The material structure described by TbAl2Si2 crystallizes in the trigonal P-3m1 space group. Tb(1) is bonded to six equivalent Si(1) atoms to form distorted TbSi6 octahedra that share corners with twelve equivalent Al(1)Si4 tetrahedra, edges with six equivalent Tb(1)Si6 octahedra, and edges with six equivalent Al(1)Si4 tetrahedra. Al(1) is bonded to four equivalent Si(1) atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent Tb(1)Si6 octahedra, corners with six equivalent Al(1)Si4 tetrahedra, edges with three equivalent Tb(1)Si6 octahedra, and edges with three equivalent Al(1)Si4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-54°. Si(1) is bonded to three equivalent Tb(1) and four equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing SiTb3Al4 pentagonal bipyramids. is represented by the CIF file [CIF]
data_Tb(AlSi)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.179
_cell_length_b   4.179
_cell_length_c   6.622
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   100.141
_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
  Tb  Tb0  1  0.000  0.000  0.000  1.0
  Al  Al1  1  0.667  0.333  0.357  1.0
  Al  Al2  1  0.333  0.667  0.643  1.0
  Si  Si3  1  0.667  0.333  0.738  1.0
  Si  Si4  1  0.333  0.667  0.262  1.0
[/CIF]
.
The material structure described by TbAl2Si2 crystallizes in the trigonal P-3m1 space group. Tb(1) is bonded to six equivalent Si(1) atoms to form distorted TbSi6 octahedra that share corners with twelve equivalent Al(1)Si4 tetrahedra, edges with six equivalent Tb(1)Si6 octahedra, and edges with six equivalent Al(1)Si4 tetrahedra. Al(1) is bonded to four equivalent Si(1) atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent Tb(1)Si6 octahedra, corners with six equivalent Al(1)Si4 tetrahedra, edges with three equivalent Tb(1)Si6 octahedra, and edges with three equivalent Al(1)Si4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-54°. Si(1) is bonded to three equivalent Tb(1) and four equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing SiTb3Al4 pentagonal bipyramids. is represented by the CIF file [CIF]
data_Tb(AlSi)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.179
_cell_length_b   4.179
_cell_length_c   6.622
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   100.141
_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
  Tb  Tb0  1  0.000  0.000  0.000  1.0
  Al  Al1  1  0.667  0.333  0.357  1.0
  Al  Al2  1  0.333  0.667  0.643  1.0
  Si  Si3  1  0.667  0.333  0.738  1.0
  Si  Si4  1  0.333  0.667  0.262  1.0
[/CIF]
.