Breakdown Phenomenon in Non-Ohmic Current-Voltage Characteristics of a Zinc Oxide-Bismuth Oxide Binary Varistor System

抄録

Switching voltage between pre-breakdown and breakdown regions in the current-voltage (I-V) characteristics of ZnO-Bi₂O₃ binary primitive varistor system is measured directly using a simple measurement system. The I-V characteristics of ZnO-x mol% Bi₂O₃ with x from 0.02 to 1.0 show non-linear curve. The switching voltage is measured in only ZnO-x mol% Bi₂O₃ with x ≥ 0.2. This result indicates that a breakdown behavior which is the change from pre-breakdown to breakdown regions occurs in only these samples. ZnO-x mol% Bi₂O₃ with x ≤ 0.1 consist of ZnO grains, and the samples with x ≥ 0.2 consist of ZnO grain with α-Bi₂O₃ grain boundary phase. Therefore, a potential barrier in the grain boundary between ZnO and α-Bi₂O₃ causes the breakdown behavior, but on the other hand the potential barrier in the grain boundary between ZnO grains has no relation to the breakdown behavior.