The material structure described by K2Bi8Se13 crystallizes in the monoclinic C2/m space group. K(1) is bonded in a 7-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(6), and two equivalent Se(7) atoms. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(4), one Se(6), two equivalent Se(2), and two equivalent Se(7) atoms to form a mixture of corner and edge-sharing BiSe6 octahedra. The corner-sharing octahedra are not tilted. In the second Bi site, Bi(2) is bonded to two equivalent Se(1) and three equivalent Se(3) atoms to form BiSe5 square pyramids that share corners with two equivalent Bi(3)Se6 octahedra and edges with four equivalent Bi(2)Se5 square pyramids. The corner-sharing octahedral tilt angles are 67°. In the third Bi site, Bi(3) is bonded to one Se(1), one Se(2), two equivalent Se(4), and two equivalent Se(6) atoms to form BiSe6 octahedra that share  a cornercorner with one Bi(3)Se6 octahedra, corners with two equivalent Bi(4)Se6 octahedra, corners with two equivalent Bi(2)Se5 square pyramids,  an edgeedge with one Bi(4)Se6 octahedra, edges with two equivalent Bi(3)Se6 octahedra, and edges with four equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the fourth Bi site, Bi(4) is bonded to one Se(7), two equivalent Se(4), and three equivalent Se(5) atoms to form a mixture of corner and edge-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are seven inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent K(1), one Bi(3), and two equivalent Bi(2) atoms to form distorted SeK2Bi3 trigonal bipyramids that share  a cornercorner with one Se(2)Bi6 octahedra, corners with two equivalent Se(4)Bi5 square pyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids,  an edgeedge with one Se(7)K2Bi3 trigonal bipyramid, edges with two equivalent Se(1)K2Bi3 trigonal bipyramids, edges with two equivalent Se(6)K2Bi3 trigonal bipyramids, and edges with three equivalent Se(3)KBi3 trigonal pyramids. The corner-sharing octahedra are not tilted. In the second Se site, Se(2) is bonded to two equivalent Bi(3) and four equivalent Bi(1) atoms to form SeBi6 octahedra that share corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with four equivalent Se(7)K2Bi3 trigonal bipyramids, edges with two equivalent Se(2)Bi6 octahedra, edges with four equivalent Se(4)Bi5 square pyramids, edges with two equivalent Se(7)K2Bi3 trigonal bipyramids, and edges with four equivalent Se(6)K2Bi3 trigonal bipyramids. In the third Se site, Se(3) is bonded to one K(1) and three equivalent Bi(2) atoms to form SeKBi3 trigonal pyramids that share corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids, edges with three equivalent Se(1)K2Bi3 trigonal bipyramids, and edges with two equivalent Se(3)KBi3 trigonal pyramids. In the fourth Se site, Se(4) is bonded to one Bi(1), two equivalent Bi(3), and two equivalent Bi(4) atoms to form SeBi5 square pyramids that share corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with three equivalent Se(6)K2Bi3 trigonal bipyramids, edges with two equivalent Se(2)Bi6 octahedra, edges with two equivalent Se(4)Bi5 square pyramids,  an edgeedge with one Se(6)K2Bi3 trigonal bipyramid, and edges with two equivalent Se(7)K2Bi3 trigonal bipyramids. In the fifth Se site, Se(5) is bonded in a distorted T-shaped geometry to three equivalent Bi(4) atoms. In the sixth Se site, Se(6) is bonded to two equivalent K(1), one Bi(1), and two equivalent Bi(3) atoms to form SeK2Bi3 trigonal bipyramids that share corners with three equivalent Se(4)Bi5 square pyramids, corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids, edges with two equivalent Se(2)Bi6 octahedra,  an edgeedge with one Se(4)Bi5 square pyramid,  an edgeedge with one Se(6)K2Bi3 trigonal bipyramid, edges with two equivalent Se(1)K2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)K2Bi3 trigonal bipyramids. In the seventh Se site, Se(7) is bonded to two equivalent K(1), one Bi(4), and two equivalent Bi(1) atoms to form distorted SeK2Bi3 trigonal bipyramids that share corners with two equivalent Se(2)Bi6 octahedra, corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids,  an edgeedge with one Se(2)Bi6 octahedra, edges with two equivalent Se(4)Bi5 square pyramids,  an edgeedge with one Se(1)K2Bi3 trigonal bipyramid, edges with two equivalent Se(6)K2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)K2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 3°. