The material described by U20Si16C3 crystallizes in the hexagonal P6/mmm space group. There are five inequivalent U sites. In the first U site, U(1) is bonded to twelve equivalent Si(2) atoms to form face-sharing USi12 cuboctahedra. In the second U site, U(2) is bonded to twelve equivalent Si(2) atoms to form face-sharing USi12 cuboctahedra. In the third U site, U(3) is bonded in a distorted single-bond geometry to two equivalent Si(1), two equivalent Si(2), and one C(1) atom. In the fourth U site, U(4) is bonded in a 8-coordinate geometry to two equivalent Si(1), four equivalent Si(2), and two equivalent C(1) atoms. In the fifth U site, U(5) is bonded in a 6-coordinate geometry to two equivalent Si(1) and four equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to three equivalent U(3), three equivalent U(4), and three equivalent U(5) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one U(1), one U(2), one U(3), two equivalent U(4), two equivalent U(5), and two equivalent Si(2) atoms. C(1) is bonded to two equivalent U(3) and four equivalent U(4) atoms to form corner-sharing CU6 octahedra. The corner-sharing octahedral tilt angles are 26°. is represented by the CIF card [CIF]
data_U20Si16C3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.337
_cell_length_b   10.337
_cell_length_c   7.858
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   727.144
_cell_formula_units_Z   1
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  0.000  0.000  0.000  1.0
  U  U1  1  0.000  0.000  0.500  1.0
  U  U2  1  0.500  0.000  0.300  1.0
  U  U3  1  0.500  0.500  0.300  1.0
  U  U4  1  0.000  0.500  0.300  1.0
  U  U5  1  0.500  0.000  0.700  1.0
  U  U6  1  0.500  0.500  0.700  1.0
  U  U7  1  0.000  0.500  0.700  1.0
  U  U8  1  0.217  0.434  0.000  1.0
  U  U9  1  0.783  0.217  0.000  1.0
  U  U10  1  0.434  0.217  0.000  1.0
  U  U11  1  0.566  0.783  0.000  1.0
  U  U12  1  0.217  0.783  0.000  1.0
  U  U13  1  0.783  0.566  0.000  1.0
  U  U14  1  0.213  0.426  0.500  1.0
  U  U15  1  0.787  0.213  0.500  1.0
  U  U16  1  0.426  0.213  0.500  1.0
  U  U17  1  0.574  0.787  0.500  1.0
  U  U18  1  0.213  0.787  0.500  1.0
  U  U19  1  0.787  0.574  0.500  1.0
  Si  Si20  1  0.333  0.667  0.254  1.0
  Si  Si21  1  0.667  0.333  0.254  1.0
  Si  Si22  1  0.667  0.333  0.746  1.0
  Si  Si23  1  0.333  0.667  0.746  1.0
  Si  Si24  1  0.227  0.000  0.249  1.0
  Si  Si25  1  0.227  0.227  0.249  1.0
  Si  Si26  1  0.000  0.773  0.249  1.0
  Si  Si27  1  0.000  0.227  0.249  1.0
  Si  Si28  1  0.773  0.773  0.249  1.0
  Si  Si29  1  0.227  0.000  0.751  1.0
  Si  Si30  1  0.773  0.773  0.751  1.0
  Si  Si31  1  0.773  0.000  0.249  1.0
  Si  Si32  1  0.000  0.227  0.751  1.0
  Si  Si33  1  0.000  0.773  0.751  1.0
  Si  Si34  1  0.773  0.000  0.751  1.0
  Si  Si35  1  0.227  0.227  0.751  1.0
  C  C36  1  0.500  0.000  0.000  1.0
  C  C37  1  0.500  0.500  0.000  1.0
  C  C38  1  0.000  0.500  0.000  1.0
[/CIF]
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The material described by U20Si16C3 crystallizes in the hexagonal P6/mmm space group. There are five inequivalent U sites. In the first U site, U(1) is bonded to twelve equivalent Si(2) atoms to form face-sharing USi12 cuboctahedra. In the second U site, U(2) is bonded to twelve equivalent Si(2) atoms to form face-sharing USi12 cuboctahedra. In the third U site, U(3) is bonded in a distorted single-bond geometry to two equivalent Si(1), two equivalent Si(2), and one C(1) atom. In the fourth U site, U(4) is bonded in a 8-coordinate geometry to two equivalent Si(1), four equivalent Si(2), and two equivalent C(1) atoms. In the fifth U site, U(5) is bonded in a 6-coordinate geometry to two equivalent Si(1) and four equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to three equivalent U(3), three equivalent U(4), and three equivalent U(5) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one U(1), one U(2), one U(3), two equivalent U(4), two equivalent U(5), and two equivalent Si(2) atoms. C(1) is bonded to two equivalent U(3) and four equivalent U(4) atoms to form corner-sharing CU6 octahedra. The corner-sharing octahedral tilt angles are 26°. is represented by the CIF card [CIF]
data_U20Si16C3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.337
_cell_length_b   10.337
_cell_length_c   7.858
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   727.144
_cell_formula_units_Z   1
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  0.000  0.000  0.000  1.0
  U  U1  1  0.000  0.000  0.500  1.0
  U  U2  1  0.500  0.000  0.300  1.0
  U  U3  1  0.500  0.500  0.300  1.0
  U  U4  1  0.000  0.500  0.300  1.0
  U  U5  1  0.500  0.000  0.700  1.0
  U  U6  1  0.500  0.500  0.700  1.0
  U  U7  1  0.000  0.500  0.700  1.0
  U  U8  1  0.217  0.434  0.000  1.0
  U  U9  1  0.783  0.217  0.000  1.0
  U  U10  1  0.434  0.217  0.000  1.0
  U  U11  1  0.566  0.783  0.000  1.0
  U  U12  1  0.217  0.783  0.000  1.0
  U  U13  1  0.783  0.566  0.000  1.0
  U  U14  1  0.213  0.426  0.500  1.0
  U  U15  1  0.787  0.213  0.500  1.0
  U  U16  1  0.426  0.213  0.500  1.0
  U  U17  1  0.574  0.787  0.500  1.0
  U  U18  1  0.213  0.787  0.500  1.0
  U  U19  1  0.787  0.574  0.500  1.0
  Si  Si20  1  0.333  0.667  0.254  1.0
  Si  Si21  1  0.667  0.333  0.254  1.0
  Si  Si22  1  0.667  0.333  0.746  1.0
  Si  Si23  1  0.333  0.667  0.746  1.0
  Si  Si24  1  0.227  0.000  0.249  1.0
  Si  Si25  1  0.227  0.227  0.249  1.0
  Si  Si26  1  0.000  0.773  0.249  1.0
  Si  Si27  1  0.000  0.227  0.249  1.0
  Si  Si28  1  0.773  0.773  0.249  1.0
  Si  Si29  1  0.227  0.000  0.751  1.0
  Si  Si30  1  0.773  0.773  0.751  1.0
  Si  Si31  1  0.773  0.000  0.249  1.0
  Si  Si32  1  0.000  0.227  0.751  1.0
  Si  Si33  1  0.000  0.773  0.751  1.0
  Si  Si34  1  0.773  0.000  0.751  1.0
  Si  Si35  1  0.227  0.227  0.751  1.0
  C  C36  1  0.500  0.000  0.000  1.0
  C  C37  1  0.500  0.500  0.000  1.0
  C  C38  1  0.000  0.500  0.000  1.0
[/CIF]
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