研究了锌硼玻璃掺杂量对低压ZnO压敏电阻微观结构和电性能的影响. 结果表明, 当掺杂量x=0.1wt%时, 可以得到较好综合性能的ZnO压敏电阻：E1mA＝36.7V/mm, α=30.4, IL=0.1μA. 并应用晶粒生长动力学唯象理论研究了锌硼玻璃掺杂低压ZnO压敏电阻的晶粒生长规律, 探讨了锌硼玻璃掺杂对低压ZnO压敏陶瓷晶粒生长的作用机理. 当烧结温度T≤1000℃时,其晶粒生长动力学指数n≈4.54, 激活能Q≈316.5kJ/mol, 这是由于未熔融的锌硼玻璃通过颗粒阻滞机理阻碍了ZnO压敏陶瓷晶粒的生长; 而当T>1000℃时, 其晶粒生长动力学指数n≈2.92, 激活能Q=187kJ/mol, 这是由于熔融的锌硼玻璃通过液相烧结机理促进了晶粒的生长.
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.
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