The material described by Ca3SiBr2 is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to four equivalent Si(1) and two equivalent Br(1) atoms to form CaSi4Br2 octahedra that share corners with four equivalent Ca(1)Si4Br2 octahedra, corners with two equivalent Ca(2)SiBr5 pentagonal pyramids, edges with four equivalent Ca(1)Si4Br2 octahedra, and edges with eight equivalent Ca(2)SiBr5 pentagonal pyramids. The corner-sharing octahedra are not tilted. In the second Ca site, Ca(2) is bonded to one Si(1) and five equivalent Br(1) atoms to form distorted CaSiBr5 pentagonal pyramids that share  a cornercorner with one Ca(1)Si4Br2 octahedra, corners with five equivalent Ca(2)SiBr5 pentagonal pyramids, edges with four equivalent Ca(1)Si4Br2 octahedra, and edges with eight equivalent Ca(2)SiBr5 pentagonal pyramids. The corner-sharing octahedra are not tilted. Si(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form a mixture of edge and corner-sharing SiCa6 octahedra. The corner-sharing octahedra are not tilted. Br(1) is bonded in a 6-coordinate geometry to one Ca(1) and five equivalent Ca(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.034
_cell_length_b   10.034
_cell_length_c   10.034
_cell_angle_alpha   155.358
_cell_angle_beta   155.358
_cell_angle_gamma   35.129
_symmetry_Int_Tables_number   1
_cell_volume   175.444
_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
  Ca  Ca0  1  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.644  0.644  0.000  1.0
  Ca  Ca2  1  0.355  0.355  0.000  1.0
  Si  Si3  1  0.500  0.500  0.000  1.0
  Br  Br4  1  0.814  0.814  0.000  1.0
  Br  Br5  1  0.186  0.186  0.000  1.0
[/CIF]
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The material described by Ca3SiBr2 is Caswellsilverite-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to four equivalent Si(1) and two equivalent Br(1) atoms to form CaSi4Br2 octahedra that share corners with four equivalent Ca(1)Si4Br2 octahedra, corners with two equivalent Ca(2)SiBr5 pentagonal pyramids, edges with four equivalent Ca(1)Si4Br2 octahedra, and edges with eight equivalent Ca(2)SiBr5 pentagonal pyramids. The corner-sharing octahedra are not tilted. In the second Ca site, Ca(2) is bonded to one Si(1) and five equivalent Br(1) atoms to form distorted CaSiBr5 pentagonal pyramids that share  a cornercorner with one Ca(1)Si4Br2 octahedra, corners with five equivalent Ca(2)SiBr5 pentagonal pyramids, edges with four equivalent Ca(1)Si4Br2 octahedra, and edges with eight equivalent Ca(2)SiBr5 pentagonal pyramids. The corner-sharing octahedra are not tilted. Si(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form a mixture of edge and corner-sharing SiCa6 octahedra. The corner-sharing octahedra are not tilted. Br(1) is bonded in a 6-coordinate geometry to one Ca(1) and five equivalent Ca(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.034
_cell_length_b   10.034
_cell_length_c   10.034
_cell_angle_alpha   155.358
_cell_angle_beta   155.358
_cell_angle_gamma   35.129
_symmetry_Int_Tables_number   1
_cell_volume   175.444
_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
  Ca  Ca0  1  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.644  0.644  0.000  1.0
  Ca  Ca2  1  0.355  0.355  0.000  1.0
  Si  Si3  1  0.500  0.500  0.000  1.0
  Br  Br4  1  0.814  0.814  0.000  1.0
  Br  Br5  1  0.186  0.186  0.000  1.0
[/CIF]
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