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 mu m and the sintered density decreased from 5.52 to 5.43 g/cm(3). The breakdown field decreased from 3856 to 922 V/cm with an increase in the sintering temperature up to 900 degrees C, whereas a further increase to 2352 V/cm at 925 degrees 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 degrees 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 degrees C exhibited the strongest stability, with %Delta E-1 mA/cm(2)=-8.8% after applying the multi-pulse current of 25 A.