Browsing by Author "Wang, Sea-Fue"

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A COMPACT CASCADE QUADRUPLET BANDPASS FILTER WITH LOW TEMPERATURE COFIRED CERAMIC TECHNOLOGY
(2008-12-01)
Lin, Hong-Ching
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Lin, Pang
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Tang, Ching-Wen
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Wang, Sea-Fue
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材料科學與工程學系
In this article, a compact cascade quadruplet bandpass filter has been proposed. This bandpass filter has been realized with the semilumped method and can generate a pair of transmission zeros at the two sides of passband by using the nonadjacent cross coupling. The analysis and design procedures are provided in this article. To miniaturize the size of the circuit and improve its performance, multilayered structure and the low-temperature cofired ceramic technology are employed to design and fabricate the filter. Measurement results agree well with the electromagnetic simulation, which can validate the proposed structure. (c) 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3218-3220, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23910
Characteristics of electrolyte supported micro-tubular solid oxide fuel cells with GDC-ScSZ bilayer electrolyte
(2014-10-13)
Hsieh, Wen-Shuo
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Lin, Pang
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Wang, Sea-Fue
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材料科學與工程學系
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Department of Materials Science and Engineering
In this study, a gadolinia-doped ceria (GDq-supported micro tubular SOFC (T-SOFC) was fabricated using extrusion and dip-coating techniques (Cell A). The effects of inserting a scandium-stabilized zirconia (ScSZ) layer as an electron blocking layer between the GDC layer and the GDC-Ni anode layer were also explored (Cell B). The microstructures and electrochemical performances of Cell A and Cell B were investigated and compared. The layer thicknesses of the GDC and ScSZ bi-layer electrolytes were approximately 285 mu m and 8 mu m respectively. With the inserted ScSZ layer, both the ohmic resistance and the polarization resistance significantly increased at all the operating temperatures. The increase in the ohmic resistance of Cell B was predominantly due to the interfacial resistance, while the substantial escalation in the polarization resistance was mainly because of the low bulk oxygen diffusion process in the ScSZ layer and the smaller charge transfer processes occurring at the interfaces. The OCV of Cell B showed a slight decrease from 1.06 to 0.98 V and that of Cell A experienced an obvious decline from 0.92 to 0.76 V as the temperature rose from 650 to 800 degrees C. The ScSZ layer of Cell B successfully inhibited the OCV loss caused by the electronic conduction in GDC. The maximum power densities (MPDs) of Cell A at 650, 700, 750, and 800 degrees C were 0.20, 0.27, 0.33, and 0.36 Wcm(-2), and those of Cell B 0.16, 0.23, 0.32, and 0.42 Wcm(-2). The MPD of Cell B was improved at temperatures above 750 degrees C but remained inferior to that of Cell A below 750 degrees C. This is due to the fact that, as operating temperature increased above 750 degrees C, the benefit of the higher OCV in Cell B surpassed the deficiency of the higher cell resistance, thereby leading to a higher MPD. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Characterization of inductor with Ni-Zn-Cu ferrite embedded in B2O3-SiO2 glass
(2007-09-01)
Jao, Jui-Chu
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Li, Pang
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Wang, Sea-Fue
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材料科學與工程學系
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Department of Materials Science and Engineering
In this study, inductors using a new low-temperature cofirable ceramic (LTCC) design, in which Ni-Zn-Cu ferrite was buried in B2O3-SiO2 glass within the core of the spiral silver coil, were fabricated. The inductance and quality factor of the inductor with embedded ferrite are larger than those of pure B2O3-SiO2 glass. Ni-Zn-Cu ferrite was incompatible with the B2O3-SiO2 glass during the cofiring process due to sintering shrinkage mismatch. The incompatibility was resolved when 35 wt % Al2O3 was doped into the B2O3-SiO2 glass, which produces a glass-ceramic, and 2 wt % of Bi2O3 was fluxed into the Ni-Zn-Cu ferrite as a sintering aid. The addition of 2 wt % of Bi2O3 not only enhances densification, but also increases the permeability of Ni-Zn-Cu ferrite.
