The crystal structure described by NdAl11O18 crystallizes in the triclinic P-1 space group. Nd(1) is bonded in a distorted linear geometry to two equivalent O(2), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms. There are six inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with three equivalent Al(5)O4 tetrahedra, corners with two equivalent Al(6)O5 trigonal bipyramids,  an edgeedge with one Al(2)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the second Al site, Al(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(8) atoms to form AlO6 octahedra that share corners with six equivalent Al(5)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the third Al site, Al(3) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted AlO6 octahedra that share corners with three equivalent Al(5)O4 tetrahedra, corners with two equivalent Al(6)O5 trigonal bipyramids,  an edgeedge with one Al(2)O6 octahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(2), one O(4), one O(6), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with three equivalent Al(5)O4 tetrahedra, corners with two equivalent Al(6)O5 trigonal bipyramids,  an edgeedge with one Al(2)O6 octahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the fifth Al site, Al(5) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-64°. In the sixth Al site, Al(6) is bonded to one O(5), one O(6), one O(9), and two equivalent O(7) atoms to form distorted AlO5 trigonal bipyramids that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent Al(3)O6 octahedra, corners with two equivalent Al(4)O6 octahedra, and  an edgeedge with one Al(6)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 46-59°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(3), one Al(4), and one Al(5) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nd(1), one Al(1), one Al(3), and one Al(4) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), one Al(3), and one Al(5) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Al(2), one Al(3), one Al(4), and one Al(5) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Al(1), one Al(3), and one Al(6) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Nd(1), one Al(3), one Al(4), and one Al(6) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Nd(1) and two equivalent Al(6) atoms. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), one Al(4), and one Al(5) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Nd(1), one Al(1), one Al(4), and one Al(6) atom. is represented by the CIF file [CIF]
data_NdAl11O18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.609
_cell_length_b   11.673
_cell_length_c   5.772
_cell_angle_alpha   106.135
_cell_angle_beta   59.385
_cell_angle_gamma   104.493
_symmetry_Int_Tables_number   1
_cell_volume   309.711
_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
  Nd  Nd0  1  0.500  0.500  1.000  1.0
  Al  Al1  1  0.086  0.782  0.093  1.0
  Al  Al2  1  0.000  1.000  0.000  1.0
  Al  Al3  1  0.085  0.775  0.587  1.0
  Al  Al4  1  0.586  0.793  0.097  1.0
  Al  Al5  1  0.351  0.057  0.354  1.0
  Al  Al6  1  0.463  0.373  0.458  1.0
  Al  Al7  1  0.537  0.627  0.542  1.0
  Al  Al8  1  0.649  0.943  0.646  1.0
  Al  Al9  1  0.414  0.207  0.903  1.0
  Al  Al10  1  0.915  0.225  0.413  1.0
  Al  Al11  1  0.914  0.218  0.907  1.0
  O  O12  1  0.293  0.892  0.291  1.0
  O  O13  1  0.110  0.294  0.101  1.0
  O  O14  1  0.275  0.892  0.808  1.0
  O  O15  1  0.197  0.103  0.186  1.0
  O  O16  1  0.111  0.287  0.604  1.0
  O  O17  1  0.410  0.708  0.380  1.0
  O  O18  1  0.678  0.504  0.555  1.0
  O  O19  1  0.193  0.097  0.726  1.0
  O  O20  1  0.388  0.695  0.909  1.0
  O  O21  1  0.612  0.305  0.091  1.0
  O  O22  1  0.807  0.903  0.274  1.0
  O  O23  1  0.322  0.496  0.445  1.0
  O  O24  1  0.590  0.292  0.620  1.0
  O  O25  1  0.889  0.713  0.396  1.0
  O  O26  1  0.803  0.897  0.814  1.0
  O  O27  1  0.725  0.108  0.192  1.0
  O  O28  1  0.707  0.108  0.709  1.0
  O  O29  1  0.890  0.706  0.899  1.0
[/CIF]
.
