Preparation of Nano-TiO_2 by Sol-Gel Method and Its Phase Transformation

TiO2 nanoparticle was prepared by sol-gel method using Ti(OBu)4 as precursor.Phase transformation of TiO2 from anatase to rutile was studied by UV Raman spectroscopy,visible Raman spectroscopy,X-ray diffraction(XRD).The results from visible Raman spectroscopy are in good agreement with those of XRD patterns.It was observed that anatase in the bulk region starts to change into rutile at 600 ℃.However,from UV Raman spectra,the anatase in the surface region transformed into the rutile phase until the calcination temperature was up to 765 ℃.The inconsistency in the results from the above three techniques suggests that the anatase phase of TiO2 at surface region can remain at relatively higher calcination temperatures than that in bulk during the phase transformation.It was suggested that the rutile phase starts to form at the interfaces between the anatase particles of the agglomerated TiO2 particles.