Characterization of the low-curing-temperature silver paste with silver 2-ethylhexanoate addition
(2007-01-01)
Lu, Chun-An
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Lin, Pang
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Lin, Hong-Ching
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Wang, Sea-Fue
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材料科學與工程學系
In this study, the effects of the solvent and atmosphere on the thermal decomposition behaviors of silver 2-ethylhexanoate and alpha-terpenol are investigated. Low-curing-temperature silver pastes made from Ag flakes, alpha-terpineol and various amounts of silver 2-ethylhexanoate, were prepared and characterized. The microstructures and resistivities of cured films screen-printed from the pastes were examined. The results of thermal analysis in oxidizing and reducing atmospheres revealed that thermal decomposition is the dominating reaction during the heating process of silver 2-ethylhexanoate, even though the differential scanning calorimetry (DSC) result revealed an exothermic reaction for silver 2-ethylhexanoate heated in air due to oxidation. Thermal decomposition left almost pure Ag particles, which is beneficial for bridging between silver flake particles in the films. On the basis of the theological behavior, microstructural evolution and electrical evaluation, it can be concluded that a low-curing-temperature silver paste with 5 wt % silver 2-ethylhexanoate addition is the best formulation, which possesses shear-thinning and thixotropic properties and a resistivity of 7.8 x 10(-6) Omega cm after being cured at 250 degrees C, which is relatively close to the bulk resistivity of Ag.
Effects of cathode materials on the characteristics of electrolyte supported micro-tubular solid oxide fuel cells
(2014-05-01)
Hsieh, Wen-Shuo
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Lin, Pang
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Wang, Sea-Fue
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材料科學與工程學系
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Department of Materials Science and Engineering
The effects of the GDC-LSCF (Ce0.8Gd0.2O0-delta-La0.6Sr0.4Co0.2Fe0.8O3-delta) cathode layer and the GDC interlayer on the electrochemical performance of the ScSZ (Zr0.8Sc0.2O2-delta) electrolyte supported (approximate to 270 mu m) micro-tubular SOFC cells are investigated in this study. Material formulation and sintering profile for fabricating the micro-tubular SOFC cells are developed to avoid physical defects caused by the large sintering shrinkage mismatch among the layers. Cell B (with the LSCF-GDC composite cathode layer and the GDC interlayer) reports an ohmic resistance slightly higher than that of Cell A (with the GDC -La0.8Sr0 2MnO3-delta., i.e. LSM, composite cathode), while its polarization resistance emerges to be significantly smaller than that of Cell A. In terms of cell performance, Cell B demonstrates an OCV value (>1.07 V) similar to that of Cell A and a maximum power density (0.26W cm(-2)) 44.4% greater than that of Cell A (0.17 W cm(-2)) at 850 degrees C. It can thus be concluded that using the LSCF-GDC composite-cathode layer and inserting the GDC interlayer help reduce the total cell impedance, thereby improving the power density of the tubular cells. (C) 2013 Elsevier B.V. All rights reserved.
Effects of metallo-organic decomposition agents on thermal decomposition and electrical conductivity of low-temperature-curing silver paste
(2006-09-01)
Lu, Chun-An
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Lin, Pang
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Lin, Hong-Ching
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Wang, Sea-Fue
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材料科學與工程學系
Six low-temperature-curing silver pastes were prepared from silver flake, alpha-terpineol and, various metallo-organic decomposition (MOD) compounds. The thermal decomposition behaviors of the pastes were determined. The microstructures and resistivities of screen-printed films on alumina substrate after thermal treatment were characterized and discussed. Results indicated that 2-ethylhexanoate possesses the lowest decomposition temperature (190.3 degrees C) among the MOD agents studied, and it forms silver particles to promote the linking of silver flake powders and thus reduces the resistivity to < 13 mu Omega.cm at a temperature as low as 200 degrees C.
