• Korean Chemical Engineering Research
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• 제45권2호
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• pp.124-132
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• 2007

본 논문에서는 Ti 모재에 대한 Pt 도금 특성 연구를 통하여 안정한 platinized Ti 전극의 제조 방법이 제시되었으며, Sn이 흡착된 platinized Ti 전극의 질산염 이온에 대한 전기화학적 특성이 연구되었다. 에칭된 Ti 모재 표면에 전착된 Pt 도금 층 내에 적당하게 공간적 틈을 갖도록 도금하는 것은 도금 후 표면에 잔존하는 도금 용액 오염원을 제거하는데 효과적이며, 또 용액과 접하게 되는 전극의 실제 표면적을 최대화할 수 있었다. 제작된 platinized Ti 전극을 끓이는 과정과 전해 세정 과정을 통해 안정적이며 재현성 있게 만드는 것은 Sn-modified platinized Ti 전극에서 표면의 Sn 덮힘율을 정량화하는데 있어 매우 중요하였다. 전해 세정 과정은 전극 표면에 형성된 솜털과 같은 미세한 돌기들이 없어지면서 전극 표면을 안정화된 구조로 변화시켰다. 본 연구의 경우 질산염 이온의 환원을 목적으로 하는 Sn-modified platinized Ti 전극은 약 30분 도금 시간을 통해 제조한 경우가 가장 좋았다.

• Journal of Photoscience
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• 제1권1호
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• pp.31-37
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• 1994

Photoirradiation at > 300 nm onto a suspension of platinized TiO$_2$ (TiO$_2$-Pt) particles in an aqueous solution. of N$_{\varepsilon}$-carbamyI-L-lysine (Lys(CONH)$_2$) induced the selective N-cyclization of Lys(CONH$_2$) into almost optically pure L-pipecolinic acid (PCA) under argon atmosphere at ambient temperature. Among various TiO$_2$-Pt catalysts, a P-25 (Degussa) powder platinized via impregnation from chloroplatinic acid followed by hydrogen reduction at 753 K exhibited the highest photocatalytic activity for Lys(CONH$_2$) consumption and L-PCA production. GC-MS analyses of L-PCA obtained photocatalytically from $^{15}$N$\alpha$-Lys(CONH$_2$) revealed the selective formation $^{15}$N-substituted L-PCA. This implies that the mechanism for L-PCA production contains selective cleavage of C$_{\varepsilon}$-N bond and intramolecular alkylation at $\alpha$-amino group. Effect of pH on the rate of this photocatalytic reaction was investigated in detail and compared with the pH-dependent charge distribution in Lys(CONH$_2$) molecule. It is clarified that protonation-deprotonation of $\alpha$-amino group gives marked influence on the rate and selectivity of the photocatalytic reaction. On the basis of these results, it is concluded that the selective production of optically pure L-PCA, especially in an acidic suspension of TiO$_2$-Pt, was attributed to the enhanced protonation of $\alpha$-amino group to prevent undesirable oxidation by photogenerated positive holes and blocking of $\varepsilon$-amino group to yield racemic Schiff base intermediate.

• Bulletin of the Korean Chemical Society
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• 제18권1호
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• pp.56-61
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• 1997

Lead zirconate titanate (PZT) thin fills were deposited onto the Pt/Ti/SiO2/Si substrate by the pulsed laser deposition with the second harmonic wavelength (532 nm) of Nd:YAG laser. In order to determine the optimum conditions for the film deposition, the phase of the films were investigated as functions of ambient oxygen pressure, substrate temperature, and laser fluence. Also the chemical composition analysis was conducted for the PZT films deposited under various ambient oxygen pressure. When the distance between substrate and bulk PZT target is set to 20 mm, the optimum conditions have been determined to be 3 torr of oxygen pressure, 1.5 J/cm2 of laser fluence, and 823-848(±10) K range of substrate temperature. At these conditions, perovskite phase PZT films were obtained on platinized silicon. The chemical composition of the films is very similar to that of PZT bulk target. The physical structure of the deposited films analyzed by scanning electron microscopy shows a columnar morphology perpendicular to the substrate surface. Capacitance-Voltage hysteresis loop measurements show also a typical characteristics of ferroelectric thin film. The dielectric constant is found to be 528 for the 0.48 μm thickness of PZT thin film.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.495-498
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• 2008

Photocatalytic water splitting into $H_2$ and $O_2$ using semiconductors has received much attention, especially for its potential application to direct production of $H_2$ for clean energy from water utilizing solar light energy. Since the report of Fujishima and Honda on the water splitting by photoelectrochemical cells, numerous different semiconducting materials have been used as photocatalysts for hydrogen generation from water. Among them, platinized titania significantly accelerates hydrogen production from water. For geometrical improvement of $TiO_2$ particle, porous $TiO_2$ structure was proposed and studied such as nanofiber, nanorod and nototubes. This research focuses on finding out the optimum temperature and electrolyte to produce $H_2$ by solar water splitting.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1309-1311
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• 1998

$Pb_{1-x}La_xTi_{1-x/4}O_3$ (PLT(x)) thin film has been regarded as one of the most promising materials for applications of sensor, optic devices, and memory devices, because it exhibits various properties as changing the amount of Lanthanum component. So we have prepared PLT thin films on platinized silicon (actually Pt/Ti/$SiO_2$/Si) substrates in oxygen ambient by laser ablation. Energy dispersive X-ray (EDX) revealed that the stoichiometric thin films were fabricated.

• 한국표면공학회지
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• 제33권2호
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• pp.77-86
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• 2000

In this study effects of La starting compounds and substrates on the densification of (P $b_{0.92}$L $a_{0.05}$)Ti $O_3$ thin films were investigated. After the heat treatment on platinized silicon at $650^{\circ}C$ for 30min thickness of PLT(i) thin films (from La-isopropoxide) shrank by 27%, while 33% reduction occurred for PLT (a) thin films (from La-acetate). These PLT(i) films showed less densified surface microstructure compared to the PLT (a) . Lower shrinkage of the films on platinized silicon than on bare silicon (41% and 40% for PLT (i) and PLT (a) respectively) is attributed to the earlier development of crystallinity in the film, which arrests film densification. In order to maximize sintering before crystallization, heat treatment at $400^{\circ}C$ for 3 hours followed by $650^{\circ}C$ for 30 min was attempted. This method increased the shrinkage of the PLT (i) and PLT (a) films two times and 1.5 times as much as that observed for the films heat treated at $650^{\circ}C$ for 30min, respectively. FTIR results indicated that first pyrolysis in the film is associated with the burning of acetate ligands. Condensation reaction between OHs was found to occur preferentially between $350^{\circ}C$ and $450^{\circ}C$, whereas majority of polycondensation between ROH-OH appears to occur until $300^{\circ}C$ and be completed below $450^{\circ}C$.EX>.

• 한국전기전자재료학회논문지
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• 제22권1호
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• pp.29-34
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• 2009

PLZT thin films were deposited on platinized silicon (Pt/$TiSiO_2$/Si) substrate by RF magnetron sputtering. A $TiO_2$ buffer layer was fabricated, prior to deposition of PLZT films. the layer was strongly affected the crystallographic orientation of the PLZT films. X-ray diffraction was performed on the films to study the crystallization of the films as various substrate temperatures (Ts). According to increasing Ts, preferred orientation of films was changed (110) plane to (111) plane. The ferroelectric, dielectric and electrical properties of the films were also investigated in detail as increased substrate temperatures. The PLZT films deposited at $400^{\circ}C$ showed good ferroelectric properties with the remnant polarization of $15.8{\mu}C/cm^2$ and leakage current of $5.4{\times}10^{-9}\;A/cm^2$.

• 한국진공학회지
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• 제9권3호
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• pp.227-232
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• 2000

광소자와 마이크로파 유전체 소자 및 절연 산화막으로의 응용을 위한 $MgTiO_3$ 박막을 펄스레이저 증착법을 이용하여 다양한 기판 위에서 증착하였다. 사파이어 기판에(c-plane Sapphire) 성장된 $MgTiO_3$ 박막은 에피텍셜 성장(epitaxial growth)이 되었으며, $SiO_2$/Si 및 Pt/Ti/$SiO_2$/Si(plantinzed silicon)기판 위에 성장된 $MgTiO_3$ 박막의 경우, 기판과 관계없이 c축 방향으로 배향(oriented)되었다. 사파이어 기판 위에 증착된 $MgTiO_3$ 박막은 가시영역에서 투명하였으며, 약 290 nm 파장을 갖는 영역에서 급격한 흡수단을 보였다. 사파이어 기판 위에 성장된 박막의 AM(Atomic Force Microscopy)분석결과 약 0.87 nm rms roughness 값을 갖는 매우 평탄한 표면상태를 갖고 있음을 확인하였다. MIM(Pt/$MgTiO_3$/Pt) 구조의 캐패시터를 형성시켜 $MgTiO_3$박막의 유전특성 (dielectric properties)을 관찰하였는데, 펄스레이저 증착법으로 성장된 $MgTiO_3$ 박막의 유전율(relative dielectric constant)은 약 24.5였으며, 1 MHz에서 약 1.5%의 유전손실(dielectric loss) 값을 보였다. 또한 이때 $MgTiO_3$박막은 낮은 유전분산을 보였다.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.214-222
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• 2019

Dye-sensitized solar cells (DSSCs) have been receiving growing attentions as a potential alternative to order photovoltaic devices due to their high efficiency and low manufacturing cost. DSSCs are composed of a photosensitizing dye adsorbed on a mesoporous film of nanocrystalline $TiO_2$ as a photoelectrode, an electrolyte containing triiodide/iodide redox couple, and a platinized counter electrode. To improve photovoltaic properties of DSSCs, new dicationic salts based on ionic liquids were synthesized. Quite comparable efficiencies were obtained from electrolytes with new dicationic iodide salts. The best cell performance of 7.96% was obtained with dicationic salt of PBDMIDI.

• Journal of Magnetics
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• 제19권3호
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• pp.227-231
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• 2014

We fabricated textured polycrystalline $CoFe_2O_4$ thin films on $Pt(111)/TiO_2/SiO_2/Si$ substrate through a sol-gel method. We varied the thickness of the films, by using precursor solutions with different concentrations of 0.1, 0.2, and 0.3 M, and by depositing 5, 8, or 10 layers on the substrate by spin-coating. X-ray diffraction spectra indicated that when the precursor concentration of the solution was higher than 0.1 M, the spin-coated films were preferentially oriented in the <111> direction. Inspection of the surface morphology by scanning electron microscopy revealed that $CoFe_2O_4$ thin films prepared with 0.2 M solution and 5-time spin-coatings had smoother surface, as compared to the other conditions. Each coating had an average thickness of about 50 nm. The magnetic properties measured by vibrating sample magnetometer showed magnetic anisotropy, as evidenced from the difference in the in-plane and out-of-plane hysteresis loops, which we attributed to the textured orientation of the $CoFe_2O_4$ thin films.