The material described by KSr2Nb4FeO15 crystallizes in the tetragonal P4bm space group. K(1) is bonded to four equivalent O(5) and eight equivalent O(2) atoms to form KO12 cuboctahedra that share faces with two equivalent K(1)O12 cuboctahedra and faces with eight equivalent Nb(1)O6 octahedra. Sr(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), and four equivalent O(4) atoms. Nb(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with five equivalent Nb(1)O6 octahedra, and faces with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-46°. Fe(1) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-36°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one K(1) and two equivalent Nb(1) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1) and two equivalent Nb(1) atoms. In the third O site, O(2) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the fourth O site, O(3) is bonded in a square co-planar geometry to two equivalent Sr(1) and two equivalent Fe(1) atoms. In the fifth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(1), one Nb(1), and one Fe(1) atom. is represented by the CIF file [CIF]
data_KSr2Nb4FeO15
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.496
_cell_length_b   12.496
_cell_length_c   4.040
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   630.759
_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
  K  K0  1  0.500  0.500  0.012  1.0
  K  K1  1  0.000  0.000  0.012  1.0
  Sr  Sr2  1  0.351  0.851  0.007  1.0
  Sr  Sr3  1  0.649  0.149  0.007  1.0
  Sr  Sr4  1  0.851  0.649  0.007  1.0
  Sr  Sr5  1  0.149  0.351  0.007  1.0
  Nb  Nb6  1  0.420  0.289  0.531  1.0
  Nb  Nb7  1  0.580  0.711  0.531  1.0
  Nb  Nb8  1  0.920  0.211  0.531  1.0
  Nb  Nb9  1  0.080  0.789  0.531  1.0
  Nb  Nb10  1  0.711  0.420  0.531  1.0
  Nb  Nb11  1  0.289  0.580  0.531  1.0
  Nb  Nb12  1  0.789  0.920  0.531  1.0
  Nb  Nb13  1  0.211  0.080  0.531  1.0
  Fe  Fe14  1  0.500  0.000  0.496  1.0
  Fe  Fe15  1  0.000  0.500  0.496  1.0
  O  O16  1  0.228  0.728  0.485  1.0
  O  O17  1  0.772  0.272  0.485  1.0
  O  O18  1  0.728  0.772  0.485  1.0
  O  O19  1  0.272  0.228  0.485  1.0
  O  O20  1  0.357  0.433  0.488  1.0
  O  O21  1  0.643  0.567  0.488  1.0
  O  O22  1  0.857  0.067  0.488  1.0
  O  O23  1  0.143  0.933  0.488  1.0
  O  O24  1  0.567  0.357  0.488  1.0
  O  O25  1  0.433  0.643  0.488  1.0
  O  O26  1  0.933  0.857  0.488  1.0
  O  O27  1  0.067  0.143  0.488  1.0
  O  O28  1  0.500  0.000  0.991  1.0
  O  O29  1  0.000  0.500  0.991  1.0
  O  O30  1  0.152  0.491  0.490  1.0
  O  O31  1  0.848  0.509  0.490  1.0
  O  O32  1  0.652  0.009  0.490  1.0
  O  O33  1  0.348  0.991  0.490  1.0
  O  O34  1  0.509  0.152  0.490  1.0
  O  O35  1  0.491  0.848  0.490  1.0
  O  O36  1  0.991  0.652  0.490  1.0
  O  O37  1  0.009  0.348  0.490  1.0
  O  O38  1  0.424  0.287  0.992  1.0
  O  O39  1  0.576  0.713  0.992  1.0
  O  O40  1  0.924  0.213  0.992  1.0
  O  O41  1  0.076  0.787  0.992  1.0
  O  O42  1  0.713  0.424  0.992  1.0
  O  O43  1  0.287  0.576  0.992  1.0
  O  O44  1  0.787  0.924  0.992  1.0
  O  O45  1  0.213  0.076  0.992  1.0
[/CIF]
.
