Luminescence and optical properties of cerium oxide nanoparticles

Cerium oxide (CeO2) nanoparticles present an interesting material for various applications in biotechnology and medicine. The mechanism of CeO2 nanoparticles activity is supposed to be related to the presence both Ce3+ and Ce4+ ions on the surface of the nanocrystal. Due to the Ce3+ ions, the charge deficiency of a crystal is compensated by oxygen vacancies in the lattice. The present work is devoted to study the cerium oxide defects by optical and luminescence spectroscopy methods. The CeO2 nanoparticles was produced by the method of pulsed electron evaporation of ceramic oxide targets with condensation of the vapors in a vacuum. The strong non-equilibrium conditions of this method could lead to higher oxygen non-stoichiometry of cerium oxide. The results of work show the cerium nanocrystal manifests an emission provided by intracenter transitions in the Ce3+ ions, F-0-centers and Ce4+-O2- complexes with charge transfer. The band gap E-g of the CeO2 nanoparticles for direct and indirect transitions was estimated. The cerium oxide was found to demonstrate catalase-mimic activity, as well as differential cytotoxicity in relation to tumor and healthy cell cultures.