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Bi8Se13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.878
_cell_length_b   13.878
_cell_length_c   12.286
_cell_angle_alpha   87.743
_cell_angle_beta   87.743
_cell_angle_gamma   17.349
_symmetry_Int_Tables_number   1
_cell_volume   705.016
_cell_formula_units_Z   1
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  0.412  0.412  0.054  1.0
  K  K1  1  0.588  0.588  0.946  1.0
  Bi  Bi2  1  0.441  0.441  0.381  1.0
  Bi  Bi3  1  0.718  0.718  0.131  1.0
  Bi  Bi4  1  0.282  0.282  0.869  1.0
  Bi  Bi5  1  0.924  0.924  0.704  1.0
  Bi  Bi6  1  0.076  0.076  0.296  1.0
  Bi  Bi7  1  0.811  0.811  0.455  1.0
  Bi  Bi8  1  0.189  0.189  0.545  1.0
  Bi  Bi9  1  0.559  0.559  0.619  1.0
  Se  Se10  1  0.140  0.140  0.118  1.0
  Se  Se11  1  0.000  0.000  0.500  1.0
  Se  Se12  1  0.710  0.710  0.912  1.0
  Se  Se13  1  0.290  0.290  0.088  1.0
  Se  Se14  1  0.860  0.860  0.882  1.0
  Se  Se15  1  0.370  0.370  0.571  1.0
  Se  Se16  1  0.744  0.744  0.641  1.0
  Se  Se17  1  0.256  0.256  0.359  1.0
  Se  Se18  1  0.630  0.630  0.429  1.0
  Se  Se19  1  0.481  0.481  0.798  1.0
  Se  Se20  1  0.519  0.519  0.202  1.0
  Se  Se21  1  0.890  0.890  0.275  1.0
  Se  Se22  1  0.110  0.110  0.725  1.0
[/CIF]
.
The material structure described by K2Bi8Se13 crystallizes in the monoclinic C2/m space group. K(1) is bonded in a 7-coordinate geometry to one Se(3), two equivalent Se(1), two equivalent Se(6), and two equivalent Se(7) atoms. There are four inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(4), one Se(6), two equivalent Se(2), and two equivalent Se(7) atoms to form a mixture of corner and edge-sharing BiSe6 octahedra. The corner-sharing octahedra are not tilted. In the second Bi site, Bi(2) is bonded to two equivalent Se(1) and three equivalent Se(3) atoms to form BiSe5 square pyramids that share corners with two equivalent Bi(3)Se6 octahedra and edges with four equivalent Bi(2)Se5 square pyramids. The corner-sharing octahedral tilt angles are 67°. In the third Bi site, Bi(3) is bonded to one Se(1), one Se(2), two equivalent Se(4), and two equivalent Se(6) atoms to form BiSe6 octahedra that share  a cornercorner with one Bi(3)Se6 octahedra, corners with two equivalent Bi(4)Se6 octahedra, corners with two equivalent Bi(2)Se5 square pyramids,  an edgeedge with one Bi(4)Se6 octahedra, edges with two equivalent Bi(3)Se6 octahedra, and edges with four equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the fourth Bi site, Bi(4) is bonded to one Se(7), two equivalent Se(4), and three equivalent Se(5) atoms to form a mixture of corner and edge-sharing BiSe6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are seven inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent K(1), one Bi(3), and two equivalent Bi(2) atoms to form distorted SeK2Bi3 trigonal bipyramids that share  a cornercorner with one Se(2)Bi6 octahedra, corners with two equivalent Se(4)Bi5 square pyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids,  an edgeedge with one Se(7)K2Bi3 trigonal bipyramid, edges with two equivalent Se(1)K2Bi3 trigonal bipyramids, edges with two equivalent Se(6)K2Bi3 trigonal bipyramids, and edges with three equivalent Se(3)KBi3 trigonal pyramids. The corner-sharing octahedra are not tilted. In the second Se