Investigation on the stability of dispersion of zirconia nanoparticles prepared by microwave- hydrothermal synthesis

Difficulties in reproducing the performances of nanoparticles dispersions are obstructive for the progress of the nanotechnology. A plausible reason for this variability is the lack of the control of the stability as well as the dimensions of the nanoparticles in the dispersions. In this work we report results of investigations on the stability of zirconia nanoparticles in aqueous medium, monitoring nanoparticles sizes by means of Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS). Nanocrystalline zirconia powders, prepared by microwave-hydrothermal synthesis, were determined to be 6-8 nm in size by TEM observations. By using DLS technique the as-prepared dispersions without any further manipulation, i.e. washing, filtering, and so on, resulted in polidispersed aggregates, constituted by the primary zirconia nanoparticles with an average diameter of 1.3 ± 0.1 mm. After eliminating sodium chloride from the synthesis solution, the nanoparticles rearrangement in a more stable suspension was found.