Realizing excellent pyroelectric performance in BNT-BNN-xLa ceramics via an A-site engineering strategy

Uncool infrared detectors based on BNT ceramics hold significant potential for applications such as infrared imaging, detection, alarm systems, and the development of advanced smart home technologies. However, the trade-off between the high depolarization temperature (Td) and large room temperature pyroelectric coefficient (p) limits the further promotion of pyroelectric performance for BNT based ceramics. In this work, La is introduced into 0.97(Bi0.5Na0.5)TiO3-0.03Ba(Ni0.5Nb0.5)O3 ceramics to diffuse into A-site to improves the hybridization between Bi and O and breaks the spatial inversion symmetry of BNT-BNN ceramics, resulting in ferroelectric distortion and improvement of polarization. Meanwhile, the introduction of La helps to make a close packing of the structure and improves the stability of BNT-BNN-xLa ceramics, maintaining the high Td. Therefore, the p of BNT-BNN-xLa increases from 3.42 × 10−4 C m−2 K−1 at x = 0 to 14.30 × 10−4 C m−2 K−1 at x = 0.75%, Meanwhile, the BNT-BNN-xLa ceramic maintained a relatively high Td about 174 °C. Moreover, the BNT-BNN-xLa ceramic with x = 0.75% exhibits remarkable pyroelectric figure of merit (FOMs) of Fi = 5.54 × 10−10 m V−1 and figure of Fv = 11.53 × 10−2 m2 C−1 and figure of Fd = 44.83 μPa−1/2. These excellent pyroelectric performances with outstanding FOMs make BNT based material a promising candidate for developing high-performance lead-free pyroelectric infrared detectors.