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 P-r, coercive field E., bias field E-bias, and strain asymmetry gamma) as well as the small signal parameters determined from field dependent converse piezoelectric measurements (remnant piezoelectric coefficient d(r), coercive field E-c, offset piezoelectric coefficient d(offset), and bias field E-bias). The local strain asymmetry gamma was found to linearly depend on the local bias field E-bias. An analogous relation is established for d(offset) and E-bias. 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. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.