The crystal structure described by K2MgNd4Nb2O12 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(2), one O(4), one O(5), one O(7), one O(8), and two equivalent O(9) atoms. In the second K site, K(2) is bonded in a 10-coordinate geometry to one Mg(1), one O(1), one O(12), one O(2), one O(4), one O(5), one O(7), one O(9), and two equivalent O(10) atoms. Mg(1) is bonded in a 5-coordinate geometry to one K(2), one O(11), one O(2), one O(5), one O(8), and one O(9) atom. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a body-centered cubic geometry to one O(1), one O(11), one O(12), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(11), one O(2), one O(3), one O(5), one O(6), one O(8), and one O(9) atom. In the third Nd site, Nd(3) is bonded to one O(1), one O(10), one O(12), one O(3), one O(4), one O(6), and one O(7) atom to form distorted NdO7 hexagonal pyramids that share  a cornercorner with one Nb(2)O5 trigonal bipyramid, corners with two equivalent Nb(1)O5 trigonal bipyramids, and  an edgeedge with one Nb(1)O5 trigonal bipyramid. In the fourth Nd site, Nd(4) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(3), one O(5), one O(6), and one O(8) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(12), one O(4), one O(7), and one O(9) atom to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nd(3)O7 hexagonal pyramids and  an edgeedge with one Nd(3)O7 hexagonal pyramid. In the second Nb site, Nb(2) is bonded to one O(10), one O(11), one O(2), one O(5), and one O(8) atom to form distorted NbO5 trigonal bipyramids that share  a cornercorner with one Nd(3)O7 hexagonal pyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one K(2), one Nd(1), one Nd(3), one Nd(4), and one Nb(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one K(1), one K(2), one Mg(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the third O site, O(3) is bonded to one Nd(1), one Nd(2), one Nd(3), and one Nd(4) atom to form edge-sharing ONd4 tetrahedra. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(1), one Nd(3), and one Nb(1) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one K(1), one K(2), one Mg(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the sixth O site, O(6) is bonded to one Nd(1), one Nd(2), one Nd(3), and one Nd(4) atom to form edge-sharing ONd4 tetrahedra. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(1), one Nd(3), and one Nb(1) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to one K(1), one Mg(1), one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one K(2), two equivalent K(1), one Mg(1), one Nd(2), and one Nb(1) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Nd(3), and one Nb(2) atom. In the eleventh O site, O(11) is bonded in a 6-coordinate geometry to one K(1), one Mg(1), one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one K(2), one Nd(1), one Nd(3), one Nd(4), and one Nb(1) atom. is represented by the CIF file [CIF]
data_K2Nd4MgNb2O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.845
_cell_length_b   7.007
_cell_length_c   8.780
_cell_angle_alpha   99.433
_cell_angle_beta   90.018
_cell_angle_gamma   114.622
_symmetry_Int_Tables_number   1
_cell_volume   321.559
_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  0.110  0.220  0.453  1.0
  K  K1  1  0.916  0.831  0.608  1.0
  Nd  Nd2  1  0.147  0.293  0.940  1.0
  Nd  Nd3  1  0.543  0.086  0.190  1.0
  Nd  Nd4  1  0.417  0.834  0.794  1.0
  Nd  Nd5  1  0.873  0.746  0.039  1.0
  Mg  Mg6  1  0.788  0.577  0.319  1.0
  Nb  Nb7  1  0.672  0.344  0.694  1.0
  Nb  Nb8  1  0.319  0.640  0.294  1.0
  O  O9  1  0.001  0.551  0.823  1.0
  O  O10  1  0.146  0.842  0.299  1.0
  O  O11  1  0.246  0.003  0.986  1.0
  O  O12  1  0.800  0.135  0.707  1.0
  O  O13  1  0.695  0.840  0.299  1.0
  O  O14  1  0.758  0.004  0.986  1.0
  O  O15  1  0.335  0.136  0.708  1.0
  O  O16  1  0.968  0.421  0.185  1.0
  O  O17  1  0.698  0.396  0.486  1.0
  O  O18  1  0.337  0.675  0.517  1.0
  O  O19  1  0.451  0.420  0.186  1.0
  O  O20  1  0.551  0.551  0.824  1.0
[/CIF]
.
