• Title/Summary/Keyword: $BiMnO_3$

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Piezoelectric and Dielectric Properties of Low Temperature Sintering Pb(Zn1/2W1/2)O3-Pb(Mn1/2Nb2/3)O3-Pb(Zr0.48Ti0.52)O3 Ceramics Manufactured by Post-annealing Method (Post-annealing 방법으로 제작된 저온소결 Pb(Zn1/2W1/2)O3-Pb(Mn1/2Nb2/3)O3-Pb(Zr0.48Ti0.52)O3 세라믹의 압전 및 유전특성)

  • Yoo, Ju-Hyun;Lee, Kab-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.3
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    • pp.227-231
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    • 2008
  • In this study, in order to improve the electrical properties of low temperature sintering piezoelectric ceramics, $[0.05Pb(Zn_{1/2}W_{1/2})-0.07Pb(Mn_{1/3}Nb_{2/3})-0.088Pb(Zr_{0.48}Ti_{0.52})]O_3$(abbreviated as PZW-PMN-PZT) ceramic systems were fabricated using $Bi_2O_3$, CuO and $Li_2CO_3$ as sintering aids and then their piezoelectric and dielectric properties were investigated according to the amount of $Li_2CO_3$ and post-annealing process. Post-annealing process enhanced all physical properties except for mechanical quality factor (Qm). 0.2 wt% $Li_2CO_3$ added and post-annealed specimen showed the excellent values suitable for low loss piezoelectric actuator application as follow: the density = 7.86 $g/cm^3$ electromechanical coupling factor (kp) = 0.575, piezoelectric constant $d_{33}$ = 370 pC/N, dielectric constant ($\varepsilon_r$) = 1546, and mechanical quality factor (Qm) = 1161, respectively.

Conduction Mechanism of Non-linearity ZnO Varistor in the Prebreakdown region (비선형성 ZnO 바리스터의 Prebreakdown 영역에서의 전도 현상)

  • 한세원;강형부
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.11a
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    • pp.74-76
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    • 1995
  • ZnO varistor with composition of ZnO(90wt%)-Bi$_2$O$_3$(3wt%)-Sb$_2$O$_3$(3.6wt%)-CO$_2$O$_3$(1.16wt%)-NiO(0.88wt%)-MnO$_2$(0.71wt%)-Cr$_2$O$_3$(0.93wt%) according to Al$_2$O$_3$addtive was fabricated by sintering methods. The effects of Al$_2$O$_3$dopant on the I-V characteristics of ZnO varistors were investigated. These changes of electric properties were found to be caused by the variation of grains and grain boundary related to Al$_2$O$_3$dopting. And the conductive mechanism of ZnO varistor in prebreakdown region were investigated with defect model.

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The Electric Properties of High Voltage Varistor with Rare Oxides (희토류 산화물 첨가에 따른 고압용 바리스터 전기적 특성)

  • Yoon, Jung-Rag;Lee, Chang-Bae
    • Proceedings of the KIEE Conference
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    • 2008.05a
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    • pp.199-200
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    • 2008
  • ZnO을 주원료로 하고 첨가제로 $Bi_2O_3$, $Sb_2O_3$, $Nd_2O_3$, CoO, $Cr_2O_3$, $MnO_2$, NiO를 고정한 후 $Y_2O_3$ 첨가량에 바리스터의 전기적 특성을 검토하였다. $Y_2O_3$ 첨가량이 증가할 수록 바리스터 전압이 직선적으로 증가함을 확인할 수 있으며 결정립계에 존재하는 스핀넬상에 $Y_2O_3$가 이차상으로 존재함을 확인 할 수 있었다. $Y_2O_3$ 첨가에 따라 ZnO 결정입자 성장을 방해하여 바리스터 전압을 증가시키는 반면 결정립의 크기를 불균일하게 하여 유전율을 감소시키고 유전손실은 증가함을 확인하였다. 본 연구 결과 $Y_2O_3$ 첨가로 바리스터 전압은 350 V/mm이상을 얻을 수 있으며 누설전류를 $1{\mu}A$이하로 하는 조성을 얻을 수 있었으며 소형 바리스터 제작이 가능함을 확인하였다.

