U4Sm4O17 is alpha bismuth trifluoride-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a body-centered cubic geometry to one O(5), two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. In the second U site, U(2) is bonded in a 10-coordinate geometry to two equivalent O(3), two equivalent O(4), two equivalent O(5), and four equivalent O(2) atoms. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. In the second Sm site, Sm(2) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(6), and four equivalent O(1) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded to one U(1), one Sm(1), and two equivalent Sm(2) atoms to form OSm3U tetrahedra that share  a cornercorner with one O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(2)SmU3 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with six equivalent O(1)Sm3U tetrahedra,  an edgeedge with one O(1)Sm3U tetrahedra,  an edgeedge with one O(2)SmU3 tetrahedra, edges with two equivalent O(6)Sm2U2 tetrahedra, and edges with two equivalent O(3)Sm3U tetrahedra. The corner-sharing octahedral tilt angles are 54°. In the second O site, O(2) is bonded to one U(1), two equivalent U(2), and one Sm(1) atom to form OSmU3 tetrahedra that share corners with two equivalent O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(1)Sm3U tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with six equivalent O(2)SmU3 tetrahedra,  an edgeedge with one O(1)Sm3U tetrahedra,  an edgeedge with one O(2)SmU3 tetrahedra, edges with two equivalent O(3)Sm3U tetrahedra, edges with two equivalent O(4)U4 tetrahedra, and  a faceface with one O(5)U6 octahedra. The corner-sharing octahedral tilt angles are 54°. In the third O site, O(3) is bonded to one U(2), one Sm(2), and two equivalent Sm(1) atoms to form OSm3U tetrahedra that share corners with two equivalent O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with four equivalent O(2)SmU3 tetrahedra, edges with two equivalent O(1)Sm3U tetrahedra, edges with two equivalent O(3)Sm3U tetrahedra, and edges with two equivalent O(2)SmU3 tetrahedra. The corner-sharing octahedral tilt angles are 56°. In the fourth O site, O(4) is bonded to two equivalent U(1) and two equivalent U(2) atoms to form OU4 tetrahedra that share corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with four equivalent O(2)SmU3 tetrahedra,  an edgeedge with one O(6)Sm2U2 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, edges with four equivalent O(2)SmU3 tetrahedra, and faces with two equivalent O(5)U6 octahedra. In the fifth O site, O(5) is bonded to two equivalent U(1) and four equivalent U(2) atoms to form OU6 octahedra that share corners with four equivalent O(6)Sm2U2 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with eight equivalent O(3)Sm3U tetrahedra, corners with eight equivalent O(2)SmU3 tetrahedra, edges with two equivalent O(5)U6 octahedra, faces with four equivalent O(2)SmU3 tetrahedra, and faces with four equivalent O(4)U4 tetrahedra. In the sixth O site, O(6) is bonded to two equivalent U(1) and two equivalent Sm(2) atoms to form OSm2U2 tetrahedra that share corners with two equivalent O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with four equivalent O(2)SmU3 tetrahedra,  an edgeedge with one O(6)Sm2U2 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and edges with four equivalent O(1)Sm3U tetrahedra. The corner-sharing octahedral tilt angles are 57°.
