Ce2Y2O7 crystallizes in the triclinic P1 space group. There are eight inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 7-coordinate geometry to one O(1), one O(15), one O(2), one O(20), one O(26), one O(5), and one O(6) atom. In the second Ce site, Ce(2) is bonded in a body-centered cubic geometry to one O(10), one O(11), one O(13), one O(14), one O(18), one O(25), one O(4), and one O(8) atom. In the third Ce site, Ce(3) is bonded to one O(12), one O(16), one O(17), one O(19), one O(22), one O(24), and one O(9) atom to form distorted CeO7 pentagonal bipyramids that share  a cornercorner with one Y(3)O7 hexagonal pyramid,  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Y(5)O6 octahedra,  an edgeedge with one Y(6)O7 hexagonal pyramid,  an edgeedge with one Y(7)O7 hexagonal pyramid,  an edgeedge with one Y(2)O6 octahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 53-57°. In the fourth Ce site, Ce(4) is bonded in a body-centered cubic geometry to one O(10), one O(15), one O(16), one O(19), one O(21), one O(25), one O(26), and one O(28) atom. In the fifth Ce site, Ce(5) is bonded in a 7-coordinate geometry to one O(11), one O(17), one O(19), one O(20), one O(23), one O(25), and one O(27) atom. In the sixth Ce site, Ce(6) is bonded in a body-centered cubic geometry to one O(11), one O(14), one O(16), one O(21), one O(22), one O(23), one O(5), and one O(6) atom. In the seventh Ce site, Ce(7) is bonded in a body-centered cubic geometry to one O(1), one O(12), one O(14), one O(15), one O(18), one O(21), one O(24), and one O(3) atom. In the eighth Ce site, Ce(8) is bonded in a 6-coordinate geometry to one O(21), one O(23), one O(27), one O(28), one O(3), and one O(7) atom. There are eight inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(13), one O(22), one O(26), one O(28), one O(4), one O(6), and one O(9) atom to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Y(7)O7 hexagonal pyramid,  a cornercorner with one Y(4)O6 octahedra,  an edgeedge with one Y(3)O7 hexagonal pyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid,  an edgeedge with one Y(2)O6 octahedra, and  an edgeedge with one Ce(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 51°. In the second Y site, Y(2) is bonded to one O(1), one O(19), one O(24), one O(28), one O(4), and one O(8) atom to form distorted YO6 octahedra that share  a cornercorner with one Y(6)O7 hexagonal pyramid,  a cornercorner with one Y(5)O6 octahedra,  an edgeedge with one Y(4)O6 octahedra,  an edgeedge with one Ce(3)O7 pentagonal bipyramid, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 61°. In the third Y site, Y(3) is bonded to one O(18), one O(2), one O(25), one O(26), one O(27), one O(3), and one O(9) atom to form distorted YO7 hexagonal pyramids that share  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Y(5)O6 octahedra,  a cornercorner with one Ce(3)O7 pentagonal bipyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 55-58°. In the fourth Y site, Y(4) is bonded to one O(1), one O(11), one O(17), one O(3), one O(6), and one O(8) atom to form distorted YO6 octahedra that share  a cornercorner with one Y(3)O7 hexagonal pyramid,  a cornercorner with one Y(7)O7 hexagonal pyramid,  a cornercorner with one Y(5)O6 octahedra,  a cornercorner with one Ce(3)O7 pentagonal bipyramid,  a cornercorner with one Y(1)O7 pentagonal bipyramid, and  an edgeedge with one Y(2)O6 octahedra. The corner-sharing octahedral tilt angles are 56°. In the fifth Y site, Y(5) is bonded to one O(10), one O(16), one O(2), one O(5), one O(7), and one O(8) atom to form distorted YO6 octahedra that share  a cornercorner with one Y(3)O7 hexagonal pyramid,  a cornercorner with one Y(2)O6 octahedra,  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Ce(3)O7 pentagonal bipyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid, and  an edgeedge with one Y(7)O7 hexagonal pyramid. The corner-sharing octahedral tilt