Lead-free NaNbO3-based ferroelectric perovskites and their polar polymer-ceramic composites: Fundamentals and potentials for electronic and biomedical applications

Ferroelectric lead-free NaNbO3-based ceramics are the most promising candidates to a wide range of advanced technological applications as sensors, transducers and actuators. In special, (K,Na)NbO3 (KNN) and (Ba,Na)(Ti,Nb)O3 (BTNN) show interesting structural properties, including morphotropic phase boundaries regions that lead to exceptional dielectric, piezoelectric and ferroelectric responses. Also, the biocompatibility of these compounds allows their application as biomedical sensors, medical devices, and bone tissue replacement. In this way, high impact applications can be achieved with ferroelectric lead free NaNbO3 – based (NN-based) ceramics. In this review, we will explore the strategies for the improvement of ferroelectric, dielectric and structural properties reviewing the effects of the synthesis process, microstructure and chemical composition of lead-free complex perovskite ceramics, specially KNN and BTNN, as well as, PVDF-KNN and PVDF-BTNN polymer-ceramic and the (PVDF-TrFE)-KNN copolymer-ceramic composites to provide new insights and research opportunities for the development and improvement of fundamental properties of such systems considering their potential for technological applications, especially for the biological ones.