The material structure described by U3Al2Si3 crystallizes in the tetragonal I4cm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 10-coordinate geometry to four equivalent Al(1), two equivalent Si(1), and four equivalent Si(2) atoms. In the second U site, U(2) is bonded in a 8-coordinate geometry to three equivalent Al(1), two equivalent Si(1), and three equivalent Si(2) atoms. Al(1) is bonded in a 3-coordinate geometry to two equivalent U(1), three equivalent U(2), and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent U(1) and four equivalent U(2) atoms to form corner-sharing SiU6 octahedra. The corner-sharing octahedral tilt angles range from 0-45°. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent U(1), three equivalent U(2), and three equivalent Al(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_U3Al2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.650
_cell_length_b   7.650
_cell_length_c   7.650
_cell_angle_alpha   120.669
_cell_angle_beta   120.669
_cell_angle_gamma   88.846
_symmetry_Int_Tables_number   1
_cell_volume   313.270
_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  0.759  0.759  0.000  1.0
  U  U1  1  0.259  0.259  0.000  1.0
  U  U2  1  0.819  0.626  0.500  1.0
  U  U3  1  0.126  0.319  0.500  1.0
  U  U4  1  0.626  0.126  0.807  1.0
  U  U5  1  0.319  0.819  0.193  1.0
  Al  Al6  1  0.527  0.308  0.500  1.0
  Al  Al7  1  0.808  0.027  0.500  1.0
  Al  Al8  1  0.308  0.808  0.781  1.0
  Al  Al9  1  0.027  0.527  0.219  1.0
  Si  Si10  1  0.011  0.011  0.000  1.0
  Si  Si11  1  0.511  0.511  0.000  1.0
  Si  Si12  1  0.439  0.640  0.500  1.0
  Si  Si13  1  0.140  0.939  0.500  1.0
  Si  Si14  1  0.640  0.140  0.200  1.0
  Si  Si15  1  0.939  0.439  0.800  1.0
[/CIF]
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The material structure described by U3Al2Si3 crystallizes in the tetragonal I4cm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a 10-coordinate geometry to four equivalent Al(1), two equivalent Si(1), and four equivalent Si(2) atoms. In the second U site, U(2) is bonded in a 8-coordinate geometry to three equivalent Al(1), two equivalent Si(1), and three equivalent Si(2) atoms. Al(1) is bonded in a 3-coordinate geometry to two equivalent U(1), three equivalent U(2), and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent U(1) and four equivalent U(2) atoms to form corner-sharing SiU6 octahedra. The corner-sharing octahedral tilt angles range from 0-45°. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent U(1), three equivalent U(2), and three equivalent Al(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_U3Al2Si3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.650
_cell_length_b   7.650
_cell_length_c   7.650
_cell_angle_alpha   120.669
_cell_angle_beta   120.669
_cell_angle_gamma   88.846
_symmetry_Int_Tables_number   1
_cell_volume   313.270
_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  0.759  0.759  0.000  1.0
  U  U1  1  0.259  0.259  0.000  1.0
  U  U2  1  0.819  0.626  0.500  1.0
  U  U3  1  0.126  0.319  0.500  1.0
  U  U4  1  0.626  0.126  0.807  1.0
  U  U5  1  0.319  0.819  0.193  1.0
  Al  Al6  1  0.527  0.308  0.500  1.0
  Al  Al7  1  0.808  0.027  0.500  1.0
  Al  Al8  1  0.308  0.808  0.781  1.0
  Al  Al9  1  0.027  0.527  0.219  1.0
  Si  Si10  1  0.011  0.011  0.000  1.0
  Si  Si11  1  0.511  0.511  0.000  1.0
  Si  Si12  1  0.439  0.640  0.500  1.0
  Si  Si13  1  0.140  0.939  0.500  1.0
  Si  Si14  1  0.640  0.140  0.200  1.0
  Si  Si15  1  0.939  0.439  0.800  1.0
[/CIF]
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