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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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    Improvement of Compact X-rays Source using Uniaxially Polarized LiNbO_3 Single Crystal

    Yang GuanShinji FukaoKazuyuki ItoYoshikazu Nakanishi...
    P.43-46页
    查看更多>>摘要：X-ray radiation using pyroelectric crystal is intermittent and the X-ray intensity is low and unstable compared with a conventional X-ray radiation method, such as X-ray tube. It is expected that the X-ray intensity becomes stable if electric field intensity and supply of electron are stable. In this study, to use X-ray radiation equipment as an electron source, tandem-type X-ray radiation equipment which is composed of two LiNbO_3 single crystals polarized in a z-axis is proposed. When the temperature gradient for each crystal was the same, the X-ray intensity became approximately 6 times higher at a maximum. When the temperature gradient for each crystal was reversed, the period of X-ray radiation became approximately two times longer and the X-ray intensity became approximately 20 times higher at a maximum. Moreover, the stability of X-ray radiation for the repetition of temperature could be improved.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Nonlinear shear response in (K,Na)NbO_3-based lead-free piezoelectric ceramics

    Manabu HagiwaraSeita TakahashiTakuya HoshinaHiroaki Takeda...
    P.47-50页
    查看更多>>摘要：The piezoelectric shear response of 94.0(Ka_(0.5), Na_(0.5))NbO_3 (KNN) + 5.0LiNbO_3 (LN) + 0.5SrTiO_3 (ST) + 0.5BiFeO_3 (BF) ceramics was investigated by Laser Doppler Vibrometry (LDV) and resonance-antiresonance method. From resonance-antiresonance method, the piezoelectric d_(15) constant was obtained to be 273 pC/N. The shear strain obtained by LDV at the frequency of 150kHz showed strong nonlinearity. This suggested that the domain contribution to piezoelectric response in shear mode of KNN-LN-ST-BF ceramics existed at the operational frequency for the shear mode divices.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Discharge Current Measurement and Depolarization Property of Lead-Free Niobate Piezoceramics

    Hitoshi MatsudoKen-ichi KakimotoIsao Kagomiya
    P.51-54页
    查看更多>>摘要：Lead-free Na_(0.5)K_(0.5)NbO_3 (NKN) piezoelectric ceramics was synthesized by an ordinal solid state reaction method. The ceramics was electrically poled under 3 kV/mm at 150 ℃ for 30 min. The discharge current-flow was measured for the poled ceramics at the heating rate of 1 ℃/min from room temperature up to 500 ℃. The two sharp peaks were observed at 209 and 417 ℃. These temperatures were corresponded to orthorhombic-tetragonal (T_O-t) and tetragonal-cubic (T_C) phase transition temperatures, respectively. The sharp peaks were mainly originated from the decrease of the spontaneous polarization. Additionally, the several large broad patterns were also observed at 280, 363 and 375 ℃, According to the electromechanical coupling factor k_p, which is the indicative parameter of the polarization, mainly decreased at T_O-t and T_C. These broad peaks were not associated with the spontaneous polarization. The peaks seem to have been originated from the discharge current of the oxygen ion migration on elevating temperature inside the poled NKN ceramics.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Dielectric and Piezoelectric Properties of (Na,Ba)(Nb,Ti)O_3 Lead-Free Piezoelectric Ceramics

    Rintaro AoyagiMakoto IwataMasaki Maeda
    P.55-58页
    查看更多>>摘要：(Na_(1-x)Ba_x)(Nb_(1-x)Ti_x)O_3 (NNBTx; x=0.0-0.21) solid-solution ceramics were synthesized and their crystal structure, dielectric properties and piezoelectric properties were investigated. The crystal structure at room temperature of NNBTx varied from orthorhombic to tetragonal with increasing BaTiO_3 content x. The phase boundary between orthorhombic and tetragonal at room temperature was confirmed BT content between x=0.08 and 0.09. For x>0.05, it was found that the Curie temperature was decreased with increasing x. The highest electromechanical coupling factor, k_p, and the largest piezoelectric constant, d_(33), were obtained at x=0.09-0.10.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Materials design and characterization of (Bi_(1/2)Na_(1/2))TiO_3-Bi(B',B")O_3 ceramics

