  Si  Si13  1  0.746  0.254  0.417  1.0
  Si  Si14  1  0.254  0.746  0.583  1.0
  Si  Si15  1  0.746  0.254  0.083  1.0
  Se  Se16  1  0.729  0.814  0.250  1.0
  Se  Se17  1  0.271  0.186  0.750  1.0
  Se  Se18  1  0.186  0.271  0.250  1.0
  Se  Se19  1  0.814  0.729  0.750  1.0
  Se  Se20  1  0.158  0.842  0.082  1.0
  Se  Se21  1  0.842  0.158  0.582  1.0
  Se  Se22  1  0.158  0.842  0.418  1.0
  Se  Se23  1  0.842  0.158  0.918  1.0
  Se  Se24  1  0.152  0.848  0.750  1.0
  Se  Se25  1  0.848  0.152  0.250  1.0
  Se  Se26  1  0.507  0.208  0.078  1.0
  Se  Se27  1  0.493  0.792  0.578  1.0
  Se  Se28  1  0.792  0.493  0.422  1.0
  Se  Se29  1  0.208  0.507  0.922  1.0
  Se  Se30  1  0.493  0.792  0.922  1.0
  Se  Se31  1  0.507  0.208  0.422  1.0
  Se  Se32  1  0.208  0.507  0.578  1.0
  Se  Se33  1  0.792  0.493  0.078  1.0
  Se  Se34  1  0.553  0.447  0.750  1.0
  Se  Se35  1  0.447  0.553  0.250  1.0
[/CIF]
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The crystal structure described by Na2Si2Se5 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(5), two equivalent Se(2), and two equivalent Se(4) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(4) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one Se(1), one Se(5), and two equivalent Se(4) atoms to form corner-sharing SiSe4 tetrahedra. In the second Si site, Si(2) is bonded to one Se(2), one Se(3), and two equivalent Se(4) atoms to form corner-sharing SiSe4 tetrahedra. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), two equivalent Na(2), and one Si(1) atom to form distorted SeNa3Si tetrahedra that share corners with six equivalent Se(2)Na4Si square pyramids and corners with two equivalent Se(1)Na3Si tetrahedra. In the second Se site, Se(2) is bonded to two equivalent Na(1), two equivalent Na(2), and one Si(2) atom to form distorted SeNa4Si square pyramids that share corners with six equivalent Se(1)Na3Si tetrahedra and edges with two equivalent Se(2)Na4Si square pyramids. In the third Se site, Se(3) is bonded in a water-like geometry to two equivalent Si(2) atoms. In the fourth Se site, Se(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the fifth Se site, Se(5) is bonded in a distorted water-like geometry to two equivalent Na(1) and two equivalent Si(1) atoms. is represented by the CIF file [CIF]
data_Na2Si2Se5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.430
_cell_length_b   9.430
_cell_length_c   10.962
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   89.800
_symmetry_Int_Tables_number   1
_cell_volume   974.827
_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
  Na  Na0  1  0.579  0.079  0.750  1.0
  Na  Na1  1  0.421  0.921  0.250  1.0
  Na  Na2  1  0.921  0.421  0.750  1.0
  Na  Na3  1  0.079  0.579  0.250  1.0
  Na  Na4  1  0.148  0.148  0.500  1.0
  Na  Na5  1  0.852  0.852  0.000  1.0
  Na  Na6  1  0.852  0.852  0.500  1.0
  Na  Na7  1  0.148  0.148  0.000  1.0
  Si  Si8  1  0.585  0.686  0.750  1.0
  Si  Si9  1  0.415  0.314  0.250  1.0
  Si  Si10  1  0.314  0.415  0.750  1.0
  Si  Si11  1  0.686  0.585  0.250  1.0
  Si  Si12  1  0.254  0.746  0.917  1.0
  Si  Si13  1  0.746  0.254  0.417  1.0
  Si  Si14  1  0.254  0.746  0.583  1.0
  Si  Si15  1  0.746  0.254  0.083  1.0
  Se  Se16  1  0.729  0.814  0.250  1.0
  Se  Se17  1  0.271  0.186  0.750  1.0
  Se  Se18  1  0.186  0.271  0.250  1.0
  Se  Se19  1  0.814  0.729  0.750  1.0
  Se  Se20  1  0.158  0.842  0.082  1.0
  Se  Se21  1  0.842  0.158  0.582  1.0
  Se  Se22  1  0.158  0.842  0.418  1.0
  Se  Se23  1  0.842  0.158  0.918  1.0
  Se  Se24  1  0.152  0.848  0.750  1.0
  Se  Se25  1  0.848  0.152  0.250  1.0
  Se  Se26  1  0.507  0.208  0.078  1.0
  Se  Se27  1  0.493  0.792  0.578  1.0
  Se  Se28  1  0.792  0.493  0.422  1.0
  Se  Se29  1  0.208  0.507  0.922  1.0
  Se  Se30  1  0.493  0.792  0.922  1.0
  Se  Se31  1  0.507  0.208  0.422  1.0
  Se  Se32  1  0.208  0.507  0.578  1.0
  Se  Se33  1  0.792  0.493  0.078  1.0
  Se  Se34  1  0.553  0.447  0.750  1.0
  Se  Se35  1  0.447  0.553  0.250  1.0
[/CIF]
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