Ac3Lu is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ac sites. In the first Ac site, Ac(1) is bonded to four equivalent Ac(1), four equivalent Ac(2), and four equivalent Lu(1) atoms to form AcAc8Lu4 cuboctahedra that share corners with twelve equivalent Ac(1)Ac8Lu4 cuboctahedra, edges with eight equivalent Ac(1)Ac8Lu4 cuboctahedra, edges with eight equivalent Ac(2)Ac8Lu4 cuboctahedra, edges with eight equivalent Lu(1)Ac12 cuboctahedra, faces with four equivalent Ac(2)Ac8Lu4 cuboctahedra, faces with four equivalent Lu(1)Ac12 cuboctahedra, and faces with ten equivalent Ac(1)Ac8Lu4 cuboctahedra. In the second Ac site, Ac(2) is bonded to eight equivalent Ac(1) and four equivalent Lu(1) atoms to form AcAc8Lu4 cuboctahedra that share corners with four equivalent Ac(2)Ac8Lu4 cuboctahedra, corners with eight equivalent Lu(1)Ac12 cuboctahedra, edges with eight equivalent Ac(2)Ac8Lu4 cuboctahedra, edges with sixteen equivalent Ac(1)Ac8Lu4 cuboctahedra, faces with four equivalent Ac(2)Ac8Lu4 cuboctahedra, faces with six equivalent Lu(1)Ac12 cuboctahedra, and faces with eight equivalent Ac(1)Ac8Lu4 cuboctahedra. Lu(1) is bonded to four equivalent Ac(2) and eight equivalent Ac(1) atoms to form LuAc12 cuboctahedra that share corners with four equivalent Lu(1)Ac12 cuboctahedra, corners with eight equivalent Ac(2)Ac8Lu4 cuboctahedra, edges with eight equivalent Lu(1)Ac12 cuboctahedra, edges with sixteen equivalent Ac(1)Ac8Lu4 cuboctahedra, faces with four equivalent Lu(1)Ac12 cuboctahedra, faces with six equivalent Ac(2)Ac8Lu4 cuboctahedra, and faces with eight equivalent Ac(1)Ac8Lu4 cuboctahedra.
Ac3Lu is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ac sites. In the first Ac site, Ac(1) is bonded to four equivalent Ac(1), four equivalent Ac(2), and four equivalent Lu(1) atoms to form AcAc8Lu4 cuboctahedra that share corners with twelve equivalent Ac(1)Ac8Lu4 cuboctahedra, edges with eight equivalent Ac(1)Ac8Lu4 cuboctahedra, edges with eight equivalent Ac(2)Ac8Lu4 cuboctahedra, edges with eight equivalent Lu(1)Ac12 cuboctahedra, faces with four equivalent Ac(2)Ac8Lu4 cuboctahedra, faces with four equivalent Lu(1)Ac12 cuboctahedra, and faces with ten equivalent Ac(1)Ac8Lu4 cuboctahedra. All Ac(1)-Ac(1) bond lengths are 3.87 Å. All Ac(1)-Ac(2) bond lengths are 3.87 Å. All Ac(1)-Lu(1) bond lengths are 3.87 Å. In the second Ac site, Ac(2) is bonded to eight equivalent Ac(1) and four equivalent Lu(1) atoms to form AcAc8Lu4 cuboctahedra that share corners with four equivalent Ac(2)Ac8Lu4 cuboctahedra, corners with eight equivalent Lu(1)Ac12 cuboctahedra, edges with eight equivalent Ac(2)Ac8Lu4 cuboctahedra, edges with sixteen equivalent Ac(1)Ac8Lu4 cuboctahedra, faces with four equivalent Ac(2)Ac8Lu4 cuboctahedra, faces with six equivalent Lu(1)Ac12 cuboctahedra, and faces with eight equivalent Ac(1)Ac8Lu4 cuboctahedra. All Ac(2)-Lu(1) bond lengths are 3.87 Å. Lu(1) is bonded to four equivalent Ac(2) and eight equivalent Ac(1) atoms to form LuAc12 cuboctahedra that share corners with four equivalent Lu(1)Ac12 cuboctahedra, corners with eight equivalent Ac(2)Ac8Lu4 cuboctahedra, edges with eight equivalent Lu(1)Ac12 cuboctahedra, edges with sixteen equivalent Ac(1)Ac8Lu4 cuboctahedra, faces with four equivalent Lu(1)Ac12 cuboctahedra, faces with six equivalent Ac(2)Ac8Lu4 cuboctahedra, and faces with eight equivalent Ac(1)Ac8Lu4 cuboctahedra.