The crystal structure described by MgEr2S4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form MgS4 tetrahedra that share corners with two equivalent Er(1)S6 octahedra, corners with four equivalent Er(2)S6 octahedra,  an edgeedge with one Er(2)S6 octahedra, and edges with two equivalent Er(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 60-66°. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form ErS6 octahedra that share corners with four equivalent Er(2)S6 octahedra, corners with two equivalent Mg(1)S4 tetrahedra, edges with two equivalent Er(1)S6 octahedra, edges with two equivalent Er(2)S6 octahedra, and edges with two equivalent Mg(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-54°. In the second Er site, Er(2) is bonded to one S(2), one S(3), and four equivalent S(1) atoms to form ErS6 octahedra that share corners with four equivalent Er(1)S6 octahedra, corners with four equivalent Er(2)S6 octahedra, corners with four equivalent Mg(1)S4 tetrahedra, edges with two equivalent Er(1)S6 octahedra, and  an edgeedge with one Mg(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-54°. There are three inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Er(1), and two equivalent Er(2) atoms. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Er(2), and two equivalent Er(1) atoms. In the third S site, S(3) is bonded to one Mg(1), one Er(2), and two equivalent Er(1) atoms to form distorted corner-sharing SEr3Mg tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2MgS4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.431
_cell_length_b   7.830
_cell_length_c   6.491
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   682.702
_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  0.000  0.000  0.500  1.0
  Er  Er1  1  0.500  0.000  0.000  1.0
  Er  Er2  1  0.500  0.500  0.000  1.0
  Er  Er3  1  0.000  0.500  0.500  1.0
  Er  Er4  1  0.232  0.750  0.001  1.0
  Er  Er5  1  0.768  0.250  0.999  1.0
  Er  Er6  1  0.268  0.250  0.501  1.0
  Er  Er7  1  0.732  0.750  0.499  1.0
  Mg  Mg8  1  0.093  0.250  0.926  1.0
  Mg  Mg9  1  0.907  0.750  0.074  1.0
  Mg  Mg10  1  0.407  0.750  0.426  1.0
  Mg  Mg11  1  0.593  0.250  0.574  1.0
  S  S12  1  0.168  0.008  0.743  1.0
  S  S13  1  0.832  0.992  0.257  1.0
  S  S14  1  0.332  0.992  0.243  1.0
  S  S15  1  0.668  0.008  0.757  1.0
  S  S16  1  0.668  0.492  0.757  1.0
  S  S17  1  0.332  0.508  0.243  1.0
  S  S18  1  0.832  0.508  0.257  1.0
  S  S19  1  0.168  0.492  0.743  1.0
  S  S20  1  0.072  0.750  0.248  1.0
  S  S21  1  0.928  0.250  0.752  1.0
  S  S22  1  0.428  0.250  0.748  1.0
  S  S23  1  0.572  0.750  0.252  1.0
  S  S24  1  0.092  0.250  0.294  1.0
  S  S25  1  0.908  0.750  0.706  1.0
  S  S26  1  0.408  0.750  0.794  1.0
  S  S27  1  0.592  0.250  0.206  1.0
[/CIF]
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The crystal structure described by MgEr2S4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form MgS4 tetrahedra that share corners with two equivalent Er(1)S6 octahedra, corners with four equivalent Er(2)S6 octahedra,  an edgeedge with one Er(2)S6 octahedra, and edges with two equivalent Er(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 60-66°. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form ErS6 octahedra that share corners with four equivalent Er(2)S6 octahedra, corners with two equivalent Mg(1)S4 tetrahedra, edges with two equivalent Er(1)S6 octahedra, edges with two equivalent Er(2)S6 octahedra, and edges with two equivalent Mg(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-54°. In the second Er site, Er(2) is bonded to one S(2), one S(3), and four equivalent S(1) atoms to form ErS6 octahedra that share corners with four equivalent Er(1)S6 octahedra, corners with four equivalent Er(2)S6 octahedra, corners with four equivalent Mg(1)S4 tetrahedra, edges with two equivalent Er(1)S6 octahedra, and  an edgeedge with one Mg(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-54°. There are three inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Er(1), and two equivalent Er(2) atoms. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Er(2), and two equivalent Er(1) atoms. In the third S site, S(3) is bonded to one Mg(1), one Er(2), and two equivalent Er(1) atoms to form distorted corner-sharing SEr3Mg tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2MgS4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.431
_cell_length_b   7.830
_cell_length_c   6.491
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   682.702
_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  0.000  0.000  0.500  1.0
  Er  Er1  1  0.500  0.000  0.000  1.0
  Er  Er2  1  0.500  0.500  0.000  1.0
  Er  Er3  1  0.000  0.500  0.500  1.0
  Er  Er4  1  0.232  0.750  0.001  1.0
  Er  Er5  1  0.768  0.250  0.999  1.0
  Er  Er6  1  0.268  0.250  0.501  1.0
  Er  Er7  1  0.732  0.750  0.499  1.0
  Mg  Mg8  1  0.093  0.250  0.926  1.0
  Mg  Mg9  1  0.907  0.750  0.074  1.0
  Mg  Mg10  1  0.407  0.750  0.426  1.0
  Mg  Mg11  1  0.593  0.250  0.574  1.0
  S  S12  1  0.168  0.008  0.743  1.0
  S  S13  1  0.832  0.992  0.257  1.0
  S  S14  1  0.332  0.992  0.243  1.0
  S  S15  1  0.668  0.008  0.757  1.0
  S  S16  1  0.668  0.492  0.757  1.0
  S  S17  1  0.332  0.508  0.243  1.0
  S  S18  1  0.832  0.508  0.257  1.0
  S  S19  1  0.168  0.492  0.743  1.0
  S  S20  1  0.072  0.750  0.248  1.0
  S  S21  1  0.928  0.250  0.752  1.0
  S  S22  1  0.428  0.250  0.748  1.0
  S  S23  1  0.572  0.750  0.252  1.0
  S  S24  1  0.092  0.250  0.294  1.0
  S  S25  1  0.908  0.750  0.706  1.0
  S  S26  1  0.408  0.750  0.794  1.0
  S  S27  1  0.592  0.250  0.206  1.0
[/CIF]
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