Non-linear dielectric and piezoelectric response in undoped and Nb5+ or Fe3+ doped PZT ceramic system

The dielectric and direct piezoelectric responses in doped and undoped Pb(Zr1−xTix)O3, with x = 0.40, 0.47 and 0.60, are experimentally studied. The permittivity and the direct piezoelectric coefficient have been measured by applying subswitching ac electric field and high ac mechanical stress. The influence of the type of defects and their concentrations on the non-linear response have been explored. The experimental data show a considerable mobility increase of ferroelectric–ferroelastic domain walls in donor-doped samples. The correlation between the dielectric constant and dielectric losses is discussed in terms of the Rayleigh law. Our results reveal that the influence of reversible and irreversible domain wall movements on the non-linear dielectric response is determined by defects associated with dopants. The role played by the crystallographic phase in the non-linear response is also analyzed.