The structure described by SrCu9Si4 crystallizes in the tetragonal I4/mcm space group. Sr(1) is bonded in a 24-coordinate geometry to eight equivalent Cu(1), eight equivalent Cu(2), and eight equivalent Si(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent Sr(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Si(1) atoms to form distorted CuSr2Cu6Si4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Si(1)Sr2Cu9Si cuboctahedra, corners with eleven equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, edges with six equivalent Si(1)Sr2Cu9Si cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Si(1)Sr2Cu9Si cuboctahedra, and faces with seven equivalent Cu(1)Sr2Cu6Si4 cuboctahedra. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to two equivalent Sr(1), one Cu(3), two equivalent Cu(1), three equivalent Cu(2), and four equivalent Si(1) atoms. In the third Cu site, Cu(3) is bonded to four equivalent Cu(1), four equivalent Cu(2), and four equivalent Si(1) atoms to form CuCu8Si4 cuboctahedra that share corners with four equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, corners with four equivalent Si(1)Sr2Cu9Si cuboctahedra, faces with eight equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, and faces with eight equivalent Si(1)Sr2Cu9Si cuboctahedra. Si(1) is bonded to two equivalent Sr(1), one Cu(3), four equivalent Cu(1), four equivalent Cu(2), and one Si(1) atom to form distorted SiSr2Cu9Si cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, corners with eleven equivalent Si(1)Sr2Cu9Si cuboctahedra, edges with six equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, and faces with nine equivalent Si(1)Sr2Cu9Si cuboctahedra. is represented by the CIF card [CIF]
data_SrCu9Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.188
_cell_length_b   8.188
_cell_length_c   8.188
_cell_angle_alpha   120.261
_cell_angle_beta   120.261
_cell_angle_gamma   89.549
_symmetry_Int_Tables_number   1
_cell_volume   386.554
_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
  Sr  Sr0  1  0.250  0.250  0.000  1.0
  Sr  Sr1  1  0.750  0.750  0.000  1.0
  Cu  Cu2  1  0.936  0.203  0.139  1.0
  Cu  Cu3  1  0.203  0.064  0.268  1.0
  Cu  Cu4  1  0.797  0.936  0.732  1.0
  Cu  Cu5  1  0.436  0.297  0.732  1.0
  Cu  Cu6  1  0.064  0.797  0.861  1.0
  Cu  Cu7  1  0.807  0.059  0.500  1.0
  Cu  Cu8  1  0.559  0.307  0.500  1.0
  Cu  Cu9  1  0.193  0.941  0.500  1.0
  Cu  Cu10  1  0.441  0.693  0.500  1.0
  Cu  Cu11  1  0.941  0.441  0.748  1.0
  Cu  Cu12  1  0.693  0.193  0.252  1.0
  Cu  Cu13  1  0.059  0.559  0.252  1.0
  Cu  Cu14  1  0.703  0.436  0.139  1.0
  Cu  Cu15  1  0.564  0.703  0.268  1.0
  Cu  Cu16  1  0.500  0.000  0.500  1.0
  Cu  Cu17  1  0.000  0.500  0.500  1.0
  Cu  Cu18  1  0.307  0.807  0.748  1.0
  Cu  Cu19  1  0.297  0.564  0.861  1.0
  Si  Si20  1  0.792  0.292  0.852  1.0
  Si  Si21  1  0.560  0.060  0.852  1.0
  Si  Si22  1  0.060  0.208  0.500  1.0
  Si  Si23  1  0.292  0.440  0.500  1.0
  Si  Si24  1  0.940  0.792  0.500  1.0
  Si  Si25  1  0.440  0.940  0.148  1.0
  Si  Si26  1  0.208  0.708  0.148  1.0
  Si  Si27  1  0.708  0.560  0.500  1.0
[/CIF]
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The structure described by SrCu9Si4 crystallizes in the tetragonal I4/mcm space group. Sr(1) is bonded in a 24-coordinate geometry to eight equivalent Cu(1), eight equivalent Cu(2), and eight equivalent Si(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent Sr(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Si(1) atoms to form distorted CuSr2Cu6Si4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Si(1)Sr2Cu9Si cuboctahedra, corners with eleven equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, edges with six equivalent Si(1)Sr2Cu9Si cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Si(1)Sr2Cu9Si cuboctahedra, and faces with seven equivalent Cu(1)Sr2Cu6Si4 cuboctahedra. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to two equivalent Sr(1), one Cu(3), two equivalent Cu(1), three equivalent Cu(2), and four equivalent Si(1) atoms. In the third Cu site, Cu(3) is bonded to four equivalent Cu(1), four equivalent Cu(2), and four equivalent Si(1) atoms to form CuCu8Si4 cuboctahedra that share corners with four equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, corners with four equivalent Si(1)Sr2Cu9Si cuboctahedra, faces with eight equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, and faces with eight equivalent Si(1)Sr2Cu9Si cuboctahedra. Si(1) is bonded to two equivalent Sr(1), one Cu(3), four equivalent Cu(1), four equivalent Cu(2), and one Si(1) atom to form distorted SiSr2Cu9Si cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, corners with eleven equivalent Si(1)Sr2Cu9Si cuboctahedra, edges with six equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Cu(1)Sr2Cu6Si4 cuboctahedra, and faces with nine equivalent Si(1)Sr2Cu9Si cuboctahedra. is represented by the CIF card [CIF]
data_SrCu9Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.188
_cell_length_b   8.188
_cell_length_c   8.188
_cell_angle_alpha   120.261
_cell_angle_beta   120.261
_cell_angle_gamma   89.549
_symmetry_Int_Tables_number   1
_cell_volume   386.554
_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
  Sr  Sr0  1  0.250  0.250  0.000  1.0
  Sr  Sr1  1  0.750  0.750  0.000  1.0
  Cu  Cu2  1  0.936  0.203  0.139  1.0
  Cu  Cu3  1  0.203  0.064  0.268  1.0
  Cu  Cu4  1  0.797  0.936  0.732  1.0
  Cu  Cu5  1  0.436  0.297  0.732  1.0
  Cu  Cu6  1  0.064  0.797  0.861  1.0
  Cu  Cu7  1  0.807  0.059  0.500  1.0
  Cu  Cu8  1  0.559  0.307  0.500  1.0
  Cu  Cu9  1  0.193  0.941  0.500  1.0
  Cu  Cu10  1  0.441  0.693  0.500  1.0
  Cu  Cu11  1  0.941  0.441  0.748  1.0
  Cu  Cu12  1  0.693  0.193  0.252  1.0
  Cu  Cu13  1  0.059  0.559  0.252  1.0
  Cu  Cu14  1  0.703  0.436  0.139  1.0
  Cu  Cu15  1  0.564  0.703  0.268  1.0
  Cu  Cu16  1  0.500  0.000  0.500  1.0
  Cu  Cu17  1  0.000  0.500  0.500  1.0
  Cu  Cu18  1  0.307  0.807  0.748  1.0
  Cu  Cu19  1  0.297  0.564  0.861  1.0
  Si  Si20  1  0.792  0.292  0.852  1.0
  Si  Si21  1  0.560  0.060  0.852  1.0
  Si  Si22  1  0.060  0.208  0.500  1.0
  Si  Si23  1  0.292  0.440  0.500  1.0
  Si  Si24  1  0.940  0.792  0.500  1.0
  Si  Si25  1  0.440  0.940  0.148  1.0
  Si  Si26  1  0.208  0.708  0.148  1.0
  Si  Si27  1  0.708  0.560  0.500  1.0
[/CIF]
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