Damage evolution in ferroelectric PZT induced by bipolar electric cycling

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 damping. 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 wall clamping due to the coalescence of point defects is presented. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.