• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1786-1790
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• 2007

The $(SrCa)TiO_3(SCT)$ thin films are deposited on Pt-coated electrode ($Pt/TiN/SiO_2/Si$) using RF sputtering method at various deposition temperature. The dielectric constant of SCT thin films were increased with the increase of deposition temperature, and changed almost linearly in temperature ranges of $-80{\sim}+90[^{\circ}C]$. Also, SCT thin films was observed the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency was observed above 200[kHz]. V-I characteristics of SCT thin films show the increasing leakage current with the increases of deposition temperature. The conduction mechanism of the SCT thin films observed in the temperature range of $25{\sim}100[^{\circ}C]$ can be divided into three characteristic regions with different mechanism by the increasing current. The region 1 below 0.8[MV/cm] shows the ohmic conduction. The region 2 can be explained by the Child's law, and the region 3 is dominated by the tunneling effect.

• Journal of Powder Materials
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• v.19 no.1
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• pp.6-12
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• 2012

Electricity is generated by the combined reactions of hydrogen oxidation and oxygen reduction which occur on the Pt/C catalyst surface. There have been lots of researches to make high performance catalysts which can reduce Pt utilization. However, most of catalysts are synthesized by wet-processes and a significant amount of chemicals are emitted during Pt/C synthesis. In this study, Pt/C catalyst was produced by arc plasma deposition process in which Pt nano-particles are directly deposited on carbon black surfaces. During the process, islands of Pt nano-particles were produced and they were very fine and well-distributed on carbon black surface. Compared with a commercialized Pt/C catalyst (Johnson & Matthey), finer particle size, narrower size distribution, and uniform distribution of APD Pt/C resulted in higher electrochemical active surface area even at the less Pt content.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.263-270
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• 2000

The Pt/copper oxide/n-Si electrodes were fabricated by depositing copper oxide thin film of 500${\AA}$ and very thin Pt layer on the n-type (100) Si substrate. hotoelectrochemical properties and stability profiles of the electrodes were investigated as a function of deposition time of Pt layer. As the deposition time of Pt layer increased up to 10 seconds, the photocurrent and quantum efficiency were increased and then decreased with further depositing time. The better cell stability was observed for the electrode with longer deposition time. The improvements in above photoelectrochemical properties indicate that Pt layer acts as a catalyst layer at electrode/electrolyte interface as well as a protective layer. The decreasing tendency of the photocurrent and efficiency for the electrode with Pt layer deposited above 20 seconds was explained as an increases in probbility of electron-hole pair recombination and also the absorbing photon loss at electrode surface due to the excessive thickness of Pt layer. The results were confirmed by impedance spectroscopy, mutiple cycle voltammograms and microstructural analyses.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1048-1054
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• 1998

The effects of deposition temperature of Pt top electrodes on the electrical properties of Pb(Zr,Ti))$O_3$, (PZT) thin film were investigated. When the Pt top electrodes were deposited at substrate temperatures of $200^{\circ}C$ or above,the ferroelectric properties of the PZT thin film under the Pt electrode were severely degraded. Whereas those of the PZT film where the Pt electrodes were not deposited were not degraded. Water vapors which remained in the vacuum chamber were dissociated into hydrogen atoms by the catalysis of Pt top electrode, and those hydrogen atoms diffused into the PZT film and produced oxygen vacancies at high substrate temperature, resulting in the degradation of the ferroelectric properties of the PZT film located under the Pt electrode. Since the water vapors could not be dissociated into hydrogen atoms without the catalysis of Pt. the degradation of the PZT film did not take place where the Pt electrode were not deposited. The degraded feroelectric properties could be recovered by rapid thermal annealing (RTA) treatment. On the other hand. leakage current characteristics were improved with increasing the deposition temperature of Pt top electrodes.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.261-261
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• 2013

The smart design of nanocatalysts can improve the catalytic activity of transition metals on reducible oxide supports, such as titania, via strong metal-support interactions. In this work, we investigatedtwo-dimensional Pt nanoparticle/titania catalytic systems under the CO oxidation reaction. Arc plasma deposition (APD) and metal impregnation techniques were employed to achieve Pt nanoparticle deposition on titania supports, which were prepared by multitarget sputtering and sol-gel techniques. APD Pt nanoparticles with an average size of 2.7 nm were deposited on sputtered and sol-gel-prepared titania films to assess the role of the titania support on the catalytic activity of Pt under CO oxidation. In order to study the nature of the dispersed metallic phase and its effect on the activity of the catalytic CO oxidation reaction, Pt nanoparticles were deposited in varying surface coverages on sputtered titania films using arc plasma deposition. Our results show an enhanced activity of Pt nanoparticles when the nanoparticle/titania interfaces are exposed. APD Pt shows superior catalytic activity under CO oxidation, as compared to impregnated Pt nanoparticles, due to the catalytically active nature of the mild surface oxidation and the active Pt metal, suggesting that APD can be used for large-scale synthesis of active metal nanocatalysts.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.05a
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• pp.90-90
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• 1998

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.214-214
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• 2010

