Electrical behavior against current impulse in ZnO–Pr6O11-based varistor ceramics with terbium addition

Tb4O7 addition effect on electrical behavior against current impulse in the Zn–Pr–Co–Cr-based varistors was investigated. The Tb4O7 did have a significant effect on electrical behavior against current impulse. Increasing Tb4O7 content improved the clamp ratio (K), reaching nearly 2 at 1.0 mol%. The best stability against current impulse of 100 A/cm2 was obtained at 0.25 mol% Tb4O7, where image and %Δα = +1.1%. In addition, the varistor doped with 0.5 mol% Tb4O7 were no less stable against current impulse than varistor doped with 0.25 mol% Tb4O7. Furthermore, the varistor doped with 0.5 mol% Tb exhibited the best surge withstand capability at a current impulse of 900 A. Conclusively, Tb4O7 content was optimized at 0.5 mol% in terms of the nonlinearity and surge withstand capability.