Electrical properties and DC-accelerated aging behavior of ZnO–Pr 6O 11–CoO–Cr 2O 3–Dy 2O 3-based varistor ceramics

Abstract

The microstructure, electrical properties, and DC-accelerated aging behavior of varistor ceramics, which are composed of ZnO–Pr 6O 11–CoO–Cr 2O 3–Dy 2O 3 (ZPCCD)-based ceramics, were investigated in the range of 0.0–2.0 mol% Dy 2O 3. As Dy 2O 3 content is increased, the density was decreased in the range of 5.53–4.43 g/cm 3 and the average ZnO grain size was decreased in the range of 18.6–4.7 μm. The varistors with Dy 2O 3 exhibited a high nonlinear exponent above 30, compared with that without Dy 2O 3. The incorporation of Dy 2O 3 significantly improved the nonlinear properties of ZPCCD-based varistors. The varistor with Dy 2O 3 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 V 1 mA /150 °C/24 h, respectively, with increasing Dy 2O 3 content.