The 0.65Pb($Mg_{1/3}Nb_{2/3})O_3-0.35PbTiO_3$ (PMN-PT) thin films with $La_{0.5}Sr_{0.5}CoO_{3-\delta}$ (LSCO) bottom electrodes were grown on $CeO_2$/YSZ/Si(001), Pt/$TiO_2$/Si and $SrTiO_3$ (STO) substrates using conventional pulsed laser deposition (PLD) at a substrate temperature of $550^{\circ}C$. Since generally the crystallographic orientation of the bottom electrode induces the orientation of the films deposited on it, it allows us to observe the influence of the PMN-PT film orientation on the electrical properties. Phi scan done on PMN-PT/LSCO thin films shows epitaxial behavior of the films grown on sto substrates and $CeO_2$/YSZ buffered Si(001) substrates, and (110) texture on Pt/$TiO_2$/Si substrates. Polarization-electricfield (P-E) measurement shows good hysteresis behavior of PMN-PT films with remnant polarization of 18.2, 8.8, and $4.4{\mu}C/cm^2$ on $CeO_2$/YSZ/Si, Pt/TiO2/Si and STO substrates respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.146.2-146.2
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• 2010

PEMFC를 구성하는 여러 부품 중 핵심부품은 MEA(Membrane Electrode Assembly)으로서 실제 연료전지 반응이 일어나며 연료전지의 성능을 결정하는 부품이다. 그러나 PEMFC의 특성 상 촉매로 귀금속인 Pt가 사용됨에 따라 경제성이 확보된 MEA의 성능을 얻기 위해선 현재 Pt 담지량을 0.3mg/$cm^2$ 이하로 크게 감소시키면서 Pt촉매의 고분산화와 미반응 사이트의 감소가 필요하다. 본 연구에서는 Pt 촉매의 미반응 사이트를 줄이고자 전기영동법에 의해 카본전극(carbon black + GDL) 상에 Pt 나노입자를 직접 석출시켜 Pt/C 촉매 전극을 제조 하였다. 본 실험에서는 가장 좋은 Pt 나노입자의 석출거동을 나타낸 30mA/$cm^2$, pH 2, duty cycle 25% 조건을 기준으로 하여 electro-deposition time을 통한 석출량 제어와 carbon paper의 wet proofing 정도에 따른 Pt의 석출거동을 조사하였으며, 종래의 방법으로 제조한 Pt/C 촉매전극의 전기화학적 특성과 비교 분석하였다. 전기영동 석출법에 사용된 Pt나노입자는 $H_2PtCl_6{\cdot}6H_2O$로부터 화학적 환원법으로 합성한 2~3nm 입경을 갖는 Pt콜로이드를 사용하였으며, magnetic stirring과 항온 ($20^{\circ}C$)을 유지하여 실험하였다. 전기영동 석출량 제어는 electro-deposition time을 5~25분까지 5분 간격으로 나누어 실험하였고 카본전극을 구성하는 carbon paper의 wet proofing 정도가 Pt 나노입자 석출거동에 미치는 영향을 조사하기 위하여 20, 40, 60%의 서로 다른 wet proofing 값을 갖는 carbon paper를 사용하여 Pt/C 촉매 전극을 제조하였다. 전기영동법으로 석출된 카본블랙 전극 상 Pt나노입자의 분산도와 담지량는 각각 FE-SEM과 TGA 장비를 사용하여 측정하였고, 제조된 Pt/C 촉매 전극의 전기화학적 촉매 특성은 cyclic voltammetry(CV)법으로 측정하였다.

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.343-347
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• 2007

Fe thin films exhibited (100) preferential orientation when they were deposited at low deposition rate of $0.1{\AA}/s$ on glass substrates by using facing target sputtering system. The (100) oriented Fe layer induces (100) orientation of Pt layer deposited on it owing to hetero-epitaxial growth. After annealing at $600^{\circ}C$ in $H_2$ atmosphere, FePt films exhibited f.c.t. (001) texture in the whole film caused by inter-diffusion between atoms. We have also confirmed that the homogeneously inter-diffused compositional modulation in the film after the annealing process. Furthermore, annealing process in $Ar+H_2$ atmosphere at $400^{\circ}C$ during Pt deposition was effective for attaining Pt (100) texture. The annealing process during Pt deposition also induced in low annealing temperature and decreased annealing time for attaining the FePt f.c.t. (001) structure.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.394-394
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• 2016

The oxygen reduction reaction (ORR) in a polymer electrolyte membrane (PEM) fuel cell requires the use of Pt-based catalysts. Due to the high cost and low abundance of Pt, many researchers have been studied to reduce the use of Pt while to enhance the catalytic performance of Pt. One of the promising strategies is the deposition of Pt as ultrathin skins of only a few atomic layers on nanoscale substrates made of another metal. This presentation will discuss the conformal deposition of Pt as uniform, ultrathin shells on Pd nanocrystals. By optimizing the catalytic behavior of Pt-based nanocrystals, we obtained the greatly enhanced ORR activity and durability.