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        검색결과 82

        41.
        2008.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Pt-loaded carbon black for the catalyst of a PEM fuel cell was synthesized with different molar ratios of polyvinylpyrrolidone and H2PtCl6 solution to improve the dispersion of Pt nanoparticles on carbon black and decrease the size of Pt nanoparticles. From transmission electron microscopy results, Pt nanoparticles of a size of approximately 2 nm were highly dispersed when the polyvinylpyrrolidone concentration was 10mM. The electrochemical activity of the synthesized Pt/C catalysts was investigated by cyclic voltammetry, showing that the as-synthesized Pt-loaded carbon black catalyst had the best activity at a polyvinylpyrrolidone concentration of 10 mM.
        4,000원
        42.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Among the efforts to increase the efficiency of organic light-emitting device (OLED), there is a way: doping phosphorescent materials. As a phosphorescent material, complexes of heavy transition metal, platinum, were synthesized. Cl- ion and phenyl group were used as ancillary ligands with 2-(2-pyridyl)benzimidazole (pbi) as a chromophore. The complexes were analysed by FAB-mass spectrometer and absorption and emission spectra were obtained. A phenyl group was able to shift the emission band of the complex even if it's not a chromorphore.
        3,000원
        44.
        2007.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ordered to FePt nanoparticles are strong candidates for high density magnetic data storage media because the phase FePt has a very high magnetocrystalline anisotropy , high coercivity and chemical stability. In this study, the ordered FePt nanoparticles were successfully fabricated by chemical vapor condensation process without a post-annealing process which causes severe particle growth and agglomeration. The nanopowder was obtained when the mixing ratio of Fe(acac) and Pt(arac) was 2.5 : 1. And the synthesized FePt nanoparticles were very fine and spherical shape with a narrow size distribution. The average particle size of the powder tended to increase from 5 nm to 10 nm with increasing reaction temperature from to . Characterisitcs of FePt nanopowder were investigated in terms of process parameters and microstructures.
        4,000원
        49.
        2005.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Platinum catalysts for the DMFC (Direct Methanol Fuel Cell) were impregnated on several carbon supports and their catalytic activities were evaluated with cyclic voltammograms of methanol electro-oxidation. To increase the activities of the Pt/C catalyst, carbon supports with high electric conductivity such as mesoporous carbon, carbon nanofiber, and carbon nanotube were employed. The Pt/e-CNF (etched carbon nanofiber) catalyst showed higher maximum current density of and lower on-set voltage of 0.54 V vs. NHE than the Pt/Vulcan XC-72 in methanol oxidation. Although the carbon named by CNT (carbon nanotube) series turned out to have larger BET surface area than the carbon named by CNF (carbon nanofiber) series, the Pt catalysts supported on the CNT series were less active than those on the CNF series due to their lower electric conductivity and lower availability of pores for Pt loading. Considering that the BET surface area and electric conductivity of the e-CNF were similar to those of the Vulcan XC-72, smaller Pt particle size of the Pt/e-CNF catalyst and stronger metal-support interaction were believed to be the main reason for its higher catalytic activity.
        4,000원
        51.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Pt-Ru/Carbon as an anode catalyst supported on the commercial activated carbon (AC) having high surface area and micropore was characterized for application of Direct Methanol Fuel Cell (DMFC). The Pt-Ru/AC anode catalyst used in this experiment showed the performance of 600 mA/cm2 current density at 0.3 V. The borohydride reduction process using NaBH4, denoted as a process A, showed much higher current and power densities than process B prepared by changing the reduction and washing process of process A. The particle sizes are strongly affected by the reduction process than the specific surface area of raw active carbon and the sizes are almost constant when the specific surface area of carbon are over than the 1200 m2/g. Smaller particle size of catalyst and more narrow intercrystalite distance increased the performance of DMFC.
        4,000원
        56.
        2001.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        상부전극, Pt, Ir, 그리고 IrO2, 에 따라 수소 열처리전과 후, 그리고 회복열처리시 누설전류특성을 고찰하였다. Pt/PLZT/Pt 케페시터는 수소열처리 후에 다시 회복열처리를 수행하면 완전히 이력곡선의 회복을 보이며 또한 피로특성도 거의 회복 된다. Pt과 IrO2 상부전극의 경우의 진 누설전류 특성은 열처리조건에 관계없이 강한 시간 의존성을 갖는 space-charge influenced injection모델에 적합하다. 반면에 Ir 상부전극의 경우는 Ir과 PLZT 사이의 계면에 헝성된 전도성 상인 IrO2로 인해 높은 누설전류 밀도를 보이면서 relaxation current 영역이 없이 steady state 영역을 보이는, 주로 Schottky barrier 모델에 의해 설명된다.
        3,000원
        58.
        2000.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        고분자전해질형 연료전지에서 촉매의 활성을 증가시키기 위하여 기존에 사용되고 있는 백금과 전이금속인 chromium, nickel과의 합금을 제조하였다. XRD를 이용하여 합금의 구조가 33˚에서 superlattice line을 가지고 있는 것으로 보아 face centered cubic 구조를 가진 ordered alloy로 이루어졌다는 것을 알 수 있었다. 열처리 온도가 증가할수록 합금의 입자 크기는 증가하였으며, 결정 격자 상수는 감소하였다. 전지성능테스트, cyclic voltammogram 등을 통하여 mass activity, specific activity, Tafel slope, 개회로 전압을 측정한 결과, 합금촉매의 활성이 순수한 백금촉매보다 크게 향상되었음을 알 수 있었다.
        4,000원
        59.
        2000.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Electrochemical promotion of the reaction rate was investigated for CO oxidation in a solid electrolyte catalytic reactor where a thin film of Pt was deposited on the yttria stabilized zirconia as an electrode as well as a catalyst. It was shown under open circuit condition that potential was a mixed potential of O2exchange reaction and electrochemical reaction induced by CO. The effect of electrochemical modification on the CO oxidation rate was studied at various overpotentials and PCOPO2.
        4,000원
        60.
        2000.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        전자싸이클로트론공명-플라즈마 화학기상증착법으로 PbTiO3박막을 증착하였다. RuO2 기판과 Pt 기판 위에 금속유기화합물 원료기체 유량 및 증착온도에 따라서 PbTiO3박막의 증착특성을 연구하였다. RuO2 기판 위에서 Pt 기판에 비하여 Pb-oxide 분자의 잔류시간이 상대적으로 크고, 페로브스카이트 핵생성 밀도는 상대적으로 작으며, 단일한 페로브스카이트 상의 PbTiO3 박막을 얻을 수 있는 공정범위가 Pt 기판보다 좁았다. PbTiO3 박막 증착 전 Ti-oxide 씨앗층을 도입함으로써 RuO2 기판에서도 페로브스카이트 핵생성 밀도를 증가시켜 단일한 페로브스카이트 박막을 얻을 수 있는 공정범위가 확장되었다. PbTiO3에서 Ti 성분을 Zr으로 일부 대체시킨 Pb(Zr,Ti)O3 (PZT) 박막의 경우에도 Ti-oxide 씨앗층을 도입함으로써 넓은 공정범위에서 단일한 페로브스카이트 PZT 박막을 RuO2기판 위에서도 제조할 수 있었다.
        4,000원
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