| Summary: | 碩士 === 國立臺灣海洋大學 === 光電科學研究所 === 101 === In this thesis, TiO2 nanostructures have been fastly synthesized from a titanium foil by CO2 laser heating under air ambient. The average growth rate of as-grown TiO2 nanostructures exceeds 2.1 m/s. We used a video camera through a microscope to record TiO2 growth process.
We used field-emission scanning electron microscope(FE-SEM) to investigate SEM images of TiO2 nanostructures from different laser synthesis time. Then we successively investigated nanoparticles, nanoflowers, and nanotrees. So we compared our as-grown products with the similar nanostructures in the literature and possible growth process of different TiO2 nanostructures was discussed.
In this study, structural analysis by X-ray diffractometer(XRD) and confocal Raman microscope showed that the as-grown TiO2 nanostructures were rutile phase. HR-TEM images confirmed that TiO2 nanoflowers and nanotrees products were composed of aggregates of nanoparticles, and then we obviously observed that different nanoparticles crystal lattice spacing were correspind to [110] plane of rutile.
Due to rapid synthesis of titanium and oxygen in air, the as-grrown TiO2 nanostructures easily lead crystal lattice defects, so the room-temperature photoluminescence peak is weak. We observed that the obvious excitation peak is at 413 nm(3.0 eV) in violet band. The CO2 laser rapid-thermal-annealing treatment can enhance the crystalline of the TiO2 nanostructures in several ten seconds to make violet light emission strongly. Compared with related literature, we successfully reduced the anneal product time very much.
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