Microstructure, electrical and dielectric properties, and impulse clamping characteristics of ZnO–V₂O₅–Mn₃O₄ semiconducting ceramics modified with Er₂O₃

Abstract

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.