Tb3Sm is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Tb(1) is bonded to eight equivalent Tb(1) and four equivalent Sm(1) atoms to form TbTb8Sm4 cuboctahedra that share corners with four equivalent Sm(1)Tb12 cuboctahedra, corners with fourteen equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with six equivalent Sm(1)Tb12 cuboctahedra, edges with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with four equivalent Sm(1)Tb12 cuboctahedra, and faces with sixteen equivalent Tb(1)Tb8Sm4 cuboctahedra. Sm(1) is bonded to twelve equivalent Tb(1) atoms to form SmTb12 cuboctahedra that share corners with six equivalent Sm(1)Tb12 cuboctahedra, corners with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with eighteen equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with eight equivalent Sm(1)Tb12 cuboctahedra, and faces with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra.
Tb3Sm is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Tb(1) is bonded to eight equivalent Tb(1) and four equivalent Sm(1) atoms to form TbTb8Sm4 cuboctahedra that share corners with four equivalent Sm(1)Tb12 cuboctahedra, corners with fourteen equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with six equivalent Sm(1)Tb12 cuboctahedra, edges with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with four equivalent Sm(1)Tb12 cuboctahedra, and faces with sixteen equivalent Tb(1)Tb8Sm4 cuboctahedra. There are a spread of Tb(1)-Tb(1) bond distances ranging from 3.59-3.67 Å. There are two shorter (3.61 Å) and two longer (3.65 Å) Tb(1)-Sm(1) bond lengths. Sm(1) is bonded to twelve equivalent Tb(1) atoms to form SmTb12 cuboctahedra that share corners with six equivalent Sm(1)Tb12 cuboctahedra, corners with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with eighteen equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with eight equivalent Sm(1)Tb12 cuboctahedra, and faces with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra.