Effect of cooling rate on electrical properties and stability of ZPCCY-based varistor ceramics

The microstructure, electrical properties, dielectric characteristics, and stability of ZPCCY-based varistors composing of ZPCCY (ZnO–Pr6O11–CoO–Cr2O3–Y2O3)-based ceramics were investigated with cooling rate in the range 120–480 °C h−1. The cooling rate relatively, slightly affected the microstructure, varistor voltage, and leakage current, whereas strongly nonlinear exponent. The varistor ceramics cooled at 120 °C h−1 exhibited the highest nonlinearity, with nonlinear exponent of 56.8 and leakage current of 1.6 μA. Further the cooling rate most greatly affected the stability against DC accelerated aging stress. The stability against DC accelerated aging stress with cooling rate found to being high in order of 480→120→360→240 °C h−1 in cooling rates.