• Title, Summary, Keyword: Nonlinear exponent

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Influence of Sintering Temperature and Electrical Properties on ZPCCE Based Varistors (ZPCCE계 바리스터의 전기적 성질에 소결온도가 미치는 영향)

  • 류정선;윤한수;남춘우
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.242-245
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    • 2000
  • The electrical properties of ZPCCE (ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Er$_2$O$_3$) based varistors were investigated with sintering temperature in range of 1335 to 135$0^{\circ}C$ for 1h. As the sintering temperature increases, the nonlinear exponent decreased, but was high beyond 40 except for 1.0 mol% Er$_2$O$_3$. Among all ZPCCE varistors, the varistor having the highest nonlinear exponent was obtained by sintering at 1335$^{\circ}C$, containing 2.0 mol% Er$_2$O$_3$ and then the nonlinear exponent was 78.05, and the varistors with 0.5 mol% Er$_2$O$_3$ exhibited the lowest leakage current of 1.92 $\mu$A.A.A.

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DC Accelerated Aging Characteristics of Zn-Pr-Co-Cr-La Oxides-Based Varistors with Sintering Temperature (소결온도에 따른 Zn-Pr-Co-Cr-La 산화물계 바리스터의 DC 가속열화 특성)

  • Kim, Myung-Jun;Yoo, Dae-Hoon;Park, Jong-Ah;Nahm, Choon-Woo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.383-386
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    • 2004
  • DC accelerated aging characteristics of Zn-Pr-Co-Cr-La oxides-based varistors were investigated with various sintering temperatures. The varistors sintered at $1240^{\circ}C$ exhibited the highest nonlinearity, with a nonlinear exponent of 79.3 and a leakage current of $0.3\;{\mu}A$, whereas completely degraded because of thermal runaway owing to low sintered density. The varistors sintered at $1250^{\circ}C$ exhibited not only a high nonlinearity with the nonlinear exponent 61.4 and the leakage current 0.7 ${\mu}A$, but also a high stability with the variation rates of varistor voltage and nonlinear exponent are -1.01% and -10.67%, respectively, under DC stress condition such as $(0.85\;V_{1mA}/115^{\circ}C/24\;h)+(0.90\;V_{1mA}/120^{\circ}C/24\;h)+(0.95\;V_{1mA}/125^{\circ}C/24\;h)+(0.95\;V_{1mA}/150^{\circ}C/24\;h)$.

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Electrical Properties of Zn-Pr-Co-Cr-Er Oxides-based Varistors (Zn-Pr-Co-Cr-Er 산화물계 바이스터의 전기적 성질)

  • 남춘우;류정선
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.5
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    • pp.362-369
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    • 2001
  • The electrical properties of varistors consisting of Zn-Pr-Co-Cr-Er oxides were investigated in the Er$_2$O$_3$content range of 0.0 to 2.0 mol%. the varistors without Er$_2$O$_3$ exhibited a relatively low nonlinearity, which was 14.24 in the nonlinear exponent and 21.47 $\mu$A in the leakage current. However, the varistors with Er$_2$O$_3$ sintered at 1335$^{\circ}C$ for 1h exhibited very high nonlinear exponent of 70, in particular, reaching a maximum value of 78.05 in 2.0 mol% Er$_2$O$_3$, and those sintered at 1335$^{\circ}C$ for 2h exhibited the nonlinear exponent close to 50, in particular, reaching a maximum value of52.76 in 0.5 mol% Er$_2$O$_3$. The others except for 0.5 mol% Er$_2$O$_3$-added varistors exhibited very high instability resulting in a thermal runaway within a short time, even a weak DC stress. Increasing soaking time decreased the nonlinearity, but increased the stability. The varistors containing 0.5mol% Er$_2$O$_3$ sintered for 2h exhibited excellent stability, in which the variation rate of the varistor voltage and nonlinear exponent was -1.70% and -7.15%, respectively, under more severe DC stress such as (0.80 V$_{1mA}$/9$0^{\circ}C$/12h)+(0.85 V$_{1mA}$/115$^{\circ}C$/12h)+(0.90 V$_{1mA}$/12$0^{\circ}C$/12h)+(0.95 V$_{1mA}$/1$25^{\circ}C$/12h)+(0.95 V$_{1mA}$/15$0^{\circ}C$/12h).TEX>/12h).

