EPR and optical study of erbium-doped CeO2 and CeO2 / CeF3 nanoparticles

Abstract

Here, the facile dry synthesis of composite CeO2/CeF3 nanoparticles doped with Er3+ probe ions using ammonium bifluoride (NH4HF2) is reported. This method allows synthesizing composite nanoparticles with different ratio of СеО2 and CeF3. The structural properties of the composite nanoparticles were studied using XRD, SEM, and TEM techniques, which confirmed the formation of composite CeO2/CeF3 nanoparticles. The luminescence spectra show that the intensity of the Ce3+ peak increases after fluorination procedure, revealing the fact that the amount of Ce3+ is increased. In particular, the total 4f-4f luminescence intensity of CeO2/CeF3:Er3+(0.1 at.%) nanoparticles is 3.5 time higher compared to CeO2:Er3+(0.1 at.%) ones under both UV or resonant pumping. Probably it can be associated with the increased concentration of trivalent rare-earth ions in a cubic-distorted environment. The same tendency is observed for the excitation spectra. EPR measurements showed that fluorination of CeO2 nanoparticles doped with different concentration of Er3+ ions leads to the formation of trigonal sites in ceria nanoparticles.