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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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    Effect of Cooling Rate on the Properties of the Grain Boundary of CaCu_3Ti_4O_(12) Ceramic

    Jinliang HeFengchao LuoJun HuYuan-Hua Lin...
    300-303页
    查看更多>>摘要：The cooling rate effect on the grain boundaries of the CaCu_3Ti_4O_(12) ceramic was investigated in this research. The resistance at the grain boundaries is found to be reduced as the cooling rate rises. The activation energies at the grain boundaries do not change with the cooling rate, suggesting that the conduction mechanism keeps the same in different cooling conditions. There is no significant difference in the permittivity of the samples. The dielectric loss can be lowered by using a smaller cooling rate. These results give clues to comprehend the conductive mechanism of the CCTO ceramic. The variation of the cooling rate may affect the re-oxidation process and cause the changes in electric properties.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Memory Properties of SrBi_2Ta_2O_9/ Ba(Zr_(0.1)Ti_(0.9))O_3 Thin Films Prepared on Si Substrate

    Wen-Cheng TzouKai-Huang ChenCheng-Fu YangYing-Chung Chen...
    304-306页
    查看更多>>摘要：In this study, ferroelectric thin films of SrBi_2Ta_2O_9(SBT) or bilayered SrBi_2Ta_2O_9/ Ba(Zr_(0.1)Ti_(0.9))O_3 (SBT/BZT) are successfully deposited on Si substrate under the optimal RF magnetron sputtering conditions, and their electrical and ferroelectric characteristics are discussed. Ferroelectric thin films are deposited on Si substrate under the RF power of 80 W, chamber pressure of 10 mTorr, substrate temperature of 550℃, and different oxygen concentrations. The surface morphology of deposited thin films is observed from the FESEM images, and the memory windows and leakage current of the Al/SBT/BZT/Si (MFS) structure are measured by an impendence phase analyzer and a semiconductor parameter analyzer, respectively. The memory window, capacitance and leakage current density of MFS structures under different oxygen concentrations are also reported. We find that the memory window of bilayered SBT/BZT structure shows larger than one of single layer SBT structure.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Structural and Dielectrics Properties of (1-x)Pb(Fe_(2/3)W_(1/3))O_3-xPbTiO_3 Ceramics

    Jose Antonio EirasBarbara M. FraygolaDucinei Garcia
    307-310页
    查看更多>>摘要：Electric and dielectric properties of (1-x)Pb(Fe2/3W(1/3)O_3-xPbTiO_3 solid solutions were investigated as a function of the frequency and temperature. Dielectric measurements over the temperature showed the presence three contributions, which were related to the ferro-paraelectric phase transition (around 180K) and to conductive contributions (in the range 200K- 700 k). The FE phase transition of Pb(Fe_(2/3)W_(1/3))O_3 (PFW) is shifted to higher temperatures by PbTiO_3 (PT) additions. Conductive contributions were associated to an electronic conductivity with activation energy around 0.45 - 0.55 eV.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Hydrothermal Synthesis of Nano-Structured Barium Titanate from Metatitanic Acid

    Jing ChuDanyu JiangNa ZhangMin Zhang...
    311-313页
    查看更多>>摘要：Nano-structured Barium Titanate (BaTiO_3) was prepared by a hydrothermal method with the reaction between metatitanic acid and an alkaline solution of Ba(OH)_2·8H_2O. The morphology of as-obtained powders of BaTiO_3 was determined by Scanning Electron Microscope, which revealed that well-dispersed nanoparticles were successfully synthesized. The phase composition was analyzed by X-ray diffraction, which shows that cubic phase of Barium Titanate was prepared. The optimal reaction conditions were discussed in detail.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of BiFeO_3 Nanopowders Using Acetylacetone as Stabilizer

