EFFECT OF ADDITIONS ON CONDUCTION PROPERTIES OF ZNO VARISTORS

In this paper, several substitutive and defect reactions have been analyzed to describe the conduction properties in ZnO varistors. The composition of ZnO varistors with added Co and Mn ions of high valence, i.e., Co3+ and Mn4+, was deduced to result in higher donor concentration, trap density, barrier height and leakage current, but a lower nonlinearity coefficient in comparison with that of ZnO varistors with added Co and Mn ions of low valence, i.e., Co2+ and Mn2+. The capacitance-voltage (C-V) and current-voltage (I-V) measurements were employed in the experiment, respectively. Theoretical inference was found to be consistent with the experimental results of electrical characteristics.