Sintering effect on electrical properties and pulse aging behavior of (V2O5-Mn3O4-Er2O3)-doped zinc oxide varistor ceramics

The effect of sintering temperature on microstructure, electrical properties, and pulse aging behavior of (V2O5-Mn3O4- Er2O3)-doped zinc oxide varistor ceramics was systematically studied. When the sintering temperature increased, the average grain size increased from 6.1 to 8.7 μm and the sintered density decreased from 5.52 to 5.43 g/cm3. The breakdown field decreased from 3856 to 922 V/cm with an increase in the sintering temperature up to 900 °C, whereas a further increase to 2352 V/cm at 925 °C. The nonlinear coefficient increased pronouncedly from 4.6 to 30.0 with an increase in the sintering temperature. The varistor ceramics sintered at 850 °C exhibited the best clamping characteristics, with the clamp voltage ratio of the range of 2.22–2.88 for pulse current of 1–25 A. The varistor ceramics sintered at 925 °C exhibited the strongest stability, with %ΔE1 mA/cm2−—8.8% after applying the multi-pulse current of 25 A.