Effect of sintering time on electrical properties and stability against DC accelerated aging of Y2O3-doped ZnO-Pr6O11-based varistor ceramics

The electrical nonlinear properties and their stability against DC accelerated aging stress of varistors composed of ZnO–Pr6O11–CoO–Cr2O3–Y2O3 (ZPCCY)-based ceramics were investigated at various sintering times. The increase of sintering time deteriorated the nonlinearity, whereas improved the stability. The highest nonlinearity was obtained from the varistor ceramics sintered for 1 h, with 51.2 in nonlinear exponent and 1.3 μA in leakage current. The varistor ceramics sintered for 2 h exhibited not only relatively high nonlinearity, which the nonlinear exponent is 38.6 and the leakage current is 3.9 μA, but also the highest stability, in which the variation rates of varistor voltage, nonlinear exponent, leakage current, and dissipation factor are −0.8%,−1.8%, +74.4%, and +0.9%, respectively, for DC accelerated aging stress such as 0.95 V1 mA/150 °C/12 h.