    Yumiko OshimaYuuki KitanakaYuji NoguchiMasaru Miyayama...
    P.59-62页
    查看更多>>摘要：0.995(Bi_(1/2)Na_(1/2))TiO_3-0.005Bi(S',B")O_3 solid-solution ceramics (B',B" denote Zn, Mg, Ni, Ti, Nb) were fabricated and their ferroelectric properties were investigated. Based on the structural characteristics of Bi(B',B")O_3 analyzed by first-principles calculations, a materials design for obtaining a large piezoelectric strain is proposed: an index Z= P_s·(ε_(33)~*·s_(33))~(1/2), where P_s is spontaneous polarization, ε_(33)~* is relative permittivity and s_(33) is elastic compliance. A positive correlation was observed between Z and effective piezoelectric constant d_(33)~* observed for strain measurements.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Ion Exchange of Layer Structured Niobate Cs_4Nb_6O_(17)·3H_2O and Its Application as Cathode Material in a Rechargeable Lithium Battery

    Masao Ohashi
    P.65-68页
    查看更多>>摘要：The layer structured niobate Cs_4Nb_6O_(17)·3H_2O has been prepared in a solid state reaction using Cs_2CO_3 and Nb_2O_5 at 1073 K. Ion exchange reactions of Cs~+ in the interlayer space were studied in aqueous solutions. The single phases of lithium, sodium and hydrogen ion exchange products were obtained and they also contained interlayer water. The interlayer water of the lithium ion exchange product was removed by heating at 453 K in a vacuum. The resulting niobate Cs_(0.26)Li_(3.01)H_(0.73)Nb_6O_(17) was evaluated for its use as the cathode in a rechargeable lithium battery. The cathode exhibited discharge and charge capacities of 120 and 110 mAhg~(-1) for the first cycle in the voltage range of 1.5 - 4.2 V. The amount of Li~+ intercalated and deintercalated were 4.0 and 3.6 of the formula unit, respectively.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Fabrication of dye-sensitized solar cells with electrolyzed TiO_2 nanotube array films

    Nakamura TakahiroHayashi KazuhoAsahara MasahiroOgihara Takashi...
    P.69-73页
    查看更多>>摘要：A TiO_2 nanotube array film was synthesized by the anodic oxidation of a Ti plate in an NH4F electrolyte. The film was broken into nanotubes by carrying out ultrasonication. The nanotube powder was mixed with TiO_2 nanoparticle powder to form a paste. The paste was used in the fabrication of ceramic porous electrodes of dye-sensitized solar cells.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Fabrication of Nanostructured NiO Thick Films by Facile Printing Method and Their Dye-Sensitized Solar Cell Performance

    Koji SakuraiShinobu Fujihara
    P.74-77页
    查看更多>>摘要：Nanostructured NiO thick films were fabricated for use in dye-sensitized solar cells (DSCs) as photocathodes. Pastes were prepared by using nanocrystalline NiO powders, polyethylene glycol (PEG) and water. The pastes were then printed on FTO glass substrates by a facile doctor-blade printing method. The NiO films were obtained by heating at 500 ℃ for 30 min in flowing oxygen. It was shown that the nanostructure of the resultant films was largely dependent on the amount of PEG in the pastes. Coumarin 343 (C343) dye was employed for sensitizing p-type NiO photocathodes. DSCs using our NiO/C343 photocathodes yielded a photocurrent density of 1.26 mA cm~(-2), an open-circuit photovoltage of 88 mV, a fill factor of 0.33, and a solar energy conversion efficiency of 0.037 %.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Advantageous Effect of Macroporous TiO_2 Particles on Dye-sensitized Solar Cells

    Naohiro HitachiShinobu Fujihara
    P.78-81页
    查看更多>>摘要：In dye-sensitized solar cells (DSC), large-size particles in photoanodes can act as light-scattering center to enhance light harvesting efficiency. In this study, macroporous secondary TiO_2 particles were prepared by a spray drying method and were introduced to DSC. A few kinds of layered structures were fabricated as photoanodes to evaluate effects of macroporous particles. It was found that open circuit voltage increased due to the presence of macroporous particles. A photoanode composed of stacked nanoparticles and macroporous particles showed better cell performance.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Synthesis and Characterization of La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.2)O_(3-δ) Nano-Particle by Aerosol Plasma Pyrolysis

    Kenichi MyoujinAraki ToriyamaTakayuki KoderaTakashi Ogihara...
    P.82-85页
    查看更多>>摘要：Spherical La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.2)O_(3-δ) (LSGM) precursor powders were synthesized by aerosol plasma pyrolysis using an aqueous solution of metal nitrate. As-prepared powders obtained by this method were found to have a spherical morphology with a bimodal size distribution of nanosized (primary) and submicron-sized (secondary) particles. The average size of the primary particles was less than 100 nm. X-ray diffraction (XRD) patterns showed that as-prepared powders crystallized to LSGM and other phases. XRD revealed that LSGM pellets were crystallized to a perovskite structure after sintering at 1300 ℃ for 10 h.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd