• Title/Summary/Keyword: Pr계 ZnO 바리스터

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The Microstructure and Electrical Characteristics of Pr-Based ZnO Variators with $La_2O_3$Additives ($La_2O_3$가 첨가된 Pr계 ZnO 바리스터의 미세구조와 전기적 특성)

  • 남춘우;박춘현
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.11
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    • pp.969-974
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    • 1998
  • The effects of $La_2O_3$on the microstructure and electrical characteristics of Pr-based ZnO varistors were investigated. The average grain size increased in the range of 21.9~56.3$\mu$ m with increasing $La_2O_3$additive content(0.0~2.0 mol%). La was, of course grain boundary, largely segregated at the nodal point. As $La_2O_3$additive content increases, threshold voltage and nonlinear coefficient decreased and leakage current increased. In particular, 2.0 mol% $La_2O_3$-added varistor exhibited low threshold voltage 17.0V/mm and nonlinear coefficient of about 6. Based on these results, this varistor can be said to be used as low-voltage varistor, if nonlinear coefficient is somewhat improved forward.

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Degradation characteristics of Praseodymium-based ZnO Varistor (프라세오디윰계 산화아연 바리스터의 노화특성)

  • 이외천;박춘현;남춘우
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.06a
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    • pp.343-346
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    • 1998
  • Degradation characteristics of the Pr-based ZnO varistor with $Y_2O_3$content (0.0-4.0 mol!%j were investigated. It was appeared that the variation of the J-E characteristics in the reverse direction before and after the applied stress with increasing $Y_2O_3$ content was larger than that of the forward direction but the variation was extrernly small. For all varistor, the leakage current with the stress time during the applied stress somewhat increased initialy but afterthat was almost constant or slightly decreased. The overall varistor voltage and nonlinear coefficient were less than 5%. Especially, in the case of Pr-based ZnO varistor containing 2.0 mol% to 4.0 mol% $Y_2O_3$, the variation of breakdown voltage and nonlinear coefficient was less than 1% and 5%. respectively. As a result, they showed good stability.

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A Study on the Microstructure and Electrical Properties of ZnO:Pr Varistor with $Y_2O_3$Additive ($Y_2O_3$ 첨가에 따른 ZnO:Pr 바리스터의 미세구조 및 전기적 특성에 관한 연구)

  • 남춘우;정순철;이외천
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.1
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    • pp.48-56
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    • 1998
  • Pr\ulcornerO\ulcorner-based ZnO varistors were fabricated in the range of $Y_2$O$_3$additive content from 0.5 to 4.0mol%, and its microstructure and electrical properties were investigated. Yttrium was distributed nearly in the grain boundaries and the cluster phase formed at nodal point but more in cluster phase. The average grain size was decreased markedly from 34.9 to 8.6${\mu}{\textrm}{m}$ with increasing $Y_2$O$_3$additive content. It is believed that the decrease of grain size is attributed to the formation of cluster phase and the weakening of driving force for liquid sintering. As a result, $Y_2$O$_3$was acted as the inhibitor of the grain growth. With increasing $Y_2$O$_3$additive content, the varistor voltage, the activation energy, and the nonlinear exponent increased whereas the leakage current decreased, especially 4.0mol% $Y_2$O$_3$-added varistor exhibited very good I-V characteristics; nonlinear exponent 87.42 and leakage current 46.77nA. On the other hand, as $Y_2$O$_3$additive content increases, the varistor showed tendency of the salient decrease for donor concentration and the increase for barrier height. Conclusively, it is estimated that ZnO:Pr varistor compositions added more than 2.0mol% $Y_2$O$_3$are to be used to fabricate useful varistors.

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The Electrical Characteristics of Pr-Based ZnO Varistors With Lanthania Additives (란탄니아 첨가량에 따른 Pr계 ZnO 바리스터의 전기적 특성)

  • Lee, Woi-Chun;Park, Choon-Hyun;Nahm, Choon-Woo
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1495-1497
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    • 1998
  • The effects of lanthania on the microstructure and electrical characteristics of Pr-based ZnO varistors were investigated. The average grain size was increased in the range of 21.9$\sim$56.3${\mu}m$ with increasing lanthania content(0.0$\sim$2.0mol%). La was largely segregated at the grain boundary. As lanthania content increases, threshold voltage and nonlinear coefficient were decreased and leakage current was increased. In particular 2.0mol% lanthania-added varistor exhibited low threshold, voltage 17.0V/mm and nonlinear coefficient of around 6. Based on these results, this varistor can be said to be used as low-voltage varistor, if nonlinear coefficient is somewhat improved forward.

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