The crystal structure described by BaCu9Si4 crystallizes in the tetragonal I4/mcm space group. Ba(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 Ba(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Si(1) atoms to form distorted CuBa2Cu6Si4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Si(1)Ba2Cu9Si cuboctahedra, corners with eleven equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, edges with six equivalent Si(1)Ba2Cu9Si cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Si(1)Ba2Cu9Si cuboctahedra, and faces with seven equivalent Cu(1)Ba2Cu6Si4 cuboctahedra. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to two equivalent Ba(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)Ba2Cu6Si4 cuboctahedra, corners with four equivalent Si(1)Ba2Cu9Si cuboctahedra, faces with eight equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, and faces with eight equivalent Si(1)Ba2Cu9Si cuboctahedra. Si(1) is bonded to two equivalent Ba(1), one Cu(3), four equivalent Cu(1), four equivalent Cu(2), and one Si(1) atom to form distorted SiBa2Cu9Si cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, corners with eleven equivalent Si(1)Ba2Cu9Si cuboctahedra, edges with six equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, and faces with nine equivalent Si(1)Ba2Cu9Si cuboctahedra. is represented by the CIF card [CIF]
data_BaCu9Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.258
_cell_length_b   8.258
_cell_length_c   8.258
_cell_angle_alpha   120.279
_cell_angle_beta   120.279
_cell_angle_gamma   89.517
_symmetry_Int_Tables_number   1
_cell_volume   396.474
_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
  Ba  Ba0  1  0.750  0.750  0.000  1.0
  Ba  Ba1  1  0.250  0.250  0.000  1.0
  Cu  Cu2  1  0.436  0.705  0.141  1.0
  Cu  Cu3  1  0.705  0.564  0.269  1.0
  Cu  Cu4  1  0.295  0.436  0.731  1.0
  Cu  Cu5  1  0.936  0.795  0.731  1.0
  Cu  Cu6  1  0.564  0.295  0.859  1.0
  Cu  Cu7  1  0.305  0.559  0.500  1.0
  Cu  Cu8  1  0.059  0.805  0.500  1.0
  Cu  Cu9  1  0.695  0.441  0.500  1.0
  Cu  Cu10  1  0.941  0.195  0.500  1.0
  Cu  Cu11  1  0.441  0.941  0.745  1.0
  Cu  Cu12  1  0.195  0.695  0.255  1.0
  Cu  Cu13  1  0.559  0.059  0.255  1.0
  Cu  Cu14  1  0.205  0.936  0.141  1.0
  Cu  Cu15  1  0.064  0.205  0.269  1.0
  Cu  Cu16  1  0.000  0.500  0.500  1.0
  Cu  Cu17  1  0.500  0.000  0.500  1.0
  Cu  Cu18  1  0.805  0.305  0.745  1.0
  Cu  Cu19  1  0.795  0.064  0.859  1.0
  Si  Si20  1  0.291  0.791  0.851  1.0
  Si  Si21  1  0.060  0.560  0.851  1.0
  Si  Si22  1  0.560  0.709  0.500  1.0
  Si  Si23  1  0.791  0.940  0.500  1.0
  Si  Si24  1  0.440  0.291  0.500  1.0
  Si  Si25  1  0.940  0.440  0.149  1.0
  Si  Si26  1  0.709  0.209  0.149  1.0
  Si  Si27  1  0.209  0.060  0.500  1.0
[/CIF]
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The crystal structure described by BaCu9Si4 crystallizes in the tetragonal I4/mcm space group. Ba(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 Ba(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Si(1) atoms to form distorted CuBa2Cu6Si4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Si(1)Ba2Cu9Si cuboctahedra, corners with eleven equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, edges with six equivalent Si(1)Ba2Cu9Si cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Si(1)Ba2Cu9Si cuboctahedra, and faces with seven equivalent Cu(1)Ba2Cu6Si4 cuboctahedra. In the second Cu site, Cu(2) is bonded in a 12-coordinate geometry to two equivalent Ba(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)Ba2Cu6Si4 cuboctahedra, corners with four equivalent Si(1)Ba2Cu9Si cuboctahedra, faces with eight equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, and faces with eight equivalent Si(1)Ba2Cu9Si cuboctahedra. Si(1) is bonded to two equivalent Ba(1), one Cu(3), four equivalent Cu(1), four equivalent Cu(2), and one Si(1) atom to form distorted SiBa2Cu9Si cuboctahedra that share  a cornercorner with one Cu(3)Cu8Si4 cuboctahedra, corners with six equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, corners with eleven equivalent Si(1)Ba2Cu9Si cuboctahedra, edges with six equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, faces with two equivalent Cu(3)Cu8Si4 cuboctahedra, faces with six equivalent Cu(1)Ba2Cu6Si4 cuboctahedra, and faces with nine equivalent Si(1)Ba2Cu9Si cuboctahedra. is represented by the CIF card [CIF]
data_BaCu9Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.258
_cell_length_b   8.258
_cell_length_c   8.258
_cell_angle_alpha   120.279
_cell_angle_beta   120.279
_cell_angle_gamma   89.517
_symmetry_Int_Tables_number   1
_cell_volume   396.474
_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
  Ba  Ba0  1  0.750  0.750  0.000  1.0
  Ba  Ba1  1  0.250  0.250  0.000  1.0
  Cu  Cu2  1  0.436  0.705  0.141  1.0
  Cu  Cu3  1  0.705  0.564  0.269  1.0
  Cu  Cu4  1  0.295  0.436  0.731  1.0
  Cu  Cu5  1  0.936  0.795  0.731  1.0
  Cu  Cu6  1  0.564  0.295  0.859  1.0
  Cu  Cu7  1  0.305  0.559  0.500  1.0
  Cu  Cu8  1  0.059  0.805  0.500  1.0
  Cu  Cu9  1  0.695  0.441  0.500  1.0
  Cu  Cu10  1  0.941  0.195  0.500  1.0
  Cu  Cu11  1  0.441  0.941  0.745  1.0
  Cu  Cu12  1  0.195  0.695  0.255  1.0
  Cu  Cu13  1  0.559  0.059  0.255  1.0
  Cu  Cu14  1  0.205  0.936  0.141  1.0
  Cu  Cu15  1  0.064  0.205  0.269  1.0
  Cu  Cu16  1  0.000  0.500  0.500  1.0
  Cu  Cu17  1  0.500  0.000  0.500  1.0
  Cu  Cu18  1  0.805  0.305  0.745  1.0
  Cu  Cu19  1  0.795  0.064  0.859  1.0
  Si  Si20  1  0.291  0.791  0.851  1.0
  Si  Si21  1  0.060  0.560  0.851  1.0
  Si  Si22  1  0.560  0.709  0.500  1.0
  Si  Si23  1  0.791  0.940  0.500  1.0
  Si  Si24  1  0.440  0.291  0.500  1.0
  Si  Si25  1  0.940  0.440  0.149  1.0
  Si  Si26  1  0.709  0.209  0.149  1.0
  Si  Si27  1  0.209  0.060  0.500  1.0
[/CIF]
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