Abstract
The ZnO-base oxides ZnO-0.5mol%Bi2O3-(0.5-x)mol%Nb2O5-xmol%TiO2-3mol%CoO (x=0-0.5) were synthesized at 1200°C, and their electrical properties were investigated. The microstructure of the sintered compacts consisted of ZnO grains containing Co and Bi-Zn-Nb-Ti-Co-O grain boundary phase. The compound composing the grain boundary phase was classified in three types depending on x. The I-V characteristic showed ohmic behavior at x=0, and non-linear behavior at x>0. The non-linear coefficient and the varistor electric field increased with increasing x, while the electrical conductivity decreased. The electrical properties are influenced by both the crystal structure and the composition of the grain boundary phase.
