Realization of the Giant Pyroelectric Response via Modulated Polar Structures

Abstract

Among pyroelectric materials, Bi0.5Na0.5TiO3 (BNT)‐based relaxors are particularly noteworthy due to their significant polarization fluctuation near the depolarization temperature (Td), resulting in a large pyroelectric response. What has been overlooked is the dynamic behavior of inherent polar structures, particularly the temperature‐dependent evolution of polar nanoregions (PNRs), which significantly impacts the pyroelectric behavior. Herein, based on the large pyroelectric response origination (the ferroelectric‐relaxor phase transition), the mixed nonergodic and ergodic relaxor (NR+ER) critical state is constructed, which is believed to trigger the easily fluctuating polarization state with excellent pyroelectric response. Composition engineering (with Li+, Sr2+, and Ta5+) strategically controls the relaxor process and modulates the dynamic behavior of inherent polar structures by the random field effect. The pyroelectric coefficient of more than 1441 µCm−2K−1 at room temperature (RT), more than 9221 µCm−2K−1 (RT), and ≈107911 µCm−2K−1 (Td) are achieved in the Li+‐doped sample, the Sr2+‐doped sample, and the (Li++Ta5+) co‐doped sample, respectively. This work earns the highest RT pyroelectric coefficient in BNT‐based relaxors, which is suitable for pyroelectric applications. Furthermore, it provides a strategy for modulating the pyroelectric performance of BNT‐based relaxors.