Variable-temperature Raman scattering study on anatase titanium dioxide nanocrystals

The temperature dependence of the Raman modes in anatase TiO2 nanocrystals has been investigated over the temperature range 77-873 K. With increasing temperature, the frequency of the E-g mode at 639 cm(-1) shifts sublinearly to the lower frequencies, however, the frequency of the lowest-frequency E, mode shifts sublinearly to the higher frequencies from 138 cm(-1) at 77 K to 152 cm(-1) at 873 K and the frequency of the Big mode at 397cm(-1) increases firstly and attains a maximum near 350K. The linewidth of all of the three modes increases linearly with increasing temperature. The anharmonic effects contribute a lot to the temperature dependence behavior of the frequency and linewidth of Raman modes in anatase TiO2 nanocrystals. (c) 2006 Elsevier Ltd. All rights reserved.