The compound described by MgSm2Se4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form MgSe4 tetrahedra that share corners with two equivalent Sm(1)Se6 octahedra, corners with four equivalent Sm(2)Se6 octahedra,  an edgeedge with one Sm(2)Se6 octahedra, and edges with two equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 59-64°. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form SmSe6 octahedra that share corners with four equivalent Sm(2)Se6 octahedra, corners with two equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sm(1)Se6 octahedra, edges with two equivalent Sm(2)Se6 octahedra, and edges with two equivalent Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-55°. In the second Sm site, Sm(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form SmSe6 octahedra that share corners with four equivalent Sm(1)Se6 octahedra, corners with four equivalent Sm(2)Se6 octahedra, corners with four equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sm(1)Se6 octahedra, and  an edgeedge with one Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-55°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sm(1), and two equivalent Sm(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sm(2), and two equivalent Sm(1) atoms. In the third Se site, Se(3) is bonded to one Mg(1), one Sm(2), and two equivalent Sm(1) atoms to form distorted corner-sharing SeSm3Mg trigonal pyramids. is represented by the CIF card [CIF]
data_Sm2MgSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.923
_cell_length_b   8.446
_cell_length_c   14.466
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   845.834
_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
  Sm  Sm0  1  0.500  0.000  0.000  1.0
  Sm  Sm1  1  0.000  0.000  0.500  1.0
  Sm  Sm2  1  0.000  0.500  0.500  1.0
  Sm  Sm3  1  0.500  0.500  0.000  1.0
  Sm  Sm4  1  0.002  0.750  0.234  1.0
  Sm  Sm5  1  0.998  0.250  0.766  1.0
  Sm  Sm6  1  0.502  0.250  0.266  1.0
  Sm  Sm7  1  0.498  0.750  0.734  1.0
  Mg  Mg8  1  0.917  0.250  0.092  1.0
  Mg  Mg9  1  0.083  0.750  0.908  1.0
  Mg  Mg10  1  0.417  0.750  0.408  1.0
  Mg  Mg11  1  0.583  0.250  0.592  1.0
  Se  Se12  1  0.744  0.010  0.169  1.0
  Se  Se13  1  0.256  0.990  0.831  1.0
  Se  Se14  1  0.244  0.990  0.331  1.0
  Se  Se15  1  0.756  0.010  0.669  1.0
  Se  Se16  1  0.756  0.490  0.669  1.0
  Se  Se17  1  0.244  0.510  0.331  1.0
  Se  Se18  1  0.256  0.510  0.831  1.0
  Se  Se19  1  0.744  0.490  0.169  1.0
  Se  Se20  1  0.247  0.750  0.071  1.0
  Se  Se21  1  0.753  0.250  0.929  1.0
  Se  Se22  1  0.747  0.250  0.429  1.0
  Se  Se23  1  0.253  0.750  0.571  1.0
  Se  Se24  1  0.285  0.250  0.092  1.0
  Se  Se25  1  0.715  0.750  0.908  1.0
  Se  Se26  1  0.785  0.750  0.408  1.0
  Se  Se27  1  0.215  0.250  0.592  1.0
[/CIF]
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The compound described by MgSm2Se4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. Mg(1) is bonded to one Se(2), one Se(3), and two equivalent Se(1) atoms to form MgSe4 tetrahedra that share corners with two equivalent Sm(1)Se6 octahedra, corners with four equivalent Sm(2)Se6 octahedra,  an edgeedge with one Sm(2)Se6 octahedra, and edges with two equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 59-64°. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form SmSe6 octahedra that share corners with four equivalent Sm(2)Se6 octahedra, corners with two equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sm(1)Se6 octahedra, edges with two equivalent Sm(2)Se6 octahedra, and edges with two equivalent Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-55°. In the second Sm site, Sm(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form SmSe6 octahedra that share corners with four equivalent Sm(1)Se6 octahedra, corners with four equivalent Sm(2)Se6 octahedra, corners with four equivalent Mg(1)Se4 tetrahedra, edges with two equivalent Sm(1)Se6 octahedra, and  an edgeedge with one Mg(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-55°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sm(1), and two equivalent Sm(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Sm(2), and two equivalent Sm(1) atoms. In the third Se site, Se(3) is bonded to one Mg(1), one Sm(2), and two equivalent Sm(1) atoms to form distorted corner-sharing SeSm3Mg trigonal pyramids. is represented by the CIF card [CIF]
data_Sm2MgSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.923
_cell_length_b   8.446
_cell_length_c   14.466
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   845.834
_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
  Sm  Sm0  1  0.500  0.000  0.000  1.0
  Sm  Sm1  1  0.000  0.000  0.500  1.0
  Sm  Sm2  1  0.000  0.500  0.500  1.0
  Sm  Sm3  1  0.500  0.500  0.000  1.0
  Sm  Sm4  1  0.002  0.750  0.234  1.0
  Sm  Sm5  1  0.998  0.250  0.766  1.0
  Sm  Sm6  1  0.502  0.250  0.266  1.0
  Sm  Sm7  1  0.498  0.750  0.734  1.0
  Mg  Mg8  1  0.917  0.250  0.092  1.0
  Mg  Mg9  1  0.083  0.750  0.908  1.0
  Mg  Mg10  1  0.417  0.750  0.408  1.0
  Mg  Mg11  1  0.583  0.250  0.592  1.0
  Se  Se12  1  0.744  0.010  0.169  1.0
  Se  Se13  1  0.256  0.990  0.831  1.0
  Se  Se14  1  0.244  0.990  0.331  1.0
  Se  Se15  1  0.756  0.010  0.669  1.0
  Se  Se16  1  0.756  0.490  0.669  1.0
  Se  Se17  1  0.244  0.510  0.331  1.0
  Se  Se18  1  0.256  0.510  0.831  1.0
  Se  Se19  1  0.744  0.490  0.169  1.0
  Se  Se20  1  0.247  0.750  0.071  1.0
  Se  Se21  1  0.753  0.250  0.929  1.0
  Se  Se22  1  0.747  0.250  0.429  1.0
  Se  Se23  1  0.253  0.750  0.571  1.0
  Se  Se24  1  0.285  0.250  0.092  1.0
  Se  Se25  1  0.715  0.750  0.908  1.0
  Se  Se26  1  0.785  0.750  0.408  1.0
  Se  Se27  1  0.215  0.250  0.592  1.0
[/CIF]
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