Major Effects on Impulse Aging Behavior of ZnO–Pr6O11–CoO–Cr2O3–Er2O3 Varistor Ceramics with Small Sintering Changes

Abstract

The impulse aging behavior of the ZnO–Pr6O11–CoO–Cr2O3–Er2O3 varistor ceramics was investigated at the sintering temperature of 1335°–1345°C. Small change in the sintering temperature significantly affected the initial electric field–current density (E–J) characteristics, which decreased from 2878 to 1839 V/cm in the breakdown field and from 70.4 to 48.3 in the nonlinear coefficient. The clamp voltage ratio (V1200A/V1mA) for impulse current (1200 A) increased from 2.48 to 2.63 with the increasing sintering temperature. The varistors sintered at 1335°C exhibited the best clamp characteristics. The varistor sintered at 1345°C exhibited the best electrical stability, with %ΔEB=−2.7%, %Δα=−11.8%, and %ΔJL=−6.7% after applying the multi‐impulse stress of 1200 A.