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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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    Preface

    Tadashi Takenaka
    A1页
    查看更多>>摘要：The 6th Asian Meeting on Electroceramics (AMEC-6) has been held in Tsukuba, Japan from October 22 to 24, 2008, in conjunction with the Electronics Division Meeting of the Ceramic Society of Japan. More than 285 researchers and engineers participated to this joint meeting to discuss and exchange information concerning the latest developments in science and technology of electroceramics.
      原文链接:
    • NETL
    • NSTL

    Phase Transition and Structural Analysis of (Li,Na,K)NbO_3 Lead-Free Piezoelectric Ceramics

    Ken-ichi KakimotoTatsuro HottaHitoshi Ohsato
    3-8页
    查看更多>>摘要：Structural characterization of various (Li,Na,K)NbO_3 solid solutions with different Li contents has been carried out by temperature-variable Raman scattering measurement. It was found that there was no clear thermal hysteresis between orthorhombic-tetragonal phase transition in the heating/cooling processes for (Li,Na,K)NbO_3 ceramics with Li content of 6 wt% and above, although a noticeable thermal hysteresis is observed in the Raman spectra and dielectric constant measurement for the other specimens with lower Li contents. It is presumed that the structural change of (Li,Na,K)NbO_3 cell tends to become insensibility against temperature as the Li content increases above 6.0 mol%.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Defect Structure and Electrical Property of Na_(0.5)K_(0.5)NbO_3 Lead-Free Piezoceramics

    Hitoshi MatsudoKen-ichi KakimotoIsao Kagomiya
    9-12页
    查看更多>>摘要：Na_(0.5)K_(0.5)NbO_3 (NKN) lead-free piezoceramics was synthesized by a solid state reaction method. The d.c. conductivity σ_(dc) and a.c. impedance of the ceramics were measured at the temperature range from 550 ℃ to room temperature on cooling process. The σ_(dc) decreased linearly with decreasing temperature on Arrhenius plot, and the activation energy at the temperature range from 450 to 390 ℃ and from 390 to 160 ℃ were 0.65 and 0.90 eV, respectively. The slope change at 390 ℃ corresponded to Curie temperature of NKN ceramics so that the carriers of these thermally active conductions were alkali metal or oxygen ions in the NKN crystal structure. The impedance of NKN ceramics at high temperature showed two relaxation processes at high and low frequencies, and the leak current was mainly attributed by the conduction through the grain boundary with low impedance value on lower frequency relaxation.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Domain wall Engineering in Lead-free Piezoelectric Materials

    Satoshi WadaPetr Pulpan
    13-16页
    查看更多>>摘要：Grain-oriented barium titanate (BaTiO_3, BT) ceramics were prepared by a templated grain growth (TGG) method using [110]-oriented BT platelike particles as a template and hydrothermal BT sphere particles with different particle sizes as a matrix. The degree of orientation along the [110] direction, F_(110), was measured using an X-ray diffraction (XRD) pattern by the Lotgering method. To obtain both a high density and a high F_(110), the preparation conditions were optimized as functions of matrix particle size, volume fraction of the template to the matrix, and sintering temperature. As for the results, BT grain-oriented ceramics with a high density of more than 96 % were successfully prepared despite various F_(110) values from 0 to 98 %. Scanning electron microscopy (SEM) revealed that their average grain sizes were always 75 μm despite various F_(100) values and there were no anisotropic microstructures. These grain-oriented BT ceramics were poled at 100 ℃, and their piezoelectric constants d_(33) was measured. As for the results, the d_(33) values increased with increasing F_(110) values, and at around an F_(110) of 85 %, d_(33) reached a maximum of 788 pC/N.
      原文链接:
    • NETL
    • NSTL

    Crystal growth and electrical properties of Na_(0.5)Bi_(0.5)TiO_3-BaTiO_3 lead-free ferroelectric piezocrystals

    Chao ChenXiangyong ZhaoHong LiuWenwei Ge...
    17-20页
    查看更多>>摘要：(1-x)(Na_(0.5)Bi_(0.5))TiO_(3-x)BaTiO_3 (abbreviated as NBBT100(1-x)/100x or NBBT100x) solid solution single crystals with x=0, 0.06, 0.08, 0.10, 0.20, 1.0 were grown using top-seeded solution growth (TSSG) method. Dielectric, piezoelectric and ferroelectric properties of NBBT crystals were investigated as a function of temperature, frequency, composition and crystal orientation. The temperature (T_m) corresponding to dielectric maximum and the depolarization temperature (T_d) decrease with increasing x. The <001> oriented NBBT90/10 single crystal shows excellent piezoelectric performance with piezoelectric constant (d_(33)) value about 275pC/N and exhibits relatively smaller coercive field (E_e) of 2.49 kV/mm and dielectric loss tanδ of 2.9 %, indicating a more adaptive engineered domain structure.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Piezoelectric properties of c-axis-oriented (Sr,Ca)_2NaNb_5O_(15) piezoelectric ceramics with single-plate type and multilayered type fabricated using crystal-oriented sheet forming

