Sergey Mamedov1
HORIBA Scientific1
Metal oxide nanoparticles are attractive for many applications but have recently become an essential part of highly efficient catalysis materials. The material's efficiency depends on size, shape, and surface chemistry, which critically determine their properties and interaction.<br/>Raman spectroscopy is a powerful method to investigate nanoparticles' vibrational properties, as the Raman band's peak and width are very sensitive to the local structure. Besides, phonons' behavior at the nanoparticle boundary strongly depends on the particle size and is a critical factor in creating a highly efficient material. It was shown that the Raman peak of TiO<sub>2</sub> at 142.9 cm<sup>-1</sup> shifted with a decrease in the nanoparticles' size due to the quantum confinement. However, nanopowders of WO<sub>3</sub> and Y<sub>2</sub>O<sub>3</sub> were not investigated yet. The samples of TiO<sub>2</sub>, WO<sub>3</sub>, and Y<sub>2</sub>O<sub>3</sub> with a mean size ranging from 5 to 40 nm were investigated by Raman spectroscopy in the broad spectral range. The model of phonon confinement was used to describe the experimental data. The correlation length of the phonons calculated from the spectra of nanoparticles shows a good correlation between grain sizes obtained from Raman spectra and XRD. Raman spectra are more sensitive to nanoparticles' structural motive compared to XRD. The Raman spectra may differ even if X-ray diffraction shows the same particle size. It reflects the differences in the surface structure of nanoparticles.