• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.415-418
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• 2001

The I-V characteristics and its stability of ZPCCL-based ceramic varistors doped with La$_2$O$_3$in the range of 0.0~4.0 mol% were investigated. The density of ceramics was increased in the range of 4.7~5.8 g/cm$^3$ with increasing La$_2$O$_3$content. As La$_2$O$_3$content is increased, the varistor voltage was decreased in the range of 503.49-9.42 V/mm up to 2.0 mol%, whereas increasing La$_2$O$_3$content further caused it to increase. The ZPCCL-based varistors were characterized by nonlinearity, in which the nonlinear exponent is in the range of 3.05~82.43 and leakage current is in the range of 0.24-100.22 $\mu$A. Among ZPCCL-based varistors, 0.5 mol% added-varistors exhibited an excellent nonlinearity, in which the nonlinear exponent is 82.43 and the leakage current is 0.24 $\mu$A. Furthermore, they exhibited a high stability, in which the variation rate of the varistor voltage and the nonlinear exponent was -1.11% and -6.72%, respectively, under 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). Consequently, it was estimated that ZPCCL-based ceramics will be applied to development of Pr$_{6}$O$_{11}$ based ZnO varistors having a high performance.e.rformance.e.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.422-425
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• 2001

The electrical properties of ZnO-$Pr_6O_{11}$-CoO-$Cr_2O_3-La_2O_3$ based varistors were investigated with sintering temperature in the range of $1240\sim1300^{\circ}C$. The varistors sintered at $1240\sim1260^{\circ}C$ exhibited high density, which was 5.50- $5.70g/cm^3$ corresponding to 95.2~98.6% of theoretical density. The varistor voltage was decreased in range of 718.47~108.00 V/mm with increasing sintering temperarture. The varistors sintered at $1240\sim1260^{\circ}C$ exhibited good electrical properties, in which the nonlinear exponent is in the range of 79.25~49.22 and leakage current is in the range of 0.26~$1.00 {\mu}A$ In particular, the varistor sintered at $1240^{\circ}C$ showed very excellent electrical properties, in which the nonlinear exponent is 79.25 and leakage current is $0.26{\mu}A$

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.422-425
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• 2001

The electrical properties of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-La$_2$O$_3$ based varistors were investigated with sintering temperature in the range of 1240~130$0^{\circ}C$. The varistors sintered at 1240~126$0^{\circ}C$ exhibited high density, which was 5.50~5.70 g/㎤ corresponding to 95.2~98.6% of theoretical density The varistor voltage was decreased in range of 718.47~108.00 V/mm with increasing sintering temperature. The varistors sintered at 1240~126$0^{\circ}C$ exhibited good electrical properties, in which the nonlinear exponent is in the range of 79.25~49.22 and leakage current is in the range of 0.26~1.00 $\mu$A. In particular, the varistor sintered at 1240\`c showed very excellent electrical properties, in which the nonlinear exponent is 79.25 and leakage current is 0.26 $\mu$A.A.A.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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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.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.416-421
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• 2006

The varistor properties of ZPCCL-based ceramics were investigated at different $La_2O_3$ contents in the range of $0{\sim}2.0$ mol%. As $La_2O_3$ content increased, the ceramic density greatly increased in the range of $4.71{\sim}5.77\;g/cm^3$ and the varistor voltage greatly decreased in the range of $503.5{\sim}9.4$ V. The varistor with 0.5 mol% $La_2O_3$ exhibited good nonlinearity, in which the nonlinear exponent is 81.6 and the leakage current is 0.2 ${\mu}A$. Furthermore, the varistors exhibited the high electrical stability, with $%{\Delta}V_{1mA}=-1.1%,%{\Delta}{\alpha}=-3.7%$, and $%{\Delta}I_L=+100%$ for DC accelerated aging stress condition of 0.95 $V_{1mA}/150^{\circ}C/24$ h.