The crystal structure described by Be12Ta crystallizes in the tetragonal I4/mmm space group. There are three inequivalent Be sites. In the first Be site, Be(1) is bonded in a 10-coordinate geometry to one Be(1), four equivalent Be(2), four equivalent Be(3), and one Ta(1) atom. In the second Be site, Be(2) is bonded to two equivalent Be(2), four equivalent Be(1), four equivalent Be(3), and two equivalent Ta(1) atoms to form a mixture of distorted corner, face, and edge-sharing BeTa2Be10 cuboctahedra. In the third Be site, Be(3) is bonded in a distorted q6 geometry to two equivalent Be(3), four equivalent Be(1), four equivalent Be(2), and two equivalent Ta(1) atoms. Ta(1) is bonded in a 20-coordinate geometry to four equivalent Be(1), eight equivalent Be(2), and eight equivalent Be(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_TaBe12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.208
_cell_length_b   5.578
_cell_length_c   5.578
_cell_angle_alpha   81.820
_cell_angle_beta   67.839
_cell_angle_gamma   67.839
_symmetry_Int_Tables_number   1
_cell_volume   112.330
_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
  Ta  Ta0  1  0.000  0.000  0.000  1.0
  Be  Be1  1  0.000  0.648  0.352  1.0
  Be  Be2  1  0.000  0.500  0.000  1.0
  Be  Be3  1  0.648  0.352  0.352  1.0
  Be  Be4  1  0.500  0.215  0.785  1.0
  Be  Be5  1  0.000  0.352  0.648  1.0
  Be  Be6  1  0.500  0.000  0.500  1.0
  Be  Be7  1  0.352  0.648  0.648  1.0
  Be  Be8  1  0.285  0.215  0.215  1.0
  Be  Be9  1  0.500  0.785  0.215  1.0
  Be  Be10  1  0.000  0.000  0.500  1.0
  Be  Be11  1  0.715  0.785  0.785  1.0
  Be  Be12  1  0.500  0.500  0.000  1.0
[/CIF]
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The crystal structure described by Be12Ta crystallizes in the tetragonal I4/mmm space group. There are three inequivalent Be sites. In the first Be site, Be(1) is bonded in a 10-coordinate geometry to one Be(1), four equivalent Be(2), four equivalent Be(3), and one Ta(1) atom. In the second Be site, Be(2) is bonded to two equivalent Be(2), four equivalent Be(1), four equivalent Be(3), and two equivalent Ta(1) atoms to form a mixture of distorted corner, face, and edge-sharing BeTa2Be10 cuboctahedra. In the third Be site, Be(3) is bonded in a distorted q6 geometry to two equivalent Be(3), four equivalent Be(1), four equivalent Be(2), and two equivalent Ta(1) atoms. Ta(1) is bonded in a 20-coordinate geometry to four equivalent Be(1), eight equivalent Be(2), and eight equivalent Be(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_TaBe12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.208
_cell_length_b   5.578
_cell_length_c   5.578
_cell_angle_alpha   81.820
_cell_angle_beta   67.839
_cell_angle_gamma   67.839
_symmetry_Int_Tables_number   1
_cell_volume   112.330
_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
  Ta  Ta0  1  0.000  0.000  0.000  1.0
  Be  Be1  1  0.000  0.648  0.352  1.0
  Be  Be2  1  0.000  0.500  0.000  1.0
  Be  Be3  1  0.648  0.352  0.352  1.0
  Be  Be4  1  0.500  0.215  0.785  1.0
  Be  Be5  1  0.000  0.352  0.648  1.0
  Be  Be6  1  0.500  0.000  0.500  1.0
  Be  Be7  1  0.352  0.648  0.648  1.0
  Be  Be8  1  0.285  0.215  0.215  1.0
  Be  Be9  1  0.500  0.785  0.215  1.0
  Be  Be10  1  0.000  0.000  0.500  1.0
  Be  Be11  1  0.715  0.785  0.785  1.0
  Be  Be12  1  0.500  0.500  0.000  1.0
[/CIF]
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