    Hiroyuki ShimizuYutaka DoshidaSatoshi TanakaKeizo Uematsu...
    21-25页
    查看更多>>摘要：Recently, we have developed crystal-oriented sheet forming (COSF) process from green sheet process and high-magnetic-field method. We formed c-axis-oriented (Sr,Ca)_2NaNb_5O_(15) (SCNN) sheets by the COSF process, and succeeded in realizing c-axis-oriented single-plate type piezoelectric ceramics (O-SP) and c-axis-oriented multilayered type piezoelectric ceramics (O-MLPC) for SCNN. From the measurement results of displacement induced by electric field, it was clarified that effective d_(33) of the O-SP was 210～240 pm/V. This value was about 3 times larger than that of the randomly oriented single-plate type, which was 70% of that of single crystal. Moreover, it was confirmed that O-MLPC indicated displacements 2.5 times as large as that of the conventional multilayer piezoelectric ceramics. In this study, we clarified that piezoelectric properties in bulk and multilayer structure can be drastically enhanced using the COSF process.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation and Characterization of Lead Free Multi-layer Ceramic Actuators with Ni Inner Electrodes Prepared by Inkjet Printing

    Yuichi SakaiTomoaki FutakuchiMasatoshi Adachi
    26-29页
    查看更多>>摘要：In order to prepare lead free multi-layer ceramic (MLC) actuators with Ni inner electrodes, inkjet ink containing NiO was prepared and its rheological properties were examined. The viscosity of the ink followed the Andrade's equation. By using this ink, Ba(Ti,Zr)O_3 based MLCs were prepared. The printed NiO layers were reduced to metal Ni and they functioned as the inner electrodes. The remanent polarization of the MLCs increased with the grain growth caused by the increase of firing temperature. The remanent polarization P_r and coercive field E_c of the MLCs fired at 1400℃ were 6.4 μC/cm~2 and 3.5 kV/cm, respectively. The displacement of the MLCs with 7 active layers was approximately 320nm at 30 kV/cm. The effective d_(33) shows approximately 160 pm/V when the electric field was 10 kV/cm.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Growth and Characterization of Bismuth Magnesium Titanate Bi(Mg_(1/2)Ti_(1/2))O_3

    Yasuhiro YonedaHiroyuki SaitohKenji YoshiiTakashi Nishida...
    30-33页
    查看更多>>摘要：A new oxide, Bi(Mg_(1/2)Ti_(1/2))O_3 was prepared using a high-pressure high-temperature technique at 8 GPa and 1000℃. As-sintered Bi(Mg_(1/2)Ti_(1/2))O_3 has the BiFeO_3-type perovskite structure with the rhombohedral R3c. After ground, crystal structure changed to tetragonal P4mm. Structure parameters of tetragonal Bi(Mg_(1/2)Ti_(1/2))O_3 were refined from laboratory X-ray powder diffraction data (a = 4.033(10) A, and c = 3.938(10) A). Bi(Mg_(1/2)Ti_(1/2))O_3 does not decompress at ambient pressure, but the structure changed from rhombohedral to tetragonal on heating above 800℃. This phase transition was nonreversible. Bi(Mg_(1/2)Ti_(1/2))O_3 is expected to be one of the end members of lead-free ferroelectric materials.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Phase Diagram and Microstructure Analysis of Barium Titanate - Potassium Niobate System Piezoelectric Ceramics

    Satoshi WadaMomoyo NittaNobuhiro KumadaDaisuke Tanaka...
    34-37页
    查看更多>>摘要：Barium titanate (BaTiO_3, BT) and potassium niobate (KNbO_3, KN) ceramics were prepared by normal sintering process. Phase diagram of BT-KN system was investigated using high-temperature XRD and dielectric measurement, and two phases coexistence between tetragonal and orthorhombic was observed at room temperature. Transmission electron microscope (TEM) observation confirmed that the microstructure of the ceramics with KN contents below 30 molar% was composed of only tetragonal BT-rich grain, while those with KN contents above 40 molar% were composed of two kinds of grains, i.e., tetragonal BT-rich and orthorhombic KN-rich grains. Phase boundary between two phases for BT-KN ceramics was grain boundary. Thus, we named two phases coexistence region for BT-KN ceramics "wide-band morphotropic phase boundary (MPB)". Finally, dielectric and piezoelectric properties were investigated, and both dielectric and apparent d_(33) maximum were observed at the 0.5BT-0.5KN ceramics.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Crystal Structure Analysis of Barium Titanate - Bismuth Perovskite-type Oxide System Ceramics and Their Piezoelectric Property

    Keisuke YamatoNobuhiro KumadaChikako MoriyoshiYoshihiro Kuroiwa...
    38-41页
    查看更多>>摘要：Barium titanate (BaTiO_3, BT) - bismuth lanthanum zinc titanium oxide [(Bi_yLa_(1-y))(Zn_(0.5)Ti_(0.5))O_3, B_yL_(1-y)ZT] solid solution ceramics were prepared to enhance Curie temperature (T_C) of BT, 132 ℃, to 200 ℃ As the raw materials, nanoparticles were used to make sintering temperatures lower. Optimization of calcination and sintering conditions resulted in a formation of a perovskite single-phase, and their densities were always greater than 94 %. The synchrotron XRD measurement revealed that the crystal structures were assigned to rhombohedral 3m. Temperature dependence of dielectric property revealed that for the 0.5BT-0.5BZT ceramics, T_C was 230 ℃. Moreover, La-doping into BT-BZT ceramics resulted in decrease of T_c significantly. Finally, their piezoelectric properties were measured by electric-field dependence of strain at room temperature, and for the 0.6BT-0.4BZT ceramics, the apparent d_(33) was measured at 250 pC/N.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd