The crystal structure described by K2Cd3Se4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form distorted KSe6 octahedra that share corners with two equivalent Cd(1)Se4 tetrahedra, corners with eight equivalent Cd(2)Se4 tetrahedra, edges with two equivalent K(1)Se6 octahedra, edges with four equivalent K(2)Se6 octahedra, edges with two equivalent Cd(1)Se4 tetrahedra, and edges with two equivalent Cd(2)Se4 tetrahedra. In the second K site, K(2) is bonded to one Se(1), one Se(2), and four equivalent Se(3) atoms to form distorted KSe6 octahedra that share corners with four equivalent Cd(1)Se4 tetrahedra, corners with eight equivalent Cd(2)Se4 tetrahedra, edges with two equivalent K(2)Se6 octahedra, edges with four equivalent K(1)Se6 octahedra,  an edgeedge with one Cd(1)Se4 tetrahedra, and edges with two equivalent Cd(2)Se4 tetrahedra. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form distorted CdSe4 tetrahedra that share corners with two equivalent K(1)Se6 octahedra, corners with four equivalent K(2)Se6 octahedra, corners with four equivalent Cd(2)Se4 tetrahedra,  an edgeedge with one K(2)Se6 octahedra, edges with two equivalent K(1)Se6 octahedra, and edges with two equivalent Cd(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-96°. In the second Cd site, Cd(2) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form distorted CdSe4 tetrahedra that share corners with four equivalent K(1)Se6 octahedra, corners with four equivalent K(2)Se6 octahedra, corners with two equivalent Cd(1)Se4 tetrahedra, corners with two equivalent Cd(2)Se4 tetrahedra,  an edgeedge with one K(1)Se6 octahedra,  an edgeedge with one K(2)Se6 octahedra,  an edgeedge with one Cd(1)Se4 tetrahedra, and  an edgeedge with one Cd(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 11-95°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Cd(1), and two equivalent Cd(2) atoms. In the second Se site, Se(2) is bonded to one K(2), two equivalent K(1), one Cd(1), and two equivalent Cd(2) atoms to form a mixture of distorted edge and corner-sharing SeK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. In the third Se site, Se(3) is bonded to one K(1), two equivalent K(2), one Cd(1), and two equivalent Cd(2) atoms to form a mixture of distorted edge and corner-sharing SeK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Cd3Se4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.909
_cell_length_b   10.707
_cell_length_c   14.405
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1065.600
_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
  K  K0  1  0.500  0.000  0.500  1.0
  K  K1  1  0.000  0.500  0.000  1.0
  K  K2  1  0.500  0.500  0.500  1.0
  K  K3  1  0.000  0.000  0.000  1.0
  K  K4  1  0.020  0.750  0.533  1.0
  K  K5  1  0.480  0.750  0.033  1.0
  K  K6  1  0.980  0.250  0.467  1.0
  K  K7  1  0.520  0.250  0.967  1.0
  Cd  Cd8  1  0.728  0.750  0.297  1.0
  Cd  Cd9  1  0.772  0.750  0.797  1.0
  Cd  Cd10  1  0.272  0.250  0.703  1.0
  Cd  Cd11  1  0.228  0.250  0.203  1.0
  Cd  Cd12  1  0.163  0.906  0.247  1.0
  Cd  Cd13  1  0.337  0.594  0.747  1.0
  Cd  Cd14  1  0.837  0.406  0.753  1.0
  Cd  Cd15  1  0.663  0.094  0.253  1.0
  Cd  Cd16  1  0.837  0.094  0.753  1.0
  Cd  Cd17  1  0.663  0.406  0.253  1.0
  Cd  Cd18  1  0.163  0.594  0.247  1.0
  Cd  Cd19  1  0.337  0.906  0.747  1.0
  Se  Se20  1  0.931  0.750  0.139  1.0
  Se  Se21  1  0.569  0.750  0.639  1.0
  Se  Se22  1  0.069  0.250  0.861  1.0
  Se  Se23  1  0.431  0.250  0.361  1.0
  Se  Se24  1  0.370  0.750  0.356  1.0
  Se  Se25  1  0.130  0.750  0.856  1.0
  Se  Se26  1  0.630  0.250  0.644  1.0
  Se  Se27  1  0.870  0.250  0.144  1.0
  Se  Se28  1  0.886  0.968  0.367  1.0
  Se  Se29  1  0.614  0.532  0.867  1.0
  Se  Se30  1  0.114  0.468  0.633  1.0
  Se  Se31  1  0.386  0.032  0.133  1.0
  Se  Se32  1  0.114  0.032  0.633  1.0
  Se  Se33  1  0.386  0.468  0.133  1.0
  Se  Se34  1  0.886  0.532  0.367  1.0
  Se  Se35  1  0.614  0.968  0.867  1.0
[/CIF]
