Statistical Study of the Thin Metal-Oxide Varistor Ceramics

In this paper, computational methods are used to study statistically the conduction phenomena in the thin zinc-oxide non-linear varistors, used to protect the electrical and electronic circuits against the overvoltages. Firstly a Monte Carlo method is utilized to model the conduction phenomena in the varistors. This approach shows that the number of ZnO grains, providing the current path between the electrodes of thin varistors fits a lognormal distribution. Furthermore it is found that the "turn on" characteristics, conduction threshold voltage and the nonlinearity coefficient of these varistors can be controlled by the fraction of non-conducting grains