The compound described by Sr3Ca is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sr(1), four equivalent Sr(2), and four equivalent Ca(1) atoms to form SrSr8Ca4 cuboctahedra that share corners with twelve equivalent Sr(1)Sr8Ca4 cuboctahedra, edges with eight equivalent Sr(1)Sr8Ca4 cuboctahedra, edges with eight equivalent Sr(2)Sr8Ca4 cuboctahedra, edges with eight equivalent Ca(1)Sr12 cuboctahedra, faces with four equivalent Sr(2)Sr8Ca4 cuboctahedra, faces with four equivalent Ca(1)Sr12 cuboctahedra, and faces with ten equivalent Sr(1)Sr8Ca4 cuboctahedra. In the second Sr site, Sr(2) is bonded to eight equivalent Sr(1) and four equivalent Ca(1) atoms to form SrSr8Ca4 cuboctahedra that share corners with four equivalent Sr(2)Sr8Ca4 cuboctahedra, corners with eight equivalent Ca(1)Sr12 cuboctahedra, edges with eight equivalent Sr(2)Sr8Ca4 cuboctahedra, edges with sixteen equivalent Sr(1)Sr8Ca4 cuboctahedra, faces with four equivalent Sr(2)Sr8Ca4 cuboctahedra, faces with six equivalent Ca(1)Sr12 cuboctahedra, and faces with eight equivalent Sr(1)Sr8Ca4 cuboctahedra. Ca(1) is bonded to four equivalent Sr(2) and eight equivalent Sr(1) atoms to form CaSr12 cuboctahedra that share corners with four equivalent Ca(1)Sr12 cuboctahedra, corners with eight equivalent Sr(2)Sr8Ca4 cuboctahedra, edges with eight equivalent Ca(1)Sr12 cuboctahedra, edges with sixteen equivalent Sr(1)Sr8Ca4 cuboctahedra, faces with four equivalent Ca(1)Sr12 cuboctahedra, faces with six equivalent Sr(2)Sr8Ca4 cuboctahedra, and faces with eight equivalent Sr(1)Sr8Ca4 cuboctahedra. is represented by the CIF file [CIF]
data_Sr3Ca
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.307
_cell_length_b   7.307
_cell_length_c   7.307
_cell_angle_alpha   131.646
_cell_angle_beta   131.646
_cell_angle_gamma   70.789
_symmetry_Int_Tables_number   1
_cell_volume   213.402
_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  0.750  0.250  0.500  1.0
  Sr  Sr1  1  0.250  0.750  0.500  1.0
  Sr  Sr2  1  0.500  0.500  0.000  1.0
  Ca  Ca3  1  0.000  0.000  0.000  1.0
[/CIF]
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The compound described by Sr3Ca is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sr(1), four equivalent Sr(2), and four equivalent Ca(1) atoms to form SrSr8Ca4 cuboctahedra that share corners with twelve equivalent Sr(1)Sr8Ca4 cuboctahedra, edges with eight equivalent Sr(1)Sr8Ca4 cuboctahedra, edges with eight equivalent Sr(2)Sr8Ca4 cuboctahedra, edges with eight equivalent Ca(1)Sr12 cuboctahedra, faces with four equivalent Sr(2)Sr8Ca4 cuboctahedra, faces with four equivalent Ca(1)Sr12 cuboctahedra, and faces with ten equivalent Sr(1)Sr8Ca4 cuboctahedra. In the second Sr site, Sr(2) is bonded to eight equivalent Sr(1) and four equivalent Ca(1) atoms to form SrSr8Ca4 cuboctahedra that share corners with four equivalent Sr(2)Sr8Ca4 cuboctahedra, corners with eight equivalent Ca(1)Sr12 cuboctahedra, edges with eight equivalent Sr(2)Sr8Ca4 cuboctahedra, edges with sixteen equivalent Sr(1)Sr8Ca4 cuboctahedra, faces with four equivalent Sr(2)Sr8Ca4 cuboctahedra, faces with six equivalent Ca(1)Sr12 cuboctahedra, and faces with eight equivalent Sr(1)Sr8Ca4 cuboctahedra. Ca(1) is bonded to four equivalent Sr(2) and eight equivalent Sr(1) atoms to form CaSr12 cuboctahedra that share corners with four equivalent Ca(1)Sr12 cuboctahedra, corners with eight equivalent Sr(2)Sr8Ca4 cuboctahedra, edges with eight equivalent Ca(1)Sr12 cuboctahedra, edges with sixteen equivalent Sr(1)Sr8Ca4 cuboctahedra, faces with four equivalent Ca(1)Sr12 cuboctahedra, faces with six equivalent Sr(2)Sr8Ca4 cuboctahedra, and faces with eight equivalent Sr(1)Sr8Ca4 cuboctahedra. is represented by the CIF file [CIF]
data_Sr3Ca
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.307
_cell_length_b   7.307
_cell_length_c   7.307
_cell_angle_alpha   131.646
_cell_angle_beta   131.646
_cell_angle_gamma   70.789
_symmetry_Int_Tables_number   1
_cell_volume   213.402
_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  0.750  0.250  0.500  1.0
  Sr  Sr1  1  0.250  0.750  0.500  1.0
  Sr  Sr2  1  0.500  0.500  0.000  1.0
  Ca  Ca3  1  0.000  0.000  0.000  1.0
[/CIF]
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