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 (T_d). However, no degradation happens when thermal heat treatments are conducted below T_d, 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(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) single crystals.