The material described by Sr2CaI6 crystallizes in the tetragonal P-4b2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a body-centered cubic geometry to four equivalent I(2) and four equivalent I(3) atoms. In the second Sr site, Sr(2) is bonded in a body-centered cubic geometry to four equivalent I(1) and four equivalent I(3) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted tetrahedral geometry to four equivalent I(2) atoms. In the second Ca site, Ca(2) is bonded in a square co-planar geometry to four equivalent I(1) atoms. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sr(2) and one Ca(2) atom. In the second I site, I(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sr(1) and one Ca(1) atom. In the third I site, I(3) is bonded to two equivalent Sr(1) and two equivalent Sr(2) atoms to form a mixture of edge and corner-sharing ISr4 tetrahedra. is represented by the CIF file [CIF]
data_Sr2CaI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.060
_cell_length_b   8.060
_cell_length_c   23.953
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1555.895
_cell_formula_units_Z   4
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  0.500  0.165  1.0
  Sr  Sr1  1  0.000  0.000  0.333  1.0
  Sr  Sr2  1  0.000  0.000  0.667  1.0
  Sr  Sr3  1  0.000  0.500  0.835  1.0
  Sr  Sr4  1  0.500  0.500  0.333  1.0
  Sr  Sr5  1  0.500  0.000  0.165  1.0
  Sr  Sr6  1  0.500  0.000  0.835  1.0
  Sr  Sr7  1  0.500  0.500  0.667  1.0
  Ca  Ca8  1  0.000  0.000  0.000  1.0
  Ca  Ca9  1  0.000  0.500  0.500  1.0
  Ca  Ca10  1  0.500  0.000  0.500  1.0
  Ca  Ca11  1  0.500  0.500  0.000  1.0
  I  I12  1  0.197  0.713  0.586  1.0
  I  I13  1  0.199  0.789  0.084  1.0
  I  I14  1  0.211  0.199  0.916  1.0
  I  I15  1  0.213  0.697  0.414  1.0
  I  I16  1  0.226  0.261  0.250  1.0
  I  I17  1  0.239  0.274  0.750  1.0
  I  I18  1  0.261  0.774  0.750  1.0
  I  I19  1  0.274  0.761  0.250  1.0
  I  I20  1  0.289  0.699  0.916  1.0
  I  I21  1  0.287  0.197  0.414  1.0
  I  I22  1  0.301  0.289  0.084  1.0
  I  I23  1  0.303  0.213  0.586  1.0
  I  I24  1  0.697  0.787  0.586  1.0
  I  I25  1  0.699  0.711  0.084  1.0
  I  I26  1  0.711  0.301  0.916  1.0
  I  I27  1  0.713  0.803  0.414  1.0
  I  I28  1  0.726  0.239  0.250  1.0
  I  I29  1  0.739  0.226  0.750  1.0
  I  I30  1  0.761  0.726  0.750  1.0
  I  I31  1  0.774  0.739  0.250  1.0
  I  I32  1  0.787  0.303  0.414  1.0
  I  I33  1  0.789  0.801  0.916  1.0
  I  I34  1  0.801  0.211  0.084  1.0
  I  I35  1  0.803  0.287  0.586  1.0
[/CIF]
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The material described by Sr2CaI6 crystallizes in the tetragonal P-4b2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a body-centered cubic geometry to four equivalent I(2) and four equivalent I(3) atoms. In the second Sr site, Sr(2) is bonded in a body-centered cubic geometry to four equivalent I(1) and four equivalent I(3) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted tetrahedral geometry to four equivalent I(2) atoms. In the second Ca site, Ca(2) is bonded in a square co-planar geometry to four equivalent I(1) atoms. There are three inequivalent I sites. In the first I site, I(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sr(2) and one Ca(2) atom. In the second I site, I(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sr(1) and one Ca(1) atom. In the third I site, I(3) is bonded to two equivalent Sr(1) and two equivalent Sr(2) atoms to form a mixture of edge and corner-sharing ISr4 tetrahedra. is represented by the CIF file [CIF]
data_Sr2CaI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.060
_cell_length_b   8.060
_cell_length_c   23.953
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1555.895
_cell_formula_units_Z   4
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  0.500  0.165  1.0
  Sr  Sr1  1  0.000  0.000  0.333  1.0
  Sr  Sr2  1  0.000  0.000  0.667  1.0
  Sr  Sr3  1  0.000  0.500  0.835  1.0
  Sr  Sr4  1  0.500  0.500  0.333  1.0
  Sr  Sr5  1  0.500  0.000  0.165  1.0
  Sr  Sr6  1  0.500  0.000  0.835  1.0
  Sr  Sr7  1  0.500  0.500  0.667  1.0
  Ca  Ca8  1  0.000  0.000  0.000  1.0
  Ca  Ca9  1  0.000  0.500  0.500  1.0
  Ca  Ca10  1  0.500  0.000  0.500  1.0
  Ca  Ca11  1  0.500  0.500  0.000  1.0
  I  I12  1  0.197  0.713  0.586  1.0
  I  I13  1  0.199  0.789  0.084  1.0
  I  I14  1  0.211  0.199  0.916  1.0
  I  I15  1  0.213  0.697  0.414  1.0
  I  I16  1  0.226  0.261  0.250  1.0
  I  I17  1  0.239  0.274  0.750  1.0
  I  I18  1  0.261  0.774  0.750  1.0
  I  I19  1  0.274  0.761  0.250  1.0
  I  I20  1  0.289  0.699  0.916  1.0
  I  I21  1  0.287  0.197  0.414  1.0
  I  I22  1  0.301  0.289  0.084  1.0
  I  I23  1  0.303  0.213  0.586  1.0
  I  I24  1  0.697  0.787  0.586  1.0
  I  I25  1  0.699  0.711  0.084  1.0
  I  I26  1  0.711  0.301  0.916  1.0
  I  I27  1  0.713  0.803  0.414  1.0
  I  I28  1  0.726  0.239  0.250  1.0
  I  I29  1  0.739  0.226  0.750  1.0
  I  I30  1  0.761  0.726  0.750  1.0
  I  I31  1  0.774  0.739  0.250  1.0
  I  I32  1  0.787  0.303  0.414  1.0
  I  I33  1  0.789  0.801  0.916  1.0
  I  I34  1  0.801  0.211  0.084  1.0
  I  I35  1  0.803  0.287  0.586  1.0
[/CIF]
.