Influence of size of seed grains and sintering condition on varistor properties of ZnO-Bi2O3-TiO2-Sb2O3 ceramics

Varistor ceramics of ZnO-Bi2O3-TiO2-Sb2O3 system have been fabricated by introducing pre-fabricated ZnO seed grains with different size distributions respectively. The results show that the varistor properties were significantly influenced by the size of introduced seed grains, and introducing larger seed grains is more advantageous to the modification of microstructure and the improvement of varistor properties. The varistor properties were considerably improved with a moderately increased sintering temperature or time, whereas degraded apparently when the sintering temperature or time was excessively increased. Compared with the sintering time, the sintering temperature plays a more critical role in determining the varistor properties. By introducing pre-fabricated ZnO seed grains into the original powders, low-voltage ZnO varistor ceramics possessing the desired electrical properties have been produced with a sintering temperature of about 1210 degreesC and a sintering temperature of 2 similar to2.5 h.