KNN composite ceramics with superior pyroelectric performance for self-powered thermal detector

The thermal detector based on pyroelectric effect has attracted widespread attention due to its self-powering and rapid response. Although phase boundary engineered lead-free potassium sodium niobate [K0.5Na0.5NbO3, KNN] based ferroelectrics exhibit promising for pyroelectric sensor application, the high dielectric constants (epsilon(r)) of these materials significantly constrain their pyroelectric figures of merit (FOMs), owing to the inverse correlation between FOMs and epsilon r. To address this problem, we innovatively introduce perovskite bismuth sodium titanate [Bi0.5Na0.5TiO3, BNT] with low epsilon(r) and high pyroelectric coefficient as the second phase to construct a KNN/BNT composite. The introduction of BNT can not only remain the high pyroelectric coefficient (p=7.12 x 10(-4) C m(-2) K-1) of KNN matrix, but also result in superior FOMs (Fv increased by 74 %), outperforming previous KNN-based pyroelectric ceramics. The excellent pyroelectric performance originates from the unique composite microstructure with compositional heterogeneity. That is, both the low epsilon r BNT enriched phase and refined grain size as well as the promoted vibration of Nb-O octahedron contribute to the superior pyroelectric performance. A selfpowered thermal detector with great thermal response has been developed, which also exhibits potential for detecting ultraviolet energy and infrared radiation.