The material structure described by Sr2CaI6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one I(1), one I(2), one I(4), one I(5), two equivalent I(3), and two equivalent I(6) atoms. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to one I(1), one I(4), one I(5), one I(6), two equivalent I(2), and two equivalent I(3) atoms. Ca(1) is bonded to one I(2), one I(4), one I(5), one I(6), and two equivalent I(1) atoms to form edge-sharing CaI6 octahedra. There are six inequivalent I sites. In the first I site, I(1) is bonded in a distorted see-saw-like geometry to one Sr(1), one Sr(2), and two equivalent Ca(1) atoms. In the second I site, I(2) is bonded to one Sr(1), two equivalent Sr(2), and one Ca(1) atom to form distorted ISr3Ca trigonal pyramids that share corners with two equivalent I(2)Sr3Ca trigonal pyramids, corners with two equivalent I(3)Sr4 trigonal pyramids, and edges with two equivalent I(3)Sr4 trigonal pyramids. In the third I site, I(3) is bonded to two equivalent Sr(1) and two equivalent Sr(2) atoms to form distorted ISr4 trigonal pyramids that share corners with two equivalent I(2)Sr3Ca trigonal pyramids, corners with two equivalent I(3)Sr4 trigonal pyramids,  an edgeedge with one I(3)Sr4 trigonal pyramid, and edges with two equivalent I(2)Sr3Ca trigonal pyramids. In the fourth I site, I(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the fifth I site, I(5) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the sixth I site, I(6) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Sr(1), and one Ca(1) atom. is represented by the CIF card [CIF]
data_Sr2CaI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.521
_cell_length_b   10.425
_cell_length_c   17.729
_cell_angle_alpha   56.681
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1470.511
_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  0.701  0.296  0.094  1.0
  Sr  Sr1  1  0.906  0.638  0.713  1.0
  Sr  Sr2  1  0.406  0.362  0.787  1.0
  Sr  Sr3  1  0.201  0.704  0.406  1.0
  Sr  Sr4  1  0.799  0.296  0.594  1.0
  Sr  Sr5  1  0.594  0.638  0.213  1.0
  Sr  Sr6  1  0.094  0.362  0.287  1.0
  Sr  Sr7  1  0.299  0.704  0.906  1.0
  Ca  Ca8  1  0.646  0.927  0.430  1.0
  Ca  Ca9  1  0.146  0.073  0.070  1.0
  Ca  Ca10  1  0.854  0.927  0.930  1.0
  Ca  Ca11  1  0.354  0.073  0.570  1.0
  I  I12  1  0.331  0.023  0.411  1.0
  I  I13  1  0.265  0.724  0.705  1.0
  I  I14  1  0.613  0.572  0.865  1.0
  I  I15  1  0.949  0.827  0.486  1.0
  I  I16  1  0.062  0.418  0.923  1.0
  I  I17  1  0.052  0.108  0.224  1.0
  I  I18  1  0.552  0.892  0.276  1.0
  I  I19  1  0.449  0.173  0.014  1.0
  I  I20  1  0.562  0.582  0.577  1.0
  I  I21  1  0.113  0.428  0.635  1.0
  I  I22  1  0.765  0.276  0.795  1.0
  I  I23  1  0.831  0.977  0.089  1.0
  I  I24  1  0.169  0.023  0.911  1.0
  I  I25  1  0.235  0.724  0.205  1.0
  I  I26  1  0.887  0.572  0.365  1.0
  I  I27  1  0.438  0.418  0.423  1.0
  I  I28  1  0.551  0.827  0.986  1.0
  I  I29  1  0.448  0.108  0.724  1.0
  I  I30  1  0.948  0.892  0.776  1.0
  I  I31  1  0.938  0.582  0.077  1.0
  I  I32  1  0.051  0.173  0.514  1.0
  I  I33  1  0.387  0.428  0.135  1.0
  I  I34  1  0.735  0.276  0.295  1.0
  I  I35  1  0.669  0.977  0.589  1.0
[/CIF]
.