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Effects of Expanders in Manufacture and Microstructure of ZnO Varistor with $Al_2O_3$ (ZnO 바리스터의 제조에서 분산제 영향 및 $Al_2O_3$ 첨가에 따른 미세구조 연구)

  • Soh, J.J.;Han, S.W.;Kim, H.S.
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.345-347
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    • 1995
  • ZnO varistor with composition of ZnO(90wt%)-$Bi_2O_3$(3wt%)-$Sb_2O_3$(3.61wt%)-$CO_2O_3$(1.16wt%)-NiO (0.88wt%)-$MnO_2$(0.71wt%)-$Cr_2O_3$(0.93wt%) according to $Al_2O_3$ addtive was fabricated by sintering methods. The optimal densification were established for the processing conditions of 8000 rpm 190$^{\circ}C$ spray drying and 1200$^{\circ}C$ 2hrs sintering. Then here investigated how additive compotions and processing variables affected the electrical and the phesical properties of these ZnO varistors.

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Ellipsometric study of Mn-doped $Bi_4Ti_3O_{12}$ thin films

  • Yoon, Jae-Jin;Ghong, Tae-Ho;Jung, Yong-Woo;Kim, Young-Dong;Seong, Tae-Geun;Kang, Lee-Seung;Nahm, Sahn
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.173-173
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    • 2010
  • $Bi_4Ti_3O_{12}$ ($B_4T_3$) is a unique ferroelectric material that has a relatively high dielectric constant, high Curie temperature, high breakdown strength, and large spontaneous polarization. As a result this material has been widely studied for many applications, including nonvolatile ferroelectric random memories, microelectronic mechanical systems, and nonlinear-optical devices. Several reports have appeared on the use of Mn dopants to improve the electrical properties of $B_4T_3$ thin films. Mn ions have frequently been used for this purpose in thin films and multilayer capacitors in situations where intrinsic oxygen vacancies are the major defects. However, no systematic study of the optical properties of $B_4T_3$ films has appeared to date. Here, we report optical data for these films, determined by spectroscopic ellipsometry (SE). We also report the effects of thermal annealing and Mn doping on the optical properties. The SE data were analyzed using a multilayer model that is consistent with the original sample structure, specifically surface roughness/$B_4T_3$ film/Pt/Ti/$SiO_2$/c-Si). The data are well described by the Tauc-Lorentz dispersion function, which can therefore be used to model the optical properties of these materials. Parameters for reconstructing the dielectric functions of these films are also reported. The SE data show that thermal annealing crystallizes $B_4T_3$ films, as confirmed by the appearance of $B_4T_3$ peaks in X-ray diffraction patterns. The bandgap of $B_4T_3$ red-shifts with increasing Mn concentration. We interpret this as evidence of the existence deep levels generated by the Mn transition-metal d states. These results will be useful in a number of contexts, including more detailed studies of the optical properties of these materials for engineering high-speed devices.

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Effects of Annealing on the Microstructure and Electrical Properties of ZnO Varistor (ZnO 바리스터 제조시 소결후 열처리 조건에 따른 미세구조 및 전기적 특성에 관한 연구)

  • Soh, J.J.;Han, S.W.;Kim, H.S.
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1679-1681
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    • 1996
  • ZnO varistor with composition of 89wt%-ZnO, 3.0wt%-$Bi_{2}O_{3}$, 3.6wt%-$Sb_{2}O_{3}$, 1.16wt%-CoO, 0.88wt%-NiO, 0.71wt%-$MnO_2$, 0.93wt%-$Cr_{2}O_{3}$, 0.013wt%-$Al_{2}O_{3}$ was fabricated by sintering methods. The effects of annealing on the J-E characteristics of ZnO varistors were investigated. These changes of electric properties were found to be caused by the variation of grains and grain boundary related to annealing. And the conductive mechanism and micostructure of ZnO varistor were researched using I-V meter, SEM and XRD.

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A study on the ZNR (Zinc Oxide Nonlinear Resistor) with $KNO_3$ ($KNO_3$의 첨가가 ZNR (Zinc Oxide Nonlinear Resistor)에 미치는 영향에 관한 연구)

  • 안영필;김복희
    • Journal of the Korean Ceramic Society
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    • v.17 no.3
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    • pp.133-140
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    • 1980
  • Nonohmic properties of ZnO ceramics with various small amounts of additives were studied in relation to sintering temperature and additive content. The kinds of additives used were basic additives ($Bi_2O_3$, $BaCO_3$, $MnCO_3$, $Cr_2O_3$) and $KNO_3$ Especially this study has focused on the effects of $KNO_3$ in ZnO ceramics with basic additives. SEM studies indicated that microstructures of ZnO, $KNO_3$ and basic additives showed homogenuous grain size in comparison to ZnO and basic additives compounds. The nonohmic exponent ($\alpha$) in ZnO, $KNO_3$ and basic additives component were measured as high as 40.