angles range from 56-61°. In the sixth Y site, Y(6) is bonded to one O(12), one O(14), one O(27), one O(4), one O(5), one O(7), and one O(9) atom to form distorted YO7 hexagonal pyramids that share  a cornercorner with one Y(2)O6 octahedra,  an edgeedge with one Y(3)O7 hexagonal pyramid,  an edgeedge with one Y(7)O7 hexagonal pyramid,  an edgeedge with one Y(5)O6 octahedra,  an edgeedge with one Ce(3)O7 pentagonal bipyramid, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 53°. In the seventh Y site, Y(7) is bonded to one O(10), one O(12), one O(13), one O(15), one O(17), one O(20), and one O(7) atom to form distorted YO7 hexagonal pyramids that share  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Y(1)O7 pentagonal bipyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid,  an edgeedge with one Y(5)O6 octahedra, and  an edgeedge with one Ce(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 57°. In the eighth Y site, Y(8) is bonded in a 7-coordinate geometry to one O(13), one O(18), one O(2), one O(20), one O(22), one O(23), and one O(24) atom. There are twenty-eight inequivalent O sites. In the first O site, O(1) is bonded to one Ce(1), one Ce(7), one Y(2), and one Y(4) atom to form distorted OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra, and  an edgeedge with one O(8)CeY3 tetrahedra. In the second O site, O(2) is bonded to one Ce(1), one Y(3), one Y(5), and one Y(8) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra, and  an edgeedge with one O(5)Ce2Y2 tetrahedra. In the third O site, O(3) is bonded to one Ce(7), one Ce(8), one Y(3), and one Y(4) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the fourth O site, O(4) is bonded to one Ce(2), one Y(1), one Y(2), and one Y(6) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra,  an edgeedge with one O(8)CeY3 tetrahedra,  an edgeedge with one O(9)CeY3 tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Ce(1), one Ce(6), one Y(5), and one Y(6) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(2)CeY3 tetrahedra, and  an edgeedge with one O(7)CeY3 tetrahedra. In the sixth O site, O(6) is bonded to one Ce(1), one Ce(6), one Y(1), and one Y(4) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(5)Ce2Y2 tetrahedra, and  an edgeedge with one O(11)Ce3Y tetrahedra. In the seventh O site, O(7) is bonded to one Ce(8), one Y(5), one Y(6), and one Y(7) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra, and  an edgeedge with one O(5)Ce2Y2 tetrahedra. In the eighth O site, O(8) is bonded to one Ce(2), one Y(2), one Y(4), and one Y(5) atom to form distorted OCeY3 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the ninth O site, O(9) is bonded to one Ce(3), one Y(1), one Y(3), and one Y(6) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the tenth O site, O(10) is bonded to one Ce(2), one Ce(4), one Y(5), and one Y(7) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra,  an edgeedge with one O(7)CeY3 tetrahedra, and  an edgeedge with one O(8)CeY3 tetrahedra. In the eleventh O site, O(11) is bonded to one Ce(2), one Ce(5), one Ce(6), and one Y(4) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra, and  an edgeedge with one O(8)CeY3 tetrahedra. In the twelfth O site, O(12) is bonded to one Ce(3), one Ce(7), one Y(6), and one Y(7) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(7)CeY3 tetrahedra, and  an edgeedge with one O(9)CeY3 tetrahedra. In the thirteenth O site, O(13) is bonded to one Ce(2), one Y(1), one Y(7), and one Y(8) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the fourteenth O site, O(14) is bonded to one Ce(2), one Ce(6), one Ce(7), and one Y(6) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(5)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra,  an edgeedge with one O(21)Ce4 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the fifteenth O site, O(15) is bonded to one Ce(1), one Ce(4), one Ce(7), and one Y(7) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the sixteenth O site, O(16) is bonded to one Ce(3), one Ce(4), one Ce(6), and one Y(5) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(5)Ce2Y2 tetrahedra,  an edgeedge with one O(19)Ce3Y tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the seventeenth O site, O(17) is bonded to one Ce(3), one Ce(5), one Y(4), and one Y(7) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(19)Ce3Y tetrahedra. In the eighteenth O site, O(18) is bonded to one Ce(2), one Ce(7), one Y(3), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra, and  an edgeedge with one O(2)CeY3 tetrahedra. In the nineteenth O site, O(19) is bonded to one Ce(3), one Ce(4), one Ce(5), and one Y(2) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the twentieth O site, O(20) is bonded to one Ce(1), one Ce(5), one Y(7), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra, and  an edgeedge with one O(2)CeY3 tetrahedra. In the twenty-first O site, O(21) is bonded to one Ce(4), one Ce(6), one Ce(7), and one Ce(8) atom to form OCe4 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the twenty-second O site, O(22) is bonded to one Ce(3), one Ce(6), one Y(1), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra, and  an edgeedge with one O(9)CeY3 tetrahedra. In the twenty-third O site, O(23) is bonded to one Ce(5), one Ce(6), one Ce(8), and one Y(8) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the twenty-fourth O site, O(24) is bonded to one Ce(3), one Ce(7), one Y(2), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra, and  an edgeedge with one O(19)Ce3Y tetrahedra. In the twenty-fifth O site, O(25) is bonded to one Ce(2), one Ce(4), one Ce(5), and one Y(3) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(19)Ce3Y tetrahedra. In the twenty-sixth O site, O(26) is bonded to one Ce(1), one Ce(4), one Y(1), and one Y(3) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(2)CeY3 tetrahedra,  an edgeedge with one O(9)CeY3 tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the twenty-seventh O site, O(27) is bonded to one Ce(5), one Ce(8), one Y(3), and one Y(6) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(7)CeY3 tetrahedra, and  an edgeedge with one O(9)CeY3 tetrahedra. In the twenty-eighth O site, O(28) is bonded to one Ce(4), one Ce(8), one Y(1), and one Y(2) atom to form distorted OCe2Y2 trigonal pyramids that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(19)Ce3Y tetrahedra,  an edgeedge with one O(21)Ce4 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra.
Ce2Y2O7 crystallizes in the triclinic P1 space group. There are eight inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a 7-coordinate geometry to one O(1), one O(15), one O(2), one O(20), one O(26), one O(5), and one O(6) atom. The Ce(1)-O(1) bond length is 2.24 Å. The Ce(1)-O(15) bond length is 2.33 Å. The Ce(1)-O(2) bond length is 2.45 Å. The Ce(1)-O(20) bond length is 2.33 Å. The Ce(1)-O(26) bond length is 2.29 Å. The Ce(1)-O(5) bond length is 2.31 Å. The Ce(1)-O(6) bond length is 2.36 Å. In the second Ce site, Ce(2) is bonded in a body-centered cubic geometry to one O(10), one O(11), one O(13), one O(14), one O(18), one O(25), one O(4), and one O(8) atom. The Ce(2)-O(10) bond length is 2.39 Å. The Ce(2)-O(11) bond length is 2.37 Å. The Ce(2)-O(13) bond length is 2.37 Å. The Ce(2)-O(14) bond length is 2.42 Å. The Ce(2)-O(18) bond length is 2.27 Å. The Ce(2)-O(25) bond length is 2.35 Å. The Ce(2)-O(4) bond length is 2.45 Å. The Ce(2)-O(8) bond length is 2.53 Å. In the third Ce site, Ce(3) is bonded to one O(12), one O(16), one O(17), one O(19), one O(22), one O(24), and one O(9) atom to form distorted CeO7 pentagonal bipyramids that share  a cornercorner with one Y(3)O7 hexagonal pyramid,  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Y(5)O6 octahedra,  an edgeedge with one Y(6)O7 hexagonal pyramid,  an edgeedge with one Y(7)O7 hexagonal pyramid,  