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CeO$_2$ 도핑에 의한 불규칙 입자형상의 이트리아 안정화 지르코니아 제조
이종국,강현희,김영정,김환,Lee, Jong-Kook,Kang, Hyun-Hee,Kim, Young-J.,Kim, Hwan 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.12
Yttria-stabilized zirconia ceramics with irregular grain shapes and curved grain boundaries was prepared by ceria doping. The amount of ceria doped into zirconia compacts by a dipping method were at range of 2 to 20 mol% Irregular grain shapes and curved grain boundaries were formed only inspecimens doped with more than 8mol% cerial. Ceria-doped specimens showed large grain size and low sintered density compared with pure yttria-stabilized zirconia which was due to the increase in the contents of stabilizer and cubic phase. The amount of doped ceria was larger on the surface than the inside regions and therefore mi-crostructure and phase on the surface were different from those in the inside regions. Transgranular frac-ture mode was observed ion ceria doped specimens due to irregular large grain sizes.
Jeong Woo Shin,Sungje Lee,Dohyun Go,Byung Chan Yang,Taeyoung Kim,Sung Eun Jo,Pei-Chen Su,Jihwan An 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.3
Designing highly active and thermally stable electrodes is crucial for realizing low-temperature solid oxide fuel cells (LT-SOFCs) with excellent performance. In this study, we fabricated an yttria-doped ceria (YDC) shell layer by atomic layer deposition (ALD) over a Pt cathode by controlling the doping concentration of yttria in YDC film. The exchange current density was enhanced by a factor of five when the ALD YDC shell layer was deposited onto the cathode surface compared to the bare Pt cathode, resulting in an 80% decrease in the activation resistance of the 19 mol%-doped ALD YDC-overcoated Pt cathode compared to that of the bare Pt cathode. Furthermore, the thermal stability was enhanced in low-to-medium-doped (7–19 mol%) ALD YDC-coated Pt cathodes, whereas the highly doped (31 mol%) cathode showed a relatively marginal improvement in stability.
Le Thu Lam,Vu Van Hung,Bui Duc Tinh 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.4
The ionic conductivities of yttria-doped ceria (YDC) and yttria-stabilized zirconia (YSZ), are investigatied using statistical moment method including the anharmonicity effects of thermal lattice vibrations. The expressions for the lattice constant and the vacancy activation energy are derived in closed analytic forms in terms of the power moments of the atomic displacements. The distribution of oxygen vacancies around dopants and the important role of cation barriers on vacancy diffusion are evaluated in detail. The lattice constants, activation energies, ionic conductivities of YDC and YSZ are calculated as functions of the dopant concentration. Notably, the ionic conductivities depend linearly on dopant concentration. Our results are in good agreement with those of both previous experiments and several theoretical calculations.
Effects of Gallia Addition on Sintering Behavior and Electrical Conductivity of Yttria-Doped Ceria
Seung-Woo Seo,Ji-Hoon Park,박민우,Ji-Hoon Koo,이기태,이주신 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.4
The densification behavior and electrical conductivity of Ce0.8Y0.2O1.9 ceramics with gallia concentrations ranging from 0 to 5 mol. % were investigated. The sintered density was found to increase with increasing Ga2O3 content up to 1 mol. % and then to decrease upon further Ga2O3 addition. Dense Ce0.8Y0.2O1.9 ceramics with 94% of the theoretical density could be obtained by sintering the milled mixture with 1 mol. % Ga2O3 addition at 1400°C for 5 h. The conductivity of the 1 mol. % Ga2O3-added specimen showed a maximum value of 1.37 × 10−2 Ω−1· cm−1 at 700°C. Pure Ce0.8Y0.2O1.9 ceramics needed to be sintered at 1550°C in order to obtain an equivalent theoretical density and conductivity. The introduction of Ga2O3 doping had a good effect on the sintering properties and electrical conductivities of Y2O3-doped CeO2.
