The compound described by Ca3SiBr2 is Caswellsilverite-like structured and crystallizes in the orthorhombic Immm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent Si(1) and four equivalent Br(1) atoms to form a mixture of distorted corner and edge-sharing CaSi2Br4 octahedra. The corner-sharing octahedral tilt angles range from 0-21°. In the second Ca site, Ca(2) is bonded to two equivalent Si(1) and four equivalent Br(1) atoms to form a mixture of corner and edge-sharing CaSi2Br4 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. Si(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form SiCa6 octahedra that share corners with two equivalent Si(1)Ca6 octahedra, corners with four equivalent Br(1)Ca6 octahedra, edges with two equivalent Si(1)Ca6 octahedra, and edges with ten equivalent Br(1)Ca6 octahedra. The corner-sharing octahedral tilt angles range from 0-9°. Br(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form BrCa6 octahedra that share corners with two equivalent Si(1)Ca6 octahedra, corners with four equivalent Br(1)Ca6 octahedra, edges with five equivalent Si(1)Ca6 octahedra, and edges with seven equivalent Br(1)Ca6 octahedra. The corner-sharing octahedral tilt angles range from 0-21°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.776
_cell_length_b   7.776
_cell_length_c   7.776
_cell_angle_alpha   147.142
_cell_angle_beta   135.248
_cell_angle_gamma   56.621
_symmetry_Int_Tables_number   1
_cell_volume   178.287
_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  0.364  0.364  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.000  1.0
  Ca  Ca2  1  0.636  0.636  0.000  1.0
  Si  Si3  1  0.500  0.000  0.500  1.0
  Br  Br4  1  0.823  0.323  0.500  1.0
  Br  Br5  1  0.177  0.677  0.500  1.0
[/CIF]
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The compound described by Ca3SiBr2 is Caswellsilverite-like structured and crystallizes in the orthorhombic Immm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent Si(1) and four equivalent Br(1) atoms to form a mixture of distorted corner and edge-sharing CaSi2Br4 octahedra. The corner-sharing octahedral tilt angles range from 0-21°. In the second Ca site, Ca(2) is bonded to two equivalent Si(1) and four equivalent Br(1) atoms to form a mixture of corner and edge-sharing CaSi2Br4 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. Si(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form SiCa6 octahedra that share corners with two equivalent Si(1)Ca6 octahedra, corners with four equivalent Br(1)Ca6 octahedra, edges with two equivalent Si(1)Ca6 octahedra, and edges with ten equivalent Br(1)Ca6 octahedra. The corner-sharing octahedral tilt angles range from 0-9°. Br(1) is bonded to two equivalent Ca(2) and four equivalent Ca(1) atoms to form BrCa6 octahedra that share corners with two equivalent Si(1)Ca6 octahedra, corners with four equivalent Br(1)Ca6 octahedra, edges with five equivalent Si(1)Ca6 octahedra, and edges with seven equivalent Br(1)Ca6 octahedra. The corner-sharing octahedral tilt angles range from 0-21°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.776
_cell_length_b   7.776
_cell_length_c   7.776
_cell_angle_alpha   147.142
_cell_angle_beta   135.248
_cell_angle_gamma   56.621
_symmetry_Int_Tables_number   1
_cell_volume   178.287
_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  0.364  0.364  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.000  1.0
  Ca  Ca2  1  0.636  0.636  0.000  1.0
  Si  Si3  1  0.500  0.000  0.500  1.0
  Br  Br4  1  0.823  0.323  0.500  1.0
  Br  Br5  1  0.177  0.677  0.500  1.0
[/CIF]
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