Journal of Inorganic Materials

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Electrical Properties and Kinetic of Crystalline Grain Growth of Low-voltage ZnO Varistor Doped with Zn-B Glass

WAN Shuai, Lv Wen-Zhong   

  1. (Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China)
  • Received:2009-06-09 Revised:2009-09-09 Published:2010-02-20 Online:2010-02-20

Abstract:

The effects of Zn-B glass additive on microstructure and electrical properties of low-voltage ZnO varistor were studied. The results show that ZnO varistor with x=0.1wt% obtains the optimal nonlinear electrical properties: E1mA=36.7V/mm, α=30.4, IL=0.1μA. The grain growth mechanism of low-voltage ZnO varistor doped with Zn-B glass is also investigated in terms of the phenomenological kinetic of crystalline grain growth. Based on the theory, the grain growth kinetic exponent n and apparent activation energy Q are calculated as 4.54 and 316.5kJ/mol for ZnO ceramics varistor sintered at the temperature below 1000℃. The grain growth mechanism is that non-melting Zn-B glass pins the ZnO grain boundaries, which inhibits the grain growth of ZnO varistor. However, n and Q value are 2.92 and 187kJ/mol at the temperature higher than 1000℃. It indicates that melting Zn-B glass wetting the ZnO grain boundaries creates a liquid phase sintering mechanism, which accelerates the grain growth of ZnO varistor.

Key words: Zn-B glass, varistor, electrical properties, kinetic exponent, apparent activation energy

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