CeO2掺杂氧化锌压敏阀片压敏电位梯度与显微组织的研究

Study on voltage and microstructure of ZnO varistor doped with CeO2

采用添加微量CeO2的方法，提高氧化锌压敏阀片的电位梯度，使之具有优良的综合性能。同时研究了微量CeO2添加剂对氧化锌压敏电阻片的压敏电位梯度的影响，并通过SEM测试手段对其微观组织结构进行了分析研究，从理论上探讨了CeO2影响氧化锌压敏阀片压敏电位梯度与组织的机理。研究结果表明，在0～0．06％（摩尔分数）成分范围内，随着CeO2含量的增加，氧化锌压敏阀片的压敏电位梯度明显提高；当CeO2含量超过0．06％（摩尔分数）时，随其含量的增加，氧化锌压敏阀片的压敏电位梯度又呈降低趋势。其原因是CeO2加入到氧化锌压敏阀片中，以原相形式独立存在的CeO2相钉扎在晶界，阻碍晶界运动，抑制了ZnO晶粒的生长；另一方面，CeO2添加剂在陶瓷烧结过程中使ZnO晶体的自由电子浓度增大，填隙锌离子Zni的总浓度下降，因而填隙锌离子的传质能力下降，抑制了ZnO晶粒的生长，因而晶粒尺寸随CeO2的添加而下降，压敏电位梯度显著提高。

CeO2 was used as an additive introduced to ZnO ceramics. The effect of CeO2 on voltage and microstructure of ZnO varistor was studied by using electrical property measurements and SEM. The mechanism of the effect was suggested based on theoretical analysis. The results show that the voltage of ZnO varistor increases with the content of CeO2 in the range of 0-0.06mo1%. But when the content of CeO2 is more than 0.06mol%, the voltage of ZnO varistor decreases with the content increase. The microstructure analysis indicates that the minimal additive lies on the boundary of ZnO grain in form of the independent phase, and it decreases the concentration of interstitial zinc [Zni], and then reduces the size of ZnO grain, and as a result, CeO2 improve the voltage character of the varistor greatly.