Electrical and dielectric behavior of a zinc oxide composite

Abstract

Room-temperature studies of I-V characteristics and variation of both the dielectric constant and dielectric loss with frequency are presented for ZnO-Bi₂O₃ samples having different compositions and prepared by sintering at different temperatures. The nonlinearity parameter, dc resistivity, dielectric constant, and dielectric loss depend on the composition and sintering temperature. These parameters have been optimized for obtaining maximum nonlinearity and dielectric constant. The occurrence of a loss peak is, however, seen to be independent of the composition and sintering temperature. The present study, supported by a scanning electron microscope analysis, confirms the necessity of a two-phase structure in the composite for its nonlinearity and high dielectric constant. The variation in the dielectric constant and nonlinearity parameter with sintering temperature for samples of different compositions has been explained on the basis of change in barrier height of Schottky barriers; the presence of these barriers has been inferred by the observed behavior of capacitance variation with bias.