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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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    Crystallization and Raman Spectra of Langasite-Type Na_2CaGe_6O_(14), Na_2SrGe_6O_(14) and Pb_3Ga_2Ge_4O_(14) in Corresponding Glasses

    Yoshihiro TakahashiTakumi FujiwaraYasuhiko BeninoTakayuki Komatsu...
    213-216页
    查看更多>>摘要：We investigated the crystallization behavior of langasite-type phases in the stoichiometric corresponding glasses, i.e., Na_2CaGe_6O_(14), Na_2SrGe_6O_(14) and Pb_3Ga_2Ge_4O_(14). The langasite-type phases singly were formed by heat-treatment in the glasses. Raman spectroscopy revealed the structural similarity on the scale of short-/medium-range order between the langasite-type phases and the corresponding glasses. Furthermore, we also examined the temperature dependence of second-harmonic (SH) intensity of the langasite-type phases. The SH-temperature curves exhibited an anomalous behavior, implying a structural change, e.g., isomorphous phase transition.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Dielectric and magnetic properties of CoFe_2O_4-BaTiO_3 composite thick film

    Ling ZhangJiwei ZhaiWeifeng MoXi Yao...
    219-222页
    查看更多>>摘要：(x)CoFe_2O_4-(1-x) BaTiO_3 thick film with x=0.2 was prepared by electrophoretic deposition technique using BaTiO_3 and CoFe_2O_4 nanopowders. X-ray diffraction indicated the film was consisted of single spinel CoFe_2O_4 and perovskite BaTiO_3 phase. The thick film exhibited good ferromagnetic and ferroelectric property. The dielectric properties were influenced by ferromagnetic phase, especially at low frequency and high temperature, which was attributed to space charge effects and Maxwell-Wagner relaxation.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Fabrication and Characterization of Perovskite SrZrO_3 Ceramics through a Combustion Technique

    Atthakorn ThongthaTheerachai Bongkarn
    223-226页
    查看更多>>摘要：Perovskite SrZrO_3 ceramics were successfully prepared via a combustion technique. The effect of calcination temperatures (900-1400℃) and sintering temperatures (1400-1650℃) on phase and morphology evolution of perovskite SrZrO_3 ceramics were studied. The highest purity of perovskite phase powder was obtained at 1250 ℃ and the purity of the perovskite phase of SrZrO_3 ceramics were detected in the samples sintered at 1550 ℃ for 6 h. The SEM results showed the average particle size (84-214 nm) and the average grain size (0.35-2.09 μm) of samples increased with the increase of firing temperatures. The shrinkage of the ceramics increased as the sintering temperatures increased. The maximum density was ～98.4% of the theoretical density for the sample sintered at 1550 ℃ for 6 h.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Stress Dependence of Dielectric Properties in Relaxor Ferroelectrics: Monte Carlo Investigation

    Yongyut LaosiritawornRattikorn YimnirunRuyan GuoAmar S. Bhalla...
    227-230页
    查看更多>>摘要：In this work, we used Monte Carlo simulation to investigate the uniaxial stress dependence of the relaxor dielectric properties. The Metropolis algorithm and the spin glass type interaction were used in updating the local polarizations (representing the polar nano-regions). The exchange interaction in the spin glass Hamiltonian was assumed to be stress dependent via the strain. From the results, the frequency dependence of the dielectric permittivity were found, where, at high enough stress, the dielectric permittivity decreases with increasing stresses in qualitatively good agreement with experiments. In addition, from the modified Curie-Weiss law, all γ's stay close to 2. Therefore, this implies the frequency dispersion universality of the relaxor system under loading conditions.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Acceptor-Doped Ferroelectric Modeling via Monte Carlo Simulation

    Sukrit SucharitakulRattikom YimnirunYongyut Laosiritaworn
    231-234页
    查看更多>>摘要：A 2D Monte Carlo simulation was done as an approach to get further insight of acceptor-doped ferroelectric material. By utilizing vector model allowing 14 directions of orientation for ferroelectric systems, Metropolis algorithm was applied on DIFFOUR Hamiltonian to obtain hysteresis profiles. Subjected to different concentration of acceptor dopants, power law scaling of hysteresis properties were obtained as functions of external parameters such as temperature, external field amplitude and frequency. The hysteresis loop shape and properties agreed well with those obtained experimentally.
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    • NETL
    • NSTL

    Sintering of Ba_(1-x)Sr_xTiO_3 powders prepared using KOH-KNO_3molten salt method

