Microstructure and Current-Voltage Characteristics of Erbium Oxide Doped Multicomponent Zinc Oxide Varistors

摘要

The present work emphasizes the influence of Er2O3 addition on the microstructure and nonlinear current-voltage characteristics of ZnO based varistors prepared by mixing in a high energy ball mill followed by compaction and sintering at a temperature of 1100°C for duration ranging from 0.5 to 8 h. Increasing sintering time is found to enhance the size of ZnO grains of the sintered pellets and thereby, degrades the electrical properties. However, Er2O3 addition retards the grain growth of ZnO due to the generation of secondary spinel phases (ErVO4 and Er-rich) at grain boundaries and triple points that restrict the grain boundary migration. Er2O3 modified ZnO varistor sintered at 1100°C for 0.5 h exhibits considerably improved electrical property with nonlinear exponent and breakdown field of 27 and 3880 V cm~(-1), respectively.