变阻器
材料科学
降级(电信)
晶界
复合材料
肖特基势垒
光电子学
电气工程
电压
二极管
微观结构
工程类
标识
DOI:10.1002/9783527684038.ch7
摘要
ZnO varistors can be electrically, chemically, thermally, or mechanically degraded during use, leading to the reduction of barrier voltage height and, consequently, to the increase of leakage current, which could be catastrophic for ZnO varistors. The long-term degradation or short-term pulse degradation phenomenon of ZnO varistors that could lead to deterioration in the electrical properties may eventually give rise to thermal runaway or destruction of the varistors. The stabilities of ZnO varistors, including the AC/DC degradation and pulse degradation characteristic, are highly concerned with their lifespans. Therefore, the degradations of ZnO varistors have attracted more attention. In this chapter, the phenomena and mechanisms of degradations of ZnO varistors are discussed thoroughly, including the variation of electrical properties of individual grain boundaries during the degradation process by microcontact measurement. The degradation phenomena under the effect of various stresses are focused, and the current achievement of investigation on degradation mechanism is presented, aiming at the constitution of a full picture of universal electrical degradation mechanism, from the perspective of defects, portraying the ion migration process that is related to the degradation of double-Schottky barrier (DSB).
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