• Journal of the Korean institute of surface engineering
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• v.55 no.3
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• pp.143-155
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• 2022

Ceramic oxide layers successfully were formed on the surface of cast Al alloys with high Si contents using plasma electrolytic oxidation (PEO) process in electrolytes containing Na₂SiO₃, NaOH, and additives. The microstructure of the oxide layers was systematically analyzed using scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (TEM), X-ray diffraction patterns (XRD), and energy X-ray dispersive spectroscopy (EDS). XRD analysis indicated that the PEO untreated high-silicon Al alloys (i.e., 17.1 and 11.7 wt.% Si) consist of Al, Si and Al₂Cu phases whereas Al₂Cu phase selectively disappeared after PEO treatment. PEO process yielded an amorphous oxide layer with few second phases including γ-Al₂O₃ and Fe-rich phases. The corrosion behaviors of high-silicon Al alloys treated by PEO process were investigated using electrochemical impedance spectroscopy (EIS) and other electrochemical techniques (i.e., open circuit potential and polarization curve). Electroanalytical studies indicated that high-silicon Al alloys treated by PEO process have greater corrosion resistance than high-silicon alloys untreated by PEO process.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1336-1338
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• 2010

Three cobalt-iron Prussian Blue Analogues (PBAs) nanotubes contained with different alkali metal cations of K, Rb or Cs, respectively, were prepared by using cetyltrimethylammonium bromide (CTAB)/ethanol-water micelles as soft templates. The products were characterized by energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron micrograph (SEM), which confirmed the composition of the substances and their unique nanotube structures. Furthermore, the formation mechanism of the PBAs nanotubes was discussed and provided useful insight for further synthesis of nanotubes of other Prussian blue analogues.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1657-1661
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• 2011

In this study, CdSe-$TiO_2$ photocatalyst were synthesized by a facile solvothermal method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and UV-vis diffuse reflectance spectrophotometer. The photocatalytic activity was investigated by degrading methylene blue (MB) in aqueous solution under irradiation of UV light as well as visible light. The absorbance of degraded MB solution was determined by UV-vis spectrophotometer. The results revealed that the CdSe-$TiO_2$ photocatalyst exhibited much higher photocatalytic activity than $TiO_2$ both under irradiation of UV light as well as visible light.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2609-2612
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• 2012

A simple green method was developed for rapid synthesis of silver and gold nanoparticles (AgNPs and AuNPs) has been reported using Lonicera japonica flower extract as a reducing and a capping agent. AgNPs and AuNPs were carried out at $70^{\circ}C$. The successful formation of AgNPs and AuNPs have been confirmed by UV-Vis spectro photometer, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray Analysis (EDAX), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). To our knowledge, this is the first report where Lonicera japonica flower was found to be a suitable plant source for the green synthesis of AgNPs and AuNPs.

• Composites Research
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• v.31 no.3
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• pp.94-98
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• 2018

Well-defined, monodispersed hollow ZnO nanoparticles were successfully synthesized by a facile one-pot solution method at room temperature. Hollow ZnO nanoparticles were fabricated using polystyrene nanoparticles as seed particles. The removal of core particles via solvent extraction yields hollow nanoparticles. The structures and morphologies of the obtained products were characterized with Fourier transform infrared (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction pattern (XRD) and Scanning electron microscopy (SEM). The formation mechanism of the hollow structure of the ZnO nanoparticles was also investigated. The technique developed here is expected to be useful in the preparation other metal oxides and hollow architectures.

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.197-200
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• 2002

The electrooxidation of methanol was studied using carbon-supported PtRu(1:1) alloy nanoparticles In sulfuric acid solution for application to a direct methanol fuel cell. The GNF-supported catalyst showed excellent catalytic activities compared to those of Vulcan XC-72. The structure and electrocatalytic activity of carbon-supported electrocatalyst were investigated using X-ray diffraction (XRD), Transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperometry (CA), X-ray photoelectron spectroscopy (XPS). The CV and CA confirmed the advantage of GNF as the supporting material. This can be explained by assuming that the enhanced activities of GNF-supported catalyst for methanol electrooxidation were caused by the unique properties of GNF.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.32.1-32.1
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• 2011

Ultra thin tantalum nitride (TaNx) films with various thicknesses (10 nm to 40 nm) have been deposited by rf magnetron sputtering technique on glass substrates. The as deposited films were systematically characterized by several analytical techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, atomic force microscopy, UV-Vis-NIR double beam spectrophotometer and four point probe method. From the XRD results, the as deposited films are in amorphous nature, irrespective of the film thicknesses. The films composition was changed greatly with increasing the film thickness. SEM micrographs exhibited the densely pack microstructure, and homogeneous surface covered by small size grains at lower thickness deposited films. The surface roughness of the films was linearly increases with increasing the films thickness, consequently the transmittance decreased. The absorption edge was shifted towards higher wavelength as the film thickness increases.

• Laser Solutions
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• v.13 no.3
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• pp.13-18
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• 2010

In this paper, polyimide (PI) surface was modified by UV Laser with a low laser fluence and investigated changes of surface geometry and chemical characteristics by SEM (scanning electron microscope), X-ray diffraction (XRD), XPS (x-ray photoelectron spectroscopy) and the measurements of contact angle of water. PI surface was peeled off and modified with microstructure fabrications by photochemical ablation over the laser fluence of 50 mJ/cm2. As laser fluence increased, delamination of PI surface was occurred largely and strongly. In chemical characteristics, the O/C and N/C atomic ratios increased and contact angle decreased from $80^{\circ}$ to $40^{\circ}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.2
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• pp.110-113
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• 2012

ZnO crystals with a baseball bat shape were synthesized without any catalysts through a simple thermal oxidation of ZnS powder in alumina crucible under air atmosphere. SEM images demonstrated that the bat structure was composed of two pieces of ZnO crystals, i.e hexagonal-shaped rod and inverted cone-shaped rod. X-ray diffraction (XRD) pattern revealed that the ZnO crystals had wurtzite hexagonal structure. Energy dispersive X-ray (EDX) spectrum showed that the ZnO was of high purity. A strong green emission peak at 510 nm was observed in cathodoluminescece spectrum.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.281-281
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• 2013

본 연구에서는 고출력 금속 인쇄회로기판(Metal PCB) 개발을 위해 절연층으로 양극산화막을 형성하고 이 절연층 위에 Screen Printing 법을 이용하여 Ag paste를 패턴 인쇄한 알루미늄 기판을 사용하였다. 이 기판 위에 무전해 방식으로 구리 박막을 성장시켜, 무전해 도금 조건이 구리 박막 성장에 미치는 영향에 대해 연구하였다. 무전해 도금 시, pH 농도와 plating 온도를 변화시켜 이 변화에 따른 무전해 구리도금 박막의 물리적/전기적 특성을 비교 분석하여 무전해 도금에 의해 형성된 구리 박막과 기판과의 상관 관계도 비교 검토하였다. XRD (X-ray Diffraction), 광학현미경, FE-SEM (Field Emission Scanning Electron Microscope)등을 이용하여 성장된 구리 박막 및 기판의 결정성, 표면 및 단면 형상 등을 측정하였고, XPS (X-ray Photoelectron Spectroscopy)를 이용하여 무전해 도금에 의한 Cu의 화학구조 및 불순물 상태를 조사하였다.