Modeling of electrical response for semiconducting ferrite

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Abstract
The electrical properties of semiconducting ferritematerials are investigated. A simplified model, consisting of bulk material separated by highly resistivegrain boundary layers, is proposed. The nature of grain boundary on its electrical behavior is also discussed. Complex impedance technique is used to analyze the electrical response of polycrystalline specimens. The characteristics of the complex impedance dispersion curves for MnZn‐ferrite specimens are affected by the sintering and annealing conditions. All the complex impedance plots differ from idealized semicircles, but can be fitted by circular arcs very well. An experimental equivalent circuit is proposed to explain the observed R‐X dispersion. The tremendous increase in the grain boundaryresistivity due to controlled‐atmosphere sintering is ascribed to the preferential oxidation. The decrease in the apparent resistance of the specimens in the high‐frequency region arises from the polarization effect. This is attributed to the special microstructure of such material, namely, semiconducting bulk material with insulating grain boundaries.