Comparison of structural and optical properties of CeO2 and CeO2:Eu3+ nanoparticles synthesized via sol-gel and flame spray pyrolysis methods

Over the last decades, a considerable attention has been drawn on the cerium dioxide (ceria, CeO2) due to promising changes in physical and chemical properties in nanoscale. The researches on CeO2 and its structural and morphological modifications have brought about remarkable applications as optical devices, sensors, medical equipments and luminescent materials. For instance, rare earth (RE) ion-doped cerium oxides have exhibited enhanced peculiar optical, catalytic and magnetic properties with respect to the dopant-free CeO2 nanoparticles. Herein we aimed to compare characteristics of undoped (CeO2) and europium (Eu3+) doped ceria (CeO2:Eu3+) nanoparticles synthesized by sol-gel (SG) and one-step flame spray pyrolysis (FSP) methods. In this work, fabricated nanoparticles were evaluated in terms of the structural, morphological, chemical and optical properties by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron (XPS) and photoluminescence spectroscopy (PL), respectively. Nanoparticles in the intended crystalline CeO2 structure were obtained for both methods. Spherical particles in nanoscale (particle size < 100 nm) and sharp edged blocky particles in sub-micron size (particles size range 200-1000 nm) were produced through FSP and SG, respectively. Nevertheless, no significant difference due to the difference in particle size was observed in optical properties. On the other hand, Eu3+ doped particles of both methods exhibited longer decay time than the undoped particles.