The compound described by MgDySe3 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form MgSe6 octahedra that share corners with eight equivalent Dy(1)Se4 tetrahedra and edges with three equivalent Mg(1)Se6 octahedra. Dy(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form DySe4 tetrahedra that share corners with eight equivalent Mg(1)Se6 octahedra and  an edgeedge with one Dy(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-74°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Dy(1) atom. In the second Se site, Se(2) is bonded to two equivalent Mg(1) and two equivalent Dy(1) atoms to form edge-sharing SeDy2Mg2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_DyMgSe3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.971
_cell_length_b   7.292
_cell_length_c   7.424
_cell_angle_alpha   60.583
_cell_angle_beta   77.276
_cell_angle_gamma   63.356
_symmetry_Int_Tables_number   1
_cell_volume   293.833
_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
  Dy  Dy0  1  0.317  0.806  1.000  1.0
  Dy  Dy1  1  0.683  0.194  0.000  1.0
  Mg  Mg2  1  1.000  0.662  0.676  1.0
  Mg  Mg3  1  1.000  0.338  0.324  1.0
  Se  Se4  1  0.203  0.880  0.341  1.0
  Se  Se5  1  0.797  0.120  0.659  1.0
  Se  Se6  1  0.797  0.779  0.341  1.0
  Se  Se7  1  0.203  0.221  0.659  1.0
  Se  Se8  1  0.744  0.540  1.000  1.0
  Se  Se9  1  0.256  0.460  0.000  1.0
[/CIF]
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The compound described by MgDySe3 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form MgSe6 octahedra that share corners with eight equivalent Dy(1)Se4 tetrahedra and edges with three equivalent Mg(1)Se6 octahedra. Dy(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form DySe4 tetrahedra that share corners with eight equivalent Mg(1)Se6 octahedra and  an edgeedge with one Dy(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-74°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one Dy(1) atom. In the second Se site, Se(2) is bonded to two equivalent Mg(1) and two equivalent Dy(1) atoms to form edge-sharing SeDy2Mg2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_DyMgSe3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.971
_cell_length_b   7.292
_cell_length_c   7.424
_cell_angle_alpha   60.583
_cell_angle_beta   77.276
_cell_angle_gamma   63.356
_symmetry_Int_Tables_number   1
_cell_volume   293.833
_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
  Dy  Dy0  1  0.317  0.806  1.000  1.0
  Dy  Dy1  1  0.683  0.194  0.000  1.0
  Mg  Mg2  1  1.000  0.662  0.676  1.0
  Mg  Mg3  1  1.000  0.338  0.324  1.0
  Se  Se4  1  0.203  0.880  0.341  1.0
  Se  Se5  1  0.797  0.120  0.659  1.0
  Se  Se6  1  0.797  0.779  0.341  1.0
  Se  Se7  1  0.203  0.221  0.659  1.0
  Se  Se8  1  0.744  0.540  1.000  1.0
  Se  Se9  1  0.256  0.460  0.000  1.0
[/CIF]
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