RESUMO
Over a period of last thirty years, use of ethanol has been historically reported for obtaining nanopowders with low agglomeration for various oxide systems. In addition to these benefits, we show for the first time that treatments in ethanol medium coupled with an ultrasonication step can impart crucial additional advantages in controlling the phase purity and stoichiometry/composition for such systems. This is an important issue especially for any complex multicationic oxide nanoparticles system and hence we selected one of the most popular catalyst systems of doped-ceria (CeO2) nanoparticles with very high (50%) level of rare-earth (lanthanum) doping for this case study. The effect of an ultrasonication combined ethanol treatment was compared with the other solvent media (pure water and ethanol) without ultrasonication. The underlying mechanism for this process involves lowering the deprotonation rate in ethanol medium which eventually reduces the condensation of the individual metal oxides while the ultrasonication ensures the reproducibility of the synthesis by providing a homogeneous colloidal solution for each washing stages. This novel modification in synthesis of nanoparticles aims to provide meaningful solutions in optimising the phase, composition and morphology of multicationic complex system of nanocrystals.
