The material structure described by UNi2Si3 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 16-coordinate geometry to four equivalent Ni(1), four equivalent Ni(2), four equivalent Si(1), and four equivalent Si(2) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent U(1), four equivalent Ni(1), and four equivalent Si(2) atoms to form a mixture of distorted corner and face-sharing NiU4Si4Ni4 cuboctahedra. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(1), one Si(2), and four equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent U(1), two equivalent Ni(2), and five equivalent Si(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent U(1), one Ni(2), and four equivalent Ni(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_USi3Ni2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.114
_cell_length_b   12.114
_cell_length_c   12.114
_cell_angle_alpha   161.531
_cell_angle_beta   161.531
_cell_angle_gamma   26.235
_symmetry_Int_Tables_number   1
_cell_volume   178.358
_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
  U  U0  1  0.850  0.850  0.000  1.0
  U  U1  1  0.150  0.150  0.000  1.0
  Si  Si2  1  0.950  0.450  0.500  1.0
  Si  Si3  1  0.450  0.950  0.500  1.0
  Si  Si4  1  0.050  0.550  0.500  1.0
  Si  Si5  1  0.550  0.050  0.500  1.0
  Si  Si6  1  0.697  0.697  0.000  1.0
  Si  Si7  1  0.303  0.303  0.000  1.0
  Ni  Ni8  1  0.750  0.250  0.500  1.0
  Ni  Ni9  1  0.250  0.750  0.500  1.0
  Ni  Ni10  1  0.600  0.600  0.000  1.0
  Ni  Ni11  1  0.400  0.400  0.000  1.0
[/CIF]
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The material structure described by UNi2Si3 crystallizes in the tetragonal I4/mmm space group. U(1) is bonded in a 16-coordinate geometry to four equivalent Ni(1), four equivalent Ni(2), four equivalent Si(1), and four equivalent Si(2) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent U(1), four equivalent Ni(1), and four equivalent Si(2) atoms to form a mixture of distorted corner and face-sharing NiU4Si4Ni4 cuboctahedra. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to four equivalent U(1), one Si(2), and four equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent U(1), two equivalent Ni(2), and five equivalent Si(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent U(1), one Ni(2), and four equivalent Ni(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_USi3Ni2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.114
_cell_length_b   12.114
_cell_length_c   12.114
_cell_angle_alpha   161.531
_cell_angle_beta   161.531
_cell_angle_gamma   26.235
_symmetry_Int_Tables_number   1
_cell_volume   178.358
_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
  U  U0  1  0.850  0.850  0.000  1.0
  U  U1  1  0.150  0.150  0.000  1.0
  Si  Si2  1  0.950  0.450  0.500  1.0
  Si  Si3  1  0.450  0.950  0.500  1.0
  Si  Si4  1  0.050  0.550  0.500  1.0
  Si  Si5  1  0.550  0.050  0.500  1.0
  Si  Si6  1  0.697  0.697  0.000  1.0
  Si  Si7  1  0.303  0.303  0.000  1.0
  Ni  Ni8  1  0.750  0.250  0.500  1.0
  Ni  Ni9  1  0.250  0.750  0.500  1.0
  Ni  Ni10  1  0.600  0.600  0.000  1.0
  Ni  Ni11  1  0.400  0.400  0.000  1.0
[/CIF]
.