Th4SmO10 is Fluorite-derived structured and crystallizes in the tetragonal I4/m space group. Th(1) is bonded in a body-centered cubic geometry to two equivalent O(2) and six equivalent O(1) atoms. Sm(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Th(1) and one Sm(1) atom to form OSmTh3 tetrahedra that share corners with four equivalent O(2)Th4 tetrahedra, corners with twelve equivalent O(1)SmTh3 tetrahedra,  an edgeedge with one O(2)Th4 tetrahedra, and edges with five equivalent O(1)SmTh3 tetrahedra. In the second O site, O(2) is bonded to four equivalent Th(1) atoms to form OTh4 tetrahedra that share corners with sixteen equivalent O(1)SmTh3 tetrahedra, edges with two equivalent O(2)Th4 tetrahedra, and edges with four equivalent O(1)SmTh3 tetrahedra.
Th4SmO10 is Fluorite-derived structured and crystallizes in the tetragonal I4/m space group. Th(1) is bonded in a body-centered cubic geometry to two equivalent O(2) and six equivalent O(1) atoms. Both Th(1)-O(2) bond lengths are 2.44 Å. There are two shorter (2.41 Å) and four longer (2.42 Å) Th(1)-O(1) bond lengths. Sm(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Sm(1)-O(1) bond lengths are 2.45 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Th(1) and one Sm(1) atom to form OSmTh3 tetrahedra that share corners with four equivalent O(2)Th4 tetrahedra, corners with twelve equivalent O(1)SmTh3 tetrahedra,  an edgeedge with one O(2)Th4 tetrahedra, and edges with five equivalent O(1)SmTh3 tetrahedra. In the second O site, O(2) is bonded to four equivalent Th(1) atoms to form OTh4 tetrahedra that share corners with sixteen equivalent O(1)SmTh3 tetrahedra, edges with two equivalent O(2)Th4 tetrahedra, and edges with four equivalent O(1)SmTh3 tetrahedra.