The crystal structure described by K2Na2Nd4Nb2O13 crystallizes in the monoclinic C2/c space group. K(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO5 trigonal bipyramids that share corners with five equivalent Nb(1)O5 trigonal bipyramids and edges with two equivalent Nd(1)O7 pentagonal bipyramids. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form distorted NdO7 pentagonal bipyramids that share  a cornercorner with one Nd(1)O7 pentagonal bipyramid,  an edgeedge with one Nd(1)O7 pentagonal bipyramid, edges with two equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Nb(1)O5 trigonal bipyramids. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NbO5 trigonal bipyramids that share corners with five equivalent Na(1)O5 trigonal bipyramids and edges with two equivalent Nd(1)O7 pentagonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent K(1), one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent K(1), one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to four equivalent K(1), one Na(1), and one Nb(1) atom. In the fifth O site, O(5) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form ONd4 tetrahedra that share corners with four equivalent O(6)NaNd2Nb tetrahedra, corners with four equivalent O(7)Nd4 tetrahedra, and edges with two equivalent O(7)Nd4 tetrahedra. In the sixth O site, O(6) is bonded to one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom to form distorted corner-sharing ONaNd2Nb tetrahedra. In the seventh O site, O(7) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form ONd4 tetrahedra that share corners with two equivalent O(5)Nd4 tetrahedra, corners with four equivalent O(6)NaNd2Nb tetrahedra,  an edgeedge with one O(5)Nd4 tetrahedra, and edges with two equivalent O(7)Nd4 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Na2Nd4Nb2O13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.535
_cell_length_b   12.535
_cell_length_c   11.361
_cell_angle_alpha   64.083
_cell_angle_beta   64.083
_cell_angle_gamma   26.471
_symmetry_Int_Tables_number   1
_cell_volume   710.965
_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  0.800  0.699  0.367  1.0
  K  K1  1  0.301  0.200  0.133  1.0
  K  K2  1  0.200  0.301  0.633  1.0
  K  K3  1  0.699  0.800  0.867  1.0
  Na  Na4  1  0.876  0.806  0.024  1.0
  Na  Na5  1  0.194  0.124  0.476  1.0
  Na  Na6  1  0.124  0.194  0.976  1.0
  Na  Na7  1  0.806  0.876  0.524  1.0
  Nd  Nd8  1  0.609  0.519  0.549  1.0
  Nd  Nd9  1  0.481  0.391  0.951  1.0
  Nd  Nd10  1  0.391  0.481  0.451  1.0
  Nd  Nd11  1  0.519  0.609  0.049  1.0
  Nd  Nd12  1  0.973  0.899  0.174  1.0
  Nd  Nd13  1  0.101  0.027  0.326  1.0
  Nd  Nd14  1  0.027  0.101  0.826  1.0
  Nd  Nd15  1  0.899  0.973  0.674  1.0
  Nb  Nb16  1  0.685  0.621  0.215  1.0
  Nb  Nb17  1  0.379  0.315  0.285  1.0
  Nb  Nb18  1  0.315  0.379  0.785  1.0
  Nb  Nb19  1  0.621  0.685  0.715  1.0
  O  O20  1  0.904  0.363  0.359  1.0
  O  O21  1  0.637  0.096  0.141  1.0
  O  O22  1  0.096  0.637  0.641  1.0
  O  O23  1  0.363  0.904  0.859  1.0
  O  O24  1  0.863  0.409  0.622  1.0
  O  O25  1  0.591  0.137  0.878  1.0
  O  O26  1  0.137  0.591  0.378  1.0
  O  O27  1  0.409  0.863  0.122  1.0
  O  O28  1  0.174  0.561  0.140  1.0
  O  O29  1  0.439  0.826  0.360  1.0
  O  O30  1  0.826  0.439  0.860  1.0
  O  O31  1  0.561  0.174  0.640  1.0
  O  O32  1  0.799  0.675  0.122  1.0
  O  O33  1  0.325  0.201  0.378  1.0
  O  O34  1  0.201  0.325  0.878  1.0
  O  O35  1  0.675  0.799  0.622  1.0
  O  O36  1  0.243  0.757  0.250  1.0
  O  O37  1  0.757  0.243  0.750  1.0
  O  O38  1  0.373  0.835  0.656  1.0
  O  O39  1  0.165  0.627  0.844  1.0
  O  O40  1  0.627  0.165  0.344  1.0
  O  O41  1  0.835  0.373  0.156  1.0
  O  O42  1  0.750  0.247  0.476  1.0
  O  O43  1  0.753  0.250  0.024  1.0
  O  O44  1  0.250  0.753  0.524  1.0
  O  O45  1  0.247  0.750  0.976  1.0
[/CIF]
.
