DOE OSTI2020
Cu3Al is beta Cu3Ti structured and crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. there are two inequivalent Cu sites. In the first Cu site, Cu is bonded to eight equivalent Cu and four equivalent Al atoms to form CuAl4Cu8 cuboctahedra that share corners with eight equivalent AlCu12 cuboctahedra, corners with ten CuAl4Cu8 cuboctahedra, edges with eighteen CuAl4Cu8 cuboctahedra, faces with six equivalent AlCu12 cuboctahedra, and faces with fourteen CuAl4Cu8 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.59–2.61 Å. There are two shorter (2.59 Å) and two longer (2.60 Å) Cu–Al bond lengths. In the second Cu site, Cu is bonded to eight Cu and four equivalent Al atoms to form CuAl4Cu8 cuboctahedra that share corners with four equivalent AlCu12 cuboctahedra, corners with fourteen CuAl4Cu8 cuboctahedra, edges with six equivalent AlCu12 cuboctahedra, edges with twelve CuAl4Cu8 cuboctahedra, faces with four equivalent AlCu12 cuboctahedra, and faces with sixteen CuAl4Cu8 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.58–2.60 Å. There are a spread of Cu–Al bond distances ranging from 2.59–2.61 Å. Al is bonded to twelve Cu atoms to form AlCu12 cuboctahedra that share corners with two equivalent AlCu12 cuboctahedra, corners with sixteen CuAl4Cu8 cuboctahedra, edges with six equivalent AlCu12 cuboctahedra, edges with twelve equivalent CuAl4Cu8 cuboctahedra, faces with six equivalent AlCu12 cuboctahedra, and faces with fourteen CuAl4Cu8 cuboctahedra.