Au supracrystal growth processes: Unexpected morphologies

Abstract

In this account we describe the various morphologies of crystalline structures called supracrystals of 5 nm Au nano-crystals used as building blocks. The Au nanocrystals are coated with dodecanthiol, except when it is mentioned in the text. It is shown that traces of water molecules markedly change the average distance between nanocrystals. Similarly, the way to solvent evaporation, solvent vapor pressure and excess of coating agents induces a transition from films to shaped supra-crystals. Furthermore, segregation between single domain and polycrystalline 5 nm Au nanocrystals takes place during the supracrystal formation. By mixing single domain Au and Co nanocrystals, vicinal surfaces are produced. A mechanism of such spontaneous formation of high index planes in Au single domain nanocrystal superlattices is proposed.