The compound described by Ba4Nd2Cu2O9 crystallizes in the tetragonal P-4n2 space group. Ba(1) is bonded in a 7-coordinate geometry to one O(3), one O(4), two equivalent O(1), and three equivalent O(2) atoms. Nd(1) is bonded to one O(1), two equivalent O(3), and four equivalent O(2) atoms to form distorted edge-sharing NdO7 hexagonal pyramids. Cu(1) is bonded in a rectangular see-saw-like geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to four equivalent Ba(1), one Nd(1), and one Cu(1) atom. In the second O site, O(2) is bonded to three equivalent Ba(1), two equivalent Nd(1), and one Cu(1) atom to form distorted OBa3Nd2Cu octahedra that share corners with three equivalent O(3)Ba2Nd2Cu2 octahedra, corners with seven equivalent O(2)Ba3Nd2Cu octahedra,  a cornercorner with one O(4)Ba4 trigonal pyramid, edges with three equivalent O(2)Ba3Nd2Cu octahedra,  an edgeedge with one O(4)Ba4 trigonal pyramid, and faces with two equivalent O(3)Ba2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 5-64°. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Nd(1), and two equivalent Cu(1) atoms to form distorted OBa2Nd2Cu2 octahedra that share corners with two equivalent O(3)Ba2Nd2Cu2 octahedra, corners with six equivalent O(2)Ba3Nd2Cu octahedra, corners with two equivalent O(4)Ba4 trigonal pyramids,  an edgeedge with one O(3)Ba2Nd2Cu2 octahedra, and faces with four equivalent O(2)Ba3Nd2Cu octahedra. The corner-sharing octahedral tilt angles range from 6-64°. In the fourth O site, O(4) is bonded to four equivalent Ba(1) atoms to form distorted OBa4 trigonal pyramids that share corners with four equivalent O(3)Ba2Nd2Cu2 octahedra, corners with four equivalent O(2)Ba3Nd2Cu octahedra, and edges with four equivalent O(2)Ba3Nd2Cu octahedra. The corner-sharing octahedral tilt angles range from 42-71°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba4Nd2Cu2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.113
_cell_length_b   12.113
_cell_length_c   3.918
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   574.937
_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
  Ba  Ba0  1  0.828  0.886  0.261  1.0
  Ba  Ba1  1  0.672  0.386  0.761  1.0
  Ba  Ba2  1  0.172  0.114  0.261  1.0
  Ba  Ba3  1  0.886  0.172  0.739  1.0
  Ba  Ba4  1  0.614  0.672  0.239  1.0
  Ba  Ba5  1  0.386  0.328  0.239  1.0
  Ba  Ba6  1  0.114  0.828  0.739  1.0
  Ba  Ba7  1  0.328  0.614  0.761  1.0
  Nd  Nd8  1  0.890  0.610  0.750  1.0
  Nd  Nd9  1  0.110  0.390  0.750  1.0
  Nd  Nd10  1  0.390  0.890  0.250  1.0
  Nd  Nd11  1  0.610  0.110  0.250  1.0
  Cu  Cu12  1  0.098  0.598  0.250  1.0
  Cu  Cu13  1  0.402  0.098  0.750  1.0
  Cu  Cu14  1  0.598  0.902  0.750  1.0
  Cu  Cu15  1  0.902  0.402  0.250  1.0
  O  O16  1  0.256  0.756  0.250  1.0
  O  O17  1  0.209  0.477  0.251  1.0
  O  O18  1  0.023  0.291  0.249  1.0
  O  O19  1  0.244  0.256  0.750  1.0
  O  O20  1  0.593  0.907  0.250  1.0
  O  O21  1  0.093  0.593  0.750  1.0
  O  O22  1  0.709  0.023  0.751  1.0
  O  O23  1  0.977  0.709  0.249  1.0
  O  O24  1  0.756  0.744  0.750  1.0
  O  O25  1  0.907  0.407  0.750  1.0
  O  O26  1  0.477  0.791  0.749  1.0
  O  O27  1  0.291  0.977  0.751  1.0
  O  O28  1  0.791  0.523  0.251  1.0
  O  O29  1  0.744  0.244  0.250  1.0
  O  O30  1  0.500  0.500  0.000  1.0
  O  O31  1  0.523  0.209  0.749  1.0
  O  O32  1  0.407  0.093  0.250  1.0
  O  O33  1  0.000  0.000  0.500  1.0
[/CIF]
