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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

半月刊

1013-9826

Key engineering materials/Journal Key engineering materials
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    Electrical Properties of Conductive Paste with Silver Nanoparticles and Its Application to Flexible Substrates

    Yukio YamamotoTakashi Ogihara
    297-300页
    查看更多>>摘要：Silver nanoparticles produced with a solid-phase thermal decomposition method were used for the preparation of a conductive paste supporting curing at low temperatures. The conducting paste was prepared by blending fine spherical silver powder and silver nanoparticles with a diameter of 20nm in order to reduce the electric resistivity of the electrodes. Although the viscosity of the conducting paste increased by about 25% after 60 days, it exhibited superior stability to dispersion in comparison to commercial paste. The electric resistivity of the electrode was of the order of 10~(-6)Ωcm at a curing temperature of 200℃. Using this conducting paste, it is possible to print at widths of 20μm. The resistivity was further reduced by 1% in the high temperature test at 120℃, by 5% in the high humidity and high temperature test, and by 5% during the thermal shock test at temperatures ranging from -45 to 80℃.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    The effect of rare earth (Ln = Gd, Dy, Y and Yb) doping on the microstructure and reliability in BaTiO_3-based monolithic ceramic capacitors (MLCs)

    Toshihiro OkamatsuHitoshi NishimuraNoriyuki InoueHarunobu Sano...
    301-304页
    查看更多>>摘要：The effect of rare earth (Ln = Gd, Dy, Y and Yb) and Mg ions on the microstructure and reliability of BaTiO_3-based monolithic ceramic capacitors (MLCs) with Ni electrodes was investigated. The X-ray diffraction results about the lattice volume of sintered specimens suggested that Gd and Dy ions predominatly substituted into the Ba-site, Yb ions gave exclusive substitution at the Ti-site, while Y ions occupied either the Ba- and Ti-site. The reliability of ceramic capacitors was increasing with increasing the ionic radius of the rare earths in this study. The nonlinearity coefficient(α) etsimated from the leakage currents and the lifetime measured from the highly accelerated lifetime testing (HALT) showed a negative correlation which was observed only from Dy and Y ions doped specimens. The quantity of Ln and Mg in the grains tended to increase with increasing the Ln ionic radius. In order to improve the reliability and the insulation property of BaTiO_3 based MLCs with Ni electrodes, it is important that acceptor ions at the Ti-site compensate donor ions which are rare earth ions at the Ba-site, so the overall quantity of the dopants required for the charge compensation with acceptor and donor ions increases accordingly.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Durability Improvement of Optical H_2 Gas Sensor Using Pd Thin Film on Sputter-Etched Glass Substrate

    Yuji YakushijiYuichiro KurokiTomoichiro OkamotoMasasuke Takata...
    307-310页
    查看更多>>摘要：A glass substrate was sputter-etched by R. F. magnetron sputtering at the powers of 100 or 200 W for 60 min in Ar gas. Pd thin film as a sensing agent of hydrogen (H_2) was deposited on the glass substrate. The durability of the sensor was evaluated during hydrogen absorption-desorption cycles. The Pd thin film on the glass substrate without sputter etching peeled off after dozens of the cycles. However, the Pd thin film on sputter-etched glass substrate didn't peel off. The contact angle of water on the glass substrate with sputter etching was smaller than that without sputter etching, suggesting that the surface energy of the substrate was increased by employing the sputter etching process. The improvement of durability for the optical hydrogen sensor using sputter etched substrate was related to the increase of surface energy induced by the sputter etching.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Sensing High Concentrations in Air of H_2 Based on Spin-coated Films of Flame-spray-made SnO_2 and Pd/SnO_2 Nanoparticles

    Chaikarn LiewhiranAnurat WisitsoraatSukon Phanichphant
    311-314页
    查看更多>>摘要：Flame Spray Pyrolysis (FSP) was performed for the synthesis of high specific surface area (SSA_(bet)) of SnO_2 nanopowders (141.6 m~3/g) and supported palladium (Pd) nanoparticles containing 0.2-3 wt%Pd with controlled size and a crystallinity in a single step. The particles properties were further characterized by XRD, BET and TEM analyses. The crystalline particles were used for sensing film preparation by spin coating. It was found that the flame-spray-made 0.2 wt%Pd/SnO_2 sensor showed higher and faster response to reducing H_2 gas than pure flame-spray-made SnO_2 sensor.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Upgrade Mechanoluminescence by Sr~(2+) Substitution in CaAl_2Si_2O_8:Eu~(2+)

    Lin ZhangChao-Nan XuHiroshi YamadaNan Bu...
    315-318页
    查看更多>>摘要：Recently we demonstrated that CaAl_2Si_2O_8: Eu~(2+) showed novel strong mechanoluminescence (ML). In order to improve the mechanoluminescence intensity, we partly substituted the Ca~(2+) ions by Sr~(2+) ions. It was found that the ML intensity was enhanced about three times as great as the one of CaAl_2Si_2O_8: Eu~(2+) by substituting 40% of Ca~(2+) ions to Sr~(2+) ions. Furthermore it was revealed that the main peaks in XRD pattern shifted to lower angle side and the emission peak shifted to a short wavelength from 428 to 418 nm, indicating that the substitution resulted in the cell volume expansion and the change of luminescent color. Based on the results of thermoluminescence and electroluminescence measurements, the possible mechanisms for the improvement of ML intensity were proposed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Triboluminescence of Highly Oriented SrAl_2O_4:Eu Film and Its Potential Role As a Stress Indicator

