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 Eg mode at 639 cm−1 shifts sublinearly to the lower frequencies, however, the frequency of the lowest-frequency Eg 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 B1g mode at 397 cm−1 increases firstly and attains a maximum near 350 K. 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.