Evaluation of the degradation of ZnO varistor with various additives

Tanigawa, Akira; Hirota, Masato; Sakaguchi, Takehiko; Yamashita, Y.; Yoshikado, Sinzo

doi:10.1541/ieejfms1990.118.2_169

Cited by 19 publications

(9 citation statements)

References 6 publications

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“…21) The relationship between the change in the interface state and the deformation of DSB caused by degradation is most important in understanding the degradation mechanism of ZnO varistors. However, to date, there are no reports on the experimental characterization of the change in distribution of the interface states caused by degradation.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Interface States in Degraded ZnO Varistors

Ohbuchi

Kawahara

Morimoto

2002

Jpn. J. Appl. Phys.

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The degradation mechanism of ZnO varistors was investigated by using spectral analysis of deep-level transient spectroscopy (SADLTS), and using the current-voltage (I-V) characteristics and the capacitance-voltage (C-V) characteristics before and after AC biasing stress. The interface states in the Pr-type ZnO varistors consist of two adjacent levels: T0 and T1 levels. The activation energy E T and the capture cross section of the interface states decrease with increasing degradation induced by AC bias stress. The decrease in E T and is related to a decrease in the barrier height caused by the degradation. In order to characterize the change in the interface states with degradation, distribution parameters (ÁE T , Á) are introduced, where the parameters for each level increase after degradation. The degradation is closely related to the distribution of the emission rate of the interface states. The degradation phenomenon is caused by migrated ions or by adsorbed ions such as oxygen. The increase in the distribution parameters upon degradation suggests activation of the oxygen ions at the grain boundaries and nonuniform migration.

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Section: Introductionmentioning

confidence: 99%

Characterization of Interface States in Degraded ZnO Varistors

Ohbuchi

Kawahara

Morimoto

2002

Jpn. J. Appl. Phys.

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“…12), 14) These results suggest that trend of increase and decrease on I r with respect to time is partially affected by Co distribution in the SRZVC.…”

Section: Apparent Density and V Bmentioning

confidence: 72%

Effect of Ni and Cr on the stability of leakage current for spinel-reduced ZnO varistor ceramics

Kato

Kawamata

Yamada

et al. 2011

J. Ceram. Soc. Japan

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With a new concept of reducing the spinel particles in ZnO varistor ceramics (ZVC), the molar ratio of Sb 2 O 3 (M S )/Bi 2 O 3 (M B ) and the effect of the sintering temperature (T S ) on densification behavior and varistor voltage (V b : V 1mA /mm) were investigated. The densification behavior of ZVC during the sintering process was significantly affected by the M S /M B , and the densification curve was shifted to a lower temperature with a decreasing M S /M B . Based on these experimental results, four types of spinelreduced ZnO varistor ceramics (SRZVC) were fabricated to investigate the effect of transition elements such as Ni and Cr on electric stability of the resistive leakage current (I r ). These experiments revealed that electric stability of I r depended on the contained transition elements, and was influenced by the segregating of transition elements in spinel particles.

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“…Moreover, it is reported that one of the mechanism of the electrical degradation is due to the diffusion of oxygen ions through the grain boundary caused by application of bias voltage and then double Schottky barriers are distorted by the re-distribution of electrons and holes near the grain boundary (1) (2) . In this study, the relationship between electrical degradation and the orientation of ZnO grains of Sb 2 O 3 -added ZnO varistors are discussed.…”

Section: Figmentioning

confidence: 99%