an edgeedge with one Y(2)O6 octahedra, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 53-57°. The Ce(3)-O(12) bond length is 2.27 Å. The Ce(3)-O(16) bond length is 2.32 Å. The Ce(3)-O(17) bond length is 2.46 Å. The Ce(3)-O(19) bond length is 2.39 Å. The Ce(3)-O(22) bond length is 2.25 Å. The Ce(3)-O(24) bond length is 2.37 Å. The Ce(3)-O(9) bond length is 2.25 Å. In the fourth Ce site, Ce(4) is bonded in a body-centered cubic geometry to one O(10), one O(15), one O(16), one O(19), one O(21), one O(25), one O(26), and one O(28) atom. The Ce(4)-O(10) bond length is 2.25 Å. The Ce(4)-O(15) bond length is 2.29 Å. The Ce(4)-O(16) bond length is 2.42 Å. The Ce(4)-O(19) bond length is 2.47 Å. The Ce(4)-O(21) bond length is 2.41 Å. The Ce(4)-O(25) bond length is 2.35 Å. The Ce(4)-O(26) bond length is 2.27 Å. The Ce(4)-O(28) bond length is 2.70 Å. In the fifth Ce site, Ce(5) is bonded in a 7-coordinate geometry to one O(11), one O(17), one O(19), one O(20), one O(23), one O(25), and one O(27) atom. The Ce(5)-O(11) bond length is 2.29 Å. The Ce(5)-O(17) bond length is 2.40 Å. The Ce(5)-O(19) bond length is 2.29 Å. The Ce(5)-O(20) bond length is 2.31 Å. The Ce(5)-O(23) bond length is 2.41 Å. The Ce(5)-O(25) bond length is 2.29 Å. The Ce(5)-O(27) bond length is 2.30 Å. In the sixth Ce site, Ce(6) is bonded in a body-centered cubic geometry to one O(11), one O(14), one O(16), one O(21), one O(22), one O(23), one O(5), and one O(6) atom. The Ce(6)-O(11) bond length is 2.29 Å. The Ce(6)-O(14) bond length is 2.39 Å. The Ce(6)-O(16) bond length is 2.42 Å. The Ce(6)-O(21) bond length is 2.35 Å. The Ce(6)-O(22) bond length is 2.36 Å. The Ce(6)-O(23) bond length is 2.44 Å. The Ce(6)-O(5) bond length is 2.40 Å. The Ce(6)-O(6) bond length is 2.45 Å. In the seventh Ce site, Ce(7) is bonded in a body-centered cubic geometry to one O(1), one O(12), one O(14), one O(15), one O(18), one O(21), one O(24), and one O(3) atom. The Ce(7)-O(1) bond length is 2.57 Å. The Ce(7)-O(12) bond length is 2.25 Å. The Ce(7)-O(14) bond length is 2.31 Å. The Ce(7)-O(15) bond length is 2.38 Å. The Ce(7)-O(18) bond length is 2.35 Å. The Ce(7)-O(21) bond length is 2.39 Å. The Ce(7)-O(24) bond length is 2.42 Å. The Ce(7)-O(3) bond length is 2.46 Å. In the eighth Ce site, Ce(8) is bonded in a 6-coordinate geometry to one O(21), one O(23), one O(27), one O(28), one O(3), and one O(7) atom. The Ce(8)-O(21) bond length is 2.30 Å. The Ce(8)-O(23) bond length is 2.23 Å. The Ce(8)-O(27) bond length is 2.35 Å. The Ce(8)-O(28) bond length is 2.20 Å. The Ce(8)-O(3) bond length is 2.29 Å. The Ce(8)-O(7) bond length is 2.26 Å. There are eight inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(13), one O(22), one O(26), one O(28), one O(4), one O(6), and one O(9) atom to form distorted YO7 pentagonal bipyramids that share  a cornercorner with one Y(7)O7 hexagonal pyramid,  a cornercorner with one Y(4)O6 octahedra,  an edgeedge with one Y(3)O7 hexagonal pyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid,  an edgeedge with one Y(2)O6 octahedra, and  an edgeedge with one Ce(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 51°. The Y(1)-O(13) bond length is 2.33 Å. The Y(1)-O(22) bond length is 2.30 Å. The Y(1)-O(26) bond length is 2.31 Å. The Y(1)-O(28) bond length is 2.53 Å. The Y(1)-O(4) bond length is 2.33 Å. The Y(1)-O(6) bond length is 2.32 Å. The Y(1)-O(9) bond length is 2.36 Å. In the second Y site, Y(2) is bonded to one O(1), one O(19), one O(24), one O(28), one O(4), and one O(8) atom to form distorted YO6 octahedra that share  a cornercorner with one Y(6)O7 hexagonal pyramid,  a cornercorner with one Y(5)O6 octahedra,  an edgeedge with one Y(4)O6 octahedra,  an edgeedge with one Ce(3)O7 pentagonal bipyramid, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 61°. The Y(2)-O(1) bond length is 2.25 Å. The Y(2)-O(19) bond length is 2.30 Å. The Y(2)-O(24) bond length is 2.29 Å. The Y(2)-O(28) bond