Microstructure and electrical properties of Y2O3-doped ZnO–Pr6O11-based varistor ceramics

The microstructure and electrical properties of the ZPCCY-based varistor ceramics composed of ZnO–Pr6O11–CoO–Cr2O3–Y2O3 ceramics were investigated in the Y2O3 content range of 0–4.0 mol%. The microstructure of ZPCCY-based varistor ceramics was composed of only ZnO grain and intergranular layer: Pr- and Y-rich phases. The increase of Y2O3 content led to the decrease of the density and the average grain size. The incorporation of Y2O3 greatly improved the nonlinear properties. The varistor ceramics with Y2O3 content of 0.5 mol% exhibited the best performance in terms of the densification, V–I characteristics, and dielectric characteristics. These varistor ceramics was characterized by 51.2 in the nonlinear exponent, 1.3 μA in the leakage current, and 0.043 in the dissipation factor. Further, these varistor ceramics exhibited the high stability, in which the variation rates of varistor voltage and nonlinear exponent are −1.4% and −4.9%, respectively, under DC accelerated aging stress.