Perovskite Na0.5Bi0.5TiO3: Potential Family of Peculiar Lead-free Electrostrictors
For perovskite ferroelectric oxides, the composition-induced transition from ferroelectrics to relaxors can enhance their electrostrictive coefficient Q33 remarkably, which is attracting more and more attentions in recent years. Chasing a larger electro-strain response is one of the most original driving forces of pursuing the higher Q33 values, while the two are often incompatible. Herein, taking the promising relaxor ferroelectrics Na0.5Bi0.5TiO3 (NBT) as the research object, we report the excellent electrostriction-like electro-strain behaviors (0.41%≤Suni≤0.46%, 25≤T≤125 ℃; Suni exhibits only 2.23% decline after 105 cycles) together with a series of enhanced Q33 values (0.029-0.047 m4/C2). Accompanied with the reconstruction of the de-coupled A-O interactions, the electric-field-induced relaxor to ferroelectric state transition contributes to the superior electro-strain behaviors, while the enhanced Q33 will greatly degenerate during this transition process. In contrast to the non-hysteretic electrostriction observed in those linear dielectrics, for NBT-based relaxor ferroelectrics, peculiar coexistence of ferroelectric in-phase a0a0c+ and anti-phase a-a-a- tiltings is suggested to contribute to the enhanced electrostriction-like behaviors observed in this work. These observations indicate that the NBT-based system can be considered as the potential family of peculiar lead-free electrostrictors for the applications in actuators area.