The material structure described by Ca3Si4 crystallizes in the hexagonal P6_3/m space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in an octahedral geometry to six equivalent Si(4) atoms. In the second Ca site, Ca(2) is bonded in a 11-coordinate geometry to two equivalent Si(3), three equivalent Si(1), and six equivalent Si(4) atoms. In the third Ca site, Ca(3) is bonded in a 9-coordinate geometry to one Si(2), two equivalent Si(1), two equivalent Si(3), and four equivalent Si(4) atoms. In the fourth Ca site, Ca(4) is bonded in a 9-coordinate geometry to three equivalent Si(1) and six equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Ca(2), one Ca(4), four equivalent Ca(3), one Si(2), and two equivalent Si(4) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Ca(3) and three equivalent Si(1) atoms. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Ca(2), six equivalent Ca(3), and three equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), four equivalent Ca(3), one Si(1), and one Si(3) atom. is represented by the CIF file [CIF]
data_Ca3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.536
_cell_length_b   8.536
_cell_length_c   14.905
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   940.523
_cell_formula_units_Z   6
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  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.500  1.0
  Ca  Ca2  1  0.667  0.333  0.750  1.0
  Ca  Ca3  1  0.333  0.667  0.250  1.0
  Ca  Ca4  1  0.579  0.906  0.903  1.0
  Ca  Ca5  1  0.421  0.094  0.097  1.0
  Ca  Ca6  1  0.328  0.421  0.903  1.0
  Ca  Ca7  1  0.421  0.094  0.403  1.0
  Ca  Ca8  1  0.672  0.579  0.097  1.0
  Ca  Ca9  1  0.579  0.906  0.597  1.0
  Ca  Ca10  1  0.094  0.672  0.903  1.0
  Ca  Ca11  1  0.672  0.579  0.403  1.0
  Ca  Ca12  1  0.906  0.328  0.097  1.0
  Ca  Ca13  1  0.328  0.421  0.597  1.0
  Ca  Ca14  1  0.906  0.328  0.403  1.0
  Ca  Ca15  1  0.094  0.672  0.597  1.0
  Ca  Ca16  1  0.000  0.000  0.750  1.0
  Ca  Ca17  1  0.000  0.000  0.250  1.0
  Si  Si18  1  0.617  0.673  0.750  1.0
  Si  Si19  1  0.383  0.327  0.250  1.0
  Si  Si20  1  0.056  0.383  0.750  1.0
  Si  Si21  1  0.944  0.617  0.250  1.0
  Si  Si22  1  0.327  0.944  0.750  1.0
  Si  Si23  1  0.673  0.056  0.250  1.0
  Si  Si24  1  0.333  0.667  0.750  1.0
  Si  Si25  1  0.667  0.333  0.250  1.0
  Si  Si26  1  0.667  0.333  0.942  1.0
  Si  Si27  1  0.333  0.667  0.058  1.0
  Si  Si28  1  0.333  0.667  0.442  1.0
  Si  Si29  1  0.667  0.333  0.558  1.0
  Si  Si30  1  0.909  0.264  0.889  1.0
  Si  Si31  1  0.091  0.736  0.111  1.0
  Si  Si32  1  0.355  0.091  0.889  1.0
  Si  Si33  1  0.091  0.736  0.389  1.0
  Si  Si34  1  0.645  0.909  0.111  1.0
  Si  Si35  1  0.909  0.264  0.611  1.0
  Si  Si36  1  0.736  0.645  0.889  1.0
  Si  Si37  1  0.645  0.909  0.389  1.0
  Si  Si38  1  0.264  0.355  0.111  1.0
  Si  Si39  1  0.355  0.091  0.611  1.0
  Si  Si40  1  0.264  0.355  0.389  1.0
  Si  Si41  1  0.736  0.645  0.611  1.0
[/CIF]
.
The material structure described by Ca3Si4 crystallizes in the hexagonal P6_3/m space group. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in an octahedral geometry to six equivalent Si(4) atoms. In the second Ca site, Ca(2) is bonded in a 11-coordinate geometry to two equivalent Si(3), three equivalent Si(1), and six equivalent Si(4) atoms. In the third Ca site, Ca(3) is bonded in a 9-coordinate geometry to one Si(2), two equivalent Si(1), two equivalent Si(3), and four equivalent Si(4) atoms. In the fourth Ca site, Ca(4) is bonded in a 9-coordinate geometry to three equivalent Si(1) and six equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Ca(2), one Ca(4), four equivalent Ca(3), one Si(2), and two equivalent Si(4) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Ca(3) and three equivalent Si(1) atoms. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Ca(2), six equivalent Ca(3), and three equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Ca(1), one Ca(2), one Ca(4), four equivalent Ca(3), one Si(1), and one Si(3) atom. is represented by the CIF file [CIF]
data_Ca3Si4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.536
_cell_length_b   8.536
_cell_length_c   14.905
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   940.523
_cell_formula_units_Z   6
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  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.500  1.0
  Ca  Ca2  1  0.667  0.333  0.750  1.0
  Ca  Ca3  1  0.333  0.667  0.250  1.0
  Ca  Ca4  1  0.579  0.906  0.903  1.0
  Ca  Ca5  1  0.421  0.094  0.097  1.0
  Ca  Ca6  1  0.328  0.421  0.903  1.0
  Ca  Ca7  1  0.421  0.094  0.403  1.0
  Ca  Ca8  1  0.672  0.579  0.097  1.0
  Ca  Ca9  1  0.579  0.906  0.597  1.0
  Ca  Ca10  1  0.094  0.672  0.903  1.0
  Ca  Ca11  1  0.672  0.579  0.403  1.0
  Ca  Ca12  1  0.906  0.328  0.097  1.0
  Ca  Ca13  1  0.328  0.421  0.597  1.0
  Ca  Ca14  1  0.906  0.328  0.403  1.0
  Ca  Ca15  1  0.094  0.672  0.597  1.0
  Ca  Ca16  1  0.000  0.000  0.750  1.0
  Ca  Ca17  1  0.000  0.000  0.250  1.0
  Si  Si18  1  0.617  0.673  0.750  1.0
  Si  Si19  1  0.383  0.327  0.250  1.0
  Si  Si20  1  0.056  0.383  0.750  1.0
  Si  Si21  1  0.944  0.617  0.250  1.0
  Si  Si22  1  0.327  0.944  0.750  1.0
  Si  Si23  1  0.673  0.056  0.250  1.0
  Si  Si24  1  0.333  0.667  0.750  1.0
  Si  Si25  1  0.667  0.333  0.250  1.0
  Si  Si26  1  0.667  0.333  0.942  1.0
  Si  Si27  1  0.333  0.667  0.058  1.0
  Si  Si28  1  0.333  0.667  0.442  1.0
  Si  Si29  1  0.667  0.333  0.558  1.0
  Si  Si30  1  0.909  0.264  0.889  1.0
  Si  Si31  1  0.091  0.736  0.111  1.0
  Si  Si32  1  0.355  0.091  0.889  1.0
  Si  Si33  1  0.091  0.736  0.389  1.0
  Si  Si34  1  0.645  0.909  0.111  1.0
  Si  Si35  1  0.909  0.264  0.611  1.0
  Si  Si36  1  0.736  0.645  0.889  1.0
  Si  Si37  1  0.645  0.909  0.389  1.0
  Si  Si38  1  0.264  0.355  0.111  1.0
  Si  Si39  1  0.355  0.091  0.611  1.0
  Si  Si40  1  0.264  0.355  0.389  1.0
  Si  Si41  1  0.736  0.645  0.611  1.0
[/CIF]
.