A series of CeO2 nanoparticles was synthesized by precipitation in reverse microemulsions in the presence of mixed aqueous-alcoholic solutions at variable and constant medium pH. It is shown that these methods promote the formation of non-agglomerated CeO2 particles with a size less than 15 nm.
TEM and XPS methods showed that the ratio of Ce3+ /Ce4+ ions increases on the surface when the size of CeO2 nanoparticles is decreased. The synthesized CeO2 nanoparticles show high stability in aqueous suspensions without using additional stabilizers (zeta > +35 mV), which is important for medical and biological application.