Solution chemistry synthesis, morphology studies, and optical properties of five distinct nanocrystalline Au-Zn intermetallic compounds

Au-Zn was used as a prototype binary system for exploring intermetallic phase accessibility in nanoparticle systems using low-temperature solution chemistry methods. By reacting Au nanoparticles with diethylzinc (Et₂Zn) in oleylamine at temperatures of 250-300 °C, nanoparticles of five distinct binary intermetallic compounds were accessible: Au₃Zn, Au₅Zn₃, AuZn, Cu₅Zn₈-type γ-(Au,Zn), and Mg-type ε-(Au,Zn). A variety of nanoparticle shapes, including spheres, triangles, hexagons, and rods, are accessible in the Au-Zn system via a pseudomorphic reaction of Au nanocrystal shapes with Et₂Zn. The Au-Zn nanoparticles have optical properties that vary with Zn content, ranging from a surface plasmon resonance peak at ∼495 nm for Au₃Zn to absorption in the ultraviolet region for the Zn-rich phases.