Effect of two-step sintering on rare earth (RE = YO, PrO) doped ZnO-BiO varistors processed from 'nano-precursor' powders.

Nano size ZnO-BiO varistor precursor powders containing YO and PrO rare earth dopants were prepared by low temperature refluxing at 80 °C. 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-BiO varistors. The study revealed that such grain size reduction is highly beneficial to attain enhanced varistor properties. [ABSTRACT FROM AUTHOR]