A systematic study of the shift and linewidth of the E-g Raman peak at 144 cm(-1) of anatase TiO2 nanopowders, produced by a flame aerosol technique, is here presented. The analysis was performed as a function of the crystal domain size and of the degree of oxidation. In the nanopowders, a clear contribution of the stoichiometry defects to the peak shift was evidenced, while the peak width seems to be less affected by the oxygen content. The Raman peak behavior due to size reduction has been interpreted in the framework of a phonon quantum confinement model. A critical review of the different approaches to this model, adopted in the literature to explain the behavior of the anatase Raman spectra as a function of the domain size, is presented. In particular, the hypothesis of a three-dimensional isotropic model for the dispersion relations is discussed. This analysis evidences general limits in the application of the phonon confinement model to the study and characterization of nanoparticles and nanostructured materials, showing how an uncritical use of the confinement theory can yield distorted results.

Raman spectroscopy characterization of titania nanoparticles produced by flame pyrolysis : the influence of size and stoichiometry / A. Li Bassi, D. Cattaneo, V. Russo, C. E. Bottani, E. Barborini, T. Mazza, P. Piseri, P. Milani, F.O. Ernst, K. Wegner, S. E. Pratsinis. - In: JOURNAL OF APPLIED PHYSICS. - ISSN 0021-8979. - 98:7(2005), pp. 074305.074305.1-074305.074305.9.

Raman spectroscopy characterization of titania nanoparticles produced by flame pyrolysis : the influence of size and stoichiometry

T. Mazza;P. Piseri;P. Milani;
2005

Abstract

A systematic study of the shift and linewidth of the E-g Raman peak at 144 cm(-1) of anatase TiO2 nanopowders, produced by a flame aerosol technique, is here presented. The analysis was performed as a function of the crystal domain size and of the degree of oxidation. In the nanopowders, a clear contribution of the stoichiometry defects to the peak shift was evidenced, while the peak width seems to be less affected by the oxygen content. The Raman peak behavior due to size reduction has been interpreted in the framework of a phonon quantum confinement model. A critical review of the different approaches to this model, adopted in the literature to explain the behavior of the anatase Raman spectra as a function of the domain size, is presented. In particular, the hypothesis of a three-dimensional isotropic model for the dispersion relations is discussed. This analysis evidences general limits in the application of the phonon confinement model to the study and characterization of nanoparticles and nanostructured materials, showing how an uncritical use of the confinement theory can yield distorted results.
crystal defects; flames; nanoparticles ; oxidation ; phonon dispersion relations ; pyrolysis ; Raman spectra ; spectral line breadth ; spectral line shift ; stoichiometry ; titanium compounds
Settore FIS/03 - Fisica della Materia
2005
Article (author)
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/66997
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 280
  • ???jsp.display-item.citation.isi??? 277
social impact