Nonlinear electrical properties and DC accelerated aging characteristics of ZnO–Pr6O11–CoO–Cr2O3–Dy2O3-based varistors

The nonlinear electrical properties and stability against DC accelerated aging stress of various varistors, which are composed of ZnO–Pr6O11–CoO–Cr2O3–Dy2O3 (ZPCCD)-based ceramics, was investigated as a function of Dy2O3 content. The varistors with Dy2O3 exhibited a high nonlinear exponent above 30, compared with that without Dy2O3. The varistor with 0.5 mol% Dy2O3 exhibited the highest nonlinearity, with a nonlinear exponent of 66.6 and a leakage current of 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 +275.0%, respectively, under DC accelerated aging stress, 0.95 V1 mA/150 °C/24 h.