Varistor behavior study in undoped tungsten trioxide ceramic

In this paper, varistor property and mechanism of undoped tungsten trioxide (WO3) ceramic have been studied. Experimental results revealed that pure WO3 ceramic could exhibit a nonohmic behavior which was formed in the cooling process of ceramic, and very sensitive to heat treatment in different atmospheres. By comparison with the reported SnO2 and ZnO varistor systems, it is supposed that the surface of WO3 grain is more ready to adsorb oxygen and form high enough barriers at grain boundaries responsible for varistor behavior. The influences of heat treatments on the varistor properties of WO3 ceramic have been investigated.