    Xiaoyan FuHiroshi YamadaChao-Nan Xu
    319-322页
    查看更多>>摘要：Highly oriented SrAl_2O_4:Eu film had been deposited on a quartz glass using the RF sputtering method. The fabricated film displayed fiber-texture with the (031) orientation. The surface of the film was smooth and compact. In addition, under the UV excitation, the film emitted green light. After the removal of UV excitation, a long afterglow phenomenon could be observed from this film. The important point of this study was that SAOE film displays strong adhesion and high green triboluminescence (Tribo-L). Such properties made the films be a potential candidate as stress indicators.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Application of Nano-Sized CeO_2 Powder for Fast Response Oxygen Sensors

    Norimitsu MurayamaNoriya IzuWoosuck ShinIchiro Matsubara...
    323-327页
    查看更多>>摘要：For resistive oxygen sensor elements of Ce_(1-x)Zr_xO_2 (x = 0.0, 0.05, 0.1, 0.2), grain diameter was varied in the range of 86 - 300 nm by changing sintering temperature or changing Zr content. The grain diameter decreased with increasing Zr content. The response time was approximately proportional to the square of the grain diameter. In the relationship between the amplitude of sensor output, A_n and the frequency,f of sine wave of variation in oxygen partial pressure, the gradient in the high-frequency region of a plot of log A_n vs. log f in was approximately -0.5. From these results, it was concluded that the sensor response was determined by the oxygen vacancy diffusion rate. The grain diameter of Ce_(0.8)Zr_(0.2)O_2 element was 86 nm and the response time at 1073 K was 9 ms, which result opens the door to the technological development of independent control of engine cylinders.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    V_2O_5 Nanotubes Novel Gas Sensor with High Sensitivity for Ethanol

    Wei JinWen ChenBaitao DongChunxia Zhao...
    328-331页
    查看更多>>摘要：Vanadium oxide nanotubes were synthesized via a rheological self-assembling process followed by a hydrothermal reaction. V_2O_5 gas sensors were fabricated from vanadium oxide nanotubess with an average diameter of around 90 nm and their gas-sensing properties were investigated. It was found that the sensors based on vanadium oxide nanotubes exhibit high responses ethanol gas at 270℃. The results indicate that vanadium oxide nanotube sensors will be promising candidates for practical detectors for ethanol.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Ultra-rapid CO Gas Detection by a Gas Sensor Based on Flame-spray-made Pt/ZnO Nanoparticles

    Nittaya TamaekongChaikarn LiewhiranAnurat WisitsoraatSukon Phanichphant...
    332-335页
    查看更多>>摘要：ZnO nanoparticles doped with 0.2-2 at.%Pt were successfully produced in a single step by flame spray pyrolysis (FSP) technique using zinc naphthenate and platinum (II) acetylacetonate dissolved in xylene. The particle properties were analyzed by XRD, BET and TEM. Depending on FSP conditions, ZnO nanoparticles and nanorods were observed. The crystallite sizes of ZnO spheroidal particles were found to be ranging from 5 to 20 nm, while ZnO nanorods were seen to be 5-20 nm in width and 20-40 nm in length. ZnO sensing films were prepared using Al_2O_3 substrate interdigitated with Au electrodes by spin-coating technique. The gas sensing properties toward carbon monoxide (CO) was studied at the operating temperatures ranging from 200 to 350℃. It was found that the 0.2 at.%Pt/ZnO sensing film showed the highest sensitivity and the fastest response time at 350℃.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Improving the Performance of High Temperature Protonic Conductor (HTPC) Electrolytes for Solid Oxide Fuel Cell (SOFC) Applications

    Emiliana FabbriDaniele PergolesiAlessandra D'EpifanioElisabetta Di Bartolomeo...
    336-339页
    查看更多>>摘要：This work investigated the possibility of coupling the high conductivity of cerates and the good chemical stability of zirconates as proton conductor electrolytes for solid oxide fuel cells (SOFCs). Two different approaches are discussed: the synthesis of barium cerate and zirconate solid solutions, and the fabrication of a bilayer electrolyte made of a Y-doped barium cerate pellet covered by a thin protecting layer of Y-doped barium zirconate. The chemical stability of the tailored samples was tested exposing them to 100% CO_2 atmosphere at 700℃ for 3 h. X-ray diffraction (XRD) analysis was used to investigate the phase composition of the specimens before and after the CO_2 treatment. Electrochemical impedance spectroscopy (EIS) measurements were carried out in humidified H_2. Hydrogen-air breathing fuel cell experiments were carried out at 700℃.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd