Varistors based in the ZnO–Bi2O3 system: Microstructure control and properties

The present contribution deals with the development of an empirical approach that will describe the evolution of the breakdown voltage in ZnO-based varistors as a function of the sintering variables. This relationship is described through the kinetic analysis of the grain growth process. It is found that for a certain range of sintering conditions the varistor breakdown voltage could be calculated from the average size that zinc oxide grains achieve, provided that the varistor microstructure evolves in a gradual and controlled manner and the distribution of the electrical interphases remains stable.