Sm3Pm is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to four equivalent Sm(1), four equivalent Sm(2), and four equivalent Pm(1) atoms to form SmPm4Sm8 cuboctahedra that share corners with twelve equivalent Sm(1)Pm4Sm8 cuboctahedra, edges with eight equivalent Sm(1)Pm4Sm8 cuboctahedra, edges with eight equivalent Sm(2)Pm4Sm8 cuboctahedra, edges with eight equivalent Pm(1)Sm12 cuboctahedra, faces with four equivalent Sm(2)Pm4Sm8 cuboctahedra, faces with four equivalent Pm(1)Sm12 cuboctahedra, and faces with ten equivalent Sm(1)Pm4Sm8 cuboctahedra. In the second Sm site, Sm(2) is bonded to eight equivalent Sm(1) and four equivalent Pm(1) atoms to form SmPm4Sm8 cuboctahedra that share corners with four equivalent Sm(2)Pm4Sm8 cuboctahedra, corners with eight equivalent Pm(1)Sm12 cuboctahedra, edges with eight equivalent Sm(2)Pm4Sm8 cuboctahedra, edges with sixteen equivalent Sm(1)Pm4Sm8 cuboctahedra, faces with four equivalent Sm(2)Pm4Sm8 cuboctahedra, faces with six equivalent Pm(1)Sm12 cuboctahedra, and faces with eight equivalent Sm(1)Pm4Sm8 cuboctahedra. Pm(1) is bonded to four equivalent Sm(2) and eight equivalent Sm(1) atoms to form PmSm12 cuboctahedra that share corners with four equivalent Pm(1)Sm12 cuboctahedra, corners with eight equivalent Sm(2)Pm4Sm8 cuboctahedra, edges with eight equivalent Pm(1)Sm12 cuboctahedra, edges with sixteen equivalent Sm(1)Pm4Sm8 cuboctahedra, faces with four equivalent Pm(1)Sm12 cuboctahedra, faces with six equivalent Sm(2)Pm4Sm8 cuboctahedra, and faces with eight equivalent Sm(1)Pm4Sm8 cuboctahedra.
Sm3Pm is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to four equivalent Sm(1), four equivalent Sm(2), and four equivalent Pm(1) atoms to form SmPm4Sm8 cuboctahedra that share corners with twelve equivalent Sm(1)Pm4Sm8 cuboctahedra, edges with eight equivalent Sm(1)Pm4Sm8 cuboctahedra, edges with eight equivalent Sm(2)Pm4Sm8 cuboctahedra, edges with eight equivalent Pm(1)Sm12 cuboctahedra, faces with four equivalent Sm(2)Pm4Sm8 cuboctahedra, faces with four equivalent Pm(1)Sm12 cuboctahedra, and faces with ten equivalent Sm(1)Pm4Sm8 cuboctahedra. All Sm(1)-Sm(1) bond lengths are 3.64 Å. All Sm(1)-Sm(2) bond lengths are 3.64 Å. All Sm(1)-Pm(1) bond lengths are 3.64 Å. In the second Sm site, Sm(2) is bonded to eight equivalent Sm(1) and four equivalent Pm(1) atoms to form SmPm4Sm8 cuboctahedra that share corners with four equivalent Sm(2)Pm4Sm8 cuboctahedra, corners with eight equivalent Pm(1)Sm12 cuboctahedra, edges with eight equivalent Sm(2)Pm4Sm8 cuboctahedra, edges with sixteen equivalent Sm(1)Pm4Sm8 cuboctahedra, faces with four equivalent Sm(2)Pm4Sm8 cuboctahedra, faces with six equivalent Pm(1)Sm12 cuboctahedra, and faces with eight equivalent Sm(1)Pm4Sm8 cuboctahedra. All Sm(2)-Pm(1) bond lengths are 3.64 Å. Pm(1) is bonded to four equivalent Sm(2) and eight equivalent Sm(1) atoms to form PmSm12 cuboctahedra that share corners with four equivalent Pm(1)Sm12 cuboctahedra, corners with eight equivalent Sm(2)Pm4Sm8 cuboctahedra, edges with eight equivalent Pm(1)Sm12 cuboctahedra, edges with sixteen equivalent Sm(1)Pm4Sm8 cuboctahedra, faces with four equivalent Pm(1)Sm12 cuboctahedra, faces with six equivalent Sm(2)Pm4Sm8 cuboctahedra, and faces with eight equivalent Sm(1)Pm4Sm8 cuboctahedra.