The material described by KNb4AsO13 crystallizes in the orthorhombic Cmc2_1 space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-42°. In the second Nb site, Nb(2) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, and  an edgeedge with one Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-28°. As(1) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form AsO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-54°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a trigonal planar geometry to two equivalent Nb(2) and one As(1) atom. In the second O site, O(6) is bonded in a trigonal planar geometry to two equivalent Nb(2) and one As(1) atom. In the third O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the fourth O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the fifth O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the sixth O site, O(2) is bonded in a 3-coordinate geometry to one K(1), one Nb(1), and one As(1) atom. In the seventh O site, O(3) is bonded in a 3-coordinate geometry to one K(1), one Nb(1), and one Nb(2) atom. In the eighth O site, O(4) is bonded in a 3-coordinate geometry to one K(1), one Nb(1), and one Nb(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KNb4AsO13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.487
_cell_length_b   7.487
_cell_length_c   10.197
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.929
_symmetry_Int_Tables_number   1
_cell_volume   571.519
_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  0.440  0.440  0.440  1.0
  K  K1  1  0.560  0.560  0.940  1.0
  Nb  Nb2  1  0.556  0.897  0.251  1.0
  Nb  Nb3  1  0.103  0.444  0.751  1.0
  Nb  Nb4  1  0.444  0.103  0.751  1.0
  Nb  Nb5  1  0.897  0.556  0.251  1.0
  Nb  Nb6  1  0.174  0.828  0.501  1.0
  Nb  Nb7  1  0.172  0.826  0.001  1.0
  Nb  Nb8  1  0.828  0.174  0.501  1.0
  Nb  Nb9  1  0.826  0.172  0.001  1.0
  As  As10  1  0.163  0.163  0.249  1.0
  As  As11  1  0.837  0.837  0.749  1.0
  O  O12  1  0.660  0.660  0.250  1.0
  O  O13  1  0.340  0.340  0.750  1.0
  O  O14  1  0.388  0.130  0.251  1.0
  O  O15  1  0.870  0.612  0.751  1.0
  O  O16  1  0.612  0.870  0.751  1.0
  O  O17  1  0.130  0.388  0.251  1.0
  O  O18  1  0.798  0.360  0.385  1.0
  O  O19  1  0.639  0.201  0.614  1.0
  O  O20  1  0.799  0.361  0.114  1.0
  O  O21  1  0.640  0.202  0.885  1.0
  O  O22  1  0.201  0.639  0.614  1.0
  O  O23  1  0.360  0.798  0.385  1.0
  O  O24  1  0.202  0.640  0.885  1.0
  O  O25  1  0.361  0.799  0.114  1.0
  O  O26  1  0.069  0.069  0.389  1.0
  O  O27  1  0.932  0.932  0.610  1.0
  O  O28  1  0.068  0.068  0.110  1.0
  O  O29  1  0.931  0.931  0.889  1.0
  O  O30  1  0.693  0.992  0.389  1.0
  O  O31  1  0.009  0.307  0.611  1.0
  O  O32  1  0.693  0.991  0.111  1.0
  O  O33  1  0.008  0.307  0.889  1.0
  O  O34  1  0.307  0.009  0.611  1.0
  O  O35  1  0.992  0.693  0.389  1.0
  O  O36  1  0.307  0.008  0.889  1.0
  O  O37  1  0.991  0.693  0.111  1.0
[/CIF]
.
The material described by KNb4AsO13 crystallizes in the orthorhombic Cmc2_1 space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(7), and one O(8) atom to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-42°. In the second Nb site, Nb(2) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, and  an edgeedge with one Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 20-28°. As(1) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form AsO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-54°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a trigonal planar geometry to two equivalent Nb(2) and one As(1) atom. In the second O site, O(6) is bonded in a trigonal planar geometry to two equivalent Nb(2) and one As(1) atom. In the third O site, O(7) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the fourth O site, O(8) is bonded in a bent 150 degrees geometry to one Nb(1) and one Nb(2) atom. In the fifth O site, O(1) is bonded in a 2-coordinate geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the sixth O site, O(2) is bonded in a 3-coordinate geometry to one K(1), one Nb(1), and one As(1) atom. In the seventh O site, O(3) is bonded in a 3-coordinate geometry to one K(1), one Nb(1), and one Nb(2) atom. In the eighth O site, O(4) is bonded in a 3-coordinate geometry to one K(1), one Nb(1), and one Nb(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_KNb4AsO13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.487
_cell_length_b   7.487
_cell_length_c   10.197
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.929
_symmetry_Int_Tables_number   1
_cell_volume   571.519
_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  0.440  0.440  0.440  1.0
  K  K1  1  0.560  0.560  0.940  1.0
  Nb  Nb2  1  0.556  0.897  0.251  1.0
  Nb  Nb3  1  0.103  0.444  0.751  1.0
  Nb  Nb4  1  0.444  0.103  0.751  1.0
  Nb  Nb5  1  0.897  0.556  0.251  1.0
  Nb  Nb6  1  0.174  0.828  0.501  1.0
  Nb  Nb7  1  0.172  0.826  0.001  1.0
  Nb  Nb8  1  0.828  0.174  0.501  1.0
  Nb  Nb9  1  0.826  0.172  0.001  1.0
  As  As10  1  0.163  0.163  0.249  1.0
  As  As11  1  0.837  0.837  0.749  1.0
  O  O12  1  0.660  0.660  0.250  1.0
  O  O13  1  0.340  0.340  0.750  1.0
  O  O14  1  0.388  0.130  0.251  1.0
  O  O15  1  0.870  0.612  0.751  1.0
  O  O16  1  0.612  0.870  0.751  1.0
  O  O17  1  0.130  0.388  0.251  1.0
  O  O18  1  0.798  0.360  0.385  1.0
  O  O19  1  0.639  0.201  0.614  1.0
  O  O20  1  0.799  0.361  0.114  1.0
  O  O21  1  0.640  0.202  0.885  1.0
  O  O22  1  0.201  0.639  0.614  1.0
  O  O23  1  0.360  0.798  0.385  1.0
  O  O24  1  0.202  0.640  0.885  1.0
  O  O25  1  0.361  0.799  0.114  1.0
  O  O26  1  0.069  0.069  0.389  1.0
  O  O27  1  0.932  0.932  0.610  1.0
  O  O28  1  0.068  0.068  0.110  1.0
  O  O29  1  0.931  0.931  0.889  1.0
  O  O30  1  0.693  0.992  0.389  1.0
  O  O31  1  0.009  0.307  0.611  1.0
  O  O32  1  0.693  0.991  0.111  1.0
  O  O33  1  0.008  0.307  0.889  1.0
  O  O34  1  0.307  0.009  0.611  1.0
  O  O35  1  0.992  0.693  0.389  1.0
  O  O36  1  0.307  0.008  0.889  1.0
  O  O37  1  0.991  0.693  0.111  1.0
[/CIF]
.