Effect of sintering temperature on varistor properties and aging characteristics of ZnO–V2O5–MnO2 ceramics

The microstructure, electrical properties, dielectric characteristics, and DC accelerated aging behavior of the ZVM-based varistors were investigated for different sintering temperatures of 800–950 °C. The microstructure of the ZVM-based ceramics consisted of mainly ZnO grain and secondary phase Zn3(VO4)2, which acts as liquid-phase sintering aid. The Zn3(VO4)2 has a significant effect on the sintered density, in the light of an experimental fact, which the decreases of the Zn3(VO4)2 distribution with increasing sintering temperature resulted in the low sintered density. The breakdown field exhibited the highest value (17,640 V/cm) at 800 °C in the sintering temperature and the lowest value (992 V/cm) at 900 °C in the sintering temperature. The nonlinear coefficient exhibited the highest value, reaching 38 at 800 °C and the lowest value, reaching 17 at 850 °C. The varistor sintered at 900 °C exhibited not only high nonlinearity with 27.2 in nonlinear coefficient, but also the highest stability, in which %ΔE1 mA = −0.6%, %Δα = −26.1%, and %Δ tan δ = +21.8% for DC accelerated aging stress of 0.85 E1 mA/85 °C/24 h.