Synthesis of monodisperse α-Al2O3 nanoparticles by a salt microemulsion method

Abstract

Alpha alumina nanocrystals that are highly dispersible and have a high specific surface area play an important role in the field of catalytic supports and others. As the phase-transformation temperature of α-Al2O3 is 1000°C, it is extremely difficult to fabricate monodisperse nanoparticles. Here, the study reports a new method, referred as the salt microemulsion method, for the fabrication of monodisperse α-Al2O3 nanoparticles, and the particle size could be tuned between 3 and 8 nm. The particles precipitated by demulsifying the microemulsion were analysed by transmission electron microscopy. The precipitated particles are found to be inclusions, with the Al2O3 precursor nanoparticles are dispersed and isolated by the K2SO4 nanoparticles. As the melting point of K2SO4 is 1065°C, the Al2O3 precursor nanoparticles are separated by the solid K2SO4 over the entire high-temperature phase-transition process. As a result, agglomeration and sintering of the α-Al2O3 nanoparticles are prevented, leading to monodisperse α-Al2O3 nanoparticles.