The crystal structure described by CaCu9Sn4 is Bergman Structure: Mg32(Al,Zn)49 Bergman-like structured and crystallizes in the tetragonal I4/mcm space group. Ca(1) is bonded in a 24-coordinate geometry to eight equivalent Cu(1), eight equivalent Cu(2), and eight equivalent Sn(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 12-coordinate geometry to two equivalent Ca(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Sn(1) atoms. In the second Cu site, Cu(2) is bonded to two equivalent Ca(1), one Cu(3), two equivalent Cu(1), three equivalent Cu(2), and four equivalent Sn(1) atoms to form distorted CuCa2Cu6Sn4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Sn4 cuboctahedra, corners with seven equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, edges with four equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, faces with two equivalent Cu(3)Cu8Sn4 cuboctahedra, and faces with five equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra. In the third Cu site, Cu(3) is bonded to four equivalent Cu(1), four equivalent Cu(2), and four equivalent Sn(1) atoms to form a mixture of corner and face-sharing CuCu8Sn4 cuboctahedra. Sn(1) is bonded in a 11-coordinate geometry to two equivalent Ca(1), one Cu(3), four equivalent Cu(1), and four equivalent Cu(2) atoms. is represented by the CIF file [CIF]
data_CaCu9Sn4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.741
_cell_length_b   8.741
_cell_length_c   8.741
_cell_angle_alpha   120.531
_cell_angle_beta   120.531
_cell_angle_gamma   89.083
_symmetry_Int_Tables_number   1
_cell_volume   468.336
_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
  Ca  Ca0  1  0.250  0.250  0.000  1.0
  Ca  Ca1  1  0.750  0.750  0.000  1.0
  Cu  Cu2  1  0.555  0.701  0.256  1.0
  Cu  Cu3  1  0.799  0.945  0.744  1.0
  Cu  Cu4  1  0.945  0.201  0.146  1.0
  Cu  Cu5  1  0.201  0.055  0.256  1.0
  Cu  Cu6  1  0.566  0.282  0.500  1.0
  Cu  Cu7  1  0.718  0.218  0.284  1.0
  Cu  Cu8  1  0.218  0.934  0.500  1.0
  Cu  Cu9  1  0.782  0.066  0.500  1.0
  Cu  Cu10  1  0.934  0.434  0.716  1.0
  Cu  Cu11  1  0.066  0.566  0.284  1.0
  Cu  Cu12  1  0.445  0.299  0.744  1.0
  Cu  Cu13  1  0.055  0.799  0.854  1.0
  Cu  Cu14  1  0.434  0.718  0.500  1.0
  Cu  Cu15  1  0.701  0.445  0.146  1.0
  Cu  Cu16  1  0.500  0.000  0.500  1.0
  Cu  Cu17  1  0.282  0.782  0.716  1.0
  Cu  Cu18  1  0.299  0.555  0.854  1.0
  Cu  Cu19  1  0.000  0.500  0.500  1.0
  Sn  Sn20  1  0.559  0.059  0.872  1.0
  Sn  Sn21  1  0.812  0.312  0.872  1.0
  Sn  Sn22  1  0.941  0.812  0.500  1.0
  Sn  Sn23  1  0.688  0.559  0.500  1.0
  Sn  Sn24  1  0.188  0.688  0.128  1.0
  Sn  Sn25  1  0.312  0.441  0.500  1.0
  Sn  Sn26  1  0.059  0.188  0.500  1.0
  Sn  Sn27  1  0.441  0.941  0.128  1.0
[/CIF]
.
The crystal structure described by CaCu9Sn4 is Bergman Structure: Mg32(Al,Zn)49 Bergman-like structured and crystallizes in the tetragonal I4/mcm space group. Ca(1) is bonded in a 24-coordinate geometry to eight equivalent Cu(1), eight equivalent Cu(2), and eight equivalent Sn(1) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 12-coordinate geometry to two equivalent Ca(1), one Cu(3), two equivalent Cu(2), three equivalent Cu(1), and four equivalent Sn(1) atoms. In the second Cu site, Cu(2) is bonded to two equivalent Ca(1), one Cu(3), two equivalent Cu(1), three equivalent Cu(2), and four equivalent Sn(1) atoms to form distorted CuCa2Cu6Sn4 cuboctahedra that share  a cornercorner with one Cu(3)Cu8Sn4 cuboctahedra, corners with seven equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, edges with four equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra, faces with two equivalent Cu(3)Cu8Sn4 cuboctahedra, and faces with five equivalent Cu(2)Ca2Cu6Sn4 cuboctahedra. In the third Cu site, Cu(3) is bonded to four equivalent Cu(1), four equivalent Cu(2), and four equivalent Sn(1) atoms to form a mixture of corner and face-sharing CuCu8Sn4 cuboctahedra. Sn(1) is bonded in a 11-coordinate geometry to two equivalent Ca(1), one Cu(3), four equivalent Cu(1), and four equivalent Cu(2) atoms. is represented by the CIF file [CIF]
data_CaCu9Sn4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.741
_cell_length_b   8.741
_cell_length_c   8.741
_cell_angle_alpha   120.531
_cell_angle_beta   120.531
_cell_angle_gamma   89.083
_symmetry_Int_Tables_number   1
_cell_volume   468.336
_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
  Ca  Ca0  1  0.250  0.250  0.000  1.0
  Ca  Ca1  1  0.750  0.750  0.000  1.0
  Cu  Cu2  1  0.555  0.701  0.256  1.0
  Cu  Cu3  1  0.799  0.945  0.744  1.0
  Cu  Cu4  1  0.945  0.201  0.146  1.0
  Cu  Cu5  1  0.201  0.055  0.256  1.0
  Cu  Cu6  1  0.566  0.282  0.500  1.0
  Cu  Cu7  1  0.718  0.218  0.284  1.0
  Cu  Cu8  1  0.218  0.934  0.500  1.0
  Cu  Cu9  1  0.782  0.066  0.500  1.0
  Cu  Cu10  1  0.934  0.434  0.716  1.0
  Cu  Cu11  1  0.066  0.566  0.284  1.0
  Cu  Cu12  1  0.445  0.299  0.744  1.0
  Cu  Cu13  1  0.055  0.799  0.854  1.0
  Cu  Cu14  1  0.434  0.718  0.500  1.0
  Cu  Cu15  1  0.701  0.445  0.146  1.0
  Cu  Cu16  1  0.500  0.000  0.500  1.0
  Cu  Cu17  1  0.282  0.782  0.716  1.0
  Cu  Cu18  1  0.299  0.555  0.854  1.0
  Cu  Cu19  1  0.000  0.500  0.500  1.0
  Sn  Sn20  1  0.559  0.059  0.872  1.0
  Sn  Sn21  1  0.812  0.312  0.872  1.0
  Sn  Sn22  1  0.941  0.812  0.500  1.0
  Sn  Sn23  1  0.688  0.559  0.500  1.0
  Sn  Sn24  1  0.188  0.688  0.128  1.0
  Sn  Sn25  1  0.312  0.441  0.500  1.0
  Sn  Sn26  1  0.059  0.188  0.500  1.0
  Sn  Sn27  1  0.441  0.941  0.128  1.0
[/CIF]
.