Advanced Materials Research Vol. 667

Abstract: A monolayer of carbon is called graphene. It exhibits unusual properties in the Hall effect and in the cyclotron resonance. It is found that it exhibits fractional charge in the Hall effect. The interactions amongst electrons almost become constant at low temperatures. Hence, the Kohn's theorem, which shows that the interactions do not play much role in determining the cyclotron resonance, becomes operative at low temperatures. The experiments on graphene do not depend on the wave vector dependence of the frequency. Hence whether the dispersion depends on k2 or on k does not matter. The Hubbard model has been very successful in explaining the ground state of several electron systems. We consider a triangle with three vortices. Each vortex can be occupied by two electrons. By using the spin in a particular way, we can obtain new features in the Hubbard model. There is a doubling in the Peierls-Luttinger phase factor and eigen values acquire higher multiplicities than are known for the usual treatment of spin. The flux is distributed on the area of the triangle. The graphene consists of hexagons of carbon atoms but the Hall effect shows that there are defects on which electrons form clusters so that there is spin wave type behaviour. A cluster of electrons shows spin-waves leading to "spin deviation" of several per cent.

Abstract: Carbon nanotubes (Cnts) produced using single furnace thermal CVD method by the floating catalyst method, at low temperature condition; 650oC. Carbon nanotubes were produced from natural source of camphor oil, using Fe/Co/Al as catalyst source, yielding a thickened submicron vapor grown of multi-wall Cnts. Carbon nanotubes are observed to form by different weight composition of catalyst. For the production of carbon nanotubes, natural precursor was used as the carbon feedstock, and the catalysts were added in a precursor compound. FESEM analysis confirms that this type of stacked-cup Cnts is produced by vaporize catalyst and mixing with the hydrocarbon source. In fact, few Cnts have either a particle tip at the end or trapped metal particle inside the wide hollow core of this type of produced carbon material. Chemical properties carried out by FTIR and Raman spectroscopy.

Abstract: Carbon nanotubes (CNTs) were produced on silicon (Si) substrate prepared by Thermal-CVD method using C55H96O6 (Palm Oil) as a starting material. Catalyst has been prepared by dissolving Nickel (II) nitrate, Ni (NO3)2.6H2O and ethyl alcohol, C2H5OH. Before the deposition process, silicon was coated with Nickel using spin coater. Various parameters such as amount of catalyst, amount of palm oil, deposition time, deposition temperature, flow rate of gas and carrier gas have been studied. By using Thermal-CVD, samples were penetrated using NH3 (argon) gas at a temperature 700 - 900oC for catalyst and 450oC for palm oil. Surface morphology and uniformity of CNTs were characterized using FESEM at different deposition temperature. Chemical functional groups of CNTs were characterized using FTIR. The surface morphology and uniformity of CNTs are dependents on parameters used.

Abstract: Fermented tapioca which is a new starting material was used as a carbon precursor. Carbon nanotubes (CNTs) were deposited on silicon wafer (Si) by Thermal Chemical Vapor Deposition (TCVD). The gas flow of Argon (Ar) was constant at 70 bubbles per minute and 20 minutes of deposition time. Before the deposition process, silicon was coated with Nickel using spin coater. Various parameters such as amount of inoculums have been studied. Chemical functional groups of carbon nanotubes were characterized using FT-IR Spectroscopy. The FT-IR result shows peaks attributed to multi–walled carbon nanotubes (MWCNT) vibration modes.

Abstract: Fermented tapioca prepared at different temperature was prepared and used as a starting material in CNTs synthesis using 2-system thermal chemical vapor deposition (TCVD) method. The CNTs was deposited on nickel coated silicon where the nickel acts as catalyst in the growth process. The size of CNTs growth is dependent to the temperature. The prepared CNTs were analyzed using Fourier transformation infrared spectroscopy (FTIR) to determine the chemical properties in the sample. Fourier transform infrared (FTIR) spectroscopy was carried out in the range of 450-4000 cm-1 to study the attachment of the impurities on carbon nanotubes.

Abstract: This paper reports a study on vertically aligned carbon nanotubes (VACNTs) synthesized by thermal chemical vapor deposition (TCVD) method using eco-friendly carbon source; palm oil. Palm oil vaporized at 450oC in argon atmosphere at ambient pressure. For better decomposition of palm oil complex structure, ferrocene were added into palm oil and stirred for 20 minutes prior to synthesis process. The synthesis and annealing duration took 30 and 10 minutes respectively. The field emission scanning electron microscopy (FESEM) and infrared spectroscopy analysis were systematically studied on CNTs produced. The detailed of CNTs properties will be discussed further.

Abstract: The properties of zinc oxide thin films were prepared by sol-gel spin-coating method have been presented. This study based on optical and electrical properties of ZnO thin film. The effects of annealing temperatures that exposed with two environments properties have been investigated. Environments exposed in room (27°C) and hot (80°C) temperatures which are stored by various days. Solution preparation, thin film deposition and characterization process were involved in this project. The ZnO films were characterized using UV-Vis-NIR spectrophotometer for optical properties. From that equipment, the percentage of transmittance (%) and absorption coefficient spectra were obtained. With two environments showed have different absorption coefficient are reveal and all films have low absorbance in visible and near infrared (IR) region but have high UV absorption properties. From SEM investigations the surface morphology of ZnO thin film shows the particles size become smaller and denser in hot temperatures while in room temperatures have porosity between particles.

Abstract: This paper focus on nanostructured Zinc Oxide (ZnO) thin film based humidity sensor prepared using sol-gel method immersion technique at different immersion time. Scanning Electron Microscopy (SEM) investigations reveal nanorods ZnO were deposited on glass substrate with nanorods length increased with immersion time. All fabricated sensors show current intensity increment response when relative humidity is increased. Sensor fabricated at 16 hr immersion time shows the highest sensitivity in this study.

Abstract: Nanostructured ZnO thin film has been prepared by using sol-gel method. The influence of annealing temperature on the structural, surface morphology and the properties has been investigated. The morphology of the nanostructured ZnO was observed by scanning electron microscopy (SEM) and their properties were measured by using the I-V measurement. The annealing temperature of 500°C, 600°C and 700°C has been observed and the I-V measurements were measured at different relative humidity to studies on the sensitivity of the nanostructured ZnO. The SEM demonstrates that the glass substrate was deformed at 700°C of annealing temperature and I-V measurement studies shows that the resistance of nanostructured ZnO thin film is decreased with annealing temperature and relative humidity. Sensitivity also decreases with the increases of annealing temperature.

Abstract: TiO2 nanocoated mild steel surface has been successfully prepared via 100 watt of RF magnetron sputtering by using TiO2 target and sputtering condition was performed in 80sccm argon gas. The studied was done in comparing the surface properties of TiO2 nanocoated mild steel between short term and long term sputtering time at 5 and 60 minutes, respectively. From the results, we have found that the long-term sputtering time producing good surface coating with lower surface roughness at 0.033 nm with thickness in nanometer scale is 169 nm via AFM. Through Auger study revealed that the coating attributed Ti and O elements at energy of 383.48 eV and 483.44 eV, respectively. It was also showed that the intensity of that element high at about 100k a.u. in long-term compared to 55k a.u. short-term of sputtering time. It is thus showed that producing coating depends upon manipulation of parameter in RF magnetron sputtering.