Electrical properties and DC-accelerated aging behavior of ZnO–Pr6O11–CoO–Cr2O3–Dy2O3-based varistor ceramics

The microstructure, electrical properties, and DC-accelerated aging behavior of varistor ceramics, which are composed of ZnO–Pr6O11–CoO–Cr2O3–Dy2O3 (ZPCCD)-based ceramics, were investigated in the range of 0.0–2.0 mol% Dy2O3. As Dy2O3 content is increased, the density was decreased in the range of 5.53–4.43 g/cm3 and the average ZnO grain size was decreased in the range of 18.6–4.7 μm. The varistors with Dy2O3 exhibited a high nonlinear exponent above 30, compared with that without Dy2O3. The incorporation of Dy2O3 significantly improved the nonlinear properties of ZPCCD-based varistors. The varistor with Dy2O3 content of 0.5 mol% exhibited the highest nonlinearity, in which a nonlinear exponent is 66.6 and a leakage current is 1.2 μA. Furthermore, this varistor showed the high stability, in which the variation rate of varistor voltage, of nonlinear exponent, and of leakage are −1.9, −10.5, and +288.8%, respectively, under DC-accelerated aging stress, 0.95 V1 mA/150 °C/24 h, respectively, with increasing Dy2O3 content.