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911.
Back SY Song CH Yu S Lee HJ Kim BS Yang NY Jeong SH Ahn H 《Journal of nanoscience and nanotechnology》2012,12(1):446-450
Electrohydrodynamic (EHD) jet printing is a technique using electric fields to eject inks through nozzle apertures. EHD jet printing is very attractive due to its non-contacting nature and compatibility with diverse materials and substrates. In this research, we have fabricated micron-sized dot arrays and line patterns with carbon black ink on Si wafer substrates using EHD jet printing. The effect of operating conditions such as applied voltage, working distance and stage speed on the size and shape of the jetted patterns and jetting cycles is investigated by using optical microscope, high speed camera and atomic force microscopy (AFM). We have also demonstrated the drop-on-demand feature of the EHD jet printing system by patterning carbon black ink lines with various widths and dot arrays with desired diameters and spacing by controlling the operating conditions. 相似文献
912.
Rahman MA Kim H Lee YK Lee C Nam H Lee JS Soh H Lee JK Lee EG Lee J 《Journal of nanoscience and nanotechnology》2012,12(2):1348-1352
The incorporation of a thin, atomic layer deposited Al2O3 layer in between a spin-coated poly-4-vinyl phenol (PVP) organic layer and octadecyltrichlorsilane (OTS) in the multilayer gate dielectric for pentacene organic thin film transistors on a n(+)-Si substrate reduced the gate leakage current and thereby significantly enhanced the current on/off ratio up to 2.8 x 10(6). Addition of the OTS monolayer on the UV-treated Al2O3 improved the crystallinity of the pentacene layer, where the OTS/UV-treated Al2O3 surfaces increased their contact angles to 100 degrees. X-ray diffraction (XRD) analysis revealed a more intense (001) crystal reflectance of pentacene deposited on OTS/UV-treated Al2O3 surface than that on OTS/Al2O3 surface. Moreover, the improved pentacene layer contributed to the field effect mobility (0.4 cm2/Vs) and subsequently improved the electrical performances of organic thin film transistor (OTFT) devices. This PVP/UV treated Al2O3/OTS multilayer gate dielectric stack was superior to those of the device with the single PVP gate dielectrics due to the improved crystallinity of pentacene. 相似文献
913.
Pukha VE Stetsenko AN Drozdov AN Jeong SH Nam SC 《Journal of nanoscience and nanotechnology》2012,12(4):3091-3100
Crystalline C60 and amorphous graphite-like films of nanocolumn arrays fabricated by glancing angle deposition of C60 fullerene at substrate temperatures of -425 K were studied by transmission electron microscopy (TEM) and atomic-force microscopy (AFM). Characteristic dimension of columns is 200-400 nm. We used co-deposition of C60 molecules and accelerated C60 ions to modify the structure and properties of nanocolumn arrays. Influence of incidence angle for C60 ions on formation of film morphology was revealed. Raman spectrum analysis showed that amorphous carbon nanocolumns consist of nanographite areas with average size of -1.5 nm. The films have high conductivity (close to graphite) and have no mechanical stresses. The carbon films were applied in all-solid-state rechargeable thin-film battery as an anode layer. The nanocolumn amorphous carbon film as anode electrode showed the discharge capacity of about 50 microAh cm(-2)microm(-1) and good cycling ability over 100 times in full cell system. 相似文献
914.
The Fe-based self-fluxing alloy powders and SiC particles were mixed and milled by high energy ball-milling, and their microstructure and micro-hardness were investigated after subsequent compaction and sintering. The initial alloy powders with a mean size of approximately 80 microm were fined to 2.1 microm after milling at 800 rpm for 5 h. However, the powder mixture of alloy powder and SiC particle showed much larger powder size compared to the initial alloy powders. The bulk composites were obtained from the powder mixture by compaction under a pressure of 800 MPa for 10 min and sintering at 1073 K for 3 h. The composites had much higher micro-hardness of more than 700 Hv compared to alloy powder. The micro-hardness of composites slightly increased with the content of SiC particles. 相似文献
915.
Water is detrimental to the performance of organic light-emitting devices and organic solar cells. A novel weight gain test (WGT) was introduced and demonstrated to measure the low permeation of water vapor through a metallic barrier coating on a polymer substrate. By using the WGT, the values of solubility, diffusivity and permeability for a sample are obtained with a simple experimental setup and diffusion equation. The WGT method has potential for the measurement of water-vapor permeation properties for samples with good barrier properties and irregular shape. 相似文献
916.
