The structure described by Ba2ErGaSe5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(4), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(5) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms. Er(1) is bonded to one Se(1), one Se(2), two equivalent Se(3), and two equivalent Se(4) atoms to form ErSe6 octahedra that share edges with two equivalent Er(1)Se6 octahedra and edges with two equivalent Ga(1)Se4 tetrahedra. Ga(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(5) atom to form GaSe4 tetrahedra that share edges with two equivalent Er(1)Se6 octahedra. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Ba(1), two equivalent Ba(2), one Er(1), and one Ga(1) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Er(1), and one Ga(1) atom. In the third Se site, Se(3) is bonded to one Ba(2), two equivalent Ba(1), two equivalent Er(1), and one Ga(1) atom to form distorted SeBa3Er2Ga octahedra that share corners with four equivalent Se(5)Ba4Ga square pyramids, corners with two equivalent Se(4)Ba3Er2 trigonal bipyramids, edges with two equivalent Se(3)Ba3Er2Ga octahedra, edges with three equivalent Se(4)Ba3Er2 trigonal bipyramids, and  a faceface with one Se(5)Ba4Ga square pyramid. In the fourth Se site, Se(4) is bonded to one Ba(1), two equivalent Ba(2), and two equivalent Er(1) atoms to form distorted SeBa3Er2 trigonal bipyramids that share corners with two equivalent Se(3)Ba3Er2Ga octahedra, corners with four equivalent Se(5)Ba4Ga square pyramids, edges with three equivalent Se(3)Ba3Er2Ga octahedra,  an edgeedge with one Se(5)Ba4Ga square pyramid, and edges with two equivalent Se(4)Ba3Er2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 6°. In the fifth Se site, Se(5) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one Ga(1) atom to form SeBa4Ga square pyramids that share corners with four equivalent Se(3)Ba3Er2Ga octahedra, corners with four equivalent Se(4)Ba3Er2 trigonal bipyramids, edges with two equivalent Se(5)Ba4Ga square pyramids,  an edgeedge with one Se(4)Ba3Er2 trigonal bipyramid, and  a faceface with one Se(3)Ba3Er2Ga octahedra. The corner-sharing octahedral tilt angles range from 44-67°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2ErGaSe5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.394
_cell_length_b   8.749
_cell_length_c   9.517
_cell_angle_alpha   103.460
_cell_angle_beta   103.156
_cell_angle_gamma   107.332
_symmetry_Int_Tables_number   1
_cell_volume   541.518
_cell_formula_units_Z   2
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
  Ba  Ba0  1  0.633  0.978  0.288  1.0
  Ba  Ba1  1  0.367  0.022  0.712  1.0
  Ba  Ba2  1  0.344  0.511  0.708  1.0
  Ba  Ba3  1  0.656  0.489  0.292  1.0
  Er  Er4  1  0.998  0.730  0.999  1.0
  Er  Er5  1  0.002  0.270  0.001  1.0
  Ga  Ga6  1  0.806  0.872  0.688  1.0
  Ga  Ga7  1  0.194  0.128  0.312  1.0
  Se  Se8  1  0.988  0.682  0.687  1.0
  Se  Se9  1  0.012  0.318  0.313  1.0
  Se  Se10  1  0.984  0.155  0.689  1.0
  Se  Se11  1  0.016  0.845  0.311  1.0
  Se  Se12  1  0.715  0.910  0.929  1.0
  Se  Se13  1  0.285  0.090  0.071  1.0
  Se  Se14  1  0.708  0.412  0.945  1.0
  Se  Se15  1  0.292  0.588  0.055  1.0
  Se  Se16  1  0.489  0.742  0.493  1.0
  Se  Se17  1  0.511  0.258  0.507  1.0
[/CIF]
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The structure described by Ba2ErGaSe5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(4), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(5) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one Se(2), one Se(3), two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms. Er(1) is bonded to one Se(1), one Se(2), two equivalent Se(3), and two equivalent Se(4) atoms to form ErSe6 octahedra that share edges with two equivalent Er(1)Se6 octahedra and edges with two equivalent Ga(1)Se4 tetrahedra. Ga(1) is bonded to one Se(1), one Se(2), one Se(3), and one Se(5) atom to form GaSe4 tetrahedra that share edges with two equivalent Er(1)Se6 octahedra. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Ba(1), two equivalent Ba(2), one Er(1), and one Ga(1) atom. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Ba(2), two equivalent Ba(1), one Er(1), and one Ga(1) atom. In the third Se site, Se(3) is bonded to one Ba(2), two equivalent Ba(1), two equivalent Er(1), and one Ga(1) atom to form distorted SeBa3Er2Ga octahedra that share corners with four equivalent Se(5)Ba4Ga square pyramids, corners with two equivalent Se(4)Ba3Er2 trigonal bipyramids, edges with two equivalent Se(3)Ba3Er2Ga octahedra, edges with three equivalent Se(4)Ba3Er2 trigonal bipyramids, and  a faceface with one Se(5)Ba4Ga square pyramid. In the fourth Se site, Se(4) is bonded to one Ba(1), two equivalent Ba(2), and two equivalent Er(1) atoms to form distorted SeBa3Er2 trigonal bipyramids that share corners with two equivalent Se(3)Ba3Er2Ga octahedra, corners with four equivalent Se(5)Ba4Ga square pyramids, edges with three equivalent Se(3)Ba3Er2Ga octahedra,  an edgeedge with one Se(5)Ba4Ga square pyramid, and edges with two equivalent Se(4)Ba3Er2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 6°. In the fifth Se site, Se(5) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one Ga(1) atom to form SeBa4Ga square pyramids that share corners with four equivalent Se(3)Ba3Er2Ga octahedra, corners with four equivalent Se(4)Ba3Er2 trigonal bipyramids, edges with two equivalent Se(5)Ba4Ga square pyramids,  an edgeedge with one Se(4)Ba3Er2 trigonal bipyramid, and  a faceface with one Se(3)Ba3Er2Ga octahedra. The corner-sharing octahedral tilt angles range from 44-67°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2ErGaSe5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.394
_cell_length_b   8.749
_cell_length_c   9.517
_cell_angle_alpha   103.460
_cell_angle_beta   103.156
_cell_angle_gamma   107.332
_symmetry_Int_Tables_number   1
_cell_volume   541.518
_cell_formula_units_Z   2
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
  Ba  Ba0  1  0.633  0.978  0.288  1.0
  Ba  Ba1  1  0.367  0.022  0.712  1.0
  Ba  Ba2  1  0.344  0.511  0.708  1.0
  Ba  Ba3  1  0.656  0.489  0.292  1.0
  Er  Er4  1  0.998  0.730  0.999  1.0
  Er  Er5  1  0.002  0.270  0.001  1.0
  Ga  Ga6  1  0.806  0.872  0.688  1.0
  Ga  Ga7  1  0.194  0.128  0.312  1.0
  Se  Se8  1  0.988  0.682  0.687  1.0
  Se  Se9  1  0.012  0.318  0.313  1.0
  Se  Se10  1  0.984  0.155  0.689  1.0
  Se  Se11  1  0.016  0.845  0.311  1.0
  Se  Se12  1  0.715  0.910  0.929  1.0
  Se  Se13  1  0.285  0.090  0.071  1.0
  Se  Se14  1  0.708  0.412  0.945  1.0
  Se  Se15  1  0.292  0.588  0.055  1.0
  Se  Se16  1  0.489  0.742  0.493  1.0
  Se  Se17  1  0.511  0.258  0.507  1.0
[/CIF]
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