The structure described by K2CaNd4Nb2O12 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(2), one O(4), one O(7), and two equivalent O(9) atoms. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(12), one O(4), one O(7), and one O(9) atom. Ca(1) is bonded in a 5-coordinate geometry to one O(10), one O(11), 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 distorted 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 in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(3), one O(4), one O(6), and one O(7) atom. In the fourth Nd site, Nd(4) is bonded in a 7-coordinate geometry to one O(1), 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 in a distorted trigonal bipyramidal geometry to one O(1), one O(12), one O(4), one O(7), and one O(9) atom. In the second Nb site, Nb(2) is bonded in a distorted trigonal bipyramidal geometry to one O(10), one O(11), one O(2), one O(5), and one O(8) atom. 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 1-coordinate geometry to one K(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 distorted ONd4 tetrahedra that share  a cornercorner with one O(10)K2CaNdNb square pyramid, corners with three equivalent O(8)CaNd3Nb trigonal bipyramids, and edges with two equivalent O(6)Nd4 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 distorted see-saw-like geometry to one Ca(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 ONd4 tetrahedra that share  a cornercorner with one O(10)K2CaNdNb square pyramid,  a cornercorner with one O(8)CaNd3Nb trigonal bipyramid, edges with two equivalent O(3)Nd4 tetrahedra, and  an edgeedge with one O(8)CaNd3Nb trigonal bipyramid. 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 to one Ca(1), one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom to form distorted OCaNd3Nb trigonal bipyramids that share corners with two equivalent O(10)K2CaNdNb square pyramids,  a cornercorner with one O(6)Nd4 tetrahedra, corners with three equivalent O(3)Nd4 tetrahedra, and  an edgeedge with one O(6)Nd4 tetrahedra. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Ca(1), one Nd(2), and one Nb(1) atom. In the tenth O site, O(10) is bonded to one K(1), one K(2), one Ca(1), one Nd(3), and one Nb(2) atom to form distorted OK2CaNdNb square pyramids that share  a cornercorner with one O(3)Nd4 tetrahedra,  a cornercorner with one O(6)Nd4 tetrahedra, and corners with two equivalent O(8)CaNd3Nb trigonal bipyramids. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one K(1), one Ca(1), one Nd(1), one Nd(2), 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_K2CaNd4Nb2O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.898
_cell_length_b   7.027
_cell_length_c   8.935
_cell_angle_alpha   104.168
_cell_angle_beta   86.303
_cell_angle_gamma   112.819
_symmetry_Int_Tables_number   1
_cell_volume   330.772
_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  0.126  0.236  0.470  1.0
  K  K1  1  0.997  0.810  0.635  1.0
  Ca  Ca2  1  0.691  0.613  0.366  1.0
  Nd  Nd3  1  0.155  0.289  0.941  1.0
  Nd  Nd4  1  0.547  0.109  0.180  1.0
  Nd  Nd5  1  0.456  0.822  0.786  1.0
  Nd  Nd6  1  0.891  0.750  0.041  1.0
  Nb  Nb7  1  0.690  0.324  0.699  1.0
  Nb  Nb8  1  0.250  0.647  0.279  1.0
  O  O9  1  0.021  0.532  0.814  1.0
  O  O10  1  0.161  0.887  0.288  1.0
  O  O11  1  0.258  0.989  0.976  1.0
  O  O12  1  0.810  0.105  0.699  1.0
  O  O13  1  0.635  0.851  0.262  1.0
  O  O14  1  0.775  0.008  0.981  1.0
  O  O15  1  0.359  0.136  0.719  1.0
  O  O16  1  0.925  0.459  0.171  1.0
  O  O17  1  0.704  0.363  0.496  1.0
  O  O18  1  0.375  0.669  0.503  1.0
  O  O19  1  0.370  0.395  0.195  1.0
  O  O20  1  0.575  0.551  0.835  1.0
[/CIF]
.
