Heterogeneity of fatigue in bulk lead zirconate titanate

The spatial heterogeneity of fatigue in commercial ferroelectric lead zirconate titanate ceramics was experimentally investigated. All parameters measured on fatigued samples are spatially highly heterogeneous including large signal polarisation and strain hysteresis loops (remnant polarisation Pr, coercive field Ec, bias field Ebias, and strain asymmetry (gamma)) as well as the small signal parameters determined from field dependent converse piezoelectric measurements (remnant piezoelectric coefficient dr, coercive field Ec, offset piezoelectric coefficient doffset, and bias field Ebias). The local strain asymmetry (gamma) was found to linearly depend on the local bias field Ebias. An analogous relation is established for doffset and Ebias. Switching time retardation is similarly heterogeneous across the sample. The previously determined stretched exponential polarisation relaxation equally well occurs locally. A spatial correlation to the observed microcrack densities could not be found.