A Strategic Two-Stage Low-Temperature Thermal Processing Leading to Fully Dense and Fine-Grained Doped-ZnO Varistors

Fully dense doped-ZnO varistors with sub- micrometer grain size (see Figure for a TEM image) can be fabricated by a strategic two-stage, one-cycle, thermal processing method at temperatures as low as 825 °C. The nonlinear coefficients α of such fully dense varistors are as high as 270, which is more than one order of magnitude higher than those currently given for commercial ZnO varistors.