High field dielectric behaviour of ferroelectric ceramics

The dielectric properties of PZT and barium titanate based ferroelectric ceramics have been determined over a wide range of electric field strength (0.05 to 4.0 kV mm(-1)) by analysis of P-E (polarisation-electric field) hysteresis data. Three different types of dielectric behaviour were identified, depending on the applied field amplitude E-0. In the 'low field' region, below a material-dependent threshold field E-t, a nearly constant or weakly field-dependent permittivity was obtained, which was attributed to a combination of the intrinsic (ionic) response with a contribution from reversible domain wall vibration. For field levels between E-t and the coercive field E-c, a linear epsilon(r)(/)-E-0 relationship was found, which is analogous to the Rayleigh Law in ferromagnetic materials. This behaviour was explained in terms of large scale ferroelectric domain wall translation about an equilibrium domain wall position. For E-0>E-c, sharp increases in epsilon(r)(/) and epsilon(r)(//) occurred as a result of hysteretic ferroelectric domain switching.