The material described by MgTm2Se4 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 trigonal pyramids that share corners with three equivalent Tm(2)Se6 octahedra and  a faceface with one Tm(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 11-66°. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 7-coordinate geometry to one Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. In the second Tm site, Tm(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form distorted TmSe6 octahedra that share corners with three equivalent Mg(1)Se4 trigonal pyramids, edges with two equivalent Tm(2)Se6 octahedra, and  a faceface with one Mg(1)Se4 trigonal pyramid. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Mg(1), two equivalent Tm(1), and two equivalent Tm(2) atoms. In the second Se site, Se(2) is bonded in a T-shaped geometry to one Mg(1), one Tm(1), and one Tm(2) atom. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Tm(2), and two equivalent Tm(1) atoms. is represented by the CIF file [CIF]
data_Tm2MgSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.065
_cell_length_b   7.725
_cell_length_c   11.945
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   744.208
_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
  Tm  Tm0  1  0.060  0.750  0.310  1.0
  Tm  Tm1  1  0.940  0.250  0.690  1.0
  Tm  Tm2  1  0.440  0.250  0.810  1.0
  Tm  Tm3  1  0.560  0.750  0.190  1.0
  Tm  Tm4  1  0.051  0.250  0.017  1.0
  Tm  Tm5  1  0.949  0.750  0.983  1.0
  Tm  Tm6  1  0.449  0.750  0.517  1.0
  Tm  Tm7  1  0.551  0.250  0.483  1.0
  Mg  Mg8  1  0.172  0.250  0.401  1.0
  Mg  Mg9  1  0.828  0.750  0.599  1.0
  Mg  Mg10  1  0.328  0.750  0.901  1.0
  Mg  Mg11  1  0.672  0.250  0.099  1.0
  Se  Se12  1  0.121  0.505  0.841  1.0
  Se  Se13  1  0.879  0.495  0.159  1.0
  Se  Se14  1  0.379  0.495  0.341  1.0
  Se  Se15  1  0.621  0.505  0.659  1.0
  Se  Se16  1  0.621  0.995  0.659  1.0
  Se  Se17  1  0.379  0.005  0.341  1.0
  Se  Se18  1  0.879  0.005  0.159  1.0
  Se  Se19  1  0.121  0.995  0.841  1.0
  Se  Se20  1  0.880  0.250  0.460  1.0
  Se  Se21  1  0.120  0.750  0.540  1.0
  Se  Se22  1  0.620  0.750  0.960  1.0
  Se  Se23  1  0.380  0.250  0.040  1.0
  Se  Se24  1  0.237  0.750  0.113  1.0
  Se  Se25  1  0.763  0.250  0.887  1.0
  Se  Se26  1  0.263  0.250  0.613  1.0
  Se  Se27  1  0.737  0.750  0.387  1.0
[/CIF]
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The material described by MgTm2Se4 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 trigonal pyramids that share corners with three equivalent Tm(2)Se6 octahedra and  a faceface with one Tm(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 11-66°. There are two inequivalent Tm sites. In the first Tm site, Tm(1) is bonded in a 7-coordinate geometry to one Se(2), two equivalent Se(3), and four equivalent Se(1) atoms. In the second Tm site, Tm(2) is bonded to one Se(2), one Se(3), and four equivalent Se(1) atoms to form distorted TmSe6 octahedra that share corners with three equivalent Mg(1)Se4 trigonal pyramids, edges with two equivalent Tm(2)Se6 octahedra, and  a faceface with one Mg(1)Se4 trigonal pyramid. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one Mg(1), two equivalent Tm(1), and two equivalent Tm(2) atoms. In the second Se site, Se(2) is bonded in a T-shaped geometry to one Mg(1), one Tm(1), and one Tm(2) atom. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Tm(2), and two equivalent Tm(1) atoms. is represented by the CIF file [CIF]
data_Tm2MgSe4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.065
_cell_length_b   7.725
_cell_length_c   11.945
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   744.208
_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
  Tm  Tm0  1  0.060  0.750  0.310  1.0
  Tm  Tm1  1  0.940  0.250  0.690  1.0
  Tm  Tm2  1  0.440  0.250  0.810  1.0
  Tm  Tm3  1  0.560  0.750  0.190  1.0
  Tm  Tm4  1  0.051  0.250  0.017  1.0
  Tm  Tm5  1  0.949  0.750  0.983  1.0
  Tm  Tm6  1  0.449  0.750  0.517  1.0
  Tm  Tm7  1  0.551  0.250  0.483  1.0
  Mg  Mg8  1  0.172  0.250  0.401  1.0
  Mg  Mg9  1  0.828  0.750  0.599  1.0
  Mg  Mg10  1  0.328  0.750  0.901  1.0
  Mg  Mg11  1  0.672  0.250  0.099  1.0
  Se  Se12  1  0.121  0.505  0.841  1.0
  Se  Se13  1  0.879  0.495  0.159  1.0
  Se  Se14  1  0.379  0.495  0.341  1.0
  Se  Se15  1  0.621  0.505  0.659  1.0
  Se  Se16  1  0.621  0.995  0.659  1.0
  Se  Se17  1  0.379  0.005  0.341  1.0
  Se  Se18  1  0.879  0.005  0.159  1.0
  Se  Se19  1  0.121  0.995  0.841  1.0
  Se  Se20  1  0.880  0.250  0.460  1.0
  Se  Se21  1  0.120  0.750  0.540  1.0
  Se  Se22  1  0.620  0.750  0.960  1.0
  Se  Se23  1  0.380  0.250  0.040  1.0
  Se  Se24  1  0.237  0.750  0.113  1.0
  Se  Se25  1  0.763  0.250  0.887  1.0
  Se  Se26  1  0.263  0.250  0.613  1.0
  Se  Se27  1  0.737  0.750  0.387  1.0
[/CIF]
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