Electrical properties and stability of Dy2O3-doped ZnO–Pr6O11-based varistors

The electrical properties and DC accelerated aging characteristics of ZnO–Pr6O11-based varistors were investigated with various Dy2O3 contents and sintering times. It was found that the Dy2O3 content and sintering time significantly affected electrical properties and their stability. The nonlinear exponent with increasing Dy2O3 content varied with -shaped, reaching maximum of 58.6 at 1.0 mol% Dy2O3 for varistors sintered for 1 h and with -shaped, reaching maximum of 46.3 at 0.5 mol% Dy2O3 for 2 h. The leakage current was in the range of 0.1–1.1 lA for varistors sintered for 1 h and 0.3–2.4 lA for 2 h. The increase of sintering time led to lowering of nonlinearity. The varistors with 0.5 mol% Dy2O3 sintered for 2 h exhibited the good stability, under DC stress of 0.95 V1 mA/150 C/24 h.