The material described by Er2S3 crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded to one S(6), two equivalent S(2), and three equivalent S(4) atoms to form ErS6 octahedra that share corners with three equivalent Er(4)S6 octahedra, corners with two equivalent Er(3)S7 pentagonal bipyramids, and edges with four equivalent Er(1)S6 octahedra. The corner-sharing octahedral tilt angles are 59°. In the second Er site, Er(2) is bonded in a 8-coordinate geometry to one S(2), two equivalent S(4), two equivalent S(5), and three equivalent S(1) atoms. In the third Er site, Er(3) is bonded to one S(2), one S(5), two equivalent S(1), and three equivalent S(3) atoms to form distorted ErS7 pentagonal bipyramids that share  a cornercorner with one Er(4)S6 octahedra, corners with two equivalent Er(1)S6 octahedra, edges with two equivalent Er(4)S6 octahedra, and edges with four equivalent Er(3)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 37-51°. In the fourth Er site, Er(4) is bonded to one S(3), two equivalent S(5), and three equivalent S(6) atoms to form ErS6 octahedra that share corners with three equivalent Er(1)S6 octahedra,  a cornercorner with one Er(3)S7 pentagonal bipyramid, edges with four equivalent Er(4)S6 octahedra, and edges with two equivalent Er(3)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. There are six inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Er(3) and three equivalent Er(2) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(4)Er5 square pyramids, corners with two equivalent S(5)Er5 trigonal bipyramids,  a cornercorner with one S(2)Er4 trigonal pyramid, corners with four equivalent S(3)Er4 trigonal pyramids,  an edgeedge with one S(4)Er5 square pyramid, edges with three equivalent S(5)Er5 trigonal bipyramids, edges with four equivalent S(1)Er5 trigonal bipyramids,  an edgeedge with one S(3)Er4 trigonal pyramid, and edges with two equivalent S(2)Er4 trigonal pyramids. In the second S site, S(2) is bonded to one Er(2), one Er(3), and two equivalent Er(1) atoms to form distorted SEr4 trigonal pyramids that share corners with two equivalent S(4)Er5 square pyramids,  a cornercorner with one S(1)Er5 trigonal bipyramid, corners with three equivalent S(5)Er5 trigonal bipyramids, corners with two equivalent S(2)Er4 trigonal pyramids, corners with two equivalent S(6)Er4 trigonal pyramids, corners with three equivalent S(3)Er4 trigonal pyramids, edges with three equivalent S(4)Er5 square pyramids, and edges with two equivalent S(1)Er5 trigonal bipyramids. In the third S site, S(3) is bonded to one Er(4) and three equivalent Er(3) atoms to form distorted SEr4 trigonal pyramids that share  a cornercorner with one S(5)Er5 trigonal bipyramid, corners with four equivalent S(1)Er5 trigonal bipyramids, corners with two equivalent S(3)Er4 trigonal pyramids, corners with three equivalent S(2)Er4 trigonal pyramids, corners with three equivalent S(6)Er4 trigonal pyramids,  an edgeedge with one S(1)Er5 trigonal bipyramid, edges with two equivalent S(5)Er5 trigonal bipyramids, and edges with two equivalent S(3)Er4 trigonal pyramids. In the fourth S site, S(4) is bonded to two equivalent Er(2) and three equivalent Er(1) atoms to form SEr5 square pyramids that share corners with two equivalent S(5)Er5 trigonal bipyramids, corners with four equivalent S(1)Er5 trigonal bipyramids, corners with two equivalent S(2)Er4 trigonal pyramids, corners with three equivalent S(6)Er4 trigonal pyramids, edges with four equivalent S(4)Er5 square pyramids,  an edgeedge with one S(1)Er5 trigonal bipyramid,  an edgeedge with one S(5)Er5 trigonal bipyramid, and edges with three equivalent S(2)Er4 trigonal pyramids. In the fifth S site, S(5) is bonded to one Er(3), two equivalent Er(2), and two equivalent Er(4) atoms to form SEr5 trigonal bipyramids that share corners with two equivalent S(4)Er5 square pyramids, corners with two equivalent S(1)Er5 trigonal bipyramids,  a cornercorner with one S(3)Er4 trigonal