• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.114-120
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• 2012

In this research, we prepared Ga doped zinc oxide(ZnO:Ga, GZO) targets each difference sintering temperature $700^{\circ}C$, $800^{\circ}C$, and doping rate 1 wt.%, 2 wt.%, 3 wt.%. The characteristics of thin film on glass substrates which deposited by facing target sputtering in pure Ar atmosphere are reported. Ga doped zinc oxide film is attracted material through low resistivity, high transmittance, etc. When prepared target powder's structure was investigated by scanning electron microscope, densification and coarsening by driving force was observed. For each ZnO:Ga films with a $Ga_2O_3$ content of 3 wt.% at input power of 45W, the lowest resistivity of $9.967{\times}10^{-4}{\Omega}{\cdot}cm$ ($700^{\circ}C$) and $9.846{\times}10^{-4}{\Omega}{\cdot}cm$ ($800^{\circ}C$) was obtained. the carrier concentration and mobility were $4.09{\times}10^{20}cm^{-3}$($700^{\circ}C$), $4.12{\times}10^{20}cm^{-3}$($800^{\circ}C$) and $15.31cm^2/V{\cdot}s(700^{\circ}C)$, $12.51cm^2/V{\cdot}s(800^{\circ}C)$, respectively. And except 1 wt.% Ga doped ZnO thin film, average transmittance of these samples in the range 350-800 nm was over 80%.

• 한국산학기술학회논문지
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• 제15권11호
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• pp.6952-6957
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• 2014

광촉매 반응에서 $TiO_2$에 금속물질을 첨가하면 촉매표면이 변화되며, 이러한 금속물질은 광분해반응의 속도를 증가시킨다. 본 연구에서는 $TiO_2$ 광촉매의 광분해능력을 향상시키기 위해 다양한 방법을 이용하여 개질하였으며, 개질된 광촉매의 광분해특성은 회분식 광반응기를 이용하여 조사하였다. 우수한 $TiO_2$ 광촉매용액을 얻기 위해 여러 종류의 분산제와 안정제를 조사하였으며, 분산제로는 isoproply alcohol, 안정제로는 sodium silicate가 적합하였다. 톨루엔 분해반응을 향상시키기 위해 다양한 금속물질을 $TiO_2$ 광촉매에 첨가하여 광분해효율을 조사한 결과 Pd가 가장 우수하였으며, Cu와 W도 우수하였다. Pd를 첨가한 경우 25%의 제거효율 향상이 있었다. 그러나 Fe의 경우 광촉매분해반응을 상당히 저해하는 것으로 나타났다. $Pd/TiO_2$ 광촉매에 Cu 또는 W를 부가적으로 첨가하여도 촉매의 광분해효율에는 증가가 없었다.

• 한국세라믹학회지
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• 제45권5호
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• pp.276-279
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• 2008

In this research, properties of $N_2$-doped $Sb_2Te_3$ thin film were evaluated using 4-point probe, XRD and AFM. $Sb_2Te_3$ material has faster crystallization rate than $Ge_2Sb_2Te_5$, but sheet resistance difference between amorphous and crystallization state is very low. This low sheet resistance difference decreases sensing margin in reading operation at PRAM device operation. Therefore, in order to overcome this weak point, $N_2$ gas was doped on $Sb_2Te_3$ thin film. Sheet resistance difference between amorphous and crystallized state of $N_2$-doped $Sb_2Te_3$ thin film showed about $10^4$ times higher than Un-doped $Sb_2Te_3$ thin film because of the grain boundary scattering.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.352-360
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• 2020

Lithium cobalt oxide (LiCoO₂, LCO) has been widely used as a cathode material for Li-ion batteries (LIBs) owing to its excellent electrochemical performance and highly reproducible synthesis even with mass production. To improve the energy density of the LIBs for their deployment in electro-mobility, the full capacity and voltage of the cathode materials need to exploited, especially by operating them at a higher voltage. Herein, we doped LCO with divalent calcium-ion (Ca²⁺) to stabilize its layered structure during the batteries' operation. The Ca-doped LCO was synthesized by two different routes, namely solid-state and co-precipitation methods, which led to different average particle sizes and levels of dopant's homogeneity. Of these two, the solid-state synthesis resulted in smaller particles with a better homogeneity of the dopant, which led to better electrochemical performance, specifically when operated at a high voltage of 4.5 V. Electrochemical simulations based on a single particle model provided theoretical corroboration for the positive effects of the reduced particle size on the higher rate capability.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.98-98
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• 1999

Highly transparent and conducting tin-doped indium oxide (ITO) films were deposited on polycarbonate substrate by ion-assited deposition. Low substrate temperature (<10$0^{\circ}C$) was maintained during deposition to prevent the polycarbonate substrate from be deformed. The influence of ion beam energy, ion current density, and tin doping, on the structural, electrical and optical properties of deposited films was investigated. Indium oxide and tin-doped indium oxide (9 wt% SnO2) sources were evaporated with assisting ionized oxygen in high vacuum chamber at a pressure of 2$\times$10-5 torr and deposition temperature was varied from room temperature to 10$0^{\circ}C$. Oxygen gas was ionized and accelerated by cold hallow-cathode type ion gun at oxygen flow rate of 1 sccm(ml/min). Ion bea potential and ion current of oxygen ions was changed from 0 to 700 V and from 0.54 to 1.62 $\mu$A. The change of microstructure of deposited films was examined by XRD and SEM. The electrical resistivity and optical transmittance were measured by four-point porbe and conventional spectrophotometer. From the results of spectrophotometer, both the refractive index and the extinction coefficient were derived.

