Significantly enhanced energy storage density in sodium bismuth titanate-based ferroelectrics under low electric fields

Bi0.5Na0.5TiO3 (BNT)-based ferroelectrics have received more and more attention due to their environment-friendliness and large maximum polarization. Herein, the enhanced energy-storage properties of BNT-based ceramics were successfully prepared by introducing multi-ions (La3+, K+, Al3+, Nb5+, Zr4+) to improve the breakdown strength and simultaneously suppress the remnant polarization. An excellent discharge energy-storage density (Wd) of 3.24 J cm−3 and a high energy-storage efficiency (η) of 82 % under 200 kV cm-1 have been recorded for Bi0.44La0.06(Na0.82K0.18)0.5Ti0.90(Al0.5Nb0.5)0.08Zr0.02O3 ceramic. Meanwhile, the outstanding thermal stability with Wd of 1.84–1.96 J·cm−3 were also achieved in 25−125 °C at 140 kV cm-1. More importantly, piezoresponse force microscopy reveals that the threshold voltage for inducing long range order enhances while the stability of polar nanoregions (PNRs) on the nanoscale decreased with the increase of La doping amount, leading to more linear polarization behavior and higher energy-storage properties. These results promote the practical applications of BNT-based ferroelectrics in advanced pulsed power systems.