CHARACTERISTIC ANALYSIS OF ZNO VARISTORS MADE WITH SPHERICAL PRECIPITATION POWDERS

Small, uniform and spherical ZnO powders for the fabrication of ZnO varistors were obtained by an aqueous precipitation method. The varistor samples made from the ZnO powders using butylamine and urea as precipitant show excellent surge response characteristics. However, the varistor samples made by the ZnO-butylamine powders gave better electrical properties, including higher nonohmic property and lower leakage current, than those made by the ZnO-urea powders, because the ZnO powders precipitated by butylamine had smaller and more homogeneous size than those precipitated by urea.