pyramid, corners with three equivalent S(2)Er4 trigonal pyramids, corners with four equivalent S(6)Er4 trigonal pyramids,  an edgeedge with one S(4)Er5 square pyramid, edges with two equivalent S(5)Er5 trigonal bipyramids, edges with three equivalent S(1)Er5 trigonal bipyramids,  an edgeedge with one S(6)Er4 trigonal pyramid, and edges with two equivalent S(3)Er4 trigonal pyramids. In the sixth S site, S(6) is bonded to one Er(1) and three equivalent Er(4) atoms to form distorted SEr4 trigonal pyramids that share corners with three equivalent S(4)Er5 square pyramids, corners with four equivalent S(5)Er5 trigonal bipyramids, corners with two equivalent S(2)Er4 trigonal pyramids, corners with two equivalent S(6)Er4 trigonal pyramids, corners with three equivalent S(3)Er4 trigonal pyramids,  an edgeedge with one S(5)Er5 trigonal bipyramid, and edges with two equivalent S(6)Er4 trigonal pyramids. is represented by the CIF file [CIF]
data_Er2S3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.891
_cell_length_b   10.903
_cell_length_c   11.160
_cell_angle_alpha   108.863
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   447.979
_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
  Er  Er0  1  0.250  0.339  0.916  1.0
  Er  Er1  1  0.750  0.661  0.084  1.0
  Er  Er2  1  0.250  0.457  0.310  1.0
  Er  Er3  1  0.750  0.543  0.690  1.0
  Er  Er4  1  0.250  0.818  0.497  1.0
  Er  Er5  1  0.750  0.182  0.503  1.0
  Er  Er6  1  0.250  0.067  0.168  1.0
  Er  Er7  1  0.750  0.933  0.832  1.0
  S  S8  1  0.250  0.390  0.538  1.0
  S  S9  1  0.750  0.610  0.462  1.0
  S  S10  1  0.250  0.691  0.249  1.0
  S  S11  1  0.750  0.309  0.751  1.0
  S  S12  1  0.250  0.023  0.387  1.0
  S  S13  1  0.750  0.977  0.613  1.0
  S  S14  1  0.250  0.581  0.902  1.0
  S  S15  1  0.750  0.419  0.098  1.0
  S  S16  1  0.750  0.246  0.277  1.0
  S  S17  1  0.250  0.754  0.723  1.0
  S  S18  1  0.750  0.898  0.063  1.0
  S  S19  1  0.250  0.102  0.937  1.0
[/CIF]
.
The material described by Er2S3 crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded to one S(6), two equivalent S(2), and three equivalent S(4) atoms to form ErS6 octahedra that share corners with three equivalent Er(4)S6 octahedra, corners with two equivalent Er(3)S7 pentagonal bipyramids, and edges with four equivalent Er(1)S6 octahedra. The corner-sharing octahedral tilt angles are 59°. In the second Er site, Er(2) is bonded in a 8-coordinate geometry to one S(2), two equivalent S(4), two equivalent S(5), and three equivalent S(1) atoms. In the third Er site, Er(3) is bonded to one S(2), one S(5), two equivalent S(1), and three equivalent S(3) atoms to form distorted ErS7 pentagonal bipyramids that share  a cornercorner with one Er(4)S6 octahedra, corners with two equivalent Er(1)S6 octahedra, edges with two equivalent Er(4)S6 octahedra, and edges with four equivalent Er(3)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 37-51°. In the fourth Er site, Er(4) is bonded to one S(3), two equivalent S(5), and three equivalent S(6) atoms to form ErS6 octahedra that share corners with three equivalent Er(1)S6 octahedra,  a cornercorner with one Er(3)S7 pentagonal bipyramid, edges with four equivalent Er(4)S6 octahedra, and edges with two equivalent Er(3)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 59°. There are six inequivalent S sites. In the first S site, S(1) is bonded to two equivalent Er(3) and three equivalent Er(2) atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent S(4)Er5 square pyramids, corners with two equivalent S(5)Er5 trigonal bipyramids,  a cornercorner with one S(2)Er4 trigonal pyramid, corners with four equivalent S(3)Er4 trigonal pyramids,  an edgeedge with one S(4)Er5 square pyramid, edges with three equivalent S(5)Er5 trigonal bipyramids, edges with four equivalent S(1)Er5 trigonal bipyramids,  an edgeedge with one S(3)Er4 trigonal pyramid, and edges with two equivalent S(2)Er4 trigonal pyramids. In the second S site, S(2) is