Understanding thermal depolarization via thermally stimulated depolarization current measurement

Thermal depolarization in poling-induced piezoelectric materials is defined as the disappearance of remanent polarization at a so-called depolarization temperature. A thermally stimulated depolarization current (TSDC) measurement is most widely used for examining depolarization as a function of temperature. TSDC results in the literature commonly show a gradual reduction of polarization even below depolarization temperature (Td). However, no degradation happens when thermal heat treatments are conducted below Td, meaning that the apparent reduction in polarization measured by TSDC is sure to be an artifact. Here, we demonstrate that such artifact is unavoidable during TSDC measurements and propose a method to circumvent it. This strategy was manifested on TSDC data collected from a relaxor ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals.