Regulating the polarization behavior of Bi_0.5Na_0.5TiO₃ through high-entropy design

Abstract Lead-free Bi 0.5 Na 0.5 TiO 3 (BNT) has received widespread attention in the field of relaxor ferroelectrics due to the presence of intrinsic polar nanoregions (PNRs) during complex phase transition. Numerous studies have demonstrated the correlation between polarization and PNRs in BNT-based materials. However, the different content of PNRs gives rise to diverse polarization behaviors, which emphasizes the importance of precise content control of the PNRs. High-entropy ceramics mostly consist of five or more cations randomly distributed on equivalent lattice sites with different radii, masses and electronegativity, accompanied by the synergistic effect of lattice distortion, sluggish diffusion and so on. This provides favorable conditions for the formation of PNRs. In this work, the (1− x )Bi 0.5 Na 0.5 TiO 3 − x Bi 0.2 Na 0.2 Ba 0.2 Sr 0.2 Mg 0.2 TiO 3 series is synthesized based on a high-entropy strategy, adjusting the ratio of the high-entropy component Bi 0.2 Na 0.2 Ba 0.2 Sr 0.2 Mg 0.2 TiO 3 . Accordingly, effective modulation is realized in the microstructure, morphology and PNRs, to comprehensively investigate the dependence of various polarizations (including the dielectric, ferroelectric, piezoelectric and pyroelectric properties) on the high-entropy component. These findings present a novel approach to performance regulation in dielectrics, as well as experimental evidence for the design and development of BNT-based devices.