The crystal structure described by NdAl11O18 crystallizes in the triclinic P-1 space group. Nd(1) is bonded in a distorted linear geometry to two equivalent O(2), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms. There are six inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with three equivalent Al(5)O4 tetrahedra, corners with two equivalent Al(6)O5 trigonal bipyramids,  an edgeedge with one Al(2)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the second Al site, Al(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(8) atoms to form AlO6 octahedra that share corners with six equivalent Al(5)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the third Al site, Al(3) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted AlO6 octahedra that share corners with three equivalent Al(5)O4 tetrahedra, corners with two equivalent Al(6)O5 trigonal bipyramids,  an edgeedge with one Al(2)O6 octahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(2), one O(4), one O(6), one O(8), and one O(9) atom to form AlO6 octahedra that share corners with three equivalent Al(5)O4 tetrahedra, corners with two equivalent Al(6)O5 trigonal bipyramids,  an edgeedge with one Al(2)O6 octahedra, edges with two equivalent Al(1)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. In the fifth Al site, Al(5) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form corner-sharing AlO4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-64°. In the sixth Al site, Al(6) is bonded to one O(5), one O(6), one O(9), and two equivalent O(7) atoms to form distorted AlO5 trigonal bipyramids that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent Al(3)O6 octahedra, corners with two equivalent Al(4)O6 octahedra, and  an edgeedge with one Al(6)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 46-59°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(3), one Al(4), and one Al(5) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nd(1), one Al(1), one Al(3), and one Al(4) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), one Al(3), and one Al(5) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Al(2), one Al(3), one Al(4), and one Al(5) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Al(1), one Al(3), and one Al(6) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Nd(1), one Al(3), one Al(4), and one Al(6) atom. In the seventh O site, O(7) is bonded in a trigonal non-coplanar geometry to one Nd(1) and two equivalent Al(6) atoms. In the eighth O site, O(8) is bonded in a rectangular see-saw-like geometry to one Al(1), one Al(2), one Al(4), and one Al(5) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Nd(1), one Al(1), one Al(4), and one Al(6) atom. is represented by the CIF file [CIF]
data_NdAl11O18
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.609
_cell_length_b   11.673
_cell_length_c   5.772
_cell_angle_alpha   106.135
_cell_angle_beta   59.385
_cell_angle_gamma   104.493
_symmetry_Int_Tables_number   1
_cell_volume   309.711
_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
  Nd  Nd0  1  0.500  0.500  1.000  1.0
  Al  Al1  1  0.086  0.782  0.093  1.0
  Al  Al2  1  0.000  1.000  0.000  1.0
  Al  Al3  1  0.085  0.775  0.587  1.0
  Al  Al4  1  0.586  0.793  0.097  1.0
  Al  Al5  1  0.351  0.057  0.354  1.0
  Al  Al6  1  0.463  0.373  0.458  1.0
  Al  Al7  1  0.537  0.627  0.542  1.0
  Al  Al8  1  0.649  0.943  0.646  1.0
  Al  Al9  1  0.414  0.207  0.903  1.0
  Al  Al10  1  0.915  0.225  0.413  1.0
  Al  Al11  1  0.914  0.218  0.907  1.0
  O  O12  1  0.293  0.892  0.291  1.0
  O  O13  1  0.110  0.294  0.101  1.0
  O  O14  1  0.275  0.892  0.808  1.0
  O  O15  1  0.197  0.103  0.186  1.0
  O  O16  1  0.111  0.287  0.604  1.0
  O  O17  1  0.410  0.708  0.380  1.0
  O  O18  1  0.678  0.504  0.555  1.0
  O  O19  1  0.193  0.097  0.726  1.0
  O  O20  1  0.388  0.695  0.909  1.0
  O  O21  1  0.612  0.305  0.091  1.0
  O  O22  1  0.807  0.903  0.274  1.0
  O  O23  1  0.322  0.496  0.445  1.0
  O  O24  1  0.590  0.292  0.620  1.0
  O  O25  1  0.889  0.713  0.396  1.0
  O  O26  1  0.803  0.897  0.814  1.0
  O  O27  1  0.725  0.108  0.192  1.0
  O  O28  1  0.707  0.108  0.709  1.0
  O  O29  1  0.890  0.706  0.899  1.0
[/CIF]
.