Influence of Sintering Temperature on Intrinsic Trapping in Zinc Oxide‐Based Varistors

The ac electrical data of the ZnO‐Bi 2 O 3 varistor system, in the frequency range 5 Hz to 13 MHz, when analyzed in the complex capacitance ( C *) plane, yields a distinct depressed semicircular relaxation having an average time constant on the order of 10 −6 s. This trapping is attributed to the possible formation of ionized intrinsic/native defects. The decrease in the depression angle and average relaxation time, monitored as a function of the increasing sintering temperature (≥1100°C), indicated an improvement in the degree of uniformity in the loss‐conductance and rapidity of response of the intrinsic trapping. The dependence of the ac parameters related to this trapping response obtained from the C * plane on the sintering temperature has been presented.