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

Abstract

The nanocrystallite growth of TiO2 surface modification with 9mol% 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 9mol% ZnO (denoted by T-9Z). The DTA result shows that the anatase TiO2 first formed at 533K and the completion of anatase TiO2 crystallization occurred at 745K 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 523–973K for 2h. When the T-9Z freeze-dried precursor powders were calcined at 973K for 2h, 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 1273K for 2h. 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.