• Journal of Information Display
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• v.10 no.1
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• pp.24-27
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• 2009

A simple nonalkoxide sol-gel route for depositing an Al-doped ZnO thin film on a glass substrate was derived in this study. The initial Al dopant concentration in the sol-gel preparation varied and ranged from 0 to 5%. The sol-gel-derived thin films showed c-plane preferred crystallization of their hexagonal phase, with nanosized grain structures. First and second post-heat-treatments were carried out to improve the film’s electrical resistivity. The carrier density and the Hall mobility were measured and discussed to explain the electrical resistivity. The optical transmittance within the visible range showed compatible properties, which indicates the possible use of A1-doped ZnO as a transparent electrode in flat panel displays.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.9
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• pp.452-455
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• 2006

The technology of wire explosion have been used to product nanopowders. A new concept was proposed to produce metallic nanosized powders, which is wire explosion in liquid media. We have exploded the Ag or Cu wires of diameter of O.3mm, 40mm long, in the de-ionized water or acetone, respectively. Electrical energy of 1.1kJ was stored in 10uF capacitor and released to the wires through a triggered spark gap switch. The process was observed by high-speed camera. Those images showed that the powders were generated by vapor condensation in the shell formed by shock wave in the water. The particles were directly dispersed into the water with collapse of the shell. The sizes of Ag and Cu nanopowders were evaluated to 35nm and 17nm, respectively.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.239-244
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• 1999

Ultrafine lead magnesium niobate $Pb(Mg_{1/3}Nb_{2/3}) O_3$ (PMN) powders have been successfully prepared via a micro-emulsion processing technique. By stepwise hydrolysis using aqueous as the precipitant, hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of a microemulsion consisting of cyclohexane, non-ionic surfactant (NP5+NP9) and an aueous phase. Upon calcination of the microemulsion-derived precursor at $800^{\circ}C$, PMN powders with 100% perovskite phase was obtained.

• Bulletin of the Korean Chemical Society
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• v.23 no.5
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• pp.699-704
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• 2002

We characterized nanoelectrode arrays prepared from self-assembled monolayers (SAMs) by adsorption from a solution containing thiolated $\beta$-cyclodextrin ($\beta$-CD) and n-alkanethiol on the gold electrode surface, using electrochemical methods. While the framework, the n-hexadecanethiol SAM, effectively blocked electron transfer between the electrode surface and solution-phase redox probe molecules, the $\beta$-CD cavities isolated in the forests of n-hexadecanethiol molecules were shown to act as an ultramicroelectrode array. The shapes of cyclic voltammograms of probe molecules were related to the number densities of $\beta$-CD molecules within the monolayer films. Probe molecules that have the correct combination of physical and chemical characteristics were shown to effectively penetrate the framework through the $\beta$-CD pores and exchange electrons with the electrode surface.

• Journal of Magnetics
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• v.20 no.3
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• pp.221-228
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• 2015

Colloidal particles consisted of individual nanosized magnetite grains on the surface of the silica cores were obtained by two-stage sol-gel technique. Size distribution and microstructure of the particles were analyzed using atomic force microscopy, X-ray diffraction and Nitrogen thermal desorption. Magnetic properties of the particles were studied by the method of the longitudinal nonlinear response. It has been shown that nanoparticles of magnetite have a size corresponding to a superparamagnetic state but exhibit hysteresis properties. The phenomenon was explained using the magnetostatic interaction model based on the hypothesis of iron oxide particles cluster aggregation on the silica surface.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.9-20
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• 2012

A brief review on the thermal plasma synthesis of nano-sized powders is presented according to the application materials, such as, metals, ceramics, glasses, carbonaceous materials and other functional composites, such as, supported metal catalyst and core-shell structured nano materials. As widely adopted plasma sources available for thermal plasma synthesis of nanosized powders, three kinds of plasma torches, such as transferred and non-transferred DC and RF plasma torches, are introduced with the main features of each torch system. In the basis of the described torch features and the properties of suggested materials, application results including synthesis mechanism are reviewed in this paper.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.163-164
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• 2012

Carbon coils could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under thermal chemical vapor deposition system. The substrate with oxygen incorporation and the substrate without oxygen incorporation were employed to elucidate the effect of substrate on the formation of carbon coils. The characteristics (formation densities, morphologies, and geometries) of the deposited carbon coils on the substrate were investigated. In case of Si substrate, the microsized carbon coils were dominant on the substrate surface. While, in case of oxygen incorporated substrate, the nanosized carbon coils were prevail on the substrate surface. The cause for the different geometry formation of carbon coils according to the different substrates was discussed in association with the different thermal expansion coefficient values between the substrate with oxygen incorporation and the substrate without oxygen incorporation.

• Macromolecular Research
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• v.13 no.5
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• pp.385-390
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• 2005

The electrospinning process is a fascinating method to fabricate small nanosized fibers of diameter several hundred nanometers. Surfactant-polymer solutions were prepared by adding poly(vinyl alcohol) (PVOH) to distilled water with cationic, anionic, amphoteric, and non-ionic surfactants. Average diameter of the electrospun PVOH fibers prepared from PVOH solution was over 300 nm, and was decreased to 150 nm for the mixture of PVOH/amphoteric surfactant. To explain the formation of ultra fine fiber, the characteristic properties in a mixture of PVOH/surfactant such as surface tension, viscosity, and conductivity were determined. In this paper, the effect of interactions between polymers with different classes of surfactants on the morphological and mechanical properties of electrospun PVOH nonwoven mats was broadly investigated.

• 한국전기화학회:학술대회논문집
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• 2003.07a
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• pp.83-88
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• 2003

PtRu alloy and $PtRu-WO_3$ nanocomposite thin-film electrodes for methanol electrooxidation were fabricated by means of a sputtering method. The structural and electrochemical properties of well-defined PtRu alloy thin-film electrodes were characterized using X-ray diffraction, Rutherford backscattering spectroscopy. X-ray photoelectron spectroscopy, and electrochemical measurements. The alloy thin-film electrodes were classified as follows: Pt-based and Ru-based alloy structure. Based on structural and electrochemical understanding of the PtRu alloy thin-film electrodes, the well-controlled physical and (electro)chemical properties of $PtRu-WO_3$, showed superior specific current to that of a nanosized PtRu alloy catalyst, The homogeneous dispersion of alloy catalyst and well-formed nanophase structure would lead to an excellent catalytic electrode reaction for high-performance fuel cells. In addition, the enhanced catalytic activity in nanocomposite electrode was found to be closely related to proton transfer in tungsten oxide using in-situ electrochemical transmittance measurement.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.350-356
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• 2015

The effects of the zinc oxide (ZnO) preparing process on the performance of inverted organic photovoltaic cells (OPVs) were explored. The morphology and size of ZnO nanoparticles were controlled, leading to more efficient charge collection from device and higher electron mobility compared with nanospheres. Nanosized ZnO particles were synthesized by using zinc acetate dihydrate and potassium hydroxide in methanol. Also, water was added into the reaction medium to control the morphology of ZnO nanocrystals from spherical particles to rods, and $NH_4OH$ was used to prevent the gelation of dispersion. Solution-processed ZnO thin films were deposited onto the ITO/glass substrate by using spin coating process and then ZnO films were used as an electron transport layer in inverted organic photovoltaic cells. The analyses were carried out by using TEM, FE-SEM, AFM, DLS, UV-Vis spectroscopy, current density-voltage characteristics and solar simulator.