Ferroelectric-quasiferroelectric-ergodic relaxor transition and multifunctional electrical properties in Bi0.5Na0.5TiO3-based ceramics

A-site substituted 0.88(Bi0.5Na0.5)(1-x)(Li0.5Nd0.5)(x)TiO3-0.12BaTiO(3) (BNTLNx-BT12) ceramics were synthesized using a conventional solid-state reaction route. The structural transformation and miscellaneous electrical properties were systematically investigated. The A-site modification induced two sequence transitions from ferroelectric tetragonal (T) to quasi-ferroelectric pseudocubic (PC) phase, followed closely by the second transition from non-ergodic to ergodic relaxor (NR-ER), and finally to dynamic polar nanoregions (PNRs). The significant enhancement in piezoelectric activity, strain response, broad plateau-like maximum dielectric permittivity over a large temperature range and energy-storage level at different compositions may be attributed to the compositionally-induced T-PC to NR-ER transition and the alignment of dynamically-fluctuating PNRs, respectively. The evolution of multifunctional electrical properties, associated with the variations in structure/microstructure, might provide a new insight to investigate the underlying mechanism of structure-electrical properties relationship in ferroelectric solid solutions.