• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.271-277
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• 2014

To overcome the limitations of the solid oxide fuel cells (SOFCs) due to the high temperature operation, there has been increasing interest in proton conducting fuel cells (PCFCs) for reduction of the operating temperature to the intermediate temperature range. In present work, the perovskite $BaCe_{0.85-x}Zr_xY_{0.15}O_{3-\delta}$ (BCZY, x = 0.1, 0.3, 0.5, and 0.7) were synthesized via solid state reaction (SSR) and adopted as an electrolyte materials for PCFCs. Powder characteristics were examined using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer, Emmett and Teller (BET) surface area analysis. Single phase BCZY were obtained in all compositions, and chemical stability was improved with increasing Zr content. Anode-supported cell with $Ni-BaCe_{0.55}Z_{0.3}Y_{0.15}O_{3-\delta}$ (BCZY3) anode, BCZY3 electrolyte and BCZY3-$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-\delta}$ (BSCF) composite cathode was fabricated and electrochemically characterized. Open-circuit voltage (OCV) was 1.05 V, and peak power density of 370 ($mW/cm^2$) was achieved at $650^{\circ}C$.

• Progress in Superconductivity
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• v.12 no.1
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• pp.6-11
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• 2010

The milling effects of a precursor $Y_2BaCuO_5$ (Y211) powder having 1 wt.% $CeO_2$ on the microstructure and critical current density ($J_c$) of liquid infiltration growth (LIG) processed $YBa_2Cu_3O_{7-y}$ (Y-123) bulk superconductors were investigated. The microstructure analysis revealed that the Y211 size in the final Y-123 products decreased with increasing the milling time and a relatively high density and uniform distribution of Y211 inclusions were observed in the sample prepared using 8 h milled powder. However, the unexpected Y211 particles coarsening was observed from the 4 h milled sample which was further increased for 10 h milled sample. Critical current density ($J_c$) of the LIG processed Y-123 bulk superconductors was found to be dependent on the milling time of the Y211 precursor powder. The $J_c$ increased with the increase of milling time and reached up to a maximum at 8 h in the self field while 10 h milled sample showed lower $J_c$ at the same field which might be due to the exaggerated growth and non-uniform distribution of Y211 particles.

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.85-85
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• 2007

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.648-653
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• 2012

Hybridization of dense ceramic membranes for hydrogen separation with an electronically conductive metallic phase is normally utilized to enhance the hydrogen permeation flux and thereby to increase the production efficiency of hydrogen. In this study, we developed a nickel and proton conducting oxide ($BaCe_{0.9}Y_{0.1}O_{3-{\delta}}$: BCY) based cermet (ceramic-metal composites) membrane. Focused on the general criteria in that the hydrogen permeation properties of a cermet membrane depend on its microstructural features, such as the grain size and the homogeneity of the mix, we tried to optimize the microstructure of Ni-BCY cermets by controlling the fabrication condition. The Ni-BCY composite powder was synthesized via a solid-state reaction using $2NiCO_3{\cdot}3Ni(OH)_2{\cdot}4H_2O$, $BaCeO_3$, $CeO_2$ and $Y_2O_3$ as a starting material. To optimize the mixing scale and homogeneity of the composite powder, we employed a high-energy milling process. With this high-energy milled composite powder, we could fabricate a fine-grained dense membrane with an excellent level of mixing homogeneity. This controlled Ni-BCY cermet membrane showed higher hydrogen permeability compared to uncontrolled Ni-BCY cermets created with a conventionally ball-milled composite powder.

• Journal of the Korean Ceramic Society
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• v.21 no.4
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• pp.373-381
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• 1984

The coloration of the $Nd_2O_3$ contained $R_2O-BaO-SrO-ZrO_2-SiO_2$ glass added the various amount of $CeO_2$ $MnO_2$, $Fe_2O_3$ and $As_2O_3$ alone or together by the irradiation of X-ray irradiation,. The glasses added $CeO_2$ in proportion to amount were more effective on preventing coloration by X-ray irradiation but the addition of $MnO_2$ produced different color according to the amount of addition. The addition of the $Fe_2O_3$, $TiO_2$ and $As_2O_3$ did not give much effects to the transmission changes of $Nd_2O_3$ contained glass by X-ray irradiation but the glass added $CeO_2$ , $Fe_2O_3$, $TiO_2$ together was most effective to prevent coloration and transmisson changes.

