Dynamic behaviour of domains during poling by acoustic emission measurements in La-modified PbTiO3 ferroelectric ceramics

In order to study the dynamic behaviour of domains during poling, the acoustic emission (AE) characteristics of two La-modified PbTiO3 ferroelectric ceramics in which 90 degrees and 180 degrees domains were respectively dominant have been investigated. One sample was a 15 mol% La-doped ceramic with a high tetragonality ratio (c/a=1.021) and the other was a 24 mol% La-doped ceramic where the tetragonality ratio was close to unity (c/a=1.007). The acoustic emission behaviour of the former sample consisted of both burst as well as continuous emission, with the latter sample mainly showing continuous emission. Energy distributions made it possible to distinguish between the AE signals resulting from 90 degrees and 180 degrees domain switching. From the observed results, it was confirmed that most of the AE occurred due to 90 degrees domain switching. By introducing an alternative switching behaviour for the 90 degrees domains, the behaviour of the AE generation during poling could be explained.