ZnO Varistors – The Ideal Microstructure and Characteristics, and Methods Investigated and Developed to Achieve These

ZnO-Bi2O3-Sb2O3 varistors have been extensively studied since their discovery 5 decades ago. Their function in protecting increasingly sensitive electronic components by absorbing random surges of energy is even more important today. Also, the metal oxides from which they are made from are becoming even more precious. Their electrical characteristics are highly dependent on their microstructural characteristics which are highly dependent on their composition and methods used. The purpose of this article is to explain the ideal microstructure required to obtain the ideal electrical characteristics, the powder preparation methods investigated and developed to achieve it, and some future directions are outlined.