Ce4YO9 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a body-centered cubic geometry to one O(2), one O(4), three equivalent O(1), and three equivalent O(3) atoms. In the second Ce site, Ce(2) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms. Y(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Ce(2) and three equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(5)Ce2Y2 tetrahedra, corners with two equivalent O(3)Ce4 tetrahedra, corners with five equivalent O(4)Ce3Y tetrahedra, corners with six equivalent O(1)Ce4 tetrahedra,  a cornercorner with one O(2)Ce3Y trigonal pyramid, edges with four equivalent O(3)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Y trigonal pyramids. In the second O site, O(2) is bonded to one Ce(1), two equivalent Ce(2), and one Y(1) atom to form distorted OCe3Y trigonal pyramids that share  a cornercorner with one O(1)Ce4 tetrahedra, corners with three equivalent O(4)Ce3Y tetrahedra, corners with four equivalent O(5)Ce2Y2 tetrahedra, corners with five equivalent O(3)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Y trigonal pyramids, edges with two equivalent O(4)Ce3Y tetrahedra, and edges with two equivalent O(1)Ce4 tetrahedra. In the third O site, O(3) is bonded to one Ce(2) and three equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(4)Ce3Y tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with six equivalent O(3)Ce4 tetrahedra, corners with five equivalent O(2)Ce3Y trigonal pyramids, edges with two equivalent O(4)Ce3Y tetrahedra, and edges with four equivalent O(1)Ce4 tetrahedra. In the fourth O site, O(4) is bonded to one Ce(1), two equivalent Ce(2), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(3)Ce4 tetrahedra, corners with three equivalent O(4)Ce3Y tetrahedra, corners with five equivalent O(1)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Y trigonal pyramids, edges with two equivalent O(5)Ce2Y2 tetrahedra, edges with two equivalent O(3)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Y trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Ce(2) and two equivalent Y(1) atoms to form OCe2Y2 tetrahedra that share corners with two equivalent O(5)Ce2Y2 tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(3)Ce4 tetrahedra, corners with eight equivalent O(2)Ce3Y trigonal pyramids, and edges with four equivalent O(4)Ce3Y tetrahedra.
Ce4YO9 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Ce sites. In the first Ce site, Ce(1) is bonded in a body-centered cubic geometry to one O(2), one O(4), three equivalent O(1), and three equivalent O(3) atoms. The Ce(1)-O(2) bond length is 2.65 Å. The Ce(1)-O(4) bond length is 2.32 Å. There are two shorter (2.37 Å) and one longer (2.46 Å) Ce(1)-O(1) bond length. There are two shorter (2.35 Å) and one longer (2.39 Å) Ce(1)-O(3) bond length. In the second Ce site, Ce(2) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms. The Ce(2)-O(1) bond length is 2.26 Å. The Ce(2)-O(3) bond length is 2.32 Å. The Ce(2)-O(5) bond length is 2.43 Å. Both Ce(2)-O(2) bond lengths are 2.43 Å. Both Ce(2)-O(4) bond lengths are 2.31 Å. Y(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Both Y(1)-O(2) bond lengths are 2.32 Å. Both Y(1)-O(4) bond lengths are 2.33 Å. Both Y(1)-O(5) bond lengths are 2.23 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Ce(2) and three equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(5)Ce2Y2 tetrahedra, corners with two equivalent O(3)Ce4 tetrahedra, corners with five equivalent O(4)Ce3Y tetrahedra, corners with six equivalent O(1)Ce4 tetrahedra,  a cornercorner with one O(2)Ce3Y trigonal pyramid, edges with four equivalent O(3)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Y trigonal pyramids. In the second O site, O(2) is bonded to one Ce(1), two equivalent Ce(2), and one Y(1) atom to form distorted OCe3Y trigonal pyramids that share  a cornercorner with one O(1)Ce4 tetrahedra, corners with three equivalent O(4)Ce3Y tetrahedra, corners with four equivalent O(5)Ce2Y2 tetrahedra, corners with five equivalent O(3)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Y trigonal pyramids, edges with two equivalent O(4)Ce3Y tetrahedra, and edges with two equivalent O(1)Ce4 tetrahedra. In the third O site, O(3) is bonded to one Ce(2) and three equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(5)Ce2Y2 tetrahedra,  a cornercorner with one O(4)Ce3Y tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with six equivalent O(3)Ce4 tetrahedra, corners with five equivalent O(2)Ce3Y trigonal pyramids, edges with two equivalent O(4)Ce3Y tetrahedra, and edges with four equivalent O(1)Ce4 tetrahedra. In the fourth O site, O(4) is bonded to one Ce(1), two equivalent Ce(2), and one Y(1) atom to form OCe3Y tetrahedra that share  a cornercorner with one O(3)Ce4 tetrahedra, corners with three equivalent O(4)Ce3Y tetrahedra, corners with five equivalent O(1)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Y trigonal pyramids, edges with two equivalent O(5)Ce2Y2 tetrahedra, edges with two equivalent O(3)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Y trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Ce(2) and two equivalent Y(1) atoms to form OCe2Y2 tetrahedra that share corners with two equivalent O(5)Ce2Y2 tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(3)Ce4 tetrahedra, corners with eight equivalent O(2)Ce3Y trigonal pyramids, and edges with four equivalent O(4)Ce3Y tetrahedra.