Effect of sintering temperature on nonlinear electrical properties and stability against DC accelerated aging stress of (CoO, Cr2O3, La2O3)-doped ZnO-Pr6O11-based varistors

The microstructure, V-I properties and its stability against DC accelerated aging stress of varistors, which are composed of (CoO, Cr2O3, La2O3)-doped ZnO-Pr6O11-based ceramics, were investigated for different sintering temperatures. The increase of sintering temperature led to more densified ceramics, whereas it decreased the nonlinear properties and varistor voltage. The highest nonlinearity was obtained from the varistors sintered at 1230 degrees C, with 77.9 in nonlinear exponent and 0.4 mu A in leakage current. The varistors sintered at 1260 degrees C exhibited the highest stability, with %Delta V-1 mA of +1.9%, %Delta alpha of -10.6%, and %Delta I-L of +20%. As a result, the nonlinear properties and stability of ZnO-Pr6O11-based varistors can be said to be affected by the sintering temperature. (c) 2006 Elsevier B.V. All rights reserved.