site, Se(2) is bonded to two equivalent Bi(3) and four equivalent Bi(1) atoms to form SeBi6 octahedra that share corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with four equivalent Se(7)K2Bi3 trigonal bipyramids, edges with two equivalent Se(2)Bi6 octahedra, edges with four equivalent Se(4)Bi5 square pyramids, edges with two equivalent Se(7)K2Bi3 trigonal bipyramids, and edges with four equivalent Se(6)K2Bi3 trigonal bipyramids. In the third Se site, Se(3) is bonded to one K(1) and three equivalent Bi(2) atoms to form SeKBi3 trigonal pyramids that share corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids, edges with three equivalent Se(1)K2Bi3 trigonal bipyramids, and edges with two equivalent Se(3)KBi3 trigonal pyramids. In the fourth Se site, Se(4) is bonded to one Bi(1), two equivalent Bi(3), and two equivalent Bi(4) atoms to form SeBi5 square pyramids that share corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with three equivalent Se(6)K2Bi3 trigonal bipyramids, edges with two equivalent Se(2)Bi6 octahedra, edges with two equivalent Se(4)Bi5 square pyramids,  an edgeedge with one Se(6)K2Bi3 trigonal bipyramid, and edges with two equivalent Se(7)K2Bi3 trigonal bipyramids. In the fifth Se site, Se(5) is bonded in a distorted T-shaped geometry to three equivalent Bi(4) atoms. In the sixth Se site, Se(6) is bonded to two equivalent K(1), one Bi(1), and two equivalent Bi(3) atoms to form SeK2Bi3 trigonal bipyramids that share corners with three equivalent Se(4)Bi5 square pyramids, corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(7)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids, edges with two equivalent Se(2)Bi6 octahedra,  an edgeedge with one Se(4)Bi5 square pyramid,  an edgeedge with one Se(6)K2Bi3 trigonal bipyramid, edges with two equivalent Se(1)K2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)K2Bi3 trigonal bipyramids. In the seventh Se site, Se(7) is bonded to two equivalent K(1), one Bi(4), and two equivalent Bi(1) atoms to form distorted SeK2Bi3 trigonal bipyramids that share corners with two equivalent Se(2)Bi6 octahedra, corners with two equivalent Se(1)K2Bi3 trigonal bipyramids, corners with two equivalent Se(6)K2Bi3 trigonal bipyramids, corners with two equivalent Se(3)KBi3 trigonal pyramids,  an edgeedge with one Se(2)Bi6 octahedra, edges with two equivalent Se(4)Bi5 square pyramids,  an edgeedge with one Se(1)K2Bi3 trigonal bipyramid, edges with two equivalent Se(6)K2Bi3 trigonal bipyramids, and edges with two equivalent Se(7)K2Bi3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 3°. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Bi8Se13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.878
_cell_length_b   13.878
_cell_length_c   12.286
_cell_angle_alpha   87.743
_cell_angle_beta   87.743
_cell_angle_gamma   17.349
_symmetry_Int_Tables_number   1
_cell_volume   705.016
_cell_formula_units_Z   1
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  0.412  0.412  0.054  1.0
  K  K1  1  0.588  0.588  0.946  1.0
  Bi  Bi2  1  0.441  0.441  0.381  1.0
  Bi  Bi3  1  0.718  0.718  0.131  1.0
  Bi  Bi4  1  0.282  0.282  0.869  1.0
  Bi  Bi5  1  0.924  0.924  0.704  1.0
  Bi  Bi6  1  0.076  0.076  0.296  1.0
  Bi  Bi7  1  0.811  0.811  0.455  1.0
  Bi  Bi8  1  0.189  0.189  0.545  1.0
  Bi  Bi9  1  0.559  0.559  0.619  1.0
  Se  Se10  1  0.140  0.140  0.118  1.0
  Se  Se11  1  0.000  0.000  0.500  1.0
  Se  Se12  1  0.710  0.710  0.912  1.0
  Se  Se13  1  0.290  0.290  0.088  1.0
  Se  Se14  1  0.860  0.860  0.882  1.0
  Se  Se15  1  0.370  0.370  0.571  1.0
  Se  Se16  1  0.744  0.744  0.641  1.0
  Se  Se17  1  0.256  0.256  0.359  1.0
  Se  Se18  1  0.630  0.630  0.429  1.0
  Se  Se19  1  0.481  0.481  0.798  1.0
  Se  Se20  1  0.519  0.519  0.202  1.0
  Se  Se21  1  0.890  0.890  0.275  1.0
  Se  Se22  1  0.110  0.110  0.725  1.0
[/CIF]
.