Effect of electrical conductivity on poling and the dielectric, pyroelectric and piezoelectric properties of ferroelectric 0-3 composites

We have investigated the effects of electrical conductivity of the constituents on the poling behavior, dielectric, pyroelectric and piezoelectric properties of ferroelectric 0-3 composites. Modeling of polarization behavior is explored for both dc and ac poling procedures. Simulated results show that, in addition to the poling schedule, conductivity plays an important role in the poling process. Calculations are carried out for the time dependent internal electric fields induced by an ac field in dielectric measurements, by modulated temperature in pyroelectric measurement or by stress in piezoelectric measurement. Our previously developed models for dielectricity, pyroelectricity and piezoelectricity have been extended to include the additional contribution from the electrical conductivities. These can be significant for ceramic/polymer composites possessing high conductivity in the matrix phase. Calculated values based on the new model are discussed and compared with the previous models, and in particular the pyroelectric activities reported in the literature for a graphite doped lead zirconate titanate / polyurethane composite. Explicit expressions for the transient and steady state responses are given and the effective permittivity, pyroelectric and piezoelectric coefficients are derived in this paper. Remarkable enhancement in these coefficients is obtained when higher conductivity is introduced in the matrix phase. C 2006 Springer Science + Business Media, Inc.