Jamil K. Salem

ZnO NANOPARTICLES PREPARED IN THE PRESENCE OF ADDITIVES BY THERMAL DECOMPOSITION METHOD

In this study, different additives such as cetyltrimethylammonium bromide (CTAB), aluminum nitrate and tri-n-octylphosphine oxide (TOPO) are selected, respectively, to bind zinc acetate in order to investigate its role in the formation of ZnO nanoparticles. Accordingly, the morphology and size of produced ZnO nanoparticles are affected by existence of the additives through XRD analyses and TEM observations. The particle size was found to be 32, 14, 15, and 28 nm for pure zinc acetate, zinc acetate/TOPO, zinc acetate/CTAB, and zinc acetate/aluminum nitrate, respectively. It is observed that the TOPO and CTAB decrease the size of ZnO nanoparticles, while the doping of aluminum to the precursor has no effect on its particle size. The obtained ZnO nanoparticles exhibited the direct optical bandgap of about 3.40–3.45 eV and their photoluminescence spectrum has a UV emission peak at about 363 nm which is slightly blue-shifted due to the smaller particle size of the ZnO nanoparticles in the presence of TOPO and CTAB additives.

Optical and magnetic properties of Fe-doped ZnO nanoparticles prepared by the sol-gel method

Fe-doped ZnO nanoparticles were prepared in a solvo-thermal via sol-gel process by base-catalysed hydrolysis of zinc acetate with doping concentrations from 2 up to 5% Fe. The structural, magnetic and optical properties of the samples were studied by using X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, superconducting quantum interferometer device (SQUID) and UV-VIS spectroscopy. A reduction in particle size was shown with increase in the dopant (Fe) concentration in ZnO. The Fe-doped ZnO samples possess ferromagnetism at room temperature with significant changes in M-H loop with increasing doping concentration. The hysteresis loops reveal that the saturation magnetisation Ms and the coercivity Hc for 2% Fe and 5% Fe-doped ZnO are 2.29 emu/g, 3.91 emu/g, 671 Oe and 659 Oe, respectively. The optical properties were determined by UV-vis spectroscopy and photoluminescent spectroscopy. In this study, the optical band gap of ZnO nanoparticles increased ...

Influence of Cationic Surfactant and Temperature on the Growth of ZnO Nanoparticles

Abstract In this study, ZnO nanoparticles were synthesized from Zn(OAc)2 · 2H2O and NaOH in 2-propanol. Nucleation and growth are fast, and hence at longer times the particle size is controlled by coarsening. The optical properties were investigated as a function of time. X-ray diffraction (XRD) also has been used to characterize ZnO nanoparticles. The wavelength onset (λons) of the absorption spectra was used to estimate the particle size. The effect of the temperature and the surfactant on the growth process of ZnO nanoparticles was followed by UV-Vis spectrophotometer using the effective mass model. Particle growth was fitted using the commonly used linear coarsening model. The linear coarsening model is applied to calculate the rate constant of growth of ZnO nanoparticles. In all cases the linear coarsening produced good fits of the data. The results reveal that the temperature and the CTAB concentration play an important role in growth process of ZnO nanoparticles.