Realizing excellent energy-storage performance under low electric fields in lead-free BiFeO3-BaTiO3-based ceramics with ultrahigh polarization difference

Abstract

Amidst the swift progress of electronic devices, there's an escalating need for capacitors to attain heightened energy storage capabilities (> 5 J/cm³) under low electric fields(< 300 kV/cm), facilitating integration and downsizing. In this research, (0.67-x)BiFeO₃–0.33BaTiO₃-xLaAlO₃ (x = 0–0.07) ceramics with ultrahigh polarization difference (ΔP = P_max-P_r) were successfully synthesized via the traditional solid-phase method. Initially, the progressive substitution of LaAlO₃ was found by XRD Rietveld refinement, PFM, and dielectric spectroscopy analysis to lead to a phase transition from the R3c phase to the Pm3m phase, obtaining ultra-small and highly electric field responsive PNRs, thus facilitating the relaxation behavior and achieving low P_r values. Moreover, the introduction of La³⁺ enables the 0.67BiFeO₃–0.33BaTiO₃ ceramics leading to an increased deviation of Bi ions from the centre, which maintains a relatively high P_max to achieve an ultrahigh ΔP (~52.43 μC/cm²), resulting in excellent energy storage density (W_rec ~ 5.71 J/cm³) under relatively low electric fields (270 kV/cm), along with super temperature stabilities. This study offers an effective pathway to explore the high energy storage capabilities of dielectric capacitors under low fields.