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The compound described by Ba4Nd2Cu2O9 crystallizes in the tetragonal P-4n2 space group. Ba(1) is bonded in a 7-coordinate geometry to one O(3), one O(4), two equivalent O(1), and three equivalent O(2) atoms. Nd(1) is bonded to one O(1), two equivalent O(3), and four equivalent O(2) atoms to form distorted edge-sharing NdO7 hexagonal pyramids. Cu(1) is bonded in a rectangular see-saw-like geometry to one O(1), two equivalent O(2), and two equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to four equivalent Ba(1), one Nd(1), and one Cu(1) atom. In the second O site, O(2) is bonded to three equivalent Ba(1), two equivalent Nd(1), and one Cu(1) atom to form distorted OBa3Nd2Cu octahedra that share corners with three equivalent O(3)Ba2Nd2Cu2 octahedra, corners with seven equivalent O(2)Ba3Nd2Cu octahedra,  a cornercorner with one O(4)Ba4 trigonal pyramid, edges with three equivalent O(2)Ba3Nd2Cu octahedra,  an edgeedge with one O(4)Ba4 trigonal pyramid, and faces with two equivalent O(3)Ba2Nd2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 5-64°. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Nd(1), and two equivalent Cu(1) atoms to form distorted OBa2Nd2Cu2 octahedra that share corners with two equivalent O(3)Ba2Nd2Cu2 octahedra, corners with six equivalent O(2)Ba3Nd2Cu octahedra, corners with two equivalent O(4)Ba4 trigonal pyramids,  an edgeedge with one O(3)Ba2Nd2Cu2 octahedra, and faces with four equivalent O(2)Ba3Nd2Cu octahedra. The corner-sharing octahedral tilt angles range from 6-64°. In the fourth O site, O(4) is bonded to four equivalent Ba(1) atoms to form distorted OBa4 trigonal pyramids that share corners with four equivalent O(3)Ba2Nd2Cu2 octahedra, corners with four equivalent O(2)Ba3Nd2Cu octahedra, and edges with four equivalent O(2)Ba3Nd2Cu octahedra. The corner-sharing octahedral tilt angles range from 42-71°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba4Nd2Cu2O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.113
_cell_length_b   12.113
_cell_length_c   3.918
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   574.937
_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
  Ba  Ba0  1  0.828  0.886  0.261  1.0
  Ba  Ba1  1  0.672  0.386  0.761  1.0
  Ba  Ba2  1  0.172  0.114  0.261  1.0
  Ba  Ba3  1  0.886  0.172  0.739  1.0
  Ba  Ba4  1  0.614  0.672  0.239  1.0
  Ba  Ba5  1  0.386  0.328  0.239  1.0
  Ba  Ba6  1  0.114  0.828  0.739  1.0
  Ba  Ba7  1  0.328  0.614  0.761  1.0
  Nd  Nd8  1  0.890  0.610  0.750  1.0
  Nd  Nd9  1  0.110  0.390  0.750  1.0
  Nd  Nd10  1  0.390  0.890  0.250  1.0
  Nd  Nd11  1  0.610  0.110  0.250  1.0
  Cu  Cu12  1  0.098  0.598  0.250  1.0
  Cu  Cu13  1  0.402  0.098  0.750  1.0
  Cu  Cu14  1  0.598  0.902  0.750  1.0
  Cu  Cu15  1  0.902  0.402  0.250  1.0
  O  O16  1  0.256  0.756  0.250  1.0
  O  O17  1  0.209  0.477  0.251  1.0
  O  O18  1  0.023  0.291  0.249  1.0
  O  O19  1  0.244  0.256  0.750  1.0
  O  O20  1  0.593  0.907  0.250  1.0
  O  O21  1  0.093  0.593  0.750  1.0
  O  O22  1  0.709  0.023  0.751  1.0
  O  O23  1  0.977  0.709  0.249  1.0
  O  O24  1  0.756  0.744  0.750  1.0
  O  O25  1  0.907  0.407  0.750  1.0
  O  O26  1  0.477  0.791  0.749  1.0
  O  O27  1  0.291  0.977  0.751  1.0
  O  O28  1  0.791  0.523  0.251  1.0
  O  O29  1  0.744  0.244  0.250  1.0
  O  O30  1  0.500  0.500  0.000  1.0
  O  O31  1  0.523  0.209  0.749  1.0
  O  O32  1  0.407  0.093  0.250  1.0
  O  O33  1  0.000  0.000  0.500  1.0
[/CIF]
.