Abstract
Raman spectra of the nanophase titanium dioxide were examined at various annealing temperatures. The temperature dependences of the Raman modes at 702, 612, 422, 230-250, and 152 cm-1 are discussed. The 702 cm-1 A2g mode belongs to first-order phonon connected to a critical nature of the selection rules with respect to the grain size. Lower anatase-rutile transition temperature 700° C is closely related to smaller grain size. The Eg mode at 422 cm-1 at room temperature shifts upward 24 cm-1 after successive annealing in air for one hour at 700° C, indicating the dependence of the lower mode frequency upon the larger oxygen deficiency.