Enhanced Pyroelectric Response in Quenched BNT‐Based Lead‐Free Ferroelectrics for Uncooled Infrared Detection

Abstract Excellent pyroelectric performance in environmentally friendly lead‐free ferroelectrics is highly demanded for uncooled infrared detector. However, the trade‐off between room temperature pyroelectric coefficient ( p room ) and depolarization temperature ( T d ) remains a major challenge of lead‐free ferroelectrics for their device applications. Herein, a superior p room of 13.8 × 10 −4 C m −2 K −1 with high T d of 155 °C is achieved in quenched BNT‐Fe/Mn‐NBT sample. Oxygen vacancy engineering is proposed to solve the constraint between p room and T d in BNT‐based ceramics. The local A/B site displacement and oxygen vacancies are constructed in the BNT‐Fe/Mn‐NBT perovskite structure by quenching treatment, resulting in larger lattice distortion and superior p room . Meanwhile, defect‐induced inhomogeneous random field compensates the ferroelectric depolarization field and down‐shifts the free energy well, maintaining high T d . The resulting pyroelectric infrared detector made from the high‐performance quenched BNT‐Fe/Mn‐NBT generates the voltage responsivity of 5906 V W −1 and specific detection rate of 1.8 × 10 8 cm Hz 1/2 W −1 , which is comparable to the commercial RD‐624 type PZT‐based pyroelectric infrared detector.