Anharmonicity Effects in Nanocrystals Studied by Raman Scattering Spectroscopy |
| Z. Dohčević-Mitrović, Z.V. Popović and M. Šćepanović
Center for Solid State Physics and New Materials, Institute of Physics, Belgrade, Serbia |
| Full Text PDF |
| Phonon-phonon interactions were investigated in various nanocrystalline powders like anatase TiO2-δ, pure CeO2-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 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 TiO2 evident blueshift of the most prominent Eg Raman mode probably originates from dominant four phonon anharmonic interactions. |
| DOI: 10.12693/APhysPolA.116.36 PACS numbers: 63.22.-m, 78.67.Bf, 78.30.-j, 61.72.uj |