Th3CeO8 is Fluorite-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. In the second Th site, Th(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Ce(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Th(1) and two equivalent Th(2) atoms to form OTh4 tetrahedra that share corners with two equivalent O(3)Ce2Th2 tetrahedra, corners with six equivalent O(1)Th4 tetrahedra, corners with eight equivalent O(2)CeTh3 tetrahedra,  an edgeedge with one O(3)Ce2Th2 tetrahedra,  an edgeedge with one O(1)Th4 tetrahedra, and edges with four equivalent O(2)CeTh3 tetrahedra. In the second O site, O(2) is bonded to one Th(2), two equivalent Th(1), and one Ce(1) atom to form OCeTh3 tetrahedra that share corners with four equivalent O(3)Ce2Th2 tetrahedra, corners with four equivalent O(1)Th4 tetrahedra, corners with eight equivalent O(2)CeTh3 tetrahedra, edges with two equivalent O(3)Ce2Th2 tetrahedra, edges with two equivalent O(2)CeTh3 tetrahedra, and edges with two equivalent O(1)Th4 tetrahedra. In the third O site, O(3) is bonded to two equivalent Th(1) and two equivalent Ce(1) atoms to form OCe2Th2 tetrahedra that share corners with two equivalent O(1)Th4 tetrahedra, corners with six equivalent O(3)Ce2Th2 tetrahedra, corners with eight equivalent O(2)CeTh3 tetrahedra,  an edgeedge with one O(3)Ce2Th2 tetrahedra,  an edgeedge with one O(1)Th4 tetrahedra, and edges with four equivalent O(2)CeTh3 tetrahedra.
Th3CeO8 is Fluorite-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Both Th(1)-O(1) bond lengths are 2.41 Å. Both Th(1)-O(3) bond lengths are 2.42 Å. All Th(1)-O(2) bond lengths are 2.42 Å. In the second Th site, Th(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Th(2)-O(1) bond lengths are 2.41 Å. All Th(2)-O(2) bond lengths are 2.42 Å. Ce(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Ce(1)-O(2) bond lengths are 2.38 Å. All Ce(1)-O(3) bond lengths are 2.39 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Th(1) and two equivalent Th(2) atoms to form OTh4 tetrahedra that share corners with two equivalent O(3)Ce2Th2 tetrahedra, corners with six equivalent O(1)Th4 tetrahedra, corners with eight equivalent O(2)CeTh3 tetrahedra,  an edgeedge with one O(3)Ce2Th2 tetrahedra,  an edgeedge with one O(1)Th4 tetrahedra, and edges with four equivalent O(2)CeTh3 tetrahedra. In the second O site, O(2) is bonded to one Th(2), two equivalent Th(1), and one Ce(1) atom to form OCeTh3 tetrahedra that share corners with four equivalent O(3)Ce2Th2 tetrahedra, corners with four equivalent O(1)Th4 tetrahedra, corners with eight equivalent O(2)CeTh3 tetrahedra, edges with two equivalent O(3)Ce2Th2 tetrahedra, edges with two equivalent O(2)CeTh3 tetrahedra, and edges with two equivalent O(1)Th4 tetrahedra. In the third O site, O(3) is bonded to two equivalent Th(1) and two equivalent Ce(1) atoms to form OCe2Th2 tetrahedra that share corners with two equivalent O(1)Th4 tetrahedra, corners with six equivalent O(3)Ce2Th2 tetrahedra, corners with eight equivalent O(2)CeTh3 tetrahedra,  an edgeedge with one O(3)Ce2Th2 tetrahedra,  an edgeedge with one O(1)Th4 tetrahedra, and edges with four equivalent O(2)CeTh3 tetrahedra.