Anharmonicity Effects in Nanocrystals Studied by Raman Scattering Spectroscopy

Z. Dohčević-Mitrović, Z.V. Popović, M. Šćepanović
2009 Acta Physica Polonica. A  
Phonon-phonon interactions were investigated in various nanocrystalline powders like anatase TiO 2−δ , pure CeO 2−δ and ceria doped with Nd(Gd) analyzing temperature dependent Raman spectra of these systems. Phonon confinement model based on size, inhomogeneous strain and anharmonic effects was used to properly describe the evident changes present in the Raman spectra of pure and doped ceria nanocrystalline samples. In small particles of pure and doped ceria nanocrystals, when size effects have
more » ... n size effects have minor impact on Raman modes, four phonon anharmonic processes prevail under the three-phonon ones. When nanopowdered particles are grown enough size effects provoke changes of the anharmonic interactions when three-phonon coupling prevails over the four-phonon anharmonic processes. In nanocrystalline anatase TiO 2 evident blueshift of the most prominent E g Raman mode probably originates from dominant four-phonon anharmonic interactions.
doi:10.12693/aphyspola.116.36 fatcat:a3jvect2d5gjxfulcn2ujfldcq