This study focuses on the effect of Er2O3 on microstructure, electrical and dielectric properties, and impulse clamping characteristics of the ZnO–V2O5–Mn3O4 varistor ceramics. Analysis of the microstructure indicated that the ZnO–V2O5–Mn3O4–Er2O3 ceramics consisted of major ZnO grain and minor secondary phases such as Zn3(VO4)2, ZnV2O4, ErVO4, and VO2. As the amount of Er2O3 increased, the densities of sintered pellets increased from 5.46 to 5.52 g/cm3, whereas the average grain size decreased from 7.2 to 6.0 μm. The breakdown field increased from 1,016 to 3,185 V/cm with an increase in the amount of Er2O3. The highest nonlinear coefficient was obtained at the varistor modified with 0.1 mol%, reaching α = 30. The clamp voltage ratio (K), which indicates an impulse absorption capability, was improved with an increase in the amount of Er2O3 and the varistor modified with 0.25 mol% exhibited the best K = 2.41.
Mn3O4 V2O5 Leakage Current Density Nonlinear Coefficient Er2O3
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