Dielectric relaxation and internal friction related to the mobility of domain wall in PZT ferroelectrics

The dielectric permittivity of Pb(Zr0.52Ti0.48)O-3 (PZT) ceramics as a function of temperature was measured in the frequency range from 1 to 10 kHz. There exists a dielectric loss peak close to and below the Curie point, the height of which decreases as frequency increases. Although the peak moves towards higher temperatures with increasing frequency, the relaxation time disagrees with the Arrhenius description In addition, the internal friction measurement at 1 Hz shows a mechanical loss peak that is of static hysteresis type. Therefore the viscous motion of domain walls in PZT is dominant in a certain frequency range of a few kHz. Dielectric loss as a function of temperature under frequencies from 1 to 10 kHz is modelled by using the dynamic equation for the viscous motion of domain walls. In the simulation, the dispersion of phase transition temperature inside the ceramics has been considered. The simulation results meet quite satisfactorily the experimental data. The two important parameters, viscous coefficient and pinning force constant, can be estimated.