The material described by EuTb2Se4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form a mixture of corner and edge-sharing TbSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-66°. In the second Tb site, Tb(2) is bonded to one Se(3), two equivalent Se(1), and three equivalent Se(4) atoms to form a mixture of corner and edge-sharing TbSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-66°. Eu(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Tb(1), two equivalent Tb(2), and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb3Eu2 trigonal bipyramids. In the second Se site, Se(2) is bonded to three equivalent Tb(1) and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb3Eu2 trigonal bipyramids. In the third Se site, Se(3) is bonded to one Tb(2), two equivalent Tb(1), and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb3Eu2 trigonal bipyramids. In the fourth Se site, Se(4) is bonded to three equivalent Tb(2) and two equivalent Eu(1) atoms to form a mixture of corner and edge-sharing SeTb3Eu2 square pyramids. is represented by the CIF file [CIF]
data_Tb2EuSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.135
_cell_length_b   12.487
_cell_length_c   14.943
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   771.558
_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
  Tb  Tb0  1  0.750  0.068  0.889  1.0
  Tb  Tb1  1  0.750  0.082  0.401  1.0
  Tb  Tb2  1  0.250  0.918  0.599  1.0
  Tb  Tb3  1  0.750  0.568  0.611  1.0
  Tb  Tb4  1  0.250  0.932  0.111  1.0
  Tb  Tb5  1  0.250  0.418  0.901  1.0
  Tb  Tb6  1  0.750  0.582  0.099  1.0
  Tb  Tb7  1  0.250  0.432  0.389  1.0
  Eu  Eu8  1  0.250  0.257  0.163  1.0
  Eu  Eu9  1  0.250  0.757  0.337  1.0
  Eu  Eu10  1  0.750  0.743  0.837  1.0
  Eu  Eu11  1  0.750  0.243  0.663  1.0
  Se  Se12  1  0.750  0.478  0.785  1.0
  Se  Se13  1  0.750  0.088  0.079  1.0
  Se  Se14  1  0.250  0.208  0.822  1.0
  Se  Se15  1  0.750  0.292  0.322  1.0
  Se  Se16  1  0.250  0.708  0.678  1.0
  Se  Se17  1  0.250  0.912  0.921  1.0
  Se  Se18  1  0.250  0.134  0.529  1.0
  Se  Se19  1  0.250  0.522  0.215  1.0
  Se  Se20  1  0.750  0.792  0.178  1.0
  Se  Se21  1  0.250  0.634  0.971  1.0
  Se  Se22  1  0.750  0.366  0.029  1.0
  Se  Se23  1  0.250  0.412  0.579  1.0
  Se  Se24  1  0.750  0.978  0.715  1.0
  Se  Se25  1  0.750  0.588  0.421  1.0
  Se  Se26  1  0.250  0.022  0.285  1.0
  Se  Se27  1  0.750  0.866  0.471  1.0
[/CIF]
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The material described by EuTb2Se4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to one Se(1), two equivalent Se(3), and three equivalent Se(2) atoms to form a mixture of corner and edge-sharing TbSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-66°. In the second Tb site, Tb(2) is bonded to one Se(3), two equivalent Se(1), and three equivalent Se(4) atoms to form a mixture of corner and edge-sharing TbSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-66°. Eu(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Tb(1), two equivalent Tb(2), and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb3Eu2 trigonal bipyramids. In the second Se site, Se(2) is bonded to three equivalent Tb(1) and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb3Eu2 trigonal bipyramids. In the third Se site, Se(3) is bonded to one Tb(2), two equivalent Tb(1), and two equivalent Eu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb3Eu2 trigonal bipyramids. In the fourth Se site, Se(4) is bonded to three equivalent Tb(2) and two equivalent Eu(1) atoms to form a mixture of corner and edge-sharing SeTb3Eu2 square pyramids. is represented by the CIF file [CIF]
data_Tb2EuSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.135
_cell_length_b   12.487
_cell_length_c   14.943
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   771.558
_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
  Tb  Tb0  1  0.750  0.068  0.889  1.0
  Tb  Tb1  1  0.750  0.082  0.401  1.0
  Tb  Tb2  1  0.250  0.918  0.599  1.0
  Tb  Tb3  1  0.750  0.568  0.611  1.0
  Tb  Tb4  1  0.250  0.932  0.111  1.0
  Tb  Tb5  1  0.250  0.418  0.901  1.0
  Tb  Tb6  1  0.750  0.582  0.099  1.0
  Tb  Tb7  1  0.250  0.432  0.389  1.0
  Eu  Eu8  1  0.250  0.257  0.163  1.0
  Eu  Eu9  1  0.250  0.757  0.337  1.0
  Eu  Eu10  1  0.750  0.743  0.837  1.0
  Eu  Eu11  1  0.750  0.243  0.663  1.0
  Se  Se12  1  0.750  0.478  0.785  1.0
  Se  Se13  1  0.750  0.088  0.079  1.0
  Se  Se14  1  0.250  0.208  0.822  1.0
  Se  Se15  1  0.750  0.292  0.322  1.0
  Se  Se16  1  0.250  0.708  0.678  1.0
  Se  Se17  1  0.250  0.912  0.921  1.0
  Se  Se18  1  0.250  0.134  0.529  1.0
  Se  Se19  1  0.250  0.522  0.215  1.0
  Se  Se20  1  0.750  0.792  0.178  1.0
  Se  Se21  1  0.250  0.634  0.971  1.0
  Se  Se22  1  0.750  0.366  0.029  1.0
  Se  Se23  1  0.250  0.412  0.579  1.0
  Se  Se24  1  0.750  0.978  0.715  1.0
  Se  Se25  1  0.750  0.588  0.421  1.0
  Se  Se26  1  0.250  0.022  0.285  1.0
  Se  Se27  1  0.750  0.866  0.471  1.0
[/CIF]
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