The structure described by K2CaNd4Nb2O12 crystallizes in the triclinic P1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(2), one O(4), one O(7), and two equivalent O(9) atoms. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(12), one O(4), one O(7), and one O(9) atom. Ca(1) is bonded in a 5-coordinate geometry to one O(10), one O(11), 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 distorted 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 in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(3), one O(4), one O(6), and one O(7) atom. In the fourth Nd site, Nd(4) is bonded in a 7-coordinate geometry to one O(1), 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 in a distorted trigonal bipyramidal geometry to one O(1), one O(12), one O(4), one O(7), and one O(9) atom. In the second Nb site, Nb(2) is bonded in a distorted trigonal bipyramidal geometry to one O(10), one O(11), one O(2), one O(5), and one O(8) atom. 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 1-coordinate geometry to one K(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 distorted ONd4 tetrahedra that share  a cornercorner with one O(10)K2CaNdNb square pyramid, corners with three equivalent O(8)CaNd3Nb trigonal bipyramids, and edges with two equivalent O(6)Nd4 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 distorted see-saw-like geometry to one Ca(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 ONd4 tetrahedra that share  a cornercorner with one O(10)K2CaNdNb square pyramid,  a cornercorner with one O(8)CaNd3Nb trigonal bipyramid, edges with two equivalent O(3)Nd4 tetrahedra, and  an edgeedge with one O(8)CaNd3Nb trigonal bipyramid. 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 to one Ca(1), one Nd(1), one Nd(2), one Nd(4), and one Nb(2) atom to form distorted OCaNd3Nb trigonal bipyramids that share corners with two equivalent O(10)K2CaNdNb square pyramids,  a cornercorner with one O(6)Nd4 tetrahedra, corners with three equivalent O(3)Nd4 tetrahedra, and  an edgeedge with one O(6)Nd4 tetrahedra. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Ca(1), one Nd(2), and one Nb(1) atom. In the tenth O site, O(10) is bonded to one K(1), one K(2), one Ca(1), one Nd(3), and one Nb(2) atom to form distorted OK2CaNdNb square pyramids that share  a cornercorner with one O(3)Nd4 tetrahedra,  a cornercorner with one O(6)Nd4 tetrahedra, and corners with two equivalent O(8)CaNd3Nb trigonal bipyramids. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one K(1), one Ca(1), one Nd(1), one Nd(2), 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_K2CaNd4Nb2O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.898
_cell_length_b   7.027
_cell_length_c   8.935
_cell_angle_alpha   104.168
_cell_angle_beta   86.303
_cell_angle_gamma   112.819
_symmetry_Int_Tables_number   1
_cell_volume   330.772
_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  0.126  0.236  0.470  1.0
  K  K1  1  0.997  0.810  0.635  1.0
  Ca  Ca2  1  0.691  0.613  0.366  1.0
  Nd  Nd3  1  0.155  0.289  0.941  1.0
  Nd  Nd4  1  0.547  0.109  0.180  1.0
  Nd  Nd5  1  0.456  0.822  0.786  1.0
  Nd  Nd6  1  0.891  0.750  0.041  1.0
  Nb  Nb7  1  0.690  0.324  0.699  1.0
  Nb  Nb8  1  0.250  0.647  0.279  1.0
  O  O9  1  0.021  0.532  0.814  1.0
  O  O10  1  0.161  0.887  0.288  1.0
  O  O11  1  0.258  0.989  0.976  1.0
  O  O12  1  0.810  0.105  0.699  1.0
  O  O13  1  0.635  0.851  0.262  1.0
  O  O14  1  0.775  0.008  0.981  1.0
  O  O15  1  0.359  0.136  0.719  1.0
  O  O16  1  0.925  0.459  0.171  1.0
  O  O17  1  0.704  0.363  0.496  1.0
  O  O18  1  0.375  0.669  0.503  1.0
  O  O19  1  0.370  0.395  0.195  1.0
  O  O20  1  0.575  0.551  0.835  1.0
[/CIF]
.