The crystal structure described by UFe7Al3Si2 is beta Uranium-derived structured and crystallizes in the monoclinic Cm space group. U(1) is bonded in a 20-coordinate geometry to one Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), four equivalent Fe(6), one Al(1), one Al(2), one Al(3), and four equivalent Si(1) atoms. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 14-coordinate geometry to one U(1), one Fe(4), one Fe(5), two equivalent Fe(3), two equivalent Fe(6), one Al(1), two equivalent Al(2), two equivalent Al(3), and two equivalent Si(1) atoms. In the second Fe site, Fe(2) is bonded to two equivalent U(1), one Fe(4), one Fe(5), two equivalent Fe(6), one Al(2), one Al(3), two equivalent Al(1), and two equivalent Si(1) atoms to form distorted FeU2Al4Fe4Si2 cuboctahedra that share corners with four equivalent Si(1)U2Al3Fe5Si2 cuboctahedra, edges with two equivalent Fe(2)U2Al4Fe4Si2 cuboctahedra, edges with two equivalent Si(1)U2Al3Fe5Si2 cuboctahedra, and faces with four equivalent Si(1)U2Al3Fe5Si2 cuboctahedra. In the third Fe site, Fe(3) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(4), one Fe(5), two equivalent Fe(1), two equivalent Fe(6), one Al(2), one Al(3), and two equivalent Si(1) atoms. In the fourth Fe site, Fe(4) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), two equivalent Fe(6), one Al(1), two equivalent Al(3), and two equivalent Si(1) atoms. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), two equivalent Fe(6), one Al(1), two equivalent Al(2), and two equivalent Si(1) atoms. In the sixth Fe site, Fe(6) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), two equivalent Fe(6), one Al(1), one Al(2), and one Al(3) atom. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 14-coordinate geometry to one U(1), one Fe(1), one Fe(4), one Fe(5), two equivalent Fe(2), two equivalent Fe(6), two equivalent Al(2), two equivalent Al(3), and two equivalent Si(1) atoms. In the second Al site, Al(2) is bonded in a 14-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), one Al(3), two equivalent Al(1), and two equivalent Si(1) atoms. In the third Al site, Al(3) is bonded in a 14-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(6), one Al(2), two equivalent Al(1), and two equivalent Si(1) atoms. Si(1) is bonded to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Al(1), one Al(2), one Al(3), and two equivalent Si(1) atoms to form distorted SiU2Al3Fe5Si2 cuboctahedra that share corners with two equivalent Fe(2)U2Al4Fe4Si2 cuboctahedra, corners with six equivalent Si(1)U2Al3Fe5Si2 cuboctahedra,  an edgeedge with one Fe(2)U2Al4Fe4Si2 cuboctahedra, faces with two equivalent Fe(2)U2Al4Fe4Si2 cuboctahedra, and faces with two equivalent Si(1)U2Al3Fe5Si2 cuboctahedra. is represented by the CIF file [CIF]
data_UAl3Fe7Si2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.720
_cell_length_b   6.322
_cell_length_c   6.418
_cell_angle_alpha   97.165
_cell_angle_beta   111.576
_cell_angle_gamma   68.081
_symmetry_Int_Tables_number   1
_cell_volume   165.179
_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  0.991  0.009  0.991  1.0
  Al  Al1  1  0.361  0.649  0.370  1.0
  Al  Al2  1  0.009  0.343  0.360  1.0
  Al  Al3  1  0.990  0.657  0.638  1.0
  Fe  Fe4  1  0.665  0.334  0.664  1.0
  Fe  Fe5  1  0.724  0.769  0.217  1.0
  Fe  Fe6  1  0.277  0.223  0.777  1.0
  Fe  Fe7  1  0.502  0.777  0.781  1.0
  Fe  Fe8  1  0.491  0.230  0.213  1.0
  Fe  Fe9  1  0.506  0.005  0.502  1.0
  Fe  Fe10  1  0.991  0.005  0.502  1.0
  Si  Si11  1  0.498  0.499  0.993  1.0
  Si  Si12  1  0.995  0.499  0.993  1.0
[/CIF]
