The crystal structure described by K2Na2MgSm2Nb2O10 crystallizes in the monoclinic Cm space group. K(1) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(7) atom. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(3), one O(8), and two equivalent O(6) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(8), and two equivalent O(4) atoms. Mg(1) is bonded in a distorted trigonal planar geometry to one O(1), one O(3), and one O(7) atom. Sm(1) is bonded to one O(3), one O(5), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form distorted SmO7 hexagonal pyramids that share  a cornercorner with one Sm(1)O7 hexagonal pyramid,  a cornercorner with one Nb(2)O5 trigonal bipyramid, edges with three equivalent Sm(1)O7 hexagonal pyramids, and  an edgeedge with one Nb(2)O5 trigonal bipyramid. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 5-coordinate geometry to one O(3), one O(7), one O(8), and two equivalent O(6) atoms. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(5), and two equivalent O(4) atoms to form NbO5 trigonal bipyramids that share corners with two equivalent Sm(1)O7 hexagonal pyramids and edges with two equivalent Sm(1)O7 hexagonal pyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Mg(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Na(2), and one Nb(2) atom. In the third O site, O(3) is bonded to one Na(1), one Mg(1), two equivalent Sm(1), and one Nb(1) atom to form edge-sharing ONaSm2MgNb trigonal bipyramids. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Sm(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded to one Na(2), two equivalent Sm(1), and one Nb(2) atom to form edge-sharing ONaSm2Nb tetrahedra. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Na(1), two equivalent Sm(1), and one Nb(1) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Mg(1), and one Nb(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), two equivalent Sm(1), and one Nb(1) atom. is represented by the CIF card [CIF]
data_K2Na2Sm2MgNb2O10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.893
_cell_length_b   5.893
_cell_length_c   9.014
_cell_angle_alpha   89.794
_cell_angle_beta   90.206
_cell_angle_gamma   86.242
_symmetry_Int_Tables_number   1
_cell_volume   312.357
_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  0.245  0.873  0.956  1.0
  K  K1  1  0.627  0.255  0.956  1.0
  Na  Na2  1  0.707  0.793  0.281  1.0
  Na  Na3  1  0.267  0.233  0.679  1.0
  Sm  Sm4  1  0.788  0.278  0.482  1.0
  Sm  Sm5  1  0.222  0.712  0.482  1.0
  Mg  Mg6  1  0.994  0.506  0.097  1.0
  Nb  Nb7  1  0.290  0.210  0.295  1.0
  Nb  Nb8  1  0.758  0.742  0.732  1.0
  O  O9  1  0.831  0.669  0.938  1.0
  O  O10  1  0.527  0.973  0.762  1.0
  O  O11  1  0.997  0.503  0.310  1.0
  O  O12  1  0.540  0.538  0.646  1.0
  O  O13  1  0.994  0.506  0.633  1.0
  O  O14  1  0.962  0.960  0.646  1.0
  O  O15  1  0.037  0.014  0.335  1.0
  O  O16  1  0.486  0.463  0.335  1.0
  O  O17  1  0.225  0.275  0.069  1.0
  O  O18  1  0.483  0.017  0.429  1.0
[/CIF]
.
The crystal structure described by K2Na2MgSm2Nb2O10 crystallizes in the monoclinic Cm space group. K(1) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(7) atom. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(3), one O(8), and two equivalent O(6) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), one O(5), one O(8), and two equivalent O(4) atoms. Mg(1) is bonded in a distorted trigonal planar geometry to one O(1), one O(3), and one O(7) atom. Sm(1) is bonded to one O(3), one O(5), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form distorted SmO7 hexagonal pyramids that share  a cornercorner with one Sm(1)O7 hexagonal pyramid,  a cornercorner with one Nb(2)O5 trigonal bipyramid, edges with three equivalent Sm(1)O7 hexagonal pyramids, and  an edgeedge with one Nb(2)O5 trigonal bipyramid. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 5-coordinate geometry to one O(3), one O(7), one O(8), and two equivalent O(6) atoms. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(5), and two equivalent O(4) atoms to form NbO5 trigonal bipyramids that share corners with two equivalent Sm(1)O7 hexagonal pyramids and edges with two equivalent Sm(1)O7 hexagonal pyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Mg(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Na(2), and one Nb(2) atom. In the third O site, O(3) is bonded to one Na(1), one Mg(1), two equivalent Sm(1), and one Nb(1) atom to form edge-sharing ONaSm2MgNb trigonal bipyramids. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Sm(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded to one Na(2), two equivalent Sm(1), and one Nb(2) atom to form edge-sharing ONaSm2Nb tetrahedra. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Na(1), two equivalent Sm(1), and one Nb(1) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to two equivalent K(1), one Mg(1), and one Nb(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), two equivalent Sm(1), and one Nb(1) atom. is represented by the CIF card [CIF]
data_K2Na2Sm2MgNb2O10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.893
_cell_length_b   5.893
_cell_length_c   9.014
_cell_angle_alpha   89.794
_cell_angle_beta   90.206
_cell_angle_gamma   86.242
_symmetry_Int_Tables_number   1
_cell_volume   312.357
_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  0.245  0.873  0.956  1.0
  K  K1  1  0.627  0.255  0.956  1.0
  Na  Na2  1  0.707  0.793  0.281  1.0
  Na  Na3  1  0.267  0.233  0.679  1.0
  Sm  Sm4  1  0.788  0.278  0.482  1.0
  Sm  Sm5  1  0.222  0.712  0.482  1.0
  Mg  Mg6  1  0.994  0.506  0.097  1.0
  Nb  Nb7  1  0.290  0.210  0.295  1.0
  Nb  Nb8  1  0.758  0.742  0.732  1.0
  O  O9  1  0.831  0.669  0.938  1.0
  O  O10  1  0.527  0.973  0.762  1.0
  O  O11  1  0.997  0.503  0.310  1.0
  O  O12  1  0.540  0.538  0.646  1.0
  O  O13  1  0.994  0.506  0.633  1.0
  O  O14  1  0.962  0.960  0.646  1.0
  O  O15  1  0.037  0.014  0.335  1.0
  O  O16  1  0.486  0.463  0.335  1.0
  O  O17  1  0.225  0.275  0.069  1.0
  O  O18  1  0.483  0.017  0.429  1.0
[/CIF]
.