Effects of silver oxalate additions on the physical characteristics of low-temperature-curing MOD silver paste for thick-film applications
(2009-11-01)
Lin, Hong-Ching
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Lin, Pang
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Lu, Chun-An
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Wang, Sea-Fue
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材料科學與工程學系
In this paper, the effect of silver oxalate addition on physical characteristics of metallo-organic-decomposition (MOD) silver screen-printable paste for thick film technology was investigated. The addition of silver oxalate in the paste not only produces fresh fine silver particles after curing, but also reduces the decomposition temperature of the lubricant coated on the silver flakes. This is an effective route to provide fine silver particles to the paste without significantly changing the theological behavior. At the curing temperature of 225 degrees C, the resistivity decreases from 180.1 to 31.9 mu Omega-cm, as the silver oxalate content increases from 0 to 10 wt%. This is due to the fact that active silver catalysts produced increase the packing density of silver flakes, and also the removal of lubricant from the surface of silver flakes enhances the electrical conductivity, thereby decreasing the resistance of film. (C) 2009 Elsevier B.V. All rights reserved.
Effects of silver oxide addition on the electrical resistivity and microstructure of low-temperature-curing metallo-organic decomposition silver pastes
(2007-07-01)
Lu, Chun-An
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Lin, Pan
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Lin, Hong-Ching
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Wang, Sea-Fue
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材料科學與工程學系
The thermal decomposition of silver paste with the addition of a metallo-organic decomposition (MOD) compound generally requires a curing time of greater than 10 min and a curing temperature greater than 250 degrees C, which does not meet the requirement for high-speed production in flexible substrates. In this study, attempts to modify the curing conditions of MOD silver pastes through the substitutions of silver flakes with silver(I) oxide (Ag2O) and silver(II) oxide (AgO) were performed. Differential thermal analysis (DTA), derivative thermogravimetric analysis (DTG), and X-ray diffraction (XRD) results indicated that the presence of residual silver oxide, which effectively catalyzes the evaporation of a-terpineol and the decomposition of silver 2-ethyl hexanoate, decreases the curing temperature and shortens the soaking time. The reduced silver and the remaining AgO enhance the connectivity and packing density of the silver flakes, and thus increase the electric conductivity of the films. For films prepared from pastes with 20 wt % Ag2O or AgO, resistivities of 14 x 10(-6) and 19 x 10(-6) mu Omega center dot cm. respectively, were successfully achieved after being cured at 200 degrees C for 5 min.
Fabrication of electrolyte supported micro-tubular SOFCs using extrusion and dip-coating
(2013-02-27)
Hsieh, Wen-Shuo
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Lin, Pang
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Wang, Sea-Fue
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材料科學與工程學系
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Department of Materials Science and Engineering
Dense electrolyte supported micro tubular solid oxide fuel cells (T-SOFCs) were prepared in this study. Green Zr0.8Sc0.2O2 - delta (ScSZ) electrolyte micro-tubes with a thickness of 300 mu m were successfully prepared by extrusion at room temperature. After firing at 1400 degrees C, the bare electrolyte micro-tube with a thickness of 210 mu m, a diameter of 3.8 mm, and a length of 40 mm reached a relative density of 96.84% and a flexural strength of 202 MPa. To achieve a better sintering shrinkage match, the electrolyte micro-tubes were pre-sintered at 1100 degrees C, coated with NiO/ScSZ (60 vol.%:40 vol.%) in the inner surface of the microtubes by dip-coating method, and then co-fired at 1400 degrees C. After co-sintering, the interface of the porous anode layer and the dense electrolyte layer demonstrated good adhesion and mechanical integrity. Subsequently, a La0.8Sr0.2MnO3 - delta (LSM)/Ce0.8Gd0.2O2 - delta (GDC) (80 vol.%:20 vol.%) cathode layer was coated on the outer surface of the micro-tubes by dip-coating method and post-sintered at 1100 degrees C. The thicknesses of the anode and cathode layers read approximately 28 and 34 mu m respectively. After thermal cycling between 30 degrees C and 800 C under 97% N-2-3%H-2 on the anode and air on the cathode, the micro T-SOFCs showed no delamination and retained good adhesion based on the SEM results. The maximum power densities (MPD) of the single cell read 0.26 and 0.23 W cm(-2) respectively at 920 and 900 degrees C, and the open circuit voltage (OCV) reported the same 1.08 V. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
High-frequency electrical properties of silver thick films measured by dielectric resonator method
(2008-09-01)
Lin, Hong-Ching
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Lin, Pang
