ZnO压敏电阻的性能优劣直接关系到ZnO避雷器性能的好坏进而影响电力系统的安全稳定运行,而 ZnO 的烧结配方是决定其性能优劣的一个主要因素.为了研究Bi2O3含量对ZnO压敏电阻片电气特性的影响规律,对不同Bi2O3含量的 ZnO 压敏电阻片试样进行热刺激电流特性测试、电子显微镜扫描测试、伏安特性测试.研究结果表明:随着Bi2O3含量的增加,ZnO晶粒尺寸增大,ZnO压敏电阻片的电压梯度降低.随着Bi2O3含量的增加,ZnO压敏电阻片的非线性系数、陷阱电荷量先增大后减小.添加剂Bi2O3可以促进液相烧结,形成陷阱和表面态,在界面上形成势垒,使材料具有优异的非线性特性,从而改善 ZnO 压敏电阻片的电气特性.
The performance of ZnO piezo-resistor directly impacts on the performance of ZnO arresters and on the reliability and stability of power systems. The dispensation is one of the factors which determines the performance of ZnO piezo-resistors. Thermally stimulated current (TSC) characteristic tests, scanning electron microscope (SEM) tests and voltage-current (V-I) tests were carried out on ZnO varistors doped with different ratio of Bi2O3, the influence of Bi2O3 ratio on the electrical properties of ZnO varistors has been studied. The results show that the grain size increases while the voltage gradient decreases as the Bi2O3 ratio increases. With the increase of Bi2O3content, the nonlinear coefficient and trapped charge of ZnO varistors initially increase and then decrease. The Bi2O3 additive can promote the liquid-phase sintering, form traps and surface state and can build potential barriers which lead to the excellent nonlinear characteristics, and greatly improve the electric characteristic of ZnO varistors.