• ETRI Journal
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• v.14 no.4
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• pp.228-235
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• 1992

EMI 필터는 주로 디지틀기기에서 불요복사를 방지하기 위한 목적으로 사용되는 대표적인 노이즈 대책부품으로 이러한 필터에 사용되는 세라믹 유전체는 온도 및 주파수 특성이 안정해야 한다. 새로운 EMI 필터용 세라믹 유전체를 개발하기 위하여 신조성인 BaO-$Nd_2$$O_3$-$CeO_2$-$TiO_2$계를 선정하고, 소결 온도 범위 $1240~1300^{\circ}C$및 $SiO_2$ 첨가량에 따라 이들 변수들이 유전체 특성에 미치는 영향을 분석하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.499-502
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• 2002

We synthesized Y$\sub$1.8/Ba$\sub$2.4/Cu$\sub$3.4/O$\sub$x/(Y123+Y211+1wt% CeO$_2$) powders using Polymeric Complex method and used raw materials; Y$_2$O$_3$, BaCO$_3$, CuO and CeO$_2$. It was formed by calcination at 850 $^{\circ}C$ for 24h in air. In comparison of solid-state method, sol-gel method etc., synthesis temperature decreased up to 100$^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.424-424
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• 2013

Ce3+, Sm3+, Eu3+, Tb3+ 등 희토류를 도핑한 여러 종류의 형광체는 백색 LED (white light-emitting diode), 전계방출표시소자(field emission display), 플라즈마디스플레이패널(plasma display panel), 약물 운송(drug delivery) 등 다양한 분야에서 응용되고 있다. 최근에는 졸-겔 방법(sol-gel method)을 이용하여Y2SiO5, Y3-XGdxAl5O12, SrAl2O4 등 여러 종류의 호스트 물질을 합성하여 형광체의 특성을 분석하는 연구가 활발히 진행되고 있다. 이러한 졸-겔 방법은 비교적 낮은 온도에서 간단한 공정으로 좋은 균질성과 높은 생산성을 갖도록 형광체를 제작할 수 있는 장점을 가지고 있다. 이에 본 연구에서는 졸-겔 방법을 이용하여 BaGd2TiO13구조를 제작하였고, 이러한 구조적, 광학적 특성을 분석하기 위하여 열분석기(thermal analyzer), 전계방출형주사전자현미경(field emission scanning electron microscopy), 투과전자현미경(field emission transmission electron microscopy)을 이용하였다. 이러한 졸-겔 방법을 이용하여 제작한 BaGd2TiO13 구조의 형광체 적용 연구를 통한 디스플레이 및 백색 LED 응용에 유용할 것으로 기대된다.

• Progress in Superconductivity and Cryogenics
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• v.13 no.1
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• pp.1-5
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• 2011

[ $CeO_2$ ]has been widely used for single buffer layer of coated conductor because of superior chemical and structural compatibility with $ReBa_2Cu_3O_{7-{\delta}}$(Re=Y, Nd, Sm, Gd, Dy, Ho, etc.). But, the surface of $CeO_2$ layer showed cracks because of the large difference in thermal expansion coefficient between metal substrate and deposited $CeO_2$ layer, when thickness of $CeO_2$ layer exceeds 100 nm on the biaxially textured Ni-3%W substrate. The deposition rate has been limited to be less than 6 $\AA$/sec in order to get a good epitaxy. In this research, we deposited $CeO_2$ single buffer layers on biaxially textured Ni-3%W substrate with 2-step process such as thin nucleation layer(>10 nm) with low deposition rate(3 $\AA$/sec) and thick homo epitaxial layer(>240 nm) with high deposition rate(30 $\AA$/sec). Effect of deposition temperature on degree of texture development was tested. Thick homo epitaxial $CeO_2$ layer with good texture without crack was obtained at $600^{\circ}C$, which has ${\Delta}{\phi}$ value of $6.2^{\circ}$, ${\Delta}{\omega}$ value of $4.3^{\circ}$ and average surface roughness(Ra) of 7.2 nm within $10{\mu}m{\times}10{\mu}m$ area. This result shows the possibility of preparing advanced Ni substrate with simplified architecture of single $CeO_2$ layer for low cost coated conductor.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.56.1-56.1
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• 2009

The intermediate operating temperature of solid oxide fuel cells (IT-SOFCs) have achieved considerable importance in the area of power fabrication. This is because to improve materials compatibility, their long-term stability and cost saving potential. However, to conserve rational cell performance at reduced-temperature regime, cathode performance should be obtained without negotiating the internal resistance and the electrode kinetics of the cell. Recently, double perovskite structure cathodes have been studied with great attention as a potential material for IT-SOFCs. In this study, double-perovskite structured cathodes of $GdBaCoCuO_{5+\delta}$, $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ compositions and $(1-x)GdBaCo_2O_{5+\delta}+xCe_{0.9}Gd_{0.1}O_{1.95}$ (x = 10, 20, 30 and 40 wt.%) composites were evaluated as the cathode for intermediate temperature solid oxide fuel cells(IT-SOFCs). Electrical conductivity of the cathodes were measured by DC 4-probe method, and the thermal expansion coefficient of each sample was measured up to $900^{\circ}C$ by a dilatometer study. Area specific resistances(ASR) of the $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ cathode and 70 wt.% $GdBaCo_2O5+\delta$ + 30wt.% Ce0.9Gd0.1O1.95 composite cathode on CGO electrolyte substrate were analyzed using AC 3-probe impedance study. The obtained results demonstrate that double perovskite-based compositions are promising cathode materials for IT-SOFCs.