Relationship between microstructure and electrical properties of ZnO-based multilayer varistor

In this study, two types of ZnO-based multilayer varistor (MLV) with two different dielectric layers (12 and 24 μm), sintered from 900 to 1000°C for 2 h were prepared to investigate the effects of microstructure such as the grain size and number of grain boundaries between two adjourn electrodes on electrical properties. The results show that the grain size linearly increases with sintering temperature, which results in an increase in the capacitance of ZnO-based MLVs. In contrast, the number of grain boundaries between two adjourn electrodes linearly decreases with sintering temperature associated with a decrease in breakdown voltage, leakage current and nonlinear coefficient of ZnO-based MLVs. The energy absorption capabilities determined from the peak current (PC) measurements of ZnO-based MLVs with sintering temperature are reported. The optimum peak currents of ZnO-based MLVs can be obtained by sintering at 950°C.