The material described by KSr2Nb4FeO15 crystallizes in the tetragonal P4bm space group. K(1) is bonded to four equivalent O(5) and eight equivalent O(2) atoms to form KO12 cuboctahedra that share faces with two equivalent K(1)O12 cuboctahedra and faces with eight equivalent Nb(1)O6 octahedra. Sr(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), and four equivalent O(4) atoms. Nb(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with five equivalent Nb(1)O6 octahedra, and faces with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-46°. Fe(1) is bonded to two equivalent O(3) and four equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra and corners with four equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-36°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one K(1) and two equivalent Nb(1) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1) and two equivalent Nb(1) atoms. In the third O site, O(2) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the fourth O site, O(3) is bonded in a square co-planar geometry to two equivalent Sr(1) and two equivalent Fe(1) atoms. In the fifth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(1), one Nb(1), and one Fe(1) atom. is represented by the CIF file [CIF]
data_KSr2Nb4FeO15
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.496
_cell_length_b   12.496
_cell_length_c   4.040
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   630.759
_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
  K  K0  1  0.500  0.500  0.012  1.0
  K  K1  1  0.000  0.000  0.012  1.0
  Sr  Sr2  1  0.351  0.851  0.007  1.0
  Sr  Sr3  1  0.649  0.149  0.007  1.0
  Sr  Sr4  1  0.851  0.649  0.007  1.0
  Sr  Sr5  1  0.149  0.351  0.007  1.0
  Nb  Nb6  1  0.420  0.289  0.531  1.0
  Nb  Nb7  1  0.580  0.711  0.531  1.0
  Nb  Nb8  1  0.920  0.211  0.531  1.0
  Nb  Nb9  1  0.080  0.789  0.531  1.0
  Nb  Nb10  1  0.711  0.420  0.531  1.0
  Nb  Nb11  1  0.289  0.580  0.531  1.0
  Nb  Nb12  1  0.789  0.920  0.531  1.0
  Nb  Nb13  1  0.211  0.080  0.531  1.0
  Fe  Fe14  1  0.500  0.000  0.496  1.0
  Fe  Fe15  1  0.000  0.500  0.496  1.0
  O  O16  1  0.228  0.728  0.485  1.0
  O  O17  1  0.772  0.272  0.485  1.0
  O  O18  1  0.728  0.772  0.485  1.0
  O  O19  1  0.272  0.228  0.485  1.0
  O  O20  1  0.357  0.433  0.488  1.0
  O  O21  1  0.643  0.567  0.488  1.0
  O  O22  1  0.857  0.067  0.488  1.0
  O  O23  1  0.143  0.933  0.488  1.0
  O  O24  1  0.567  0.357  0.488  1.0
  O  O25  1  0.433  0.643  0.488  1.0
  O  O26  1  0.933  0.857  0.488  1.0
  O  O27  1  0.067  0.143  0.488  1.0
  O  O28  1  0.500  0.000  0.991  1.0
  O  O29  1  0.000  0.500  0.991  1.0
  O  O30  1  0.152  0.491  0.490  1.0
  O  O31  1  0.848  0.509  0.490  1.0
  O  O32  1  0.652  0.009  0.490  1.0
  O  O33  1  0.348  0.991  0.490  1.0
  O  O34  1  0.509  0.152  0.490  1.0
  O  O35  1  0.491  0.848  0.490  1.0
  O  O36  1  0.991  0.652  0.490  1.0
  O  O37  1  0.009  0.348  0.490  1.0
  O  O38  1  0.424  0.287  0.992  1.0
  O  O39  1  0.576  0.713  0.992  1.0
  O  O40  1  0.924  0.213  0.992  1.0
  O  O41  1  0.076  0.787  0.992  1.0
  O  O42  1  0.713  0.424  0.992  1.0
  O  O43  1  0.287  0.576  0.992  1.0
  O  O44  1  0.787  0.924  0.992  1.0
  O  O45  1  0.213  0.076  0.992  1.0
[/CIF]
.