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

Abstract 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 Zn 3 (VO 4 ) 2 , which acts as liquid-phase sintering aid. The Zn 3 (VO 4 ) 2 has a significant effect on the sintered density, in the light of an experimental fact, which the decreases of the Zn 3 (VO 4 ) 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 %Δ E 1 mA = −0.6%, %Δ α = −26.1%, and %Δ tan δ = +21.8% for DC accelerated aging stress of 0.85 E 1 mA /85 °C/24 h.