Suppressing phase transformation-induced depolarization in PMN-PT single crystals through high-temperature AC poling

Alternating current (AC) poling has been found to be more effective in optimizing the performance of [001]-oriented rhombohedral relaxor-PbTiO₃ single crystals. However, these materials undergo ferroelectric phase transformations, during which structural changes result in loss of polarization and property degradation. In this study, we focus on a strategy to mitigate phase transformation-induced depolarization in Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) single crystals through high-temperature AC poling. Our results reveal that thermal depolarization is significantly reduced when AC poling is conducted at high temperature near the rhombohedral-to-tetragonal transformation temperature compared to the room-temperature poling. Furthermore, in-situ X-ray diffraction and Raman spectroscopy demonstrates that high-temperature AC poling can achieve a metastable phase and suppress symmetry changes during the ferroelectric phase transformation, contributing to reduced property degradation in the materials. Our findings highlight the potential of a novel domain engineering technique to enhance structural stability and mitigate depolarization in PMN-PT single crystals.