Key Engineering Materials Vols. 675-676

Abstract: Periodic nanohole pattern was created in spin-coated photoresist S1805 on Si substrates by Laser Interference Lithography (LIL). Wavelength of a laser source used in the optical system is 442 nm with the photon energy 2.80 eV. The system was set up to employ two laser beams from a beam splitter to generate interference pattern and expose to the photoresist. There are two parameters (incident angle and exposure time) which are determined due to affecting the ordering and feature of nanohole array. Therefore, the relation of these two parameters and actual dose were investigated and theoretically analyzed to optimize the resolution of LIL technique for nanoholes. The prepared samples after developing in the M26A for 5 sec were analyzed by field-emission scanning electron microscopy (FE-SEM). The results show that the pitch of the pattern is 440 nm and the smallest hole size is 190 nm The best feature is found for a laser fluence of 140 mJ/cm². This nanohole array patterned by LIL consists of periodic nanostructures for high density storage to fabricate various nanodevices.

Abstract: Hybrid nanomaterials exhibit multi-functionalities, which is synergy or enhanced physical and optical properties over their single components with promising potentials for various applications in dye-sensitized solar cell and photocatalytic materials. In this present research, the Au nanoparticles were prepared at HAuCl₄ concentration of 0.5 mM on ZnO nanorod templates and silicon wafer substrate by hydrothermal reaction process. The prepared samples were investigated the crystal structure, chemical composition and morphologies by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and field-emission scanning electron microscopy (FESEM), respectively. The XRD results shown that ZnO was preferred orientation along the c-axis (002). The FE-SEM images indicated to the difference of size-Au NPs decorated on ZnO nanorods and silicon wafer. The relationship between the surface area and the size of Au NPs of the prepared samples was investigated and possible growing mechanism of Au NPs on ZnO nanorods templates will be discussed.

Abstract: F-doped ZnO nanorod structures were synthesized via hydrothermal process with variation of doping content starting from zinc nitrate solution and zinc oxide thin film used as seeding layer. The zinc oxide seeding film was fabricated by spin coating on glass substrate using zinc acetate precursor and annealed at 500 °C for 2 h. Relevant properties of ZnO:F nanorod structures were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and UV-VIS spectrophotometer. Corresponding results indicated that ZnO:F nanorod array, grown in (002) plane, has the characteristics of good crystallinity. In addition, this study showed that ZnO:F nanorod with exceptional structure can be obtained by hydrothermal process, operated at proper treatment time, temperature and F-doping content.

Abstract: Zinc oxide (ZnO) nanorods (NRs) promise high potentials in several applications, such as photovoltaic device, thermoelectric device, sensor and solar cell. In this research, the vertical alignment of ZnO NRs was fabricated by hydrothermal method with various precursor concentrations and growth time on different seed layers (ZnO and Au), which deposited on silicon wafer substrate (100). The crystalline structure and morphology of ZnO NRs have been characterized by x-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) techniques, respectively. The x-ray diffraction pattern shows that the prepared samples have a strong preferred orientation (002) plane. FE-SEM images of the ZnO NRs, it found that the density and aspect ratio were strongly influenced by the seed layer and precursor concentration. In addition, the aspect ratio of ZnO NRs was increased with increasing growth time. This study provides a cost effective method for the fabrication of well aligned ZnO NRs for nano-electronic devices.

Abstract: The aim of this study was to develop a nanoemulsion of Sacha inchi oil for cosmetic application by the emulsion phase inversion (EPI) method. The influence of surfactant type and surfactant-to-oil ratio (SOR) on the particle size distributions of the nanoemulsion was studied. The results obtained showed that nanoemulsion droplet size, and stability of nanoemulsions were varied considerably. At optimal condition, the smallest size (41.43 ± 0.12 nm.) and high zeta potential values were obtained

Abstract: ZnO nanoparticles were successfully synthesized via the co-precipitation method using zinc nitrate and sodium hydroxide as raw materials. Size and shape of ZnO nanoparticles were well controlled by varying the ratio of sodium hydroxide solutions (0.5-0.9 mole) and the synthesized temperatures (65, 75 and 85 °C). ZnO nanoparticles exhibited a high degree crystallinity with wurtzite hexagonal structure for all conditions carried out using SEM, XRD, EDS and Raman. It was clearly observed that both sodium hydroxide solution and synthesized temperatures strongly affected on the size and shape of ZnO nanoparticles. The smallest ZnO nanoparticle was observed to be 47 nm with 0.7 mole of sodium hydroxide solution at 75 °C. Uniformed ZnO nanoparticles were obtained at synthesized temperatures above 65 °C. Optical properties of ZnO nanoparticles were also studied and carried out as absorbance spectra. In addition, optical energy band gap of ZnO nanoparticles was in the range of 3.24-3.35 eV.

Abstract: The bioactive compounds in Mango seed kernel have high antioxidant activities which can be used as an ingredient in cosmetic products. The aim of this study was to improve the stability of bioactive compound in seed kernel extract by preparation in the form of solid lipid nanoparticles (SLN). Solid lipid nanoparticles (SLN) were prepared by high-speed homogenization technique. The effect of formulation on introduction the extract in to the base solid lipid nanoparticle system was investigated. At the optimal condition, the particle size was 329.1 nm. The highest load efficiency was 89.12%. The physical stability under the different storage temperature for 15 days indicated that the mango kernel extract entrapped in nanoparticles showed good stability. No obvious changes of clarity and degradation were found.

Abstract: In this work, we reported the preparation of F-doped ZnO nanoparticles by facile precipitation process using zinc nitrate and ammonium fluoride as starting precursors for Zn and F, respectively dissolved in deionized water. The precursor solution was prepared at various fluoride composition ranging from 1-5 wt%. The as-precipitated powders were calcined at different temperature from 500 °C to 700 °C for 2 h. Effect of calcination temperature and fluoride concentration on structural, morphologies, optical and electrical properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis spectroscopy, respectively. XRD results indicated the complete formation of hexagonal wurtzite structure of ZnO. SEM micrographs showed the agglomeration for each sample that noticeably influenced by fluoride content.

Abstract: Silver nanoparticles (Ag NPs) were synthesized by sparking process. The NPs were continuously deposited onto the substrate by varying the number of sparking cycles ranging from 100-200 and deposited on the glass substrate and annealing at 250-500 °C for 1 hr. The effect of Ag NPs on their structure and optical characteristics were investigated. The optical properties of the NPs have been studied from by Raman spectroscopy and UV-vis spectrophotometer. The morphology of Ag NP was characterized by Scanning Electron Microscope (SEM) and Atomic force microscope (AFM). The results have shown mainly spherical structure of Ag NPs in diameter ranging from 80-100 nm. This study demonstrated that the Ag NPs can be synthesized by sparking process and simply with low cost.

Abstract: The aim of the present work was to extract the seed fat of Rambutan (Nephelium lappaceum L.) for developing nanostructured lipid carriers. Effect of material: solvent ratio and material size time on fat content were investigated. Nanostructured lipid carriers were prepared by melt-emulsification technique. Stearic acid (SA) and the rambutan seed fat (RF) was used as solid and liquid lipid, respectively. Surfactant was Tween 20 as well as Vitamin E was entrapment chemical. Effect of surfactant concentration on formation and stability of solid lipid nanoparticles (SLN) was investigated. At higher surfactant concentrations, NLC had smaller particle size and better stability of nanoparticles. At the optimal concentration of Tween 20 (5% w/w), NLC had a mean particle diameter of 139.43 ± 1.15 nm and a polydispersity index of 0.165 ± 0.017. Zeta potential was above 30 mV.