The effects of crystal size on the Raman spectra of nanophase TiO2

Raman scattering was applied as a probe for the evolution of the crystallin e size and distribution of nanosized TiO2, Small physical dimensions of TiO 2 crystals lead to a shift and broadening of the first-order Raman lines th rough a relaxation of the q = 0 selection rule and affects on to the positi on of a low-frequency Raman (LFR) band. The details of the evolution of the 144 cm(-1) Raman line shape (frequency, broadening and asymmetry) on the s ize and distributions of the nanocrystals are presented. The methodologies for the size determination of nanocrystals using the LFR mode together with a deconvolution treatment to obtain the size distribution were analyzed. B oth the Raman results were compared with the grain size distribution obtain ed by high-resolution electron microscopy. (C) 1999 Elsevier Science B.V. A ll rights reserved.