U4Sm4O17 is alpha bismuth trifluoride-derived structured and crystallizes in the orthorhombic Cmmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded in a body-centered cubic geometry to one O(5), two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms. The U(1)-O(5) bond length is 2.74 Å. Both U(1)-O(1) bond lengths are 2.19 Å. Both U(1)-O(2) bond lengths are 2.26 Å. Both U(1)-O(4) bond lengths are 2.26 Å. Both U(1)-O(6) bond lengths are 2.30 Å. In the second U site, U(2) is bonded in a 10-coordinate geometry to two equivalent O(3), two equivalent O(4), two equivalent O(5), and four equivalent O(2) atoms. Both U(2)-O(3) bond lengths are 2.18 Å. Both U(2)-O(4) bond lengths are 2.39 Å. Both U(2)-O(5) bond lengths are 2.64 Å. All U(2)-O(2) bond lengths are 2.39 Å. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Both Sm(1)-O(1) bond lengths are 2.40 Å. Both Sm(1)-O(2) bond lengths are 2.34 Å. All Sm(1)-O(3) bond lengths are 2.42 Å. In the second Sm site, Sm(2) is bonded in a body-centered cubic geometry to two equivalent O(3), two equivalent O(6), and four equivalent O(1) atoms. Both Sm(2)-O(3) bond lengths are 2.46 Å. Both Sm(2)-O(6) bond lengths are 2.41 Å. All Sm(2)-O(1) bond lengths are 2.41 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one U(1), one Sm(1), and two equivalent Sm(2) atoms to form OSm3U tetrahedra that share  a cornercorner with one O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(2)SmU3 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with six equivalent O(1)Sm3U tetrahedra,  an edgeedge with one O(1)Sm3U tetrahedra,  an edgeedge with one O(2)SmU3 tetrahedra, edges with two equivalent O(6)Sm2U2 tetrahedra, and edges with two equivalent O(3)Sm3U tetrahedra. The corner-sharing octahedral tilt angles are 54°. In the second O site, O(2) is bonded to one U(1), two equivalent U(2), and one Sm(1) atom to form OSmU3 tetrahedra that share corners with two equivalent O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(1)Sm3U tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with six equivalent O(2)SmU3 tetrahedra,  an edgeedge with one O(1)Sm3U tetrahedra,  an edgeedge with one O(2)SmU3 tetrahedra, edges with two equivalent O(3)Sm3U tetrahedra, edges with two equivalent O(4)U4 tetrahedra, and  a faceface with one O(5)U6 octahedra. The corner-sharing octahedral tilt angles are 54°. In the third O site, O(3) is bonded to one U(2), one Sm(2), and two equivalent Sm(1) atoms to form OSm3U tetrahedra that share corners with two equivalent O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with four equivalent O(2)SmU3 tetrahedra, edges with two equivalent O(1)Sm3U tetrahedra, edges with two equivalent O(3)Sm3U tetrahedra, and edges with two equivalent O(2)SmU3 tetrahedra. The corner-sharing octahedral tilt angles are 56°. In the fourth O site, O(4) is bonded to two equivalent U(1) and two equivalent U(2) atoms to form OU4 tetrahedra that share corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with four equivalent O(2)SmU3 tetrahedra,  an edgeedge with one O(6)Sm2U2 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, edges with four equivalent O(2)SmU3 tetrahedra, and faces with two equivalent O(5)U6 octahedra. In the fifth O site, O(5) is bonded to two equivalent U(1) and four equivalent U(2) atoms to form OU6 octahedra that share corners with four equivalent O(6)Sm2U2 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with eight equivalent O(3)Sm3U tetrahedra, corners with eight equivalent O(2)SmU3 tetrahedra, edges with two equivalent O(5)U6 octahedra, faces with four equivalent O(2)SmU3 tetrahedra, and faces with four equivalent O(4)U4 tetrahedra. In the sixth O site, O(6) is bonded to two equivalent U(1) and two equivalent Sm(2) atoms to form OSm2U2 tetrahedra that share corners with two equivalent O(5)U6 octahedra, corners with two equivalent O(6)Sm2U2 tetrahedra, corners with two equivalent O(4)U4 tetrahedra, corners with four equivalent O(1)Sm3U tetrahedra, corners with four equivalent O(3)Sm3U tetrahedra, corners with four equivalent O(2)SmU3 tetrahedra,  an edgeedge with one O(6)Sm2U2 tetrahedra,  an edgeedge with one O(4)U4 tetrahedra, and edges with four equivalent O(1)Sm3U tetrahedra. The corner-sharing octahedral tilt angles are 57°.