length is 2.34 Å. The Y(2)-O(4) bond length is 2.26 Å. The Y(2)-O(8) bond length is 2.30 Å. In the third Y site, Y(3) is bonded to one O(18), one O(2), one O(25), one O(26), one O(27), one O(3), and one O(9) atom to form distorted YO7 hexagonal pyramids that share  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Y(5)O6 octahedra,  a cornercorner with one Ce(3)O7 pentagonal bipyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 55-58°. The Y(3)-O(18) bond length is 2.33 Å. The Y(3)-O(2) bond length is 2.40 Å. The Y(3)-O(25) bond length is 2.30 Å. The Y(3)-O(26) bond length is 2.26 Å. The Y(3)-O(27) bond length is 2.41 Å. The Y(3)-O(3) bond length is 2.40 Å. The Y(3)-O(9) bond length is 2.34 Å. In the fourth Y site, Y(4) is bonded to one O(1), one O(11), one O(17), one O(3), one O(6), and one O(8) atom to form distorted YO6 octahedra that share  a cornercorner with one Y(3)O7 hexagonal pyramid,  a cornercorner with one Y(7)O7 hexagonal pyramid,  a cornercorner with one Y(5)O6 octahedra,  a cornercorner with one Ce(3)O7 pentagonal bipyramid,  a cornercorner with one Y(1)O7 pentagonal bipyramid, and  an edgeedge with one Y(2)O6 octahedra. The corner-sharing octahedral tilt angles are 56°. The Y(4)-O(1) bond length is 2.34 Å. The Y(4)-O(11) bond length is 2.27 Å. The Y(4)-O(17) bond length is 2.33 Å. The Y(4)-O(3) bond length is 2.31 Å. The Y(4)-O(6) bond length is 2.24 Å. The Y(4)-O(8) bond length is 2.27 Å. In the fifth Y site, Y(5) is bonded to one O(10), one O(16), one O(2), one O(5), one O(7), and one O(8) atom to form distorted YO6 octahedra that share  a cornercorner with one Y(3)O7 hexagonal pyramid,  a cornercorner with one Y(2)O6 octahedra,  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Ce(3)O7 pentagonal bipyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid, and  an edgeedge with one Y(7)O7 hexagonal pyramid. The corner-sharing octahedral tilt angles range from 56-61°. The Y(5)-O(10) bond length is 2.31 Å. The Y(5)-O(16) bond length is 2.24 Å. The Y(5)-O(2) bond length is 2.32 Å. The Y(5)-O(5) bond length is 2.35 Å. The Y(5)-O(7) bond length is 2.29 Å. The Y(5)-O(8) bond length is 2.26 Å. In the sixth Y site, Y(6) is bonded to one O(12), one O(14), one O(27), one O(4), one O(5), one O(7), and one O(9) atom to form distorted YO7 hexagonal pyramids that share  a cornercorner with one Y(2)O6 octahedra,  an edgeedge with one Y(3)O7 hexagonal pyramid,  an edgeedge with one Y(7)O7 hexagonal pyramid,  an edgeedge with one Y(5)O6 octahedra,  an edgeedge with one Ce(3)O7 pentagonal bipyramid, and  an edgeedge with one Y(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 53°. The Y(6)-O(12) bond length is 2.28 Å. The Y(6)-O(14) bond length is 2.36 Å. The Y(6)-O(27) bond length is 2.38 Å. The Y(6)-O(4) bond length is 2.26 Å. The Y(6)-O(5) bond length is 2.36 Å. The Y(6)-O(7) bond length is 2.43 Å. The Y(6)-O(9) bond length is 2.38 Å. In the seventh Y site, Y(7) is bonded to one O(10), one O(12), one O(13), one O(15), one O(17), one O(20), and one O(7) atom to form distorted YO7 hexagonal pyramids that share  a cornercorner with one Y(4)O6 octahedra,  a cornercorner with one Y(1)O7 pentagonal bipyramid,  an edgeedge with one Y(6)O7 hexagonal pyramid,  an edgeedge with one Y(5)O6 octahedra, and  an edgeedge with one Ce(3)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 57°. The Y(7)-O(10) bond length is 2.29 Å. The Y(7)-O(12) bond length is 2.32 Å. The Y(7)-O(13) bond length is 2.32 Å. The Y(7)-O(15) bond length is 2.30 Å. The Y(7)-O(17) bond length is 2.49 Å. The Y(7)-O(20) bond length is 2.34 Å. The Y(7)-O(7) bond length is 2.41 Å. In the eighth Y site, Y(8) is bonded in a 7-coordinate geometry to one O(13), one O(18), one O(2), one O(20), one O(22), one O(23), and one O(24) atom. The Y(8)-O(13) bond length is 2.28 Å. The Y(8)-O(18) bond length is 2.30 Å. The Y(8)-O(2) bond length is 2.48 Å. The Y(8)-O(20) bond length is 2.41 