Praseodium and aluminium oxide effect on the electrical properties of zinc oxide-based varistors

The zinc oxide-based varistors is a polycristalline ceramic with a highly non-linear current-voltage characteristic. The conventional chemical composition of this material contains several metallic oxides such as the Bi2O3, Sb2O3, Mn2O3, Cr2O3... etc. With these oxides commercialised varistors with a threshold field of around 200V/mm are obtained. The research aiming to increase the threshold field confronted a delicate problem: a decrease in the energy absorption capacity. The study of the electrical property behaviour of zinc oxide-based varistors containing Pr6O11 oxide permit to increase the threshold field up to 350V/mm while keeping the energy absorption capacity. The praseodium oxide effect in the material structure is explained by a potential barrier height increase in the grain boundary and the grain size homogenisation. This work consists of the sample fabrication with different doses of Pr6011 and Al2O3 (9H2O), the material characterization before and after degradation as well as interpretation with respect to the existing results.