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Phonon confinement studies in nanocrystalline anatase‐TiO 2 thin films by micro Raman spectroscopy
Author(s) -
Balaji S.,
Djaoued Y.,
Robichaud J.
Publication year - 2006
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1566
Subject(s) - raman spectroscopy , anatase , nanocrystalline material , phonon , full width at half maximum , crystallite , materials science , thin film , analytical chemistry (journal) , nanotechnology , condensed matter physics , optics , chemistry , physics , optoelectronics , photocatalysis , organic chemistry , metallurgy , catalysis
Raman studies were performed on titania thin films prepared by polyethylene glycol (PEG) assisted, low‐temperature, sol–gel method. The Raman spectra of the films show a systematic blue shift in the peak position and a broadening in the full width at half‐maximum (FWHM) when compared with those of the bulk anatase TiO 2 powder. Several reports have appeared indicating this kind of peak shift and broadening of FWHM, which were attributed to the confinement of phonons in the anatase nanocrystallites. In this paper, we report an analysis of quantum size effect in the Raman spectra of nanocrystalline TiO 2 thin films performed by utilizing the phonon dispersion relation of the anatase phase which has been obtained from a work based on density functional perturbation theory (DFPT). For comparison purposes the quantum size effect calculations have also been done utilizing the dispersion relations of the rutile phase. There is good agreement between the crystallite sizes evaluated from the equally weighted Raman line intensity of the dispersion relations obtained from the DFPT and those determined by X‐ray diffraction. Copyright © 2006 John Wiley & Sons, Ltd.