Doping-Induced Combined Fano and Phonon Confinement Effect in La-Doped CeO2: Raman Spectroscopy Analysis

Abstract

The effect of La-doping on the crystallographic structure and the Raman line-shape of CeO2 has been investigated. X-ray diffraction analysis suggests that the lattice parameter and the Ce/La-O bond length gradually increase with La-doping. The Williamson-Hall plot method has been used to investigate structural coherency and lattice strain. Scanning electron microscopy and energy-dispersive X-ray spectroscopy have been carried out to study the particle size distribution and weight percentage doping of La in CeO2, respectively. Intrinsic and extrinsic oxygen vacancies have been understood in terms of ionic radii mismatch and the mixed oxidation state of the host and dopant. Furthermore, Raman spectroscopy results indicate the appearance of red-shift, peak broadening, and asymmetry with an antiresonance dip in the Raman line-shape (F2g). The observed changes in the Raman line-shape have been explained, considering electron-phonon-coupling-induced Fano scattering and phonon confinement effects. © 2021 American Chemical Society.