Å. The Y(8)-O(22) bond length is 2.33 Å. The Y(8)-O(23) bond length is 2.35 Å. The Y(8)-O(24) bond length is 2.31 Å. There are twenty-eight inequivalent O sites. In the first O site, O(1) is bonded to one Ce(1), one Ce(7), one Y(2), and one Y(4) atom to form distorted OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra, and  an edgeedge with one O(8)CeY3 tetrahedra. In the second O site, O(2) is bonded to one Ce(1), one Y(3), one Y(5), and one Y(8) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra, and  an edgeedge with one O(5)Ce2Y2 tetrahedra. In the third O site, O(3) is bonded to one Ce(7), one Ce(8), one Y(3), and one Y(4) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the fourth O site, O(4) is bonded to one Ce(2), one Y(1), one Y(2), and one Y(6) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra,  an edgeedge with one O(8)CeY3 tetrahedra,  an edgeedge with one O(9)CeY3 tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Ce(1), one Ce(6), one Y(5), and one Y(6) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(2)CeY3 tetrahedra, and  an edgeedge with one O(7)CeY3 tetrahedra. In the sixth O site, O(6) is bonded to one Ce(1), one Ce(6), one Y(1), and one Y(4) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(5)Ce2Y2 tetrahedra, and  an edgeedge with one O(11)Ce3Y tetrahedra. In the seventh O site, O(7) is bonded to one Ce(8), one Y(5), one Y(6), and one Y(7) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra, and  an edgeedge with one O(5)Ce2Y2 tetrahedra. In the eighth O site, O(8) is bonded to one Ce(2), one Y(2), one Y(4), and one Y(5) atom to form distorted OCeY3 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the ninth O site, O(9) is bonded to one Ce(3), one Y(1), one Y(3), and one Y(6) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the tenth O site, O(10) is bonded to one Ce(2), one Ce(4), one Y(5), and one Y(7) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra,  an edgeedge with one O(7)CeY3 tetrahedra, and  an edgeedge with one O(8)CeY3 tetrahedra. In the eleventh O site, O(11) is bonded to one Ce(2), one Ce(5), one Ce(6), and one Y(4) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra, and  an edgeedge with one O(8)CeY3 tetrahedra. In the twelfth O site, O(12) is bonded to one Ce(3), one Ce(7), one Y(6), and one Y(7) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(7)CeY3 tetrahedra, and  an edgeedge with one O(9)CeY3 tetrahedra. In the thirteenth O site, O(13) is bonded to one Ce(2), one Y(1), one Y(7), and one Y(8) atom to form OCeY3 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the fourteenth O site, O(14) is bonded to one Ce(2), one Ce(6), one Ce(7), and one Y(6) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(5)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra,  an edgeedge with one O(21)Ce4 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra. In the fifteenth O site, O(15) is bonded to one Ce(1), one Ce(4), one Ce(7), and one Y(7) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the sixteenth O site, O(16) is bonded to one Ce(3), one Ce(4), one Ce(6), and one Y(5) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(5)Ce2Y2 tetrahedra,  an edgeedge with one O(19)Ce3Y tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the seventeenth O site, O(17) is bonded to one Ce(3), one Ce(5), one Y(4), and one Y(7) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(19)Ce3Y tetrahedra. In the eighteenth O site, O(18) is bonded to one Ce(2), one Ce(7), one Y(3), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra, and  an edgeedge with one O(2)CeY3 tetrahedra. In the nineteenth O site, O(19) is bonded to one Ce(3), one Ce(4), one Ce(5), and one Y(2) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the twentieth O site, O(20) is bonded to one Ce(1), one Ce(5), one Y(7), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  an edgeedge with one O(17)Ce2Y2 tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra, and  an edgeedge with one O(2)CeY3 tetrahedra. In the twenty-first O site, O(21) is bonded to one Ce(4), one Ce(6), one Ce(7), and one Ce(8) atom to form OCe4 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(14)Ce3Y tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the twenty-second O site, O(22) is bonded to one Ce(3), one Ce(6), one Y(1), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(24)Ce2Y2 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(16)Ce3Y tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(13)CeY3 tetrahedra, and  an edgeedge with one O(9)CeY3 tetrahedra. In the twenty-third O site, O(23) is bonded to one Ce(5), one Ce(6), one Ce(8), and one Y(8) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(20)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(21)Ce4 tetrahedra. In the twenty-fourth O site, O(24) is bonded to one Ce(3), one Ce(7), one Y(2), and one Y(8) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(1)Ce2Y2 tetrahedra,  an edgeedge with one O(12)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(22)Ce2Y2 tetrahedra, and  an edgeedge with one O(19)Ce3Y tetrahedra. In the twenty-fifth O site, O(25) is bonded to one Ce(2), one Ce(4), one Ce(5), and one Y(3) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(10)Ce2Y2 tetrahedra,  an edgeedge with one O(18)Ce2Y2 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(27)Ce2Y2 tetrahedra,  an edgeedge with one O(11)Ce3Y tetrahedra, and  an edgeedge with one O(19)Ce3Y tetrahedra. In the twenty-sixth O site, O(26) is bonded to one Ce(1), one Ce(4), one Y(1), and one Y(3) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  an edgeedge with one O(6)Ce2Y2 tetrahedra,  an edgeedge with one O(15)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(2)CeY3 tetrahedra,  an edgeedge with one O(9)CeY3 tetrahedra, and  an edgeedge with one O(28)Ce2Y2 trigonal pyramid. In the twenty-seventh O site, O(27) is bonded to one Ce(5), one Ce(8), one Y(3), and one Y(6) atom to form OCe2Y2 tetrahedra that share  a cornercorner with one O(12)Ce2Y2 tetrahedra,  a cornercorner with one O(17)Ce2Y2 tetrahedra,  a cornercorner with one O(18)Ce2Y2 tetrahedra,  a cornercorner with one O(20)Ce2Y2 tetrahedra,  a cornercorner with one O(26)Ce2Y2 tetrahedra,  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(11)Ce3Y tetrahedra,  a cornercorner with one O(14)Ce3Y tetrahedra,  a cornercorner with one O(19)Ce3Y tetrahedra,  a cornercorner with one O(21)Ce4 tetrahedra,  a cornercorner with one O(2)CeY3 tetrahedra,  a cornercorner with one O(4)CeY3 tetrahedra,  a cornercorner with one O(28)Ce2Y2 trigonal pyramid,  an edgeedge with one O(3)Ce2Y2 tetrahedra,  an edgeedge with one O(23)Ce3Y tetrahedra,  an edgeedge with one O(25)Ce3Y tetrahedra,  an edgeedge with one O(7)CeY3 tetrahedra, and  an edgeedge with one O(9)CeY3 tetrahedra. In the twenty-eighth O site, O(28) is bonded to one Ce(4), one Ce(8), one Y(1), and one Y(2) atom to form distorted OCe2Y2 trigonal pyramids that share  a cornercorner with one O(1)Ce2Y2 tetrahedra,  a cornercorner with one O(10)Ce2Y2 tetrahedra,  a cornercorner with one O(22)Ce2Y2 tetrahedra,  a cornercorner with one O(24)Ce2Y2 tetrahedra,  a cornercorner with one O(27)Ce2Y2 tetrahedra,  a cornercorner with one O(3)Ce2Y2 tetrahedra,  a cornercorner with one O(6)Ce2Y2 tetrahedra,  a cornercorner with one O(15)Ce3Y tetrahedra,  a cornercorner with one O(16)Ce3Y tetrahedra,  a cornercorner with one O(23)Ce3Y tetrahedra,  a cornercorner with one O(25)Ce3Y tetrahedra,  a cornercorner with one O(13)CeY3 tetrahedra,  a cornercorner with one O(7)CeY3 tetrahedra,  a cornercorner with one O(8)CeY3 tetrahedra,  a cornercorner with one O(9)CeY3 tetrahedra,  an edgeedge with one O(26)Ce2Y2 tetrahedra,  an edgeedge with one O(19)Ce3Y tetrahedra,  an edgeedge with one O(21)Ce4 tetrahedra, and  an edgeedge with one O(4)CeY3 tetrahedra.