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  • Title/Summary/Keyword: ZrO_2$

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Preparation and Characterization of Cu/CexZr1xO2 Catalysts for Preferential Oxidation of Carbon Monoxide (일산화탄소의 선택적 산화반응을 위한 Cu/CexZr1xO2 촉매의 합성과 특성분석)

  • Lee, So-Yeon;Lee, Suk-Hee;Cheon, Jae-Kee;Woo, Hee-Chul
    • Clean Technology
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    • v.13 no.1 s.36
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    • pp.54-63
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    • 2007
  • Even traces of CO in the hydrogen-rich feed gas to proton exchange membrane fuel cells (PEMFC) poison the platinum anode electrode and dramatically decrease the power output. In this work, a variety of catalytic materials consisting of Cu/CexZr1xO2, (x = 0.0-1.0) were synthesised, characterized and tested for CO oxidation and preferential oxidation of CO (PROX). These catalysts prepared by hydrothermal and deposition-precipitation methods. The catalysts were characterized by XRD, XRF, SEM, BET, N2O titration and oxygen storage capacity (OSC) measurement. The effects of composition of the support and degree of excess oxygen were investigated fur activity and CO2 selectivity with different temperatures. The composition of the support markedly influenced the PROX activity. Among the various Cu/CexZr1xO2 catalysts having different composition, Cu/Ce0.9Zr0.1O2 and Cu/Ce0.7Zr0.3O2 showed the highest activities (>99%) and selectivities (ca.50%) in the temperature range of 150160C. It was found that by using of CexZr1xO2 mixed oxide support which possesses a high oxygen storage capacity, oxidation-reduction activity of Cu-based catalyst was improved, which resulted in the increase of catalytic activity and selectivity of CO oxidation in excess H2 environments.

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Development of Novel Techniques for Determining the Oxygen Tracer Diffusion Coefficients in Oxides II - Measurements of the Depth Profiles of 18O Concentration in the solid Samples by Raman Spectroscopy (산화물에서의 산소추적자확산계수를 결정하는 새로운 방법의 개발 II - 라만분광법에 의한 고체시료 중의 시간에 따른 18O 농도변화 측정 -)

  • 김병국;마하구찌히로오;박순자
    • Journal of the Korean Ceramic Society
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    • v.31 no.12
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    • pp.1459-1466
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    • 1994
  • A novel technique for determining the oxygen tracer diffusion coefficients in oxides was developed. After the 16O-18O solid-gas exchange reactions between 16O in the oxides and 18O in the ambient gas, Raman spectra of the cross sections of oxide samples were measured in a spatial resolution of 5 {\mu}{\textrm}{m}. From thus obtained Raman spectra, depth profiles of 18O concentration in the oxide samples were calculated. The oxygen tracer diffusion coefficients and the surface exchange coefficients were determined under the assumptions that samples are semi-infinite slab and that the surface exchange reactionsare not negligible. The oxygen tracer diffusion coefficient of 2.8 mol% Y2O3-containing tetragonal ZrO2 polycrystals, 8 mol% Y2O3-containing ZrO2 polycrystals, and 10 mol% Y2O3-containing cubic ZrO2 single crystals (along the a axis) are as follows.

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Properties of ZrO2 Gas Barrier Film using Facing Target Sputtering System with Low Temperature Deposition Process for Flexible Displays (플렉서블 디스플레이용 저온공정을 갖는 대향 타겟식 스퍼터링 장치를 이용한 ZrO2 가스 차단막의 특성)

  • Kim, Ji-Hwan;Cho, Do-Hyun;Sohn, Sun-Young;Kim, Hwa-Min;Kim, Jong-Jae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.5
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    • pp.425-430
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    • 2009
  • ZrO2 film was deposited by facing target sputtering (FTS) system on polyethylene naphthalate (PEN) substrate as a gas barrier layer for flexible organic light emitting devices (FOLEDs), In order to control the heat of the FTS system caused by the ion bombardment in the cathode compared with the conventional sputtering system, the process characteristics of the FTS apparatus are investigated under various sputtering conditions such as the distance between two targets (dTT), the distance between the target and the substrate (dTS), and the deposition time. The ZrO2 film by the FTS system can reduce the damage on the films because the ion bombardment with high-energy particles like gamma-electrons, Moreover, the ZrO2 film with optimized condition (dTT=140 mm) as a function of the distance from center to edge showed a very uniform thickness below 5 % for a deposition time of 3 hours, which can improve the interface property between the anode and the plastics substrate for flexible displays, It is concluded that the ZrO2 film prepared by the FTS system can be applied as a gas barrier layer or an interlayer between the anode and the plastic substrate with good properties of an uniform thickness and a low deposition-temperature.

