Tb3Sm is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to four equivalent Tb(1), four equivalent Tb(2), and four equivalent Sm(1) atoms to form TbTb8Sm4 cuboctahedra that share corners with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with eight equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with eight equivalent Tb(2)Tb8Sm4 cuboctahedra, edges with eight equivalent Sm(1)Tb12 cuboctahedra, faces with four equivalent Tb(2)Tb8Sm4 cuboctahedra, faces with four equivalent Sm(1)Tb12 cuboctahedra, and faces with ten equivalent Tb(1)Tb8Sm4 cuboctahedra. In the second Tb site, Tb(2) is bonded to eight equivalent Tb(1) and four equivalent Sm(1) atoms to form TbTb8Sm4 cuboctahedra that share corners with four equivalent Tb(2)Tb8Sm4 cuboctahedra, corners with eight equivalent Sm(1)Tb12 cuboctahedra, edges with eight equivalent Tb(2)Tb8Sm4 cuboctahedra, edges with sixteen equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with four equivalent Tb(2)Tb8Sm4 cuboctahedra, faces with six equivalent Sm(1)Tb12 cuboctahedra, and faces with eight equivalent Tb(1)Tb8Sm4 cuboctahedra. Sm(1) is bonded to four equivalent Tb(2) and eight equivalent Tb(1) atoms to form SmTb12 cuboctahedra that share corners with four equivalent Sm(1)Tb12 cuboctahedra, corners with eight equivalent Tb(2)Tb8Sm4 cuboctahedra, edges with eight equivalent Sm(1)Tb12 cuboctahedra, edges with sixteen equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with four equivalent Sm(1)Tb12 cuboctahedra, faces with six equivalent Tb(2)Tb8Sm4 cuboctahedra, and faces with eight equivalent Tb(1)Tb8Sm4 cuboctahedra.
Tb3Sm is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to four equivalent Tb(1), four equivalent Tb(2), and four equivalent Sm(1) atoms to form TbTb8Sm4 cuboctahedra that share corners with twelve equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with eight equivalent Tb(1)Tb8Sm4 cuboctahedra, edges with eight equivalent Tb(2)Tb8Sm4 cuboctahedra, edges with eight equivalent Sm(1)Tb12 cuboctahedra, faces with four equivalent Tb(2)Tb8Sm4 cuboctahedra, faces with four equivalent Sm(1)Tb12 cuboctahedra, and faces with ten equivalent Tb(1)Tb8Sm4 cuboctahedra. All Tb(1)-Tb(1) bond lengths are 3.58 Å. All Tb(1)-Tb(2) bond lengths are 3.58 Å. All Tb(1)-Sm(1) bond lengths are 3.58 Å. In the second Tb site, Tb(2) is bonded to eight equivalent Tb(1) and four equivalent Sm(1) atoms to form TbTb8Sm4 cuboctahedra that share corners with four equivalent Tb(2)Tb8Sm4 cuboctahedra, corners with eight equivalent Sm(1)Tb12 cuboctahedra, edges with eight equivalent Tb(2)Tb8Sm4 cuboctahedra, edges with sixteen equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with four equivalent Tb(2)Tb8Sm4 cuboctahedra, faces with six equivalent Sm(1)Tb12 cuboctahedra, and faces with eight equivalent Tb(1)Tb8Sm4 cuboctahedra. All Tb(2)-Sm(1) bond lengths are 3.58 Å. Sm(1) is bonded to four equivalent Tb(2) and eight equivalent Tb(1) atoms to form SmTb12 cuboctahedra that share corners with four equivalent Sm(1)Tb12 cuboctahedra, corners with eight equivalent Tb(2)Tb8Sm4 cuboctahedra, edges with eight equivalent Sm(1)Tb12 cuboctahedra, edges with sixteen equivalent Tb(1)Tb8Sm4 cuboctahedra, faces with four equivalent Sm(1)Tb12 cuboctahedra, faces with six equivalent Tb(2)Tb8Sm4 cuboctahedra, and faces with eight equivalent Tb(1)Tb8Sm4 cuboctahedra.