Low Temperature Growth of One-Dimensional Al and Al2O3 Nano/Micro-Structures Using Al and SnO2 Powder Mixture

Abstract

One-dimensional Al and Al2O3 nano/microstructures were fabricated via thermal oxidation of Al and SnO2 powder mixtures at temperatures below the melting point of Al (660 oC). Furthermore, the synthesis process was carried out in air at atmospheric pressure, which made the process very simple and easy. Sn metal particles with spherical shape were observed on the tips of the Al and Al2O3 nano/microstructures, suggesting that the nano/microstructures were grown via a catalyst-assisted growth mechanism. The Sn acted as a catalyst for growing the Al and Al2O3 nano/microstructures. The Sn with low melting point (232 oC) was produced via the reduction of SnO2 by Al, and formed catalyst droplets at the growth temperatures. Al atoms diffused and dissolved into the Sn liquid droplets, leading to the nucleation and then the growth of the Al and Al2O3 nano/microstructures. At 400 oC, the diffusion of Al atoms into the Sn liquid droplets was associated with high stress generated at the Al2O3/Al interface. At 600 oC close to the melting point of Al, Al atoms were diffused from the thin Al liquid layer, which was formed on the surface of the Al powder, to the Sn liquid droplets. Simultaneously, the Al atoms reacted with oxygen in air and formed solid Al2O3 nuclei. A relatively strong ultraviolet emission band centered at 330 nm was observed in the sample prepared at 600 oC.