Non-ohmic properties and impulse aging behavior of quaternary ZnO–V2O5–Mn3O4–Er2O3 semiconducting varistors with sintering processing

This paper focuses on the effect of sintering process on the varistor properties and impulse aging behavior of ZnO–V2O5–Mn3O4–Er2O3 semiconducting varistors. The average grain size increased (5.7–8.1 μm) and the sintered density decreased (5.55–5.45 g/cm3) with an increase in the sintering temperature. The breakdown field decreased with an increase in the sintering temperature up to 925 °C, whereas a further increase increased it. The non-ohmic coefficient increased noticeably from 3.8 to 40.8 with an increase in the sintering temperature. The sample sintered at 925 °C exhibited the best clamping characteristics, in which the clamp voltage ratio is in the range of 1.96–3.19 for impulse current of 1–50 A. Furthermore, this sample exhibited the strongest stability, with %ΔE1mA/cm2=−9.8% applying the multi-impulse current of 25 A.