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The crystal structure described by K2Cd3Se4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form distorted KSe6 octahedra that share corners with two equivalent Cd(1)Se4 tetrahedra, corners with eight equivalent Cd(2)Se4 tetrahedra, edges with two equivalent K(1)Se6 octahedra, edges with four equivalent K(2)Se6 octahedra, edges with two equivalent Cd(1)Se4 tetrahedra, and edges with two equivalent Cd(2)Se4 tetrahedra. In the second K site, K(2) is bonded to one Se(1), one Se(2), and four equivalent Se(3) atoms to form distorted KSe6 octahedra that share corners with four equivalent Cd(1)Se4 tetrahedra, corners with eight equivalent Cd(2)Se4 tetrahedra, edges with two equivalent K(2)Se6 octahedra, edges with four equivalent K(1)Se6 octahedra,  an edgeedge with one Cd(1)Se4 tetrahedra, and edges with two equivalent Cd(2)Se4 tetrahedra. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form distorted CdSe4 tetrahedra that share corners with two equivalent K(1)Se6 octahedra, corners with four equivalent K(2)Se6 octahedra, corners with four equivalent Cd(2)Se4 tetrahedra,  an edgeedge with one K(2)Se6 octahedra, edges with two equivalent K(1)Se6 octahedra, and edges with two equivalent Cd(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-96°. In the second Cd site, Cd(2) is bonded to one Se(1), one Se(2), and two equivalent Se(3) atoms to form distorted CdSe4 tetrahedra that share corners with four equivalent K(1)Se6 octahedra, corners with four equivalent K(2)Se6 octahedra, corners with two equivalent Cd(1)Se4 tetrahedra, corners with two equivalent Cd(2)Se4 tetrahedra,  an edgeedge with one K(1)Se6 octahedra,  an edgeedge with one K(2)Se6 octahedra,  an edgeedge with one Cd(1)Se4 tetrahedra, and  an edgeedge with one Cd(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 11-95°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Cd(1), and two equivalent Cd(2) atoms. In the second Se site, Se(2) is bonded to one K(2), two equivalent K(1), one Cd(1), and two equivalent Cd(2) atoms to form a mixture of distorted edge and corner-sharing SeK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. In the third Se site, Se(3) is bonded to one K(1), two equivalent K(2), one Cd(1), and two equivalent Cd(2) atoms to form a mixture of distorted edge and corner-sharing SeK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-68°. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Cd3Se4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.909
_cell_length_b   10.707
_cell_length_c   14.405
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1065.600
_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
  K  K0  1  0.500  0.000  0.500  1.0
  K  K1  1  0.000  0.500  0.000  1.0
  K  K2  1  0.500  0.500  0.500  1.0
  K  K3  1  0.000  0.000  0.000  1.0
  K  K4  1  0.020  0.750  0.533  1.0
  K  K5  1  0.480  0.750  0.033  1.0
  K  K6  1  0.980  0.250  0.467  1.0
  K  K7  1  0.520  0.250  0.967  1.0
  Cd  Cd8  1  0.728  0.750  0.297  1.0
  Cd  Cd9  1  0.772  0.750  0.797  1.0
  Cd  Cd10  1  0.272  0.250  0.703  1.0
  Cd  Cd11  1  0.228  0.250  0.203  1.0
  Cd  Cd12  1  0.163  0.906  0.247  1.0
  Cd  Cd13  1  0.337  0.594  0.747  1.0
  Cd  Cd14  1  0.837  0.406  0.753  1.0
  Cd  Cd15  1  0.663  0.094  0.253  1.0
  Cd  Cd16  1  0.837  0.094  0.753  1.0
  Cd  Cd17  1  0.663  0.406  0.253  1.0
  Cd  Cd18  1  0.163  0.594  0.247  1.0
  Cd  Cd19  1  0.337  0.906  0.747  1.0
  Se  Se20  1  0.931  0.750  0.139  1.0
  Se  Se21  1  0.569  0.750  0.639  1.0
  Se  Se22  1  0.069  0.250  0.861  1.0
  Se  Se23  1  0.431  0.250  0.361  1.0
  Se  Se24  1  0.370  0.750  0.356  1.0
  Se  Se25  1  0.130  0.750  0.856  1.0
  Se  Se26  1  0.630  0.250  0.644  1.0
  Se  Se27  1  0.870  0.250  0.144  1.0
  Se  Se28  1  0.886  0.968  0.367  1.0
  Se  Se29  1  0.614  0.532  0.867  1.0
  Se  Se30  1  0.114  0.468  0.633  1.0
  Se  Se31  1  0.386  0.032  0.133  1.0
  Se  Se32  1  0.114  0.032  0.633  1.0
  Se  Se33  1  0.386  0.468  0.133  1.0
  Se  Se34  1  0.886  0.532  0.367  1.0
  Se  Se35  1  0.614  0.968  0.867  1.0
[/CIF]
.