Crystallite growth kinetics of TiO2 surface modification with 9Â mol% ZnO prepared by a coprecipitation process

The nanocrystallite growth of TiO2 surface modification with 9 mol% ZnO prepared by a coprecipitation process has been studied. Thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV-VIS-NIR spectrophotometry have been utilized to characterize the TiO2 nanocrystallites surface modification with 9 mol% ZnO (denoted by T-9Z). The DTA result shows that the anatase TiO2 first formed at 533 K and the completion of anatase TiO2 crystallization occurred at 745 K for the T-9Z freeze-dried precursor powders. XRD results reveal that the anatase and rutile TiO2 coexist when the T-9Z freeze-dried precursor powders were calcined at 523-973 K for 2 h. When the T-9Z freeze-dried precursor powders were calcined at 973 K for 2 h, rutile TiO2 was the major phase, and the minor phases were anatase TiO2 and Zn2Ti3O8. The phase was composed of the rutile TiO2 and Zn2TiO4 for the T-9Z freeze-dried precursor powders after calcination at 1273 K for 2 h. The growth kinetics of TiO2 nanocrystallites in T-9Z powders were described as: DA,92=2.42×105×exp(-39.9×103/RT)and DR,92=8.49×105×exp(-47.6×103/RT) for anatase and rutile TiO2 nanocrystallites respectively. The analysis results of UV/VIS/NIR spectra reveal that the T-9Z freeze-dried precursor powders after calcination have a red-shifted effect with increasing calcination temperature and can be used as a UVA-attenuating agent.