The crystal structure described by K2Na2Nd4Nb2O13 crystallizes in the monoclinic C2/c space group. K(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO5 trigonal bipyramids that share corners with five equivalent Nb(1)O5 trigonal bipyramids and edges with two equivalent Nd(1)O7 pentagonal bipyramids. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form distorted NdO7 pentagonal bipyramids that share  a cornercorner with one Nd(1)O7 pentagonal bipyramid,  an edgeedge with one Nd(1)O7 pentagonal bipyramid, edges with two equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Nb(1)O5 trigonal bipyramids. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted NbO5 trigonal bipyramids that share corners with five equivalent Na(1)O5 trigonal bipyramids and edges with two equivalent Nd(1)O7 pentagonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent K(1), one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent K(1), one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to four equivalent K(1), one Na(1), and one Nb(1) atom. In the fifth O site, O(5) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form ONd4 tetrahedra that share corners with four equivalent O(6)NaNd2Nb tetrahedra, corners with four equivalent O(7)Nd4 tetrahedra, and edges with two equivalent O(7)Nd4 tetrahedra. In the sixth O site, O(6) is bonded to one Na(1), one Nd(1), one Nd(2), and one Nb(1) atom to form distorted corner-sharing ONaNd2Nb tetrahedra. In the seventh O site, O(7) is bonded to two equivalent Nd(1) and two equivalent Nd(2) atoms to form ONd4 tetrahedra that share corners with two equivalent O(5)Nd4 tetrahedra, corners with four equivalent O(6)NaNd2Nb tetrahedra,  an edgeedge with one O(5)Nd4 tetrahedra, and edges with two equivalent O(7)Nd4 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_K2Na2Nd4Nb2O13
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.535
_cell_length_b   12.535
_cell_length_c   11.361
_cell_angle_alpha   64.083
_cell_angle_beta   64.083
_cell_angle_gamma   26.471
_symmetry_Int_Tables_number   1
_cell_volume   710.965
_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  0.800  0.699  0.367  1.0
  K  K1  1  0.301  0.200  0.133  1.0
  K  K2  1  0.200  0.301  0.633  1.0
  K  K3  1  0.699  0.800  0.867  1.0
  Na  Na4  1  0.876  0.806  0.024  1.0
  Na  Na5  1  0.194  0.124  0.476  1.0
  Na  Na6  1  0.124  0.194  0.976  1.0
  Na  Na7  1  0.806  0.876  0.524  1.0
  Nd  Nd8  1  0.609  0.519  0.549  1.0
  Nd  Nd9  1  0.481  0.391  0.951  1.0
  Nd  Nd10  1  0.391  0.481  0.451  1.0
  Nd  Nd11  1  0.519  0.609  0.049  1.0
  Nd  Nd12  1  0.973  0.899  0.174  1.0
  Nd  Nd13  1  0.101  0.027  0.326  1.0
  Nd  Nd14  1  0.027  0.101  0.826  1.0
  Nd  Nd15  1  0.899  0.973  0.674  1.0
  Nb  Nb16  1  0.685  0.621  0.215  1.0
  Nb  Nb17  1  0.379  0.315  0.285  1.0
  Nb  Nb18  1  0.315  0.379  0.785  1.0
  Nb  Nb19  1  0.621  0.685  0.715  1.0
  O  O20  1  0.904  0.363  0.359  1.0
  O  O21  1  0.637  0.096  0.141  1.0
  O  O22  1  0.096  0.637  0.641  1.0
  O  O23  1  0.363  0.904  0.859  1.0
  O  O24  1  0.863  0.409  0.622  1.0
  O  O25  1  0.591  0.137  0.878  1.0
  O  O26  1  0.137  0.591  0.378  1.0
  O  O27  1  0.409  0.863  0.122  1.0
  O  O28  1  0.174  0.561  0.140  1.0
  O  O29  1  0.439  0.826  0.360  1.0
  O  O30  1  0.826  0.439  0.860  1.0
  O  O31  1  0.561  0.174  0.640  1.0
  O  O32  1  0.799  0.675  0.122  1.0
  O  O33  1  0.325  0.201  0.378  1.0
  O  O34  1  0.201  0.325  0.878  1.0
  O  O35  1  0.675  0.799  0.622  1.0
  O  O36  1  0.243  0.757  0.250  1.0
  O  O37  1  0.757  0.243  0.750  1.0
  O  O38  1  0.373  0.835  0.656  1.0
  O  O39  1  0.165  0.627  0.844  1.0
  O  O40  1  0.627  0.165  0.344  1.0
  O  O41  1  0.835  0.373  0.156  1.0
  O  O42  1  0.750  0.247  0.476  1.0
  O  O43  1  0.753  0.250  0.024  1.0
  O  O44  1  0.250  0.753  0.524  1.0
  O  O45  1  0.247  0.750  0.976  1.0
[/CIF]
.