Admittance—Frequency Response in Zinc Oxide Varistor Ceramics

The lumped parameter/complex plane analysis technique revealed several contributions to the terminal admittance of the ZnO—Bi 2 O 3 based varistor grain‐boundary ac response. The terminal capacitance has been elucidated via the multiple trapping phenomena, a barrier layer polarization, and a resonance effect in the frequency range 10 −2 ≤ f ≤ 10 9 Hz. The characterization of the trapping relaxation behavior near ∼ 10 5 Hz (∼ 10 −6 s) provided a better understanding of a previously reported loss‐peak. The possible nonuniformity in this trapping activity associated with its conductance term observed via the depression angle of a semicircular relaxation in the complex capacitance ( C *) plane has been postulated.