The structure described by SrCaSi4 is hexagonal omega structure-derived structured and crystallizes in the tetragonal I-4m2 space group. Sr(1) is bonded to four Si(1,1) and eight equivalent Si(2) atoms to form SrSi12 cuboctahedra that share edges with four equivalent Sr(1)Si12 cuboctahedra, edges with eight equivalent Ca(1)Si12 cuboctahedra, faces with four equivalent Sr(1)Si12 cuboctahedra, and faces with four equivalent Ca(1)Si12 cuboctahedra. Ca(1) is bonded to four Si(2,2) and eight equivalent Si(1) atoms to form CaSi12 cuboctahedra that share edges with four equivalent Ca(1)Si12 cuboctahedra, edges with eight equivalent Sr(1)Si12 cuboctahedra, faces with four equivalent Sr(1)Si12 cuboctahedra, and faces with four equivalent Ca(1)Si12 cuboctahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), four equivalent Ca(1), one Si(1), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Sr(1), two equivalent Ca(1), one Si(2), and two equivalent Si(1) atoms. In the third Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Sr(1), two equivalent Ca(1), one Si(2), and two equivalent Si(1) atoms. In the fourth Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), four equivalent Ca(1), one Si(1), and two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_SrCaSi4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.489
_cell_length_b   7.489
_cell_length_c   7.489
_cell_angle_alpha   146.136
_cell_angle_beta   146.136
_cell_angle_gamma   48.645
_symmetry_Int_Tables_number   1
_cell_volume   129.855
_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
  Sr  Sr0  1  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.250  0.750  0.500  1.0
  Si  Si2  1  0.666  0.166  0.500  1.0
  Si  Si3  1  0.586  0.586  0.000  1.0
  Si  Si4  1  0.834  0.334  0.500  1.0
  Si  Si5  1  0.414  0.414  0.000  1.0
[/CIF]
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The structure described by SrCaSi4 is hexagonal omega structure-derived structured and crystallizes in the tetragonal I-4m2 space group. Sr(1) is bonded to four Si(1,1) and eight equivalent Si(2) atoms to form SrSi12 cuboctahedra that share edges with four equivalent Sr(1)Si12 cuboctahedra, edges with eight equivalent Ca(1)Si12 cuboctahedra, faces with four equivalent Sr(1)Si12 cuboctahedra, and faces with four equivalent Ca(1)Si12 cuboctahedra. Ca(1) is bonded to four Si(2,2) and eight equivalent Si(1) atoms to form CaSi12 cuboctahedra that share edges with four equivalent Ca(1)Si12 cuboctahedra, edges with eight equivalent Sr(1)Si12 cuboctahedra, faces with four equivalent Sr(1)Si12 cuboctahedra, and faces with four equivalent Ca(1)Si12 cuboctahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), four equivalent Ca(1), one Si(1), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Sr(1), two equivalent Ca(1), one Si(2), and two equivalent Si(1) atoms. In the third Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Sr(1), two equivalent Ca(1), one Si(2), and two equivalent Si(1) atoms. In the fourth Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), four equivalent Ca(1), one Si(1), and two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_SrCaSi4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.489
_cell_length_b   7.489
_cell_length_c   7.489
_cell_angle_alpha   146.136
_cell_angle_beta   146.136
_cell_angle_gamma   48.645
_symmetry_Int_Tables_number   1
_cell_volume   129.855
_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
  Sr  Sr0  1  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.250  0.750  0.500  1.0
  Si  Si2  1  0.666  0.166  0.500  1.0
  Si  Si3  1  0.586  0.586  0.000  1.0
  Si  Si4  1  0.834  0.334  0.500  1.0
  Si  Si5  1  0.414  0.414  0.000  1.0
[/CIF]
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