Effect of pH on nucleation and agglomeration/morphology of nanocrystalline TiO{sub}2

摘要

Nanocrystalline titanium dioxide powder was prepared by sol-gel process. The pH effects on their nucleation and structural properties were investigated. The variation of pH from 1 to 10 was systematically examined. The prepared nanocrystalline materials were characterized by x-ray diffraction (XRD), SDT (simultaneous DSC and TGA), UV-Vis spectrometer, zeta size measurement, transmission electron microscopy (TEM) and field emission gun scanning electron microscopy (FEGSEM). The influence of pH values on the particles agglomeration, size and on the surface structure has been investigated. The crystallite size of titanium oxide thin films was also investigated by x-ray diffraction (XRD). From X-ray diffractometric measurements, it has been confirmed that the synthesized nanomaterial have an rutile structure at pH 1 and 2 but the ratio of rutile to anatase decreases with increase in pH. Rheology studies showed that there is a strong link between phase transformation, pH and gel drying temperature. The FEGSEM results show that the surface texture was changed dramatically with different pH values. pH was maintained by HCl and NaOH and calcination temperature during all the experiments was 550°C.