bonded to one Er(2), one Er(3), and two equivalent Er(1) atoms to form distorted SEr4 trigonal pyramids that share corners with two equivalent S(4)Er5 square pyramids,  a cornercorner with one S(1)Er5 trigonal bipyramid, corners with three equivalent S(5)Er5 trigonal bipyramids, corners with two equivalent S(2)Er4 trigonal pyramids, corners with two equivalent S(6)Er4 trigonal pyramids, corners with three equivalent S(3)Er4 trigonal pyramids, edges with three equivalent S(4)Er5 square pyramids, and edges with two equivalent S(1)Er5 trigonal bipyramids. In the third S site, S(3) is bonded to one Er(4) and three equivalent Er(3) atoms to form distorted SEr4 trigonal pyramids that share  a cornercorner with one S(5)Er5 trigonal bipyramid, corners with four equivalent S(1)Er5 trigonal bipyramids, corners with two equivalent S(3)Er4 trigonal pyramids, corners with three equivalent S(2)Er4 trigonal pyramids, corners with three equivalent S(6)Er4 trigonal pyramids,  an edgeedge with one S(1)Er5 trigonal bipyramid, edges with two equivalent S(5)Er5 trigonal bipyramids, and edges with two equivalent S(3)Er4 trigonal pyramids. In the fourth S site, S(4) is bonded to two equivalent Er(2) and three equivalent Er(1) atoms to form SEr5 square pyramids that share corners with two equivalent S(5)Er5 trigonal bipyramids, corners with four equivalent S(1)Er5 trigonal bipyramids, corners with two equivalent S(2)Er4 trigonal pyramids, corners with three equivalent S(6)Er4 trigonal pyramids, edges with four equivalent S(4)Er5 square pyramids,  an edgeedge with one S(1)Er5 trigonal bipyramid,  an edgeedge with one S(5)Er5 trigonal bipyramid, and edges with three equivalent S(2)Er4 trigonal pyramids. In the fifth S site, S(5) is bonded to one Er(3), two equivalent Er(2), and two equivalent Er(4) atoms to form SEr5 trigonal bipyramids that share corners with two equivalent S(4)Er5 square pyramids, corners with two equivalent S(1)Er5 trigonal bipyramids,  a cornercorner with one S(3)Er4 trigonal pyramid, corners with three equivalent S(2)Er4 trigonal pyramids, corners with four equivalent S(6)Er4 trigonal pyramids,  an edgeedge with one S(4)Er5 square pyramid, edges with two equivalent S(5)Er5 trigonal bipyramids, edges with three equivalent S(1)Er5 trigonal bipyramids,  an edgeedge with one S(6)Er4 trigonal pyramid, and edges with two equivalent S(3)Er4 trigonal pyramids. In the sixth S site, S(6) is bonded to one Er(1) and three equivalent Er(4) atoms to form distorted SEr4 trigonal pyramids that share corners with three equivalent S(4)Er5 square pyramids, corners with four equivalent S(5)Er5 trigonal bipyramids, corners with two equivalent S(2)Er4 trigonal pyramids, corners with two equivalent S(6)Er4 trigonal pyramids, corners with three equivalent S(3)Er4 trigonal pyramids,  an edgeedge with one S(5)Er5 trigonal bipyramid, and edges with two equivalent S(6)Er4 trigonal pyramids. is represented by the CIF file [CIF]
data_Er2S3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.891
_cell_length_b   10.903
_cell_length_c   11.160
_cell_angle_alpha   108.863
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   447.979
_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
  Er  Er0  1  0.250  0.339  0.916  1.0
  Er  Er1  1  0.750  0.661  0.084  1.0
  Er  Er2  1  0.250  0.457  0.310  1.0
  Er  Er3  1  0.750  0.543  0.690  1.0
  Er  Er4  1  0.250  0.818  0.497  1.0
  Er  Er5  1  0.750  0.182  0.503  1.0
  Er  Er6  1  0.250  0.067  0.168  1.0
  Er  Er7  1  0.750  0.933  0.832  1.0
  S  S8  1  0.250  0.390  0.538  1.0
  S  S9  1  0.750  0.610  0.462  1.0
  S  S10  1  0.250  0.691  0.249  1.0
  S  S11  1  0.750  0.309  0.751  1.0
  S  S12  1  0.250  0.023  0.387  1.0
  S  S13  1  0.750  0.977  0.613  1.0
  S  S14  1  0.250  0.581  0.902  1.0
  S  S15  1  0.750  0.419  0.098  1.0
  S  S16  1  0.750  0.246  0.277  1.0
  S  S17  1  0.250  0.754  0.723  1.0
  S  S18  1  0.750  0.898  0.063  1.0
  S  S19  1  0.250  0.102  0.937  1.0
[/CIF]
.