Papers by Keyword: Enhanced Nanocrystallinity

Abstract: In the current research, ZnO nanoparticles have been synthesized via sol-gel technique assisted by a pre-hydrothermal treatment at 150oC with various holding time of 0, 24, 48 and 72 hours. This route was specifically aimed at investigating the effect of this treatment on the nanocrystallite size, crystallinity and band gap energy of the resulting nanoparticles. The results of investigation showed that an increasing of pre-hydrothermal treatment duration from 0 to 72 hours has increased the crystallite size of ZnO nanoparticles from 3.47 to 13.85 nm, and decreased the band gap energy from 3.10 to 3.08 eV.

Abstract: Nanocomposite thin film containing TiO₂ nanoparticles in polymethyl methacrylate (PMMA) is a new class of potential materials for optoelectronic applications. Among the various processing techniques for these nanocomposites, in situ sol−gel process is well known to be versatile as it enables control of the inorganic-organic interaction at various molecular, nanometer and micrometer scales. However, the resulting TiO₂ phase is largely amorphous, as a consequence of the relatively low processing temperatures. Therefore, the current research is aimed at enhancing the nanocrystallinity of TiO₂ nanoparticles in nanocomposites. For this purpose, pre-hydrothermal treatment was carried on the inorganic sols. The nanocrystallinity degree of the resulting TiO₂ nanoparticles was studied by XRD and FTIR. The studies showed that the nanocrystallinity of TiO₂ nanoparticles synthesized from the inorganic sol can be enhanced significantly by the pre-hydrothermal treatment, as a result of the completion of hydrolysis stage during sol-gel process.

Abstract: In the present research, a modified post-hydrothermal treatment with different temperature of 80-150°C has been applied on as-annealed TiO₂ nanotubes derived from conventional hydrothermal process. The treatment has two-fold objectives, i.e. enhancing the nanocrystallinity of anatase TiO₂, and at the same time maintaining the integrity of nanotube structures. The resulting TiO₂ nanotubes were characterized by using XRD and UV-Vis spectroscopy. The XRD analysis revealed that the as dried TiO₂ nanotubes contain combined crystalline structures of sodium-titanate and anatase. It was also found that by increasing the post-hydrothermal temperature from 80 to 150°C, the nanocrystallinity of nanotubes enhances as indicated by increasing the crystallite size of anatase TiO₂ from 6.93 to 7.81 nm. The anatase crystallite growth affected the optical characteristic of nanotubes, as represented with the reduction of the band gap energy, E_g from 3.75 to 3.67 eV by using Kubelka-Munk analysis for the obtained UV-Vis reflectance spectra. TEM observation confirms that the integrity of nanotubes structure can be well-maintained upon post-hydrothermal treatment.