Effective complex permittivity and AC conductivity of (Bi0.5Na0.5)0.94Ba0.06 TiO3-PVDF 0-3 composite

Abstract

The present study addresses the problem of quantitative prediction of effective complex relative permittivity and ac conductivity of (Bi0.5Na0.5)0.94Ba0.06TiO3-Polyvenylidene Fluoride (BNBT06-PVDF) 0-3 composite samples (prepared by solution cast method at an elevated temperature) having 10, 20 and 30 volume percentage of BNBT06 powder. SEM micrographs of the fractured surfaces showed that the particle distribution in the grains is not strictly homogeneous. Some areas of agglomeration of particles in the grains are also seen in the micrographs. EDAX patterns confirmed the presence of different constituent elements of the composite samples. The resulting data for room temperature real and imaginary parts of relative permittivity as well as real part of ac conductivity showed an increasing trend with increasing volume fraction of the ceramic filler. The 30 vol. % of BNBT06-PVDF composite had the highest dielectric constant of 75.3 and dielectric loss of ~6.09 i.e., loss tangent ~0.08. Among the dielectric mixing models presented, Rother-Lichtenecker model showed the best fit to the experimental data for the test composite. Similar equations for effective ac conductivity in terms of conductivity of the constituent phases of the composite were proposed in the present work to be fitted to find that none except Rother-Lichtenecker equation fitted the experimental data well. First order exponential growth type of equation applicable to all the three properties fitting the experimental data excellently is also proposed in the present work. © 2014 VBRI press.