Er ₂ O ₃ Doping Effect on Varistor Properties and Multiimpulse Stress Behavior of ZnO – PrO _1.83 – CoO – Cr ₂ O ₃ – Dy ₂ O ₃ Ceramics

Abstract

The Er 2 O 3 doping effects on varistor properties and impulse aging behavior of the ZnO – PrO 1.83 – CoO – Cr 2 O 3 – Dy 2 O 3 ceramics were investigated in the range of 0–2.0 mol%. The nonlinear coefficient increased from 42 to 56 with an increase in the amount of Er 2 O 3 . The clamp voltage ratio ( K ) decreased with an increase in the amount of Er 2 O 3 . The varistors doped with 2.0 mol% in the amount of Er 2 O 3 exhibited the best clamping characteristics, with K = 1.43–1.83 at an impulse current of 1–50 A. The varistors doped with 0.25 mol% in the amount of Er 2 O 3 exhibited the strongest electrical stability, with the variation rate of the breakdown field of −0.5%, the variation rate of the nonlinear coefficient of −5.5%, and the variation rate of the leakage current of −1.5% after applying 400 times at an impulse current of 400 A