Dielectric properties of zinc oxide based varistors

Dielectric spectroscopy was used to investigate conduction processes in zinc oxide varistors. Initial results on the complex dielectric permittivity with and without an applied DC bias are presented. Some novel features in the dielectric properties of ZnO varistors that deserve further study were revealed. The differences between the measured epsilon (f) of thick and thin samples are little understood at present. A possibility is that uninterrupted channels of intergranular Bi-rich phases are more likely to be present in thin samples, increasing the importance of this conduction path.<>