The crystal structure described by K2MgNd4Nb2O12 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(2), one O(4), one O(5), one O(7), one O(8), and two equivalent O(9) atoms. In the second K site, K(2) is bonded in a 10-coordinate geometry to one Mg(1), one O(1), one O(12), one O(2), one O(4), one O(5), one O(7), one O(9), and two equivalent O(10) atoms. Mg(1) is bonded in a 5-coordinate geometry to one K(2), one O(11), one O(2), one O(5), one O(8), and one O(9) atom. There are four inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a body-centered cubic geometry to one O(1), one O(11), one O(12), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. In the second Nd site, Nd(2) is bonded in a 7-coordinate geometry to one O(11), one O(2), one O(3), one O(5), one O(6), one O(8), and one O(9) atom. In the third Nd site, Nd(3) is bonded to one O(1), one O(10), one O(12), one O(3), one O(4), one O(6), and one O(7) atom to form distorted NdO7 hexagonal pyramids that share  a cornercorner with one Nb(2)O5 trigonal bipyramid, corners with two equivalent Nb(1)O5 trigonal bipyramids, and  an edgeedge with one Nb(1)O5 trigonal bipyramid. In the fourth Nd site, Nd(4) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(3), one O(5), one O(6), and one O(8) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(12), one O(4), one O(7), and one O(9) atom to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nd(3)O7 hexagonal pyramids and  an edgeedge with one Nd(3)O7 hexagonal pyramid. In the second Nb site, Nb(2) is bonded to one O(10), one O(11), one O(2), one O(5), and one O(8) atom to form distorted NbO5 trigonal bipyramids that share  a cornercorner with one Nd(3)O7 hexagonal pyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one K(2), one Nd(1), one Nd(3), one Nd(4), and one Nb(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one K(1), one K(2), one Mg(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the third O site, O(3) is bonded to one Nd(1), one Nd(2), one Nd(3), and one Nd(4) atom to form edge-sharing ONd4 tetrahedra. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(1), one Nd(3), and one Nb(1) atom. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one K(1), one K(2), one Mg(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the sixth O site, O(6) is bonded to one Nd(1), one Nd(2), one Nd(3), and one Nd(4) atom to form edge-sharing ONd4 tetrahedra. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Nd(1), one Nd(3), and one Nb(1) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to one K(1), one Mg(1), one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one K(2), two equivalent K(1), one Mg(1), one Nd(2), and one Nb(1) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one K(1), two equivalent K(2), one Nd(3), and one Nb(2) atom. In the eleventh O site, O(11) is bonded in a 6-coordinate geometry to one K(1), one Mg(1), one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one K(2), one Nd(1), one Nd(3), one Nd(4), and one Nb(1) atom. is represented by the CIF file [CIF]
data_K2Nd4MgNb2O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.845
_cell_length_b   7.007
_cell_length_c   8.780
_cell_angle_alpha   99.433
_cell_angle_beta   90.018
_cell_angle_gamma   114.622
_symmetry_Int_Tables_number   1
_cell_volume   321.559
_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  0.110  0.220  0.453  1.0
  K  K1  1  0.916  0.831  0.608  1.0
  Nd  Nd2  1  0.147  0.293  0.940  1.0
  Nd  Nd3  1  0.543  0.086  0.190  1.0
  Nd  Nd4  1  0.417  0.834  0.794  1.0
  Nd  Nd5  1  0.873  0.746  0.039  1.0
  Mg  Mg6  1  0.788  0.577  0.319  1.0
  Nb  Nb7  1  0.672  0.344  0.694  1.0
  Nb  Nb8  1  0.319  0.640  0.294  1.0
  O  O9  1  0.001  0.551  0.823  1.0
  O  O10  1  0.146  0.842  0.299  1.0
  O  O11  1  0.246  0.003  0.986  1.0
  O  O12  1  0.800  0.135  0.707  1.0
  O  O13  1  0.695  0.840  0.299  1.0
  O  O14  1  0.758  0.004  0.986  1.0
  O  O15  1  0.335  0.136  0.708  1.0
  O  O16  1  0.968  0.421  0.185  1.0
  O  O17  1  0.698  0.396  0.486  1.0
  O  O18  1  0.337  0.675  0.517  1.0
  O  O19  1  0.451  0.420  0.186  1.0
  O  O20  1  0.551  0.551  0.824  1.0
[/CIF]
.