Electrical Property Improvements of Multiple Dopant ZnO/Bi2O3 Varistor By Liquid Phase Method

Abstract

Although ZnO Varistor is widely used in surge protection due to its unique I-V characteristics, its key influencing factors of grain size and uniformity are difficult to be guaranteed by traditional solid phase method. In this paper, the ZnO/Bi2O3 varistor was prepared by liquid phase co-deposition method and the sintering temperature also has been optimized. For samples prepared by the liquid-phase method, as the sintering temperature increases, the grain size gradually increases, the grain distribution becomes initially more uniform and later more disordered, and the crystallinity gradually increases. In comparison to solid-phase method, samples prepared by liquid-phase method exhibit smaller grain sizes and more uniform grain size distribution. Based on this, samples sintered at 1100 °C by the liquid-phase method demonstrate optimal electrical performance: the voltage gradient is 520 V/mm, the nonlinear coefficient is 44, and the leakage current is 5.8 μA/cm2. This paper has theoretical support for the study of preparation of varistor for achieving excellent electrical performance for being used in the field of surge protection.