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Influence of the Conduction Properties on ZnO-Based Ceramic Varistor with $TiO_2$ Additives ($TiO_2$의 첨가가 ZnO계 세라믹 바리스타에 미치는 전기적인 영향)

  • Lee, S.S.;Jang, K.U.;Lee, J.U.
    • Proceedings of the KIEE Conference
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    • 1987.11a
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    • pp.234-238
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    • 1987
  • In this paper, the used specimen composition was added basic additives ($Bi_2O_3\;lmol%$, $Sb_2O_3\;lmol%$, CoO 0.5 mol%, MnO 0.5mol%) to ZnO powder, and $TiO_2$ (1,2,3,4 mol%) to the above basic composition. It appears that there are four regions of conduction current depended upon the strength of the applied electric field ; Ohimic region, Poole-Frenkel region, Schottky region and Tunneling region. Increasing of $TiO_2mol%$, the breakdown voltages of ZnO ceramic varistors are decreased. The decrease of breakdown voltages was explained with the decrease of potential barrier height. Moreover, V-I characteristics with temperature dependence are decreased with increasing of $TiO_2mol%$.

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W-Sn-Bi-Mo Mineralization of Shizhuyuan deposit, Hunan Province, China (중국 호남성 시죽원 광상의 W-Sn-Bi-Mo광화작용)

  • 윤경무;김상중;이현구;이찬희
    • Economic and Environmental Geology
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    • v.35 no.3
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    • pp.179-189
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    • 2002
  • The Geology of the Shizhuyuan W-Sn-Bi-Mo deposits, situated 16 Ian southeast of Chengzhou City, Hunan Province, China, consist of Proterozoic metasedimentary rocks, Devonian carbonate rocks, Jurassic granitic rocks, Cretaceous granite porphyry and ultramafic dykes. The Shizhuyuan polymetallic deposits were associated with medium- to coarse-grained biotite granite of stage I. According to occurrences of ore body, ore minerals and assemblages, they might be classified into three stages such as skarn, greisen and hydrothernlal stages. The skarn is mainly calcic skarn, which develops around the Qianlishan granite, and consists of garnet, pyroxene, vesuvianite, wollastonite, amphibolite, fluorite, epidote, calcite, scheelite, wolframite, bismuthinite, molybdenite, cassiterite, native bismuth, unidetified Bi- Te-S system mineral, magnetite, and hematite. The greisen was related to residual fluid of medium- to coarse-grained biotite granite, and is classified into planar and vein types. It is composed of quartz, feldspar, muscovite, chlorite, tourmaline, topaz, apatite, beryl, scheelite, wolframite, bismuthinite, molybdenite, cassiterite, native bismuth, unknown uranium mineral, unknown REE mineral, pyrite, magnetite, and chalcopyrite with minor hematite. The hydrothermal stage was related to Cretaceous porphyry, and consist of quartz, pyrite and chalcopyrite. Scheelite shows a zonal texture, and higher MoO) content as 9.17% in central part. Wolframite is WO); 71.20 to 77.37 wt.%, FeO; 9.37 to 18.40 wt.%, MnO; 8.17 to 15.31 wt.% and CaO; 0.01 to 4.82 wt.%. FeO contents of cassiterite are 0.49 to 4.75 wt.%, and show higher contents (4.]7 to 4.75 wt.%) in skarn stage (Stage I). Te and Se contents of native bismuth range from 0.00 to 1.06 wt.% and from 0.00 to 0.57 wt.%, respectively. Unidentified Bi-Te-S system mineral is Bi; 78.62 to 80.75 wt.%, Te; 12.26 to 14.76 wt.%, Cu; 0.00 to 0.42 wt.%, S; 5.68 to 6.84 wt.%, Se; 0.44 to 0.78 wt.%.

Effect of sintering process on the electrical protection performance in a ZnO-based ceramic varistor (ZnO varistor의 소결온도와 첨가물혼합비가 전기적 보호특성에 미치는 영향)

  • 오명환;이경재
    • 전기의세계
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    • v.31 no.6
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    • pp.445-449
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    • 1982
  • This Paper describes the influence of additive concentrations and sintering temperature on the surge protection performance in ZnO ceramic varistors. It is found from the experiments that the metal-oxide semiconductors based oi ZnO with an additive incorporation of 0.50% molx(Bi$\_$2/O$\_$3/+MnO+CoO+Cr$\_$2/O$\_$3/+2Sb$\_$2/O$\_$3/) and sintered at 1250.deg. C present excellent V-I characteristics in view of transient surge suppression. Gapless arrester element with aluminum electrodes shows also good reliability against impulse shock and marks a low voltage clamping ratio(V$\_$1KA/V$\_$1mA/<2.0) compared with the conventional SiC varistors.

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