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Impulse Aging Behavior Against of Zn–Pr–Co–Cr–Dy Varistors with Cobalt Addition


  • Choon-W. Nahm

    Corresponding author
    1. Semiconductor Ceramics Lab., Department of Electrical Engineering, Dongeui University, Busan 614 714, Korea
      †Author to whom correspondence should be addressed. e-mail:
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  • B. Loncar—contributing editor

†Author to whom correspondence should be addressed. e-mail:


The CoO-doping effect on impulse aging behavior of the Zn–Pr–Co–Cr–Dy varistors was investigated in the range of 0.5–2.0 mol%. The clamp voltage ratio (K) increased with increasing CoO content. The varistors doped with 0.5 mol% CoO exhibited the best clamping characteristics, which the K value is 2.05–2.53 at an impulse current of 400–1200 A. The best stability was obtained from the varistor doped with 1.0 mol% CoO, withinline image, %Δα=−4.4%, and %ΔJL=−2.3% after applying the impulse stress of 1200 A.

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