A supercapacitor has the advantages of both the conventional capacitors and the rechargeable batteries. Mn oxide is generally recognized one of the potential materials that can be used for a supercapacitor, but its low conductivity is a limiting factor for electrode materials. In this study, a hybrid of amorphous Mn oxide (AMO) and ordered mesoporous carbon (OMC) was prepared and characterized using X-ray diffraction, transmission electron microscopy, N2/77 K sorption techniques, and electrochemical analyses. The findings indicate that the electrochemical activities of Mn oxide were facilitated when it was in the hybrid state because OMC acted as a pathway for both the electrolyte ions and the electrons due to the characteristics of the ordered mesoporous structure. The ordered mesoporous structure of OMC was well maintained even after hybridization with amorphous Mn oxide. The electrochemical-activity tests revealed that the AMO/OMC hybrid had a higher specific capacitance and conductivity than pure Mn oxide. In the case where the Mn/C weight ratio was 0.75, the composite showed a high capacitance of 153 F/g, which was much higher than that for pure Mn oxide, due to the structural effects of OMC. 相似文献
917.
One-dimensional (1-D) nanostructures such as tubes, rods, wires, and belts have attracted considerable research activities owing to their strong application potential as components for nanosize electronic or optoelectronic devices utilizing superior optical and electrical properties. Characterizing the mechanical properties of nanostructure is of great importance for their applications in electronics, optoelectronics, sensors, actuators. Wide-bandgap SnO2 semiconducting material (Eg = 3.6 eV at room temperature) is one of the attractive candidates for optoelectronic devices operating at room temperature, gas sensors, and transparent conducting electrodes. The synthesis and gas sensing properties of semiconducting SnO2 nanomaterials have became one of important research issues since the first synthesis of SnO2 nanobelts. Considering the important application of SnO2 in sensors, these structures are not only ideal systems for fundamental understanding at the nanoscale level, but they also have potential applications as nanoscale sensors, resonator, and transducers. The structured SnO2 nanorods have been grown on silicon substrates with Au catalytic layer by thermal evporation process over 800 degrees C. The resulting sample is characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and energy-dispersive X-ray spectroscopy (EDS). The morphology and structural properties of SnO2 nanowires were measured by scanning electron microscopy and high-resolution transmission electron microscopy. The mean diameter of the SnO2 nanorods grown on Au coated silicon (100) substrate is approximately 80 nm. In addition, X-ray diffraction measurements show that SnO2 nanorods have a rutile structure. The formation of SnO2 nanowires has been attributed to the vapor-liquid-solid (VLS) growth mechanisms depending on the processing conditions. We investigated the growth behavior of the SnO2 nanowires by variation of the growth conditions such as gas partial pressure and temperature. 相似文献
918.
In an attempt to enhance the biocompatibility and mechanical strength of fibrous polymeric scaffold systems, nanocrystalline hydroxyapatite (HAp) particles were incorporated into the electrospun poly(L ‐lactide) (PLLA) fibers and then mechanically interlocked using a vapor‐phase solvent adsorption method. The solvent‐assisted compression molding substantially increased the tensile strength (from 4.61 to 12.63 MPa) and mechanical modulus (from 50.6 to 627.7 MPa) of the fibrous scaffold, which maintained the interstitial space between the fibers to allow the facile transport of nutrients and waste during cell growth and polymer biodegradation. Macrometer‐sized pores (ca. 100–400 µm) were introduced into the scaffolds in a controlled fashion using the salt leaching/gas forming technique to give desired space for a facile cell implantation and growth. Overall, the developed methodology allows the polymer‐based scaffold systems to be tailored for various applications in light of surface characteristics, mechanical strength, and pore size of engineered scaffolds.
919.
Sahng Ha Lee Dong Heon Nam Chan Beum Park 《Advanced Synthesis \u0026amp; Catalysis》2009,351(16):2589-2594
Regeneration of the nicotinamide cofactor is a critical issue in biocatalysis. Herein we have screened xanthene dyes for a highly efficient, visible light‐driven photochemical regeneration of cofactors and enzymatic synthesis. Superior catalytic performance was observed with several xanthene dyes such as phloxine B, erythrosine B, eosin Y, and rose bengal. We found that the photo‐ and electrochemical properties of the xanthene dyes were affected by the halogen atom substitution, which is a key factor in the efficient light‐induced electron transfer from the donor molecule to the catalytic mediator. 相似文献
920.
Hee Su Kim Sung Pil Yoon Jeong Woo Yun Shin Ae Song Seong-Cheol Jang Suk Woo Nam Yong-Gun Shul 《International Journal of Hydrogen Energy》2012
Yttria-doped strontium titanium oxide (Sr0.92Y0.08TiO3−δ; SYT) was investigated as an alternative anode material for solid oxide fuel cells (SOFCs). The SYT synthesized by the Pechini method exhibits excellent phase stability during the cell fabrication processes and SOFC operation and good electrical conductivity (about 0.85 S/cm, porosity 30%) in reducing atmosphere. The performance of SYT anode is characterized by slow electrochemical reactions except for the gas-phase diffusion reactions. The cell performance with the SYT anode running on methane fuel was improved about 5 times by SDC film coating, which increased the number of reaction sites and also accelerated electrochemical reaction kinetics of the anode. In addition, the SDC-coated SYT anode cell was stably operated for 900 h with methane. These results show that the SDC-coated SYT anode can be a promising anode material for high temperature SOFCs running directly on hydrocarbon fuels. 相似文献