Preparation of Spherical (Zr, Sn)TiO4 Powders by Ultrasonic Spray Pyrolysis (초음파 분무 열분해법에 의한 (Zr,SN)TiO4 구형 미분말의 합성)

  • 조서용;이종흔;김명철;박순자
    • Journal of the Korean Ceramic Society
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    • v.31 no.5
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    • pp.465-470
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    • 1994
  • Fine, spherical (Zr, SN)TiO4 powders were prepared from the aqueous solution of metal chlorides by ultrasonic spray pyrolysis. Single phase (Zr, SN)TiO4 powders could be obtained above 700C (=temperature of the reactor) and all powders exhibited sizes in the range of 0.1 to 2.0 {\mu}{\textrm}{m} and a narrow size distribution. The sintering properties of the prepared powders were better than those of the powders from solid-state reaction.

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The Microstructure and Electrical Properties in the Pb(Sb1/2 Nb1/2)O3-PbTiO3-PbZrO3 System with MnO2 Addition (Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3에서의 MnO2 첨가에 따른 미세구조와 전기적 물성변화에 대한 연구)

  • 강원호;박원규;김호기
    • Journal of the Korean Ceramic Society
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    • v.24 no.6
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    • pp.537-542
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    • 1987
  • The microstructure and electrical properties of Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3 with MnO2 addition have been investigated in this work. The amount of MnO2 addition was 0, 0.4, 0.8, 1.2, 2.0 wt%, respectively. The soild solution range of MnO2 that assumed in this composition according to thevariations of micro-structure and electrical properties was 0.4-0.8 wt%.

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Optical Coating for SHG device by RF Sputtering Method (RF 스퍼터링방법에 의한 제2고조파소자의 광학박막 제작)

  • Kim, Yong-Hun;Lee, Seong-Guk;Ma, Dong-Jun;Han, Jae-Yong;Park, Seong-Su;Lee, Sang-Hak
    • Korean Journal of Materials Research
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    • v.6 no.6
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    • pp.636-643
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    • 1996
  • 공진기형 제 2고조파소자(SHG)는 레이저 빔의 에너지 밀도가 높아 고내구성 박막이 필요하다. 본 연구에서는 광학박막 재료로 고융점 산화물인 ZrO2, TiO2, SiO2를 사용하였다. 반응성 스퍼터링 방법으로 제작한 ZrO2, TiO2, SiO2 박막을 XRD, SAM을 사용하여 분석하였고, 박막의 광학적 특성을 평가하였다. SHG 소자의 KTP 및 Nd:YAG 결정의 반사방지막(A/R 코팅)구성은 ZrO2와 SiO2를 사용하여 컴퓨터로 계산하였는데 기본파인 1064nm와 제 2고조파인 532nm에서 각각 0.1%, 0.5%이하의 반사율을 갖도록 하였다. 또한 고반사막(H/R 코팅)의 경우 1064nm에서 99.9%의 반사율을 갖도록 TiO2와 SiO2로 디자인하였다. 제작한 광학박막의 광학적 특성, 레이저 내구성(laser damage threshold), 온습도 안정성 실험 등을 통해 광학박막을 평가하였다.

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Preparation and Characteristics of Y2O3CeO2ZrO2Structural Ceramics ; I. Synthesis and Sinterability of Powder (Y2O3CeO2ZrO2 구조세라믹스의 제조 및 특성 : I 분말의 합성 및 소결성)

  • 오혁상;이윤복;김영우;오기동;박흥채
    • Journal of the Korean Ceramic Society
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    • v.33 no.9
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    • pp.1057-1063
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    • 1996
  • Y2O3-CeO2-ZrO2 powders were prepared from water-soluble salts using a coprecipitation method. The forming process of oxide and the characteristics of the calcined powders treated in different drying conditions were investigated. The oxidation was occurred at the temperature of around 400C and the main crystallization of ZrO2 around 600C. On calcination at 600C heating lamp-dried powders consisted of agglomerates of globular morphology with average agglomerate size of 2.27{\mu}{\textrm}{m} and specific surface area of 68.3m2/g and spray dried powders contained dense spheric particles with average agglomerate size of 1.35{\mu}{\textrm}{m} and specific surface area of 11.0m2/g which exhibited low agglomeration tendency. Removal of the water by a freeze-drying technique produced calcined powders containing flake-like secondary particle structures with wide agglomerate size distri-bution of 0.1-60{\mu}{\textrm}{m} and specific surface area of 24.5{\mu}{\textrm}{m}. The 20 MPa-pressed density (36.8-41.4% T,D) of calcined powders did not nealy depend on drying methods whilst compaction ratio of calcined powders derived from freeze-drying was the highest ( 6.24) among three drying methods. On continuous heating up to 1500C the sinterability of calcined powders derived from heating lamp-drying was superior to those derived from spray-and freeze-drying. The final sintered density of calcined powders was the highest (96% T,D at 1500C) in case of heating lamp-drying.