    Tomohiko KishikiMasashi HiguchiTakashi AsakaYasuo Azuma...
    235-238页
    查看更多>>摘要：Barium strontium titanate (BST), which has a typical perovskite-type structure, shows excellent electrical properties. BST powders were synthesized by heating mixtures of commercial reagents with an excess of TiO_2 in molten salts of KOH and KNO_3, and the sintering behavior of the resulting powders was evaluated. The sample with the highest density of 95% was obtained by sintering of the BST powders.
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    • NETL
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    Properties of Barium Stannate Titanate with Boron Oxide Addition

    Nattaya TawichaiSukum EitssayeamUraiwan IntathaKamonpan Pengpat...
    239-242页
    查看更多>>摘要：In this study, barium stannate titanate ceramics with an addition of boron oxide were synthesized via a solid-state sintering method. The effect of sintering aid on electrical and mechanical properties of barium stannate titanate ceramics was investigated. It was found that, the ceramic with 2 wt% boron oxide showed the lowest porosity and the highest dielectric constant of ～ 13700 at room temperature. In addition, an increase in the boron oxide content was observed to enhance the hardness of the ceramics. These results may be helpful in the multilayer capacitor applications.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    The Effect of Calcination Temperatures on the Phase Formation and Microstructure of (Pb_(1-x)Sr_x)TiO_3 Powders

    R. SumangT. Bongkarn
    243-246页
    查看更多>>摘要：(Pb_(1-x)Sr_x)TiO_3 (PST) (x=0.25, 0.50) powders were synthesized by a mixed oxide solid-state reaction method under various calcination temperatures (600-1100℃). Powder samples were characterized using thermogravimetric (TGA), differential thermal analysis (DTA), x-ray diffractrometer (XRD) and scanning electron microscopy (SEM). The results showed that a single-phase of PST for x=0.25 and 0.50 powders was successfully obtained with a calcination condition of 950 ℃ for 2 h with a heating/cooling rate of 5℃/min. The TGA-DTA results corresponded to the XRD investigation. The lattice parameter a increased whilst the lattice parameter c decreased with increasing calcination temperatures. The tetragonality of powders decreased with an increase of calcination temperatures. The average particle size of the powders increased with the increase of calcination temperature.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Influences of Firing Temperatures on Phase and Morphology Evolution of (Ba_(0.25)Sr_(0.75))(Zr_(0.75)Ti_(0.25))O_3 Ceramics Synthesized via Solid-State Reaction Method

    Atthakorn ThongthaKritsana AngsukasedTheerachai Bongkarn
    247-250页
    查看更多>>摘要：The effect of calcination (1000-1400 ℃) and sintering temperatures (1400-1600 ℃) on the phase formation and microstructure of barium strontium zirconate titanate [(Ba_(0.25)Sr_(0.75))(Zr_(0.75)Ti_(0.25))O_3; BSZT] ceramics were investigated. BSZT powders were prepared by the solid-state reaction method. Higher calcination temperatures increased the percentage of the perovskite phase, but decreased the lattice parameter a of BSZT powders. The pure perovskite phase of BSZT powders was detected above the calcination temperature of 1350 ℃. The microstructure of BSZT powders exhibited an almost-spherical morphology and had a porous agglomerated form. The average particle size and the average grain size of the ceramics were increased with the increase of calcination and sintering temperatures. The highest density of the samples was 5.42 g/cm~3 which was obtained from ceramic sintered at 1550 ℃ for 2 h.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    EFFECTS OF IRON ADDITION ON AGING BEHAVIOR OF BARIUM TITANATE CERAMICS UNDER COMPRESSIVE STRESS

    Jirapa TangsritrakulMuangjai UnmanPiyachon KetsuwanNarit Triamnak...
    251-254页
    查看更多>>摘要：In this study, a room temperature aging behavior of Ba(Ti_(0.99)Fe_(0.01))O_3 was investigated. It was found that the dielectric constant decreased with time and ferroelectric P-E hysteresis loops became constricted loops after aging. Moreover, the room temperature aging behavior under various stresses was also observed. It was found that the relative changes of dielectric constant with time of Ba(Ti_(0.99)Fe_(0.01))O_3 ceramics under stress were lower than those under the stress-free condition. For P-E hysteresis loop measurement, it can be observed that P-E hysteresis loop of Ba(Ti_(0.99)Fe_(0.01))O_3 ceramics became constricted loops and remanant polarizations (P_r), saturated polarizations (P_s) were decreased after aging under all stress levels. These results suggested that the applied stress may partly clamp the domain wall motion, and altered the aging behavior of the ceramics.
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    • NETL
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    • Trans Tech Publications Ltd