• 분석과학
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• 제14권3호
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• pp.259-265
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• 2001

ZnO, CdS, rutile-$TiO_2$ 및 혼합 rutile-$TiO_2$/ZnO와 같은 여러 반도체를 이용하여 Congo Red를 광 촉매 분해시켰다. 연구 결과 ZnO, CdS, rutile-$TiO_2$ 중에서는 CdS의 광 촉매 효과가 제일 컸는데 이것은 CdS가 제일 작은 band gap 에너지를 가지고 있기 때문이었다. 또한 혼합 촉매에서는 ZnO의 함량이 rutile-$TiO_2$에 비하여 상대적으로 높을수록 분해 반응을 촉진하였다. 이것은 $Zn^{2+}$ 가수분해 생성물이 구조적으로 안정한 화합물인 rutile-$TiO_2$의 표면을 덮음으로서 자외선 흡수를 차단하기 때문에 라디칼 생성을 저해하기 때문이었다.

• 한국분말재료학회지
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• 제20권6호
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• pp.474-478
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• 2013

The most general photocatalyst, $TiO_2$ and $WO_3$, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with $TiO_2$ and $WO_3$. In the $TiO_2-WO_3$ composite, $WO_3$ absorbs visible light creating excited electrons and holes while some of the excited electrons move to $TiO_2$ and the holes remain in $WO_3$. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor, retarding the recombination rate of excited electrons and holes. In making a mixture of $TiO_2-WO_3$ composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of $TiO_2(4)$ and $WO_3(6)$ shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.

• 한국세라믹학회지
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• 제30권5호
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• pp.397-403
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• 1993

Widely used dielectrics, barium titanate was promising material for ceramic capacitor. It was produced by specific formulation with various dopants-La2O3, ZrO2, SnO2, CaZrO3, CaTiO3, CaSnO3, Bi2O3, and etc.-according to demanded properties of capacitor. In this study, we would examinate the study of dielectric properties and temperatuer characteristics (T.C.) with the amount of Bi2O3. The sample was prepared with [BaTiO3]10＋[BaZrO3, SnO2, La2O3, ZrO2]10 and Bi2O3 varied from 1.0, 1.5, 2.0, 2.5 to 3.0wt%. After milling and mixing for 15hrs, each sample was dried and then pressed at 700kg/$\textrm{cm}^2$ into pellets. Pellets were fired at 131$0^{\circ}C$, for 3hrs in air. As the result of measurements, dielectric constant, break down voltage, and insulation resistance were increased with the amount of Bi2O3, and the resonant frequency was shifted from high frequency to low frequency range. In the case of temperature characteristics, capacitance change rate was symmetrically changed at -$25^{\circ}C$ and ＋85$^{\circ}C$ respectively. Therefore, it is recognized that the temperature characteristics can be moderated with doping Bi2O3 in our study.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.399-402
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• 2002

This paper is researched that electric characteristic of Digital x-ray radiography technique with changing composition ratio of Iodine. Dopant material, Iodine is evaporated with amorphous selenium. Thorugh the old papers say, doponted Iodine will be down the created trap level because of Arsenic dopant material in amorphous selenium. Arsenic material of Composition ratio in amorphous selenium is fixed with 0.3% and test sample is deposited composition of 30, 100, 300, 500, 700ppm with thermal evaporate system. Experimental measurement is performed by dark current and x-ray sensitivity in amorphous selenium based radition detector sensor. Fabricated test sample thickness is $30{\mu}m$ and injected voltage is $3{\mu}m$，$6{\mu}m$，$9{\mu}m$ to both electrode. Experimental results showed that the net charge of composition rate of 30ppm is 398.88 pc/mR/$cm^2$ very high. And increase of the Iodine composition ratio is tendency to the decrease of net charge. Doping changing composition of Iodine in amorphous selenium detector offered to basical information of amorphous selenium material.

• 한국재료학회지
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• 제30권1호
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• pp.14-21
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• 2020

Carbon supports for dispersed platinum (Pt) electrocatalysts in direct methanol fuel cells (DMFCs) are being continuously developed to improve electrochemical performance and catalyst stability. However, carbon supports still require solutions to reduce costs and improve catalyst efficiency. In this study, we prepare well-dispersed Pt electrocatalysts by introducing titanium dioxide (TiO₂) into biomass based nitrogen-doped carbon supports. In order to obtain optimized electrochemical performance, different amounts of TiO₂ component are controlled by three types (Pt/TNC-2 wt%, Pt/TNC-4 wt%, and Pt/TNC-6 wt%). Especially, the anodic current density of Pt/TNC-4 wt% is 707.0 mA g^-1_pt, which is about 1.65 times higher than that of commercial Pt/C (429.1 mA g^-1_pt); Pt/TNC-4wt% also exhibits excellent catalytic stability, with a retention rate of 91 %. This novel support provides electrochemical performance improvement including several advantages of improved anodic current density and catalyst stability due to the well-dispersed Pt nanoparticles on the support by the introduction of TiO₂ component and nitrogen doping in carbon. Therefore, Pt/TNC-4 wt% may be electrocatalyst a promising catalyst as an anode for high-performance DMFCs.