Microstructure, electrical and dielectric properties, and impulse clamping characteristics of ZnO-V_2O_5-Mn_3O_4 semiconducting ceramics modified with Er_2O_3

摘要

This study focuses on the effect of Er_2O_3 on microstructure, electrical and dielectric properties, and impulse clamping characteristics of the ZnO-V_2O_5-Mn_3O_4 varistor ceramics. Analysis of the microstructure indicated that the ZnO-V_2O_5-Mn_3O_4-Er_2O_3 ceramics consisted of major ZnO grain and minor secondary phases such as Zn_3( VO_4)_2, Zn V_2O_4, ErVO_4, and VO_2. As the amount of Er_2O_3 increased, the densities of sintered pellets increased from 5.46 to 5.52 g/cm~3, 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 Er_2O_3. 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 Er_2O_3 and the varistor modified with 0.25 mol% exhibited the best K = 2.41.