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Lu, Chun-An
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Wang, Sea-Fue
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材料科學與工程學系
The electrical properties of silver films, prepared using a low-curing-temperature metallo-organic-decomposition (MOD) paste and a high-temperature silver paste screen-printed on polished and nonpolished alumina substrates, at microwave frequency were characterized in this Study. Surface resistance and effective conductivity of the silver films at microwave frequency (approximately 4 GHz) were evaluated using the TE(011) mode of the resonator cavities method. Devices of T-type resonator circuits were fabricated to determine the simulated and measured Q-values and to evaluate the effects of silver films and the surrounding substrate. The surface roughness of the fired films printed on nonpolished Al(2)O(3) substrate is slightly less than those on polished Substrate. because the surface energy of the nonpolished alumina (29.81 mN/m) is slightly less than that of the polished alumina (36.69 mN/m). The calculated effective conductivities at 4.3 GHz are slightly less than the DC conductivities of the films. Moreover, the films prepared using the high temperature silver paste have higher electrical conductivity ranging from 4.08 x 10(7) to 4.13 x 10(7) S/m, Since the high-temperature firing process leads to an improved connectivity of the silver particles. The results indicate that the films screen-printed on the polished substrate have a higher Q and a lower Delta Q value than those of films that are screen-printed on the nonpolished substrate. For the silver films prepared using the high-temperature silver paste, both the Q and Delta Q values were the highest among the films studied, which is consistent with the observation of the dense microstructure of the silver film and the interfacial reaction between the Mass in the film and tie Substrate as a result of high firing temperature.
Microstructure and Electrical Resistivity of Low-Temperature-Cured Silver Films Prepared Using Silver Oxide and Silver Stearate Pastes
(2009-01-01)
Lin, Hong-Ching
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Lin, Pang
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Lu, Chun-An
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Wang, Sea-Fue
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材料科學與工程學系
In this study, paste formulations containing silver oxide coated with a metallo-organic decomposition (MOD) agent of silver stearate were prepared without using any silver powders or silver flakes. Results indicate that all pastes appear to have a pseudoplastic flow property that is acceptable for roll-to-roll printing and screen printing. The pastes were screen-printed on an alumina substrate and then thermally treated in a range of temperatures. The lowest electrical resistivity of 13.2 x 10(-6) Omega.cm was obtained for the film prepared from paste with a Ag(2)O/silver stearate ratio of 100 : 5 at a solid loading of 80 wt % in the solvent a-terpineol, after being cured at 160 degrees C for 5 min, which meets the requirements of low-temperature and high-speed manufacturing for practical applications. The low resistivity of the film is facilitated by the combination of Ag(2)O and silver stearate added to the paste. Ag(2)O produces a high density of silver matrix after being reduced at low temperatures, and the presence of silver stearate contributes to the rheological behavior of the paste after dissolution in the solvent. Coexistence of Ag(2)O and silver stearate induces their simultaneous transformation to the silver form at temperatures below 160 degrees C. (c) 2009 The Japan Society of Applied Physics
Microstructures and microwave dielectric properties of Li2O-Nb2O5-ZrO2 ceramics
(2007)
Lu, Chun-An
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Lin, Pang
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Wang, Sea-Fue
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材料科學與工程學系
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Department of Materials Science and Engineering
Solid solution of Li1-4y-xZry+4xNb1-3xO3 system is anew non-stoichiomettic compound with orthorhombic perovskite structure. In this study, the effects of the calcination and the sintering temperatures on the microstructural evolution and microwave dielectric properties of Li1-4y-xZry+4xNb1-3xO3 ceramics were performed. Dense Li0.774Zr0.057NbO3 ceramics can be obtained at the sintering temperature of 1150 degrees C. Li0.774Zr0.057NbO3 phase exists as the main phase with the existence of a minor LiNb3O8 phase. Typical microwave dielectric properties for dense Li0.774Zr0.057NbO3 ceramics are as followed: epsilon(r) approximate to 39, Q x f approximate to 4500, and tau(f) = -16.6 ppm/degrees C, measured at 6 GHz. (c) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Preface
(2017-01-01)
Tuan, Wei-Hsing
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Chou, Chen-Chia
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Tseng, Tseung-Yuen
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Wang, Sea-Fue
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Tseng, Wen-Jea