DAMAGE EVOLUTION IN FERROELECTRIC PZT INDUCED BY BlPOLAR ELECTRIC CYCLING

摘要

The fatigue behaviour of commercial bulk Lead Zirconate Titanate (PZT) induced by bipolar cycling was investigated. Polarisation and strain hysteresis loops as well as acoustic emissions (AE) were monitored. Higher cycling fields (2xE_c) yield stronger fatigue, higher AE energy values and lower threshold values for the onset of AE events at high cycle numbers. AE amplitudes and energies were found to be a measure for the degree of domain clamping. Cycling at 2 E_c leads to an increasing asymmetry of the strain hysteresis, which is explained by an offset polarisation. Corrosion paths were observed by SEM, most numerously in the centre of a strongly fatigued sample. A damage scenario based on domain waII clamping due to the coalescence of point defects is presented.