Low temperature sintering ZnO - Bi2O3 based varistor ceramics with low electrical breakdown voltage and high nonlinear coefficient

Abstract In this study, a novel pre-synthesized Bi–Sb–O phase was produced and doped into the ZnO– Bi2O3– Co2O3– MnO2 (ZBCM)- based varistor to make an improvement in nonlinear coefficient (α) and a decrease in breakdown voltage (E1mA). Results showed that the ZBCM- Bi–Sb–O ceramics can be well sintered with high sintering density above 0.98 of the ZnO theoretical density at a low sintering temperature of 900 °C. A large average grain size (d) of 6.89 μm was obtained in the ZBCM – 3 wt% Bi–Sb–O varistor, which leads to a low E1mA of 235.0 V/mm. At the same time, the α increases to 53.0 due to the improved barrier height (ϕb) of 1.85 eV. Furthermore, the lowest dielectric loss (tanδ) at low frequency as well as the increased grain resistance (Rg) made the smallest leakage current density (IL) of 0.005 μA mm−2 in the same Bi–Sb–O doping content. Besides, a considerable low E1mA of 168.91 V/mm with a mildly α of 37.4 was obtained in the ZBCM– 1 wt% Bi–Sb–O varistor. Hopefully, this novel research provided a new strategy to prepare low-voltage ZnO– Bi2O3- based varistors at low sintering temperature.