The material structure described by Sr2CaI6 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one I(1), one I(2), one I(4), one I(5), two equivalent I(3), and two equivalent I(6) atoms. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to one I(1), one I(4), one I(5), one I(6), two equivalent I(2), and two equivalent I(3) atoms. Ca(1) is bonded to one I(2), one I(4), one I(5), one I(6), and two equivalent I(1) atoms to form edge-sharing CaI6 octahedra. There are six inequivalent I sites. In the first I site, I(1) is bonded in a distorted see-saw-like geometry to one Sr(1), one Sr(2), and two equivalent Ca(1) atoms. In the second I site, I(2) is bonded to one Sr(1), two equivalent Sr(2), and one Ca(1) atom to form distorted ISr3Ca trigonal pyramids that share corners with two equivalent I(2)Sr3Ca trigonal pyramids, corners with two equivalent I(3)Sr4 trigonal pyramids, and edges with two equivalent I(3)Sr4 trigonal pyramids. In the third I site, I(3) is bonded to two equivalent Sr(1) and two equivalent Sr(2) atoms to form distorted ISr4 trigonal pyramids that share corners with two equivalent I(2)Sr3Ca trigonal pyramids, corners with two equivalent I(3)Sr4 trigonal pyramids,  an edgeedge with one I(3)Sr4 trigonal pyramid, and edges with two equivalent I(2)Sr3Ca trigonal pyramids. In the fourth I site, I(4) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the fifth I site, I(5) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Ca(1) atom. In the sixth I site, I(6) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Sr(1), and one Ca(1) atom. is represented by the CIF card [CIF]
data_Sr2CaI6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.521
_cell_length_b   10.425
_cell_length_c   17.729
_cell_angle_alpha   56.681
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1470.511
_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  0.701  0.296  0.094  1.0
  Sr  Sr1  1  0.906  0.638  0.713  1.0
  Sr  Sr2  1  0.406  0.362  0.787  1.0
  Sr  Sr3  1  0.201  0.704  0.406  1.0
  Sr  Sr4  1  0.799  0.296  0.594  1.0
  Sr  Sr5  1  0.594  0.638  0.213  1.0
  Sr  Sr6  1  0.094  0.362  0.287  1.0
  Sr  Sr7  1  0.299  0.704  0.906  1.0
  Ca  Ca8  1  0.646  0.927  0.430  1.0
  Ca  Ca9  1  0.146  0.073  0.070  1.0
  Ca  Ca10  1  0.854  0.927  0.930  1.0
  Ca  Ca11  1  0.354  0.073  0.570  1.0
  I  I12  1  0.331  0.023  0.411  1.0
  I  I13  1  0.265  0.724  0.705  1.0
  I  I14  1  0.613  0.572  0.865  1.0
  I  I15  1  0.949  0.827  0.486  1.0
  I  I16  1  0.062  0.418  0.923  1.0
  I  I17  1  0.052  0.108  0.224  1.0
  I  I18  1  0.552  0.892  0.276  1.0
  I  I19  1  0.449  0.173  0.014  1.0
  I  I20  1  0.562  0.582  0.577  1.0
  I  I21  1  0.113  0.428  0.635  1.0
  I  I22  1  0.765  0.276  0.795  1.0
  I  I23  1  0.831  0.977  0.089  1.0
  I  I24  1  0.169  0.023  0.911  1.0
  I  I25  1  0.235  0.724  0.205  1.0
  I  I26  1  0.887  0.572  0.365  1.0
  I  I27  1  0.438  0.418  0.423  1.0
  I  I28  1  0.551  0.827  0.986  1.0
  I  I29  1  0.448  0.108  0.724  1.0
  I  I30  1  0.948  0.892  0.776  1.0
  I  I31  1  0.938  0.582  0.077  1.0
  I  I32  1  0.051  0.173  0.514  1.0
  I  I33  1  0.387  0.428  0.135  1.0
  I  I34  1  0.735  0.276  0.295  1.0
  I  I35  1  0.669  0.977  0.589  1.0
[/CIF]
.