SmCe4O9 crystallizes in the orthorhombic Imm2 space group. Sm(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. 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(3), three equivalent O(1), and three equivalent O(4) atoms. In the second Ce site, Ce(2) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing CeO7 hexagonal pyramids. 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)Ce2Sm2 tetrahedra, corners with two equivalent O(4)Ce4 tetrahedra, corners with five equivalent O(3)Ce3Sm tetrahedra, corners with six equivalent O(1)Ce4 tetrahedra,  a cornercorner with one O(2)Ce3Sm trigonal pyramid, edges with four equivalent O(4)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Sm trigonal pyramids. In the second O site, O(2) is bonded to one Sm(1), one Ce(1), and two equivalent Ce(2) atoms to form distorted OCe3Sm trigonal pyramids that share  a cornercorner with one O(1)Ce4 tetrahedra, corners with three equivalent O(3)Ce3Sm tetrahedra, corners with four equivalent O(5)Ce2Sm2 tetrahedra, corners with five equivalent O(4)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Sm trigonal pyramids, edges with two equivalent O(3)Ce3Sm tetrahedra, and edges with two equivalent O(1)Ce4 tetrahedra. In the third O site, O(3) is bonded to one Sm(1), one Ce(1), and two equivalent Ce(2) atoms to form OCe3Sm tetrahedra that share  a cornercorner with one O(4)Ce4 tetrahedra, corners with three equivalent O(3)Ce3Sm tetrahedra, corners with five equivalent O(1)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Sm trigonal pyramids, edges with two equivalent O(5)Ce2Sm2 tetrahedra, edges with two equivalent O(4)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Sm trigonal pyramids. In the fourth O site, O(4) is bonded to one Ce(2) and three equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(5)Ce2Sm2 tetrahedra,  a cornercorner with one O(3)Ce3Sm tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with six equivalent O(4)Ce4 tetrahedra, corners with five equivalent O(2)Ce3Sm trigonal pyramids, edges with two equivalent O(3)Ce3Sm tetrahedra, and edges with four equivalent O(1)Ce4 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Sm(1) and two equivalent Ce(2) atoms to form OCe2Sm2 tetrahedra that share corners with two equivalent O(5)Ce2Sm2 tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(4)Ce4 tetrahedra, corners with eight equivalent O(2)Ce3Sm trigonal pyramids, and edges with four equivalent O(3)Ce3Sm tetrahedra.
SmCe4O9 crystallizes in the orthorhombic Imm2 space group. Sm(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both Sm(1)-O(2) bond lengths are 2.37 Å. Both Sm(1)-O(3) bond lengths are 2.38 Å. Both Sm(1)-O(5) bond lengths are 2.28 Å. 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(3), three equivalent O(1), and three equivalent O(4) atoms. The Ce(1)-O(2) bond length is 2.68 Å. The Ce(1)-O(3) bond length is 2.34 Å. There are two shorter (2.37 Å) and one longer (2.47 Å) Ce(1)-O(1) bond length. There are two shorter (2.36 Å) and one longer (2.38 Å) Ce(1)-O(4) bond length. In the second Ce site, Ce(2) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of distorted corner and edge-sharing CeO7 hexagonal pyramids. The Ce(2)-O(1) bond length is 2.26 Å. The Ce(2)-O(4) bond length is 2.34 Å. The Ce(2)-O(5) bond length is 2.43 Å. Both Ce(2)-O(2) bond lengths are 2.42 Å. Both Ce(2)-O(3) bond lengths are 2.32 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)Ce2Sm2 tetrahedra, corners with two equivalent O(4)Ce4 tetrahedra, corners with five equivalent O(3)Ce3Sm tetrahedra, corners with six equivalent O(1)Ce4 tetrahedra,  a cornercorner with one O(2)Ce3Sm trigonal pyramid, edges with four equivalent O(4)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Sm trigonal pyramids. In the second O site, O(2) is bonded to one Sm(1), one Ce(1), and two equivalent Ce(2) atoms to form distorted OCe3Sm trigonal pyramids that share  a cornercorner with one O(1)Ce4 tetrahedra, corners with three equivalent O(3)Ce3Sm tetrahedra, corners with four equivalent O(5)Ce2Sm2 tetrahedra, corners with five equivalent O(4)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Sm trigonal pyramids, edges with two equivalent O(3)Ce3Sm tetrahedra, and edges with two equivalent O(1)Ce4 tetrahedra. In the third O site, O(3) is bonded to one Sm(1), one Ce(1), and two equivalent Ce(2) atoms to form OCe3Sm tetrahedra that share  a cornercorner with one O(4)Ce4 tetrahedra, corners with three equivalent O(3)Ce3Sm tetrahedra, corners with five equivalent O(1)Ce4 tetrahedra, corners with three equivalent O(2)Ce3Sm trigonal pyramids, edges with two equivalent O(5)Ce2Sm2 tetrahedra, edges with two equivalent O(4)Ce4 tetrahedra, and edges with two equivalent O(2)Ce3Sm trigonal pyramids. In the fourth O site, O(4) is bonded to one Ce(2) and three equivalent Ce(1) atoms to form OCe4 tetrahedra that share  a cornercorner with one O(5)Ce2Sm2 tetrahedra,  a cornercorner with one O(3)Ce3Sm tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with six equivalent O(4)Ce4 tetrahedra, corners with five equivalent O(2)Ce3Sm trigonal pyramids, edges with two equivalent O(3)Ce3Sm tetrahedra, and edges with four equivalent O(1)Ce4 tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Sm(1) and two equivalent Ce(2) atoms to form OCe2Sm2 tetrahedra that share corners with two equivalent O(5)Ce2Sm2 tetrahedra, corners with two equivalent O(1)Ce4 tetrahedra, corners with two equivalent O(4)Ce4 tetrahedra, corners with eight equivalent O(2)Ce3Sm trigonal pyramids, and edges with four equivalent O(3)Ce3Sm tetrahedra.