Optically tuned pyroelectric, electrocaloric parameters and stability of the tetragonal phase at higher temperatures of lead-based ferroelectrics.

The driving force of photogenerated carriers in ferroelectrics is closely related to spontaneous polarization in photoferroelectrics. This makes the probability of tuning pyroelectricity and electrocaloric parameters under irradiation. All these phenomena can possible in optically active ferroelectrics, where ferroelectricity can easily be tuned under irradiation. To make optically active ferroelectrics Li and Bi-doped into tetragonal phase PZT. The ferroelectric polarization and displacement current were abruptly changed unexpectedly by 200-300% under 405 nm near-ultraviolet laser light (30 mW). Under illuminated conditions, there is an enhancement in the pyroelectric coefficient at room temperature. Temperature-dependent ferroelectricity was measured under dark and illuminated conditions. The calculated pyroelectric coefficient increased by 120 %, under illuminated conditions. The cross-coupled Electrocaloric (EC) parameters ΔT and ΔS improved by 100 % and 80 %, at 10 Hz, and 20 ℃ respectively, under illumination. The temperature-dependent structural and dielectric analysis shows the maintaining tetragonality of the phase. While around 390 ℃ ferroelectric phase transition occurs. This study provides a comprehensive understanding and new insights into the photo-dielectric, ferroelectric, pyroelectric and electrocaloric mechanisms in lead-based electroceramics. Which further encourages to design of modern and smart thermal sensor devices.