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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 and Phase Transition Behavior of (Li,Na,Ba)(Nb,Ti)O_3 Lead-Free Piezoelectric Ceramics

    Rintaro AoyagiRian RinaldiNaoki SumiyamaMakoto Iwata...
    42-45页
    查看更多>>摘要：The electrical properties and phase transition behavior of the sodium niobate-based solid solution (1-x)Li_(0.12)Na_(0.88)NbO_(3-x)Na_(0.91)Ba_(0.09)Nb_(0.91)Ti_(0.09)O_3 [(1-x)LNN12-xNNBT9] ceramics were investigated. The lattice constant changes became discontinuitous between LNNBT0.5 and LNNBT0.7. Moreover, the peak dielectric constant of LNNBT0.7 is twice that of LNNBT0.5. X-ray diffraction analysis and dielectric study confirmed that the different crystal phases of what are LNN-type rhombohedral (x=0), LNN-type orthorhombic (x=0.1, 0.3 and 0.5), NNBT-type orthorhombic (x= 0.7 and 0.9) and NNBT-type tetragonal (x= 1.0) phases. An electromechanical coupling factor of 0.244 was obtained for LNNBT0.7 whose composition is near the boundary between the LNN-type and NNBT-type orthorhombic phases.
      原文链接:
    • NETL
    • NSTL
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    Electrical Properties and Piezoelectric Properties of CaBi_2Ta_2O_9-Based Ceramics

    Toji TokusuHirokazu MiyabayashiYuji HirumaHajime Nagata...
    46-49页
    查看更多>>摘要：Electrical and piezoelectric properties of CaBi_2Ta_2O_9-based ceramics have been studied. Temperature dependence of dielectric properties indicated that the Curie temperature, T_C, was 923℃. Coercive field, E_C, and remanent polarization, P_r became saturated with increasing temperature. It is expected that higher-temperature than 250℃ could promote the domain wall motion during the poling treatment. From resonance and antiresonance measurements, piezoelectric properties such as the maximum phase, θ_(max), electromechanical coupling factor, K_(33), and piezoelectric g constant, g_(33), were 86.1°, 0.085 and 8.4 × 10~(-3) V·m/N, at room temperature, respectively.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Preparation of CaBi_4Ti_4O_(15) based thick films on Si substrates by screen printing

    Tatsunori KakudaTomoaki FutakuchiTsutomu ObataYuichi Sakai...
    50-53页
    查看更多>>摘要：CaBi_4Ti_4O_(15) based thick films were prepared by screen-printing method on Si substrates. Screen-printable pastes were prepared by kneading the CaBi_4Ti_4O_(15) powder in a three-roll mill with an organic vehicle. The remanent polarization of 6.3 μC/cm~2 and coercive field of 130kV/cm were obtained for the CaBi_4Ti_4O_(15) with Nb_2O_5 1wt% thick film fired at 1130℃. The cavity structure was prepared by etching of Si substrate. The displacement-electric field butterfly curves were obtained.
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    • NSTL
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    Effects of Compressive Stress on Dielectric Properties of Lead-Free (Bi_(1/2)Na_(1/2))TiO_3-(K_(1/2)Na_(1/2))NbO_3 Ceramic Systems

    Thanapong SareeinMuanjai UnruanAthipong NgamjarurojanaSupon Ananta...
    54-57页
    查看更多>>摘要：Lead-free, bismuth sodium titanate-potassium sodium niobate piezoelectric ceramics (Bi_(1/2)Na_(1/2))TiO_3-(K_(1/2)Na_(1/2))NbO_3 have been prepared by a conventional mixed-oxide method via vibro-milling technique. The (K_(1/2)Na_(1/2))NbO_3-based compositions with a morphotropic phase boundary (MPB) have shown greater advantages over another typical lead-free piezoelectric candidate material system, (Bi_(1/2)Na_(1/2))TiO_3 (BNT)-based MPB materials. More importantly, when used this type of material is often subjected to self-induced or external stress. It is. therefore, of interest to investigate influence of stress on properties of the ceramics. In this study, the influences of compressive stress on the dielectric properties of BNT-KNN ceramics were investigated. The dielectric properties were determined under compressive stress applied parallel to electric field. The results indicate significant changes of both properties with the imposed compressive stress. The results were explained in terms of non-180° domain switching and de-aging of the dielectric properties under the influence of the applied stress.
      原文链接:
    • NETL
    • NSTL

    Dielectric Properties of Low-Temperature Sintered Ba_(0.6)Sr_(0.4)TiO_3 Ceramics by addition of Bi_2O_3-CuO mixed oxides

    Haitao JiangJiwei ZhaiJingji ZhangXi Yao...
    61-64页
    查看更多>>摘要：The effect of 9Bi_2O_3-CuO mixed oxides as sintering agent on sintering behaviors and dielectric properties of Ba_(0.6)Sr_(0.4)TiO_3 (BST) ceramics were investigated. It was found that 9Bi_2O_3-CuO mixed oxides lowered the sintering temperature about 300℃ and that highly denser BST ceramic pellets were obtained by sintering at 975℃ with addition of 5,0-10.0wt% mixed oxides. For BST ceramics with 5.0wt% CB content sintered at 975℃, had a moderate dielectric constant (ε=1315), low dielectric loss (0.0067) and high tunability (36%) at dc electric field of 20kV/cm and at room temperature and at 10kHz.
      原文链接:
    • NETL
    • NSTL
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    Investigation on the effect of Mn on the dielectric properties of Ba_(0.4)Sr_(0.6)TiO_3/MgAl_2O_4/MgO composite ceramics

