The structure described by Ce9YO20 is Fluorite-derived structured and crystallizes in the triclinic P-1 space group. There are five inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a body-centered cubic geometry to one O(5), one O(6), one O(7), one O(9), two equivalent O(1), and two equivalent O(3) atoms. In the second Ce site, Ce(2) is bonded in a body-centered cubic geometry to one O(1), one O(10), one O(3), one O(7), one O(8), one O(9), and two equivalent O(2) atoms. In the third Ce site, Ce(3) is bonded in a body-centered cubic geometry to two equivalent O(4), two equivalent O(6), two equivalent O(8), and two equivalent O(9) atoms. In the fourth Ce site, Ce(4) is bonded in a body-centered cubic geometry to one O(1), one O(4), one O(6), one O(7), two equivalent O(10), and two equivalent O(5) atoms. In the fifth Ce site, Ce(5) is bonded in a body-centered cubic geometry to one O(10), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(8) atoms. Y(1) is bonded in a body-centered cubic geometry to two equivalent O(2), two equivalent O(4), two equivalent O(7), and two equivalent O(9) atoms. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Ce(2), one Ce(4), and two equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(5)Ce4 tetrahedra, corners with three equivalent O(3)Ce4 tetrahedra, corners with four equivalent O(7)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra, and  an edgeedge with one O(6)Ce4 tetrahedra. In the second O site, O(2) is bonded to one Ce(5), two equivalent Ce(2), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra, corners with two equivalent O(7)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with three equivalent O(3)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the third O site, O(3) is bonded to one Ce(2), one Ce(5), and two equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(10)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Y tetrahedra, corners with three equivalent O(9)Ce3Y tetrahedra, corners with three equivalent O(1)Ce4 tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the fourth O site, O(4) is bonded to one Ce(3), one Ce(4), one Ce(5), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with two equivalent O(6)Ce4 tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with three equivalent O(10)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the fifth O site, O(5) is bonded to one Ce(1), one Ce(5), and two equivalent Ce(4) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with three equivalent O(10)Ce4 tetrahedra, corners with four equivalent O(6)Ce4 tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra, and  an edgeedge with one O(5)Ce4 tetrahedra. In the sixth O site, O(6) is bonded to one Ce(1), one Ce(3), one Ce(4), and one Ce(5) atom to form OCe4 tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(7)Ce3Y tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with four equivalent O(5)Ce4 tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the seventh O site, O(7) is bonded to one Ce(1), one Ce(2), one Ce(4), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with two equivalent O(6)Ce4 tetrahedra, corners with four equivalent O(1)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra, and  an edgeedge with one O(5)Ce4 tetrahedra. In the eighth O site, O(8) is bonded to one Ce(2), one Ce(3), and two equivalent Ce(5) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(5)Ce4 tetrahedra, corners with two equivalent O(6)Ce4 tetrahedra, corners with three equivalent O(10)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the ninth O site, O(9) is bonded to one Ce(1), one Ce(2), one Ce(3), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(7)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with three equivalent O(3)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the tenth O site, O(10) is bonded to one Ce(2), one Ce(5), and two equivalent Ce(4) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra, corners with two equivalent O(3)Ce4 tetrahedra, corners with three equivalent O(4)Ce3Y tetrahedra, corners with three equivalent O(5)Ce4 tetrahedra, corners with three equivalent O(8)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra, and  an edgeedge with one O(6)Ce4 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ce9YO20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.650
_cell_length_b   7.678
_cell_length_c   8.588
_cell_angle_alpha   102.922
_cell_angle_beta   97.408
_cell_angle_gamma   106.756
_symmetry_Int_Tables_number   1
_cell_volume   400.329
_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
  Ce  Ce0  1  0.800  0.601  0.602  1.0
  Ce  Ce1  1  0.600  0.199  0.199  1.0
  Ce  Ce2  1  0.000  0.500  0.000  1.0
  Ce  Ce3  1  0.800  0.100  0.602  1.0
  Ce  Ce4  1  0.200  0.399  0.398  1.0
  Ce  Ce5  1  0.602  0.701  0.199  1.0
  Ce  Ce6  1  0.398  0.299  0.801  1.0
  Ce  Ce7  1  0.200  0.900  0.398  1.0
  Ce  Ce8  1  0.400  0.801  0.801  1.0
  Y  Y9  1  0.000  0.000  0.000  1.0
  O  O10  1  0.850  0.325  0.451  1.0
  O  O11  1  0.648  0.924  0.051  1.0
  O  O12  1  0.449  0.524  0.650  1.0
  O  O13  1  0.950  0.773  0.151  1.0
  O  O14  1  0.851  0.826  0.450  1.0
  O  O15  1  0.749  0.375  0.750  1.0
  O  O16  1  0.252  0.126  0.252  1.0
  O  O17  1  0.649  0.425  0.050  1.0
  O  O18  1  0.950  0.277  0.151  1.0
  O  O19  1  0.449  0.025  0.650  1.0
  O  O20  1  0.551  0.975  0.350  1.0
  O  O21  1  0.050  0.723  0.849  1.0
  O  O22  1  0.748  0.874  0.748  1.0
  O  O23  1  0.251  0.625  0.250  1.0
  O  O24  1  0.351  0.575  0.950  1.0
  O  O25  1  0.050  0.227  0.849  1.0
  O  O26  1  0.551  0.476  0.350  1.0
  O  O27  1  0.149  0.174  0.550  1.0
  O  O28  1  0.352  0.076  0.949  1.0
  O  O29  1  0.150  0.675  0.549  1.0
[/CIF]
.
The structure described by Ce9YO20 is Fluorite-derived structured and crystallizes in the triclinic P-1 space group. There are five inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a body-centered cubic geometry to one O(5), one O(6), one O(7), one O(9), two equivalent O(1), and two equivalent O(3) atoms. In the second Ce site, Ce(2) is bonded in a body-centered cubic geometry to one O(1), one O(10), one O(3), one O(7), one O(8), one O(9), and two equivalent O(2) atoms. In the third Ce site, Ce(3) is bonded in a body-centered cubic geometry to two equivalent O(4), two equivalent O(6), two equivalent O(8), and two equivalent O(9) atoms. In the fourth Ce site, Ce(4) is bonded in a body-centered cubic geometry to one O(1), one O(4), one O(6), one O(7), two equivalent O(10), and two equivalent O(5) atoms. In the fifth Ce site, Ce(5) is bonded in a body-centered cubic geometry to one O(10), one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(8) atoms. Y(1) is bonded in a body-centered cubic geometry to two equivalent O(2), two equivalent O(4), two equivalent O(7), and two equivalent O(9) atoms. There are ten inequivalent O sites. In the first O site, O(1) is bonded to one Ce(2), one Ce(4), and two equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(5)Ce4 tetrahedra, corners with three equivalent O(3)Ce4 tetrahedra, corners with four equivalent O(7)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra, and  an edgeedge with one O(6)Ce4 tetrahedra. In the second O site, O(2) is bonded to one Ce(5), two equivalent Ce(2), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra, corners with two equivalent O(7)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with three equivalent O(3)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the third O site, O(3) is bonded to one Ce(2), one Ce(5), and two equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(10)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Y tetrahedra, corners with three equivalent O(9)Ce3Y tetrahedra, corners with three equivalent O(1)Ce4 tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the fourth O site, O(4) is bonded to one Ce(3), one Ce(4), one Ce(5), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with two equivalent O(6)Ce4 tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with three equivalent O(10)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the fifth O site, O(5) is bonded to one Ce(1), one Ce(5), and two equivalent Ce(4) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with three equivalent O(10)Ce4 tetrahedra, corners with four equivalent O(6)Ce4 tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra, and  an edgeedge with one O(5)Ce4 tetrahedra. In the sixth O site, O(6) is bonded to one Ce(1), one Ce(3), one Ce(4), and one Ce(5) atom to form OCe4 tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(7)Ce3Y tetrahedra, corners with two equivalent O(8)Ce4 tetrahedra, corners with four equivalent O(5)Ce4 tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the seventh O site, O(7) is bonded to one Ce(1), one Ce(2), one Ce(4), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(4)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with two equivalent O(6)Ce4 tetrahedra, corners with four equivalent O(1)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra, and  an edgeedge with one O(5)Ce4 tetrahedra. In the eighth O site, O(8) is bonded to one Ce(2), one Ce(3), and two equivalent Ce(5) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(3)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(5)Ce4 tetrahedra, corners with two equivalent O(6)Ce4 tetrahedra, corners with three equivalent O(10)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(9)Ce3Y tetrahedra,  an edgeedge with one O(3)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the ninth O site, O(9) is bonded to one Ce(1), one Ce(2), one Ce(3), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(10)Ce4 tetrahedra,  a cornercorner with one O(5)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra,  a cornercorner with one O(8)Ce4 tetrahedra, corners with two equivalent O(2)Ce3Y tetrahedra, corners with two equivalent O(4)Ce3Y tetrahedra, corners with two equivalent O(7)Ce3Y tetrahedra, corners with two equivalent O(9)Ce3Y tetrahedra, corners with three equivalent O(3)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(4)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(6)Ce4 tetrahedra, and  an edgeedge with one O(8)Ce4 tetrahedra. In the tenth O site, O(10) is bonded to one Ce(2), one Ce(5), and two equivalent Ce(4) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(2)Ce3Y tetrahedra,  a cornercorner with one O(7)Ce3Y tetrahedra,  a cornercorner with one O(9)Ce3Y tetrahedra,  a cornercorner with one O(1)Ce4 tetrahedra,  a cornercorner with one O(6)Ce4 tetrahedra, corners with two equivalent O(3)Ce4 tetrahedra, corners with three equivalent O(4)Ce3Y tetrahedra, corners with three equivalent O(5)Ce4 tetrahedra, corners with three equivalent O(8)Ce4 tetrahedra,  an edgeedge with one O(2)Ce3Y tetrahedra,  an edgeedge with one O(7)Ce3Y tetrahedra,  an edgeedge with one O(1)Ce4 tetrahedra,  an edgeedge with one O(10)Ce4 tetrahedra,  an edgeedge with one O(5)Ce4 tetrahedra, and  an edgeedge with one O(6)Ce4 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ce9YO20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.650
_cell_length_b   7.678
_cell_length_c   8.588
_cell_angle_alpha   102.922
_cell_angle_beta   97.408
_cell_angle_gamma   106.756
_symmetry_Int_Tables_number   1
_cell_volume   400.329
_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
  Ce  Ce0  1  0.800  0.601  0.602  1.0
  Ce  Ce1  1  0.600  0.199  0.199  1.0
  Ce  Ce2  1  0.000  0.500  0.000  1.0
  Ce  Ce3  1  0.800  0.100  0.602  1.0
  Ce  Ce4  1  0.200  0.399  0.398  1.0
  Ce  Ce5  1  0.602  0.701  0.199  1.0
  Ce  Ce6  1  0.398  0.299  0.801  1.0
  Ce  Ce7  1  0.200  0.900  0.398  1.0
  Ce  Ce8  1  0.400  0.801  0.801  1.0
  Y  Y9  1  0.000  0.000  0.000  1.0
  O  O10  1  0.850  0.325  0.451  1.0
  O  O11  1  0.648  0.924  0.051  1.0
  O  O12  1  0.449  0.524  0.650  1.0
  O  O13  1  0.950  0.773  0.151  1.0
  O  O14  1  0.851  0.826  0.450  1.0
  O  O15  1  0.749  0.375  0.750  1.0
  O  O16  1  0.252  0.126  0.252  1.0
  O  O17  1  0.649  0.425  0.050  1.0
  O  O18  1  0.950  0.277  0.151  1.0
  O  O19  1  0.449  0.025  0.650  1.0
  O  O20  1  0.551  0.975  0.350  1.0
  O  O21  1  0.050  0.723  0.849  1.0
  O  O22  1  0.748  0.874  0.748  1.0
  O  O23  1  0.251  0.625  0.250  1.0
  O  O24  1  0.351  0.575  0.950  1.0
  O  O25  1  0.050  0.227  0.849  1.0
  O  O26  1  0.551  0.476  0.350  1.0
  O  O27  1  0.149  0.174  0.550  1.0
  O  O28  1  0.352  0.076  0.949  1.0
  O  O29  1  0.150  0.675  0.549  1.0
[/CIF]
.