Value-addition of ZnO used in glazing industry for varistor application

摘要

The feasibility of using industrial-grade (IG) ZnO raw materials to produce electroceramics has been examined. A certain degree of agglomeration of particles was observed with sizes ranging in the hundreds of nanometer. The morphology of IG particles was less crystallographically defined compared to the reagent-grade powders. The apparent particle densities were also significantly different. The examined composition was of typical varistor in the ZnO-Bi2O3-CoO system. The solution-coated samples sintered much slower than the oxide samples. This could be caused by compositional change of the eutectic system. The varistor properties were dependent on the sintering temperature. At 1,000 degrees C, the varistor fabricated from the IG powders yielded a breakdown field as high as 4500 V cm(-1), comparing to 3600 V cm(-1) from the oxide route; whereas the coefficients of non-linearity were in the same range for both. These comparable varistor properties have demonstrated the potential for fabrication of electroceramic devices.