Effect of Er2O3Content on Nonlinear Properties and Impulse Clamping Characteristics of Pr/Co/Cr/Al Co-doped Zinc Oxide Ceramics

The microstructure, nonlinear properties, and impulse clamping characteristics of Pr/Co/Cr/Al co-doped zinc oxide ceramics were investigated with various contents of Er 2 O 3 .Increasing Er 2 O 3 content increased the density of the sintered pellets from 5.69 to 5.83 g/cm 3 , and decreased the average grain size from 10.6 to 6.5 µm.With increased Er 2 O 3 content, the breakdown field increased from 2318 to 4205 V/cm, and the nonlinear coefficient increased from 19.4 to 40.2.The clamp characteristics were improved with the increase of the content of Er 2 O 3 .The varistors doped with 2.0 mol% exhibited the best clamp characteristics, in which the clamp voltage ratio was 1.40-1.73at 1-50 A in an impulse current.