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Fabrication of Noble-metal Nanoparticle-doped SiO2-B2O3-P2O5 Waveguide Films
Hunhyeong Lee,강민경,William Thomas Nichols,신동욱 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.9
In this article, we report the fabrication and the characterization of Pt/SiO2-B2O3-P2O5 and Au/SiO2-B2O3-P2O5 composite thin films suitable for planar lightwave circuits (PLCs). The host material was prepared by using flame hydrolysis deposition (FHD). Platinum was doped from colloidal solutions with concentrations of 500, 1000, and 2000 ppm. Gold was doped by sputtering with various deposition times. The samples displayed absorption peaks originating from the surface plasmon resonance (SPR) of the dopant metal particles. With increasing dopant particle size, the absorption peak shifted toward longer wavelength, and the full width at half maximum (FWHM) of the absorption band broadened. The Maxwell-Garnett theory was used to explain the size dependence of the plasmon peaks. The dopant metal particles were found to order as a monolayer within the silica matrix, opening the possibility for surface-plasmon-resonance-based waveguiding in optical devices.
Improved chemical stability and conductivity of barium cerate nanopowders by Lanthanum doping.
Lee, Hunhyeong,Park, Inyu,Shin, Dongwook American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.9
<P>Despite of the highest proton conductivity, barium cerate electrolytes are well known for the deficiency of chemical stability at elevated temperature under CO2 atmosphere. This work is focused on improving chemical stability of lanthanum doped barium cerate (BCL) powder for electrolyte. Although lanthanum doping causes distortion of perovskite structure lattice, immoderate doping could stabilize structure due to increasing symmetry of structure lattices. The thermogravimetric analysis and AC impedance measurements revealed that the lanthanum doping suppresses the reaction between barium and carbonate and this effect results in sufficient improvement in ionic conductivity in operating temperatures range. It was confirmed that BaCe0.7La0.3O3-delta (BCL30) was the most stable composition and the conductivity of BCL30 is high as 3.8 S x cm(-1) x K at 700 degrees C.</P>
Bae, Kiho,Lee, Sewook,Jang, Dong Young,Kim, Hyun Joong,Lee, Hunhyeong,Shin, Dongwook,Son, Ji-Won,Shim, Joon Hyung American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.14
<P>In this study, we used a compositionally gradient anode functional layer (AFL) consisting of Ni-BaCe0.5Zr0.35Y0.15O3-delta (BCZY) with increasing BCZY contents toward the electrolyte -anode interface for high-performance protonic ceramic fuel cells. It is identified that conventional homogeneous AFLs fail to stably accommodate a thin film of BCZY electrolyte. In contrast, a dense 2 mu m thick BCZY electrolyte was successfully deposited onto the proposed gradient AFL with improved adhesion. A fuel cell containing this thin electrolyte showed a promising maximum peak power density of 635 mW cm(-2) at 600 degrees C, with an open-circuit voltage of over 1 V. Impedance analysis confirmed that minimizing the electrolyte thickness is essential for achieving a high power output, suggesting that the anode structure is important in stably accommodating thin electrolytes.</P>
Improvement of Chemical Stability of BaCe0.9Y0.1O3/BaCe0.6Zr0.3Y0.1O3 Bi-Layer Electrolyte.
Kim, Jeongin,Park, Inyu,Lee, Hunhyeong,Shin, Dongwook American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.1
<P>Doped-BaCeO3 has high protonic conductivity at intermediate temperature, but poor chemical stability. In contrast, doped-BaZrO3 is rather stable, but has poor protonic conductivity. In this study, the BCY-BCZY bi-layer system was investigated in the hope of the synergetic improvement of high conductivity and good chemical stability. Nano-sized the BCY and modified-BCZY powders were prepared by the citric-nitrate route and bi-layer electrolyte made of BCY covered with a thin film BCY-BCZY deposited by the electrostatic slurry spray deposition. The improvement of chemical stability, measured in CO2 atmosphere, is turned out to be resulted from the substitution of Zr4+ cation. Overall, the BCY-BCZY bi-layer electrolyte shows promising improvement in chemical stability against produced water on the cathode side during the cell operation.</P>