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Electrical Properties of $Pre_{6}O_{11}$-Based Varistors with $Y_{2}O_3$ Addition ($Y_{2}O_3$ 첨가에 따른 $Pre_{6}O_{11}$계 바리스터의 전기적 특성)

  • Ryu, Jung-Sun;Yoon, Han-Soo;Nahm, Choon-Woo
    • Proceedings of the KIEE Conference
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    • pp.1676-1678
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    • 2000
  • The electrical characteristics of $Pre_{6}O_{11}$-based ZnO varistors doped with $Y_{2}O_3$ in the range 0.0-4.0 mol% sintered at 1350$^{\circ}C$ were investigated. The varistor without $Y_{2}O_3$ exhibited very low nonlinearity, which the nonlinear exponent is 4.54 and leakage current is 87.91${\mu}A$. However the varistors with $Y_{2}O_3$ exhibited in the range of 30.00-51.19 in the nonlinear exponent and 0.52-3.89${\mu}A$ in the leakage current. Especially, the varistor with $Y_{2}O_3$ of 0.5 mol% exhibited the nonlinear exponent of 51.19 and the leakage current of 1.32${\mu}A$.

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The Electrical Properties and Stability of ZPCCY-Based Ceramic Varistors with Sintering Timpertature (ZPCCY계 세라믹 바리스터의 소결시간에 따른 전기적 특성 및 안정성)

  • Jung, Yung-Chul;Ryu, Jung-Sun;Nahm, Choon-Woo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.472-475
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    • 2001
  • The electrical properties and stability of ZPCCY-based varistors composing of $ZnO-Pr_{6}O_{11}-CoO-Cr_{2}O_{3}-Y_{2}O_{3}$ ceramics were investigated with sintering time. As sintering time is increased, the nonlinear exponent decreased in the range of 51.19~26.70. Among varistors having above 30 in nonlinear exponent, for the varistor sintered for 1h, the nonlinearity was superior to the stability comparatively and, in the case of 2h, the stability was superior to the nonlinearity relatively. Consequently, it is estimated that the varistors sintered for 1~2h will be applied to various fields by trade-off between nonlinearity and stability.

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DC Accelerated Aging Characteristics of ZPCCL-Based Varistor Ceramics (ZPCCL계 바리스터 세라믹스의 DC 가속열화특성)

  • Kim, Hyang-Suk;Nahm, Choon-Woo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.629-633
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    • 2002
  • The degradation behaviour of ZPCCL-based varistor ceramics composed of 97.5 mol%ZnO-0.5 mol% $Pr_6O_{11}-1.0$ mol% $Cr_2O_3-0.5$ mol% $La_2O_3$ was investigated under various DC accelerated aging streses. The varistor ceramics sintered for 1 h exhibited excellent nonlinearity, in which the nonlinear exponent is 81.6 and the leakage current is $0.2{\mu}A$. It was found that this varistor ceramics possess high stability, in which the variation rates of varistor voltage, nonlinear exponent, and leakage current are -1.14%, -3.7%, and 85.0%, respectively, against DC accelerated aging stress. On the contrary, the varistor ceramics sintered for 2 h also exhibited high nonlinearity and stability, but they were bad characteristics, compared with the varistor ceramics sintered for 1 h.

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The Electrical Properties and Salability of ZPCCY-Based Ceramic Varistors wish Sintering Timperature (ZPCCY계 세라믹 바리스터의 소결시간에 따른 전기적 특성 및 안정성)

  • 정영철;류정선;남춘우
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.472-475
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    • 2001
  • The electrical properties and stability of ZPCCY-based varistors composing of ZnO-Pr$_{6}$ O$_{11}$ -CoO-Cr$_2$O$_3$-Y$_2$O$_3$ ceramics were investigated with sintering time. As sintering time is increased, the nonlinear exponent decreased in the range of 51.19∼26.70. Among varistors having above 30 in nonlinear exponent, for the varistor sintered for 1h, the nonlinearity was superior to the stability comparatively and, in the case of 2h, the stability was superior to the nonlinearity relatively. Consequently, it is estimated that the varistors sintered for 1∼2h will be applied to various fields by trade-off between nonlinearity and stability.

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CHAOS AND LYAPUNOV EXPONENT

  • Yu, Se-Ra;Kim, Yon-Mi
    • The Pure and Applied Mathematics
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    • v.7 no.2
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    • pp.87-100
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    • 2000
  • In this paper, we try to approach chasos with numerical method. After investigating nonlinear dynamcis (chaos) theory, we introduce Lyapunov exponent as chaos\`s index. To look into the existence of chaos in 2-dimensional difference equation we computes Lypunov exponent and examine the various behaviors of solutions by difurcation map.

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Nonlinear Properties of ZnO Varistors Doped with Rare earth Oxides (희토류 산화물이 첨가된 ZnO 바리스터의 비직선 특성)

  • Park, Jong-Ah;Lee, Hong-Hee;Kim, Myung-Jun;Ryu, Jung-Sun;Nahm, Choon-Woo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.747-750
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    • 2003
  • The microstructure and nonlinear properties of ZPCMR-based varistors were investigated with various additives. The density of varistors were gradually decreased for the same R in order of NiO, MgO, and $Cr_2O_3$, respectively. The ZPCR-based varistors were not affected by NiO and MgO additives in nonlinear properties, whereas greatly affected by $Cr_2O_3$. Among the ZPCCR-based varistors, ZPCCD varistor exhibited the highest nonlinear properties, in which the nonlinear exponent is in the range of $40.5{\sim}67.4$ and the leakage current is in the range of $1.2{\sim}2.7{\mu}A$.

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Effect of Sintering Temperature on Electrical Stability of $Pr_{6}O_{11}$-Based ZnO Varistors ($Pr_{6}O_{11}$계 ZnO 바리스터의 전기적 안정성에 소결온도의 영향)

  • 남춘우;류정선
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.8
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    • pp.640-646
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    • 2001
  • The electrical stability for DC stress of Pr$_{6}$O$_{11}$-based ZnO varistos consisting of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Er$_2$O$_3$-based ceramics were investigated with sintering temperature in the range of 1325~1345$^{\circ}C$. A the sintering temperature is raised, the nonlinear exponent of varistors was decreased, whereas the stability was markedly improved. The density of ceramics was found to greatly affect the electrical stability for DC stress. The varistors sintered at 13$25^{\circ}C$ were completely degraded because of thermal runaway attributing to low density. The varistors sintered at 1335$^{\circ}C$ exhibited the highest nonlinearity, with a nonlinear exponent of 70.53 and a leakage current of 1.92$\mu$A, whereas they did not exhibit relatively high stability. On the contrary, the varistors sintered at >134$0^{\circ}C$ exhibited not only a high nonlinearity marking the nonlinear exponent above 50 and the leakage current below 3$\mu$A, but also a high stability marking the variation rate of the varistor voltage below 2%, even under DC stress such as (0.80V$_{1mA}$/9$0^{\circ}C$/12h)+(0.85V$_{1mA}$/115$^{\circ}C$/12h)+(0.90V$_{1mA}$/12$0^{\circ}C$/12h)+(0.95V$_{1mA}$/1$25^{\circ}C$/12h)+(0.95V$_{1mA}$/15$0^{\circ}C$/12h). In particular, ti was found that the varistors sintered at 134$0^{\circ}C$ were more nonlinear and more stable, compared with that of 1345$^{\circ}C$.EX>.}C$.EX>.

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