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The crystal structure described by UFe7Al3Si2 is beta Uranium-derived structured and crystallizes in the monoclinic Cm space group. U(1) is bonded in a 20-coordinate geometry to one Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), four equivalent Fe(6), one Al(1), one Al(2), one Al(3), and four equivalent Si(1) atoms. There are six inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 14-coordinate geometry to one U(1), one Fe(4), one Fe(5), two equivalent Fe(3), two equivalent Fe(6), one Al(1), two equivalent Al(2), two equivalent Al(3), and two equivalent Si(1) atoms. In the second Fe site, Fe(2) is bonded to two equivalent U(1), one Fe(4), one Fe(5), two equivalent Fe(6), one Al(2), one Al(3), two equivalent Al(1), and two equivalent Si(1) atoms to form distorted FeU2Al4Fe4Si2 cuboctahedra that share corners with four equivalent Si(1)U2Al3Fe5Si2 cuboctahedra, edges with two equivalent Fe(2)U2Al4Fe4Si2 cuboctahedra, edges with two equivalent Si(1)U2Al3Fe5Si2 cuboctahedra, and faces with four equivalent Si(1)U2Al3Fe5Si2 cuboctahedra. In the third Fe site, Fe(3) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(4), one Fe(5), two equivalent Fe(1), two equivalent Fe(6), one Al(2), one Al(3), and two equivalent Si(1) atoms. In the fourth Fe site, Fe(4) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), two equivalent Fe(6), one Al(1), two equivalent Al(3), and two equivalent Si(1) atoms. In the fifth Fe site, Fe(5) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), two equivalent Fe(6), one Al(1), two equivalent Al(2), and two equivalent Si(1) atoms. In the sixth Fe site, Fe(6) is bonded in a 12-coordinate geometry to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), two equivalent Fe(6), one Al(1), one Al(2), and one Al(3) atom. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 14-coordinate geometry to one U(1), one Fe(1), one Fe(4), one Fe(5), two equivalent Fe(2), two equivalent Fe(6), two equivalent Al(2), two equivalent Al(3), and two equivalent Si(1) atoms. In the second Al site, Al(2) is bonded in a 14-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), two equivalent Fe(5), two equivalent Fe(6), one Al(3), two equivalent Al(1), and two equivalent Si(1) atoms. In the third Al site, Al(3) is bonded in a 14-coordinate geometry to one U(1), one Fe(2), one Fe(3), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(6), one Al(2), two equivalent Al(1), and two equivalent Si(1) atoms. Si(1) is bonded to two equivalent U(1), one Fe(1), one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Al(1), one Al(2), one Al(3), and two equivalent Si(1) atoms to form distorted SiU2Al3Fe5Si2 cuboctahedra that share corners with two equivalent Fe(2)U2Al4Fe4Si2 cuboctahedra, corners with six equivalent Si(1)U2Al3Fe5Si2 cuboctahedra,  an edgeedge with one Fe(2)U2Al4Fe4Si2 cuboctahedra, faces with two equivalent Fe(2)U2Al4Fe4Si2 cuboctahedra, and faces with two equivalent Si(1)U2Al3Fe5Si2 cuboctahedra. is represented by the CIF file [CIF]
data_UAl3Fe7Si2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.720
_cell_length_b   6.322
_cell_length_c   6.418
_cell_angle_alpha   97.165
_cell_angle_beta   111.576
_cell_angle_gamma   68.081
_symmetry_Int_Tables_number   1
_cell_volume   165.179
_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  0.991  0.009  0.991  1.0
  Al  Al1  1  0.361  0.649  0.370  1.0
  Al  Al2  1  0.009  0.343  0.360  1.0
  Al  Al3  1  0.990  0.657  0.638  1.0
  Fe  Fe4  1  0.665  0.334  0.664  1.0
  Fe  Fe5  1  0.724  0.769  0.217  1.0
  Fe  Fe6  1  0.277  0.223  0.777  1.0
  Fe  Fe7  1  0.502  0.777  0.781  1.0
  Fe  Fe8  1  0.491  0.230  0.213  1.0
  Fe  Fe9  1  0.506  0.005  0.502  1.0
  Fe  Fe10  1  0.991  0.005  0.502  1.0
  Si  Si11  1  0.498  0.499  0.993  1.0
  Si  Si12  1  0.995  0.499  0.993  1.0
[/CIF]
.