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Synthesis of Ni supported on Ce-ZrO2 for HDO Reaction to Produce New Generation Bio-diesel (차세대 바이오디젤 생산을 위한 HDO 반응용 Ce-ZrO2에 담지된 Ni 촉매 합성)

  • Jeong, Dae-Woon;Eum, Ic-Hwan;Kim, Ki-Sun;Ko, Chang-Hyun;Roh, Hyun-Seog
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.527-527
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    • 2009
  • 1세대 바이오디젤인 fatty acid methyl ester(FAME)의 문제점을 극복하기 위하여 많은 연구가 진행 중 이다. 소위 차세대 바이오디젤은 triglyceride의 산소 화합물을 제거하여 정유 공정을 통해 생산된 디젤과 동일한 특성을 지닌 탄화수소로 전환시킨 오일이다. 이를 위하여 수소를 첨가하여 산소를 제거 시키는 Hydrodeoxygenation(HDO) 반응이 필요하다. 고온(300400C), 고압(50-100 bar)의 혹독한 조건에서 높은 수율과 안정성을 보이는 촉매 개발이 필요하다. 이를 위하여 반응물중의 산소를 효과적으로 제거하기 위하여 산소 전달능이 뛰어난 CeO2 담체에 열안정성을 높이는 ZrO2를 조합한 CeZrO2 담체를 선정하였으며 수소첨가 탈산소 반응에 활성을 나타낼 것으로 예상되는 니켈을 활성성분으로 선정하였다. 본 연구에서는 15%Ni-Ce(1x)Zr(x)O2 (0x1)촉매를 공침법(co-precipitation)으로 제조하였으며 500C에서 소성하였다. 촉매 특성분석은 XRD, BET, H2-TPR을 이용하였다.

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A Study on the Dielectric and Pyroelectric Properties of the PSS-PT-PZ Ceramics Added MnO2 (MnO2가 첨가될 PSS-PT-PZ 세라믹의 유전 및 초전특성에 관한 연구)

  • Lee, Sung-Gap;Ryu, Ki-Won;Lee, Young-Hie;Bae, Seon-Gi;Park, Chang-Yub
    • Proceedings of the KIEE Conference
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    • 1991.07a
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    • pp.194-197
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    • 1991
  • In this study, (Pb0.99La0.01)[(Sb1/2Sn1/2)0.10Ti0.25Zr0.65]O3, added MnO2 (0-0.30[mol%]) ceramics were fabricated by the mixed oxide method. The sintering temperature and time were 1250[C], 2[hr], respectively. In the (Pb0.99La0.01)[(Sb1/2Sn1/2)0.10Ti0.25Zr0.65]O3 added MnO2 (0.24[mol%]) specimens, relative dielectric constant and dielectric loss were minimum values 3.52, 0.003, respectively, and Curie temperature were highest values 256[C]. Pyroelectric coefficient and voltage responsivity of the (Pb0.99La0.01)[(Sb1/2Sn1/2)0.10Ti0.25Zr0.65]O3, and added MnO2 (0.24[mol%]) specimen were good values, 6.73×108[C/cm2K],125[v/W], respectively. Figure of merit of pyroelectric current, voltage and detectivity of the specimen, (Pb0.99La0.01)[(Sb1/2Sn1/2)0.10Ti0.25Zr0.65]O3 added MnO2 (0.24[mol%]) were good values 2.714×108[Ccm/J],7.706×1011[Ccm/J],2.640×108[Ccm/J], respectively. Voltage responsivity of the (Pb0.99La0.01)[(Sb1/2Sn1/2)0.10Ti0.25Zr0.65]O3 added MnO2 (0.24[mol%]) specimens were decreased with increasing the chopper frequency.

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A Study on Improvement of Fracture Toughness of βSiCZrB2Composites (βSiCZrB2 복합체의 파괴인성 증진연구)

  • Shin Yong-Deok;Ju, Jin-Young;Yoon, Se-Won;Hwang, Chul;Song, Joon-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.05a
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    • pp.291-294
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    • 1999
  • The effect of AI2O3+Y2O3additives on fracture toughness of β-SiC-ZrB2composites by hot-pressed sintering were Investigated. The β-SiC-ZrB2 ceramic composites were hot-presse sintered and annealed by adding 1, 2, 3wt% AI2O3+Y2O3(6:4wt%) powder as a liquid forming additives at 1950C for 4h. In this microstructures, no reactions were observed between β-SiC and ZrB2, and the relative density Is over 90.79% of the theoretical density and the porosity decreased with increasing AI2O3+Y2O3 contents. Owing to crack deflection and crack bridging of fracture toughness mechanism, the fracture toughness showed the highest of 5.5328MPa . m12/ for composites added with 2wt% AI2O3+Y2O3 additives at room temperature. But the standard deviation of fracture toughness of specimens decreased with increasing AI2O3+Y2O3 contents and showed the highest of 0.8624 for composite tilth 1wt%, AI2O3+Y2O3additives.

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