No abstract

A conventional ceramic processing method was applied to manufacture high-density 20-nm ZnO-Bi 2 O 3-Mn 2 O 3 varistor ceramics. Different cooling rates in the range of 135-540 C/h led to a relatively slight influence on the microstructure, varistor voltage, and leakage current. In contrast, these rates strongly affected the nonlinear exponent. The specific surface area of the 20-nm ZnO nanoparticle may have led to an intense solid-state reaction even at a low cooling rate. Superior nonlinearity, with 59.7 μA nonlinear current leakage and 273.5 μA leakage current, was achieved at the 135 C/h cooling rate. The differences in the cooling rates led to a remarkable change in the material's stability under direct current (DC)-accelerated aging stress in the following order: 135 C/hr > 270 C/hr>405 C/hr > 540 C/hr.