    Jingji ZhangTiwei ZhaiMingwei ZhangXi Yao...
    65-68页
    查看更多>>摘要：xMnCO_3-(1-x)[70wt% (10wt% MgO-90wt% Ba_(0.4)Sr_(0.6)TiO_3)-30wt% MgAl_2O_4] (where x=0.0, 0.5, 1.0, 2.0, 5.0 and 10.0wt%) composite ceramics have been prepared through the solid-state reactions. Three phases, corresponding to the Ba_(0.4)Sr_(0.6)TiO_3(BST), MgAl_2O_4(MA) and MgO phases, are clearly visible in the composite ceramics. The permittivity peak is initially enhanced and shifted toward a higher temperature and then suppressed, shifted toward a lower temperature. Meanwhile, the tunability (calculated by [ε(E_0)-ε(E)]/ε(E_0)) is also initially improved and then decreased by doping MnCO_3.
      原文链接:
    • NETL
    • NSTL
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    B-O Bond Character and Microwave Dielectric Properties of (1-x)CaTiO_(3_x)Ca(Zn_(1/3)Nb_(2/3))O_3 Perovskite Ceramics

    Jie ShenWen ChenJing ZhouJie Zhu...
    69-72页
    查看更多>>摘要：The relationship between the character of the B-site cation-oxygen bond and the microwave dielectric properties in perovskites dielectric materials was studied in this paper. The atomic net charge of CaTiO_3 (CT) and Ca(Zn_(1/3)Nb_(2/3)O_3 (CZN) was calculated respectively. The calculating result implies that the covalency of B-O bonds in CZN is stronger than that in CT. This predicted that the dielectric constant and loss of the ceramics will decrease after CZN incorporated in CT. To confirme the prediction, (1-x)CT-xCZN microwave dielectric ceramics were prepared by solid state reaction method with ZnNb_2O_6 as precursor. The structure analysis in terms of tolerance factor gives an identical result as calculation. The microwave dielectric properties, such as dielectric constants, Q×f values and τ_f were studied as a function of composition. With x increasing from 0.2 to 0.8, the dielectric constant linearly decreases from 109 to 49.37, the Q×f value increases from 8,340 to 13,200 GHz, and τ_f decreases from 321 to -18 ppm/℃. The properties trends are consistent with the previous calculation results, and confirm the relationship between the character of B-O bond and dielectric properties.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Microwave Characterization Techniques for High K Thin Films

    K.SudheendranK.C.James Raju
    73-76页
    查看更多>>摘要：Characterization of the dielectric properties of bulk materials in the microwave frequency range is well developed while that of thin films is a challenge. New microwave characterization techniques are needed for thin films taking in to account the fact that they are always deposited on a dielectric or conducting substrate and the thickness of the film is too small compared to the wavelength involved. In this paper we are demonstrating various techniques that can be used for the microwave characterization of thin films. The microwave dielectric properties of the bismuth zinc niobate (BZN) thin films were characterized at different frequencies using a few techniques by involving coplanar waveguide (CPW) transmission lines circular patch capacitors and split post dielectric resonators. The first two are broadband measurement techniques while the third one is a spot frequency technique.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Origin of High Q for Microwave Complex Perovskite

    Hitoshi OhsatoEiichi KogaIsao KagomiyaKen-ichi Kakimoto...
    77-80页
    查看更多>>摘要：Origins of high Q are considered on intrinsic as high symmetry, ordering structure and high density crystal structure. It was concluded that the high symmetry brings high Q instead of ordering comparing some cases as follows: As if ordering ratio of Ba(Zn_(1/3)Ta_(2/3))O_3 (BZT) is high of about 80%, Q values are distributed from low to high Q. Disordered BZT ceramics with high density obtained for short sintering time by spark plasma sintering (SPS) showed high Q. Ba(Zn_(1/3)Nb_(2/3))O_3 (BZN) with order-disorder transition showed high Q at disorder form sintered over the transition temperature. And, the disordered BZN with high Q annealed at lower temperature changed to order structure without improvement of Q.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    ZnO nanoarrays film grown by forced-hydrolysis-initiated-nucleation technique and its photo-induced electrical property

    Xiulan HuYoshitake MasudaTatsuki OhjiKazumi Kato...
    83-86页
    查看更多>>摘要：Anhydrous zinc acetate pre-coated on the FTO substrate was served as a template layer, and ZnO nanowhisker arrays were simply and successfully fabricated by its forced-hydrolysis-initiated-nucleation of the layer in an aqueous solution at low temperature below 100 ℃. The technique doesn't need any expensive metal catalyst and high-temperature treatment. The density, diameter and length of whiskers were controllable by changing the deposition time. As-grown ZnO nanoarrays showed photo-induced electrical property. Enhanced photo-induced current (2.0～3.0 × 10~(-5) A) was detected under laser irradiation after DNA molecules labeled with dye molecules were loaded on the ZnO nanowhisker arrays.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd