a b s t r a c t l-lysine coated iron oxide (LCIO) nanoparticles were synthesized by a co-precipitation method in the presence of amino acid. XRD analysis confirmed the presence of cubic magnetite phase with an average crystallite size of 8 ± 4 nm. Particle size estimated from TEM, by log-normal fitting, is ∼114 nm. The difference between the crystallite size from XRD and particle size from TEM indicates polycrystalline nature of synthesized particles. FT-IR show that the binding of l-lysine on the surface of iron oxide through carboxyl groups is via unidentate linkage. The presence of l-lysine on iron oxide is also confirmed by zeta potential measurements on LCIO nanoparticles, revealing a partial coverage of iron oxide with l-lysine. In order to obtain chemically stable, well-dispersed and uniform sized nanoparticles, amino acids are suitable because they play a very important role in the body. Conductivity measurements were performed to investigate the influence of the coating on the conduction characteristics of iron oxide and results show the existence of a hopping conduction mechanism. Magnetic transition is observed at ∼70 • C for uncoated iron oxide and LCIO samples. Frequency (1 Hz to 3 MHz) and temperature (290-420 K) dependant AC conductivity measurements have resulted in AC activation energies between 0.048 and 0.041 eV for uncoated and 0.050-0.044 eV for LCIO nanoparticles. Temperature-dependant DC resistivity measurements of iron oxide and LCIO at high temperatures resulted in the DC activation energies of 0.22 and 0.43 eV respectively. The higher activation energy value for LCIO is the result of coating by insulating l-lysine layer.

In this work, LaCrO3 and Ir doped LaCrO3 compounds were synthesized and their frequency dependent electrical properties were studied.

No abstract

In this study, graphene oxide/zinc oxide (GO/ZnO) nanocomposite was prepared by the decoration of thermally expanded and chemically oxidized graphite oxide nanosheets with zinc oxide (ZnO) nanoparticles synthesized via two-step sol-gel deposition method and used as an effective photocatalyst for degradation of basic fuchsin (BF) dye. Structural properties of GO/ZnO nanocomposite were characterized with X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) methods, and Brunauer-Emmett-Teller (BET) surface area measurement. It was found that the GO/ZnO nanocomposite formed a two-dimensional (2D) structure having a composition of 0.54GO/0.46ZnO (w/w) and average ZnO partic le size of 25-30 nm. The band gap of ZnO nanoparticles onto GO nanosheets was found to be 3.25 eV while that of bulk ZnO nanoparticles was determined as 3.70 eV. Photocatalytic degradation works were performed into a UV-chamber by following the concentration of BF dye. Degradation reaction was modeled with the Langmuir-Hinshelwood pseudo first-order kinetic model. GO/ZnO nanocomposite increased the apparent reaction rate constant (k) about three times compared to bulk ZnO nanoparticles under UV light.[a] Dr. Z. Durmus

No abstract