Effect of two-step sintering on rare earth (RE = Y_2O_3,Pr6O_(11))doped ZnO-Bi_2O_3 varistors processed from ‘nano-precursor'powders

摘要

Nano size ZnO-Bi_2O_3 varistor precursor powders containing Y_2O_3 and Pr_6O_11 rare earth dopants were prepared by low temperature refluxing at 80 ℃. Effect of rare earth dopants, densification by two-step sintering, evolution of microstructures and their influence on varistor properties were investigated. Chemically synthesized nano-precursor varistor powders produced controlled grain size in two-step sintering in which the average sintered ZnO grain size was reduced to at least half compared to the conventionally processed ZnO-Bi_2O_3 varistors. The study revealed that such grain size reduction is highly beneficial to attain enhanced varistor properties.