Seung-Woo Seo,정상진,박민우,유승민,이기태,이주신 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1
The densification behavior and electrical conductivity of Ce0.8Y0.2O1.9 ceramics with strontium gallate concentrations ranging from 0 to 5 mol. % were investigated. The sintered density was found to increase rapidly for concentrations up to 0.5 mol. % Sr2Ga2O5 and then to decrease upon further Sr2Ga2O5 addition. It was possible to obtain dense Ce0.8Y0.2O1.9 ceramics with 95% of the theoretical density using a 0.5 mol. % Sr2Ga2O5- added specimen sintered at 1250°C for 5 h, whereas pure Ce0.8Y0.2O1.9 ceramics needed to be sintered at 1550°C in order to obtain an equivalent theoretical density. The electrical conductivity was measured as a function of the dopant content over the temperature range of 450°C - 700°C in air. The conductivity of the 0.5 mol. % Sr2Ga2O5-added specimen showed a maximum value of 4.43 × 10−3 Ω−1·cm−1 at 700°C. The addition of Sr2Ga2O5 was found to promote the sintering properties and electrical conductivities of Y2O3-doped CeO2.
공침법으로 제조된 Yttira Doped Ceria분체의 건조방법에 따른 입자특성 고찰
변윤기,이상훈,최성철 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.8
In synthesis of nano powders, the hard agglomeration for the synthesized powders occurred during the drying processing. In order to avoid hard agglomeration in particles the freeze drying process was used in this experiment. e fabricated the Yttira-Doped Ceria(YDC) nano powder by co-precipitation. Starting materials used in experiments were the cerium(III) nitrate and yttrium(III) nitrate solution with 야-water, which two solutions were mixed and then the precipitated hydroxides were prepared for adding sodium hydroxide. The co-precipitated powders were dried by the thermal drying at 8$0^{\circ}C$ for 24 h and by freeze drying at -4$0^{\circ}C$, 30 mtorr for 72 h. The lattice parameter and crystallite size as a function of calcination temperature was characterized by XRD analysis. The lattice parameter of YDC was decreased with addition amount of yttrium and was estimated as 5.401683 $\AA$ at $700^{\circ}C$. Crystallite size were calculated by XRD-LB method, and morphologies were confirmed with the observation of TEM and SEM. The freeze dried YDC powders had medium diameter of 17 nm with more uniform size distribution than the thermal dried YDC posers, which were mainly ascribed to the difference of agglomerates formation during drying stage.
Joo-Sin Lee 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.10
The densification behavior and electrical conductivity of Ce0.8Y0.2O1.9 ceramics with lithium oxide concentrations ranging from0 to 7 mol% were investigated. The sintered density was found to increase with increasing Li2Ocontent up to 2 mol% and thento decrease somewhat upon further Li2O addition. It was possible to obtain dense Ce0.8Y0.2O1.9 ceramics with 97% of thetheoretical density using a 2 mol% Li2O-added specimen sintered at 1300 oC for 5 hrs, whereas pure Ce0.8Y0.2O1.9 ceramicsneeded to be sintered at 1550 oC in order to obtain an equivalent theoretical density. The electrical conductivity was measuredas a function of the dopant content over the temperature range 450 oC ~ 700 oC in air. The conductivity of the 2 mol% Li2Oaddedspecimen showed a maximum value of 1.15 × 10−2 Ω−1·cm−1at 700. The introduction of Li2O doping had a good effecton the sintering properties and electrical conductivities of Y2O3-doped CeO2.
Kim, H.J.,Kim, M.,Neoh, K.C.,Han, G.D.,Bae, K.,Shin, J.M.,Kim, G.T.,Shim, J.H. Elsevier Sequoia 2016 Journal of power sources Vol. No.
Thin ceramic bi-layered membrane comprising yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC) is fabricated by the cost-effective slurry spin coating technique, and it is evaluated as an electrolyte of solid oxide fuel cells (SOFCs). It is demonstrated that the slurry spin coating method is capable of fabricating porous ceramic films by adjusting the content of ethyl-cellulose binders in the source slurry. The porous GDC layer deposited by spin coating under an optimal condition functions satisfactorily as a cathode-electrolyte interlayer in the test SOFC stack. A 2-μm-thick electrolyte membrane of the spin-coated YSZ/GDC bi-layer is successfully deposited as a dense and stable film directly on a porous NiO-YSZ anode support without any interlayers, and the SOFC produces power output over 200 mW cm<SUP>-2</SUP> at 600 <SUP>o</SUP>C, with an open circuit voltage close to 1 V. Electrochemical impedance spectra analysis is conducted to evaluate the performance of the fuel cell components in relation with the microstructure of the spin-coated layers.