Electrical properties of ZnO-based varistors prepared by combustion synthesis

Ceramic varistors are generally produced by the oxide mixing method or by chemical methods, such as sol-gel, precipitation and others. Chemical methods produce powders that are highly reactive, allowing for increased microstructural homogeneity and control of grain growth during sintering, which is essential for good varistor performance. The purpose of this work was to study the electrical characteristics of ZnO varistors produced from stoichiometric mixtures of water-soluble metal nitrates, such as precursor cations and urea as a fuel. This method, called combustion synthesis, stands out for its simplicity (a single-step reaction), purity, chemical homogeneity, and the high reactivity of the precursor powder. After sintering at 1050 degreesC using this method, varistors with a non-linear coefficient of 40 and the lowest leakage were obtained. (C) 2002 Kluwer Academic Publishers.