Cu3Al is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to eight Cu(1,1) and four equivalent Al(1) atoms to form CuAl4Cu8 cuboctahedra that share corners with four equivalent Al(1)Cu12 cuboctahedra; corners with fourteen equivalent Cu(1)Al4Cu8 cuboctahedra; edges with six equivalent Al(1)Cu12 cuboctahedra; edges with twelve Cu(1,1)Al4Cu8 cuboctahedra; faces with four equivalent Al(1)Cu12 cuboctahedra; and faces with sixteen Cu(1,1)Al4Cu8 cuboctahedra. In the second Cu site, Cu(1) is bonded to eight equivalent Cu(1) and four equivalent Al(1) atoms to form CuAl4Cu8 cuboctahedra that share corners with four equivalent Al(1)Cu12 cuboctahedra; corners with fourteen Cu(1,1)Al4Cu8 cuboctahedra; edges with six equivalent Al(1)Cu12 cuboctahedra; edges with twelve equivalent Cu(1)Al4Cu8 cuboctahedra; faces with four equivalent Al(1)Cu12 cuboctahedra; and faces with sixteen Cu(1,1)Al4Cu8 cuboctahedra. Al(1) is bonded to twelve Cu(1,1) atoms to form AlCu12 cuboctahedra that share corners with six equivalent Al(1)Cu12 cuboctahedra; corners with twelve Cu(1,1)Al4Cu8 cuboctahedra; edges with eighteen Cu(1,1)Al4Cu8 cuboctahedra; faces with eight equivalent Al(1)Cu12 cuboctahedra; and faces with twelve Cu(1,1)Al4Cu8 cuboctahedra.
Cu3Al is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to eight Cu(1,1) and four equivalent Al(1) atoms to form CuAl4Cu8 cuboctahedra that share corners with four equivalent Al(1)Cu12 cuboctahedra; corners with fourteen equivalent Cu(1)Al4Cu8 cuboctahedra; edges with six equivalent Al(1)Cu12 cuboctahedra; edges with twelve Cu(1,1)Al4Cu8 cuboctahedra; faces with four equivalent Al(1)Cu12 cuboctahedra; and faces with sixteen Cu(1,1)Al4Cu8 cuboctahedra. There are a spread of Cu(1)-Cu(1,1) bond distances ranging from 2.55-2.59 Å. There are two shorter (2.57 Å) and two longer (2.58 Å) Cu(1)-Al(1) bond lengths. In the second Cu site, Cu(1) is bonded to eight equivalent Cu(1) and four equivalent Al(1) atoms to form CuAl4Cu8 cuboctahedra that share corners with four equivalent Al(1)Cu12 cuboctahedra; corners with fourteen Cu(1,1)Al4Cu8 cuboctahedra; edges with six equivalent Al(1)Cu12 cuboctahedra; edges with twelve equivalent Cu(1)Al4Cu8 cuboctahedra; faces with four equivalent Al(1)Cu12 cuboctahedra; and faces with sixteen Cu(1,1)Al4Cu8 cuboctahedra. There are two shorter (2.57 Å) and two longer (2.58 Å) Cu(1)-Al(1) bond lengths. Al(1) is bonded to twelve Cu(1,1) atoms to form AlCu12 cuboctahedra that share corners with six equivalent Al(1)Cu12 cuboctahedra; corners with twelve Cu(1,1)Al4Cu8 cuboctahedra; edges with eighteen Cu(1,1)Al4Cu8 cuboctahedra; faces with eight equivalent Al(1)Cu12 cuboctahedra; and faces with twelve Cu(1,1)Al4Cu8 cuboctahedra.