Low voltage varistors based on CeO2

The nonlinear current (I)–voltage (V) characteristics of cerium dioxide containing few dopants such as a donor (Nb2O5 or Ta2O5 (0.5 at.%) and a rare earth element oxide (La2O3) or alkaline earth element oxide (BaO) (0.5 at.%) shows promising values of nonlinear coefficient (α) values (∼5–6) with very low breakdown voltages (EB ∼10–20 V mm−1). The pentavalent tantalum or niobium acts as donor and increases the electronic conductivity. The oxygen adsorbed at the grain boundary acceptors states during sintering and cooling leads to the formation of grain boundary barrier.