Influence of sintering time on electrical and dielectric behavior, and DC accelerated aging characteristics of Dy3+-doped ZnO-Pr6O11-based varistors

The influence of sintering time on microstructure, electrical and dielectric behavior, and DC accelerated aging characteristics of varistors composed of ZnO-Pr6O11-CoO-Cr2O3-Dy2O3 (ZPCCD)-based ceramics were investigated. The increase of sintering time gave rise to the decrease of nonlinearity as exhibiting the range of 55.3-38.2 for nonlinear exponent and 0.1-1.1 μA for leakage current. The donor concentration and the density of interface states in C-V characteristics, and the apparent dielectric constant and the dissipation factor in dielectric characteristics were increased with increasing sintering time. The highest nonlinearity was obtained from the varistor sintered for 1 h, with 55.3 in nonlinear exponent and 0.1 μA in leakage current. The varistor sintered for 2 h exhibited not only relatively high nonlinearity, in which the nonlinear exponent is 46 and the leakage current is 0.3 μA, but also the highest stability, in which the variation rates of varistor voltage, nonlinear exponent, leakage current, and dissipation factor were −3.0%, −4.1%, +166.7%, and −12.5%, respectively, under DC accelerated aging stress of 0.95 V1 mA/150 °C/24 h.