    Jia-Huan XuHua KeDe-Chang JiaWen Wang...
    314-317页
    查看更多>>摘要：The present investigation reports on the preparation of BiFeO_3 nanopowders by a sol-gel method using acetylacetone as a stabilizer. Single-phase BiFeO_3 nanopowders without any impurity or amorphous phases were obtained when the precursor was thermal treated at temperatures as low as 400℃ for 2 h. Acetylacetone (acac) plays an important role on lowering the formation temperature of pure phase BiFeO_3 nanopowders. It is found that Bi/acac molar ratio of 1/30 was favorable for a stable sol and for the lowest crystallization temperature of pure BiFeO_3 nanopowders. X-ray diffraction and Fourier transform infrared spectroscopy revealed that thermally induced crystallization process of BiFeO_3 nanopowders from Bi-Fe polymeric precursor. When the thermal treated temperature was below 200℃, only amorphous phase existed. With the temperature increasing up to 300℃, crystallized phase, carbonate, were detected. After annealed at 400℃, Bi-Fe precursor totally changed to rhombohedral BiFeO_3 nanopowders. Scanning electron microscopy characterized morphologies of BiFeO_3 nanopowders calcined at 400℃ and 500℃. The ferroelectric transition of BiFeO_3 nanopowders at 827℃ has been detected by differential thermal analysis.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Microstructure and Electrical Properties of Bi~(3+) Modified ZnO Ceramics

    J. D. S. GuerraY. LeyetF. GuerreroY. Romaguera...
    318-323页
    查看更多>>摘要：High-quality bismuth modified zinc oxide ceramics were obtained by conventional ceramic method. The phase analysis revealed pure hexagonal ZnO phase in all the samples. High relative density (above 95%), when compared with theoretical density of ZnO, was achieved by the Arquimides' method. Non-linear coefficients, obtained from the J-E curves, shown an increase in their values as the bismuth content increases. Complex impedance analysis revealed an increase of the semicircle diameters with the increase of the bismuth content. The obtained results will be discussed within the framework of the current theoretical model proposed in the literature.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Low Sintering of the Temperature-Stable Dielectric Ceramics Based on Barium Titanate in Reducing Atmosphere

    Changku SunXiaohui WangLongtu LiTae-Ho Songl...
    324-327页
    查看更多>>摘要：The optimized composition and sintering process of the low sintering X7R-type temperature-stable dielectric ceramics based on Barium Titanate in reducing atmosphere have been investigated. Flux aids SiO_2-B_2O_3-Li_2O were used in the experiments. The influence of composition and the content of flux agent on the microstructures and properties of ceramics materials were systemically studied. The X7R-type dielectric ceramics materials could be sintered at low temperature of 950℃ in H_2/N_2 atmosphere, by optimizing flux content and adjusting process parameters. The dielectric constant of ceramics was effectively improved using two-step sintering process.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Synthesis of BaTiO_3 Nanorods at Room Temperature and Normal Pressure

    Tieyu SunXiaohui WangXiaoquan ZhangLongtu Li...
    328-330页
    查看更多>>摘要：In this paper, a method to synthesis barium titanate nanorods at room temperature and normal pressure by soft chemical is devoloped. Oleic acid is one important raw material in this method which will help to form reaction containers. The nanorods crystallized in the process. Samples were investigate by XRD, TEM and SAD and so on.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation and Characteristics of BiFeO_3 Ceramics Doped by MnO_2 and CO_2O_3

    Yu XiaohuaGu HongxingWu BolinWang Jian...
    331-334页
    查看更多>>摘要：BiFeO_3-based single-phase multiferroics have been widely studied in both ceramics and films. However, the macroscopic magnetic properties of BiFeO_3 ceramics were now most very weak. In this work, MnO_2 and CO_2O_3 were used as B-site substitutes in BiFeO_3 ceramics in order to the enhancement of magnetic properties. The change of magnetization was analyzed based on the phase composition and the microstructure of ceramics.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Effect of Gel-Calcination on Piezoelectric Property in (1 -x)BiScO_3-xPbTiO_3 Ferroelectrics

    Han WangXiaohui WangShaopeng ZhangLongtu Li...
    335-339页
    查看更多>>摘要：In this paper, the effect of gel-calcination on piezoelectric property in (1-x) BiScO_3-xPbTiO_3 with the composition of x=0.635 is investigated. According to previous work, the heating rate of 200℃/h and holding for 210min having been taken as the basic processing condition. The BSPT powders were obtained from the same sol solution but calcined at different temperatures, and then the powders were used to prepare BSPT ceramics. The result shows that for the bulk ceramics with higher relative density (higher than 95%), with the increasing calcining temperature of the gel (from 420℃ to 500℃), the piezoelectric coefficient d_(33) of ceramic specimens first increases to maximum of 636pC/N at 450℃, then shows a fluctuation. In this work how the powder activity and the grain size affect (which was leaded by powder particle size) piezoelectric properties of BSPT ceramics are discussed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd