Designing lead-free bismuth ferrite-based ceramics learning from relaxor ferroelectric behavior for simultaneous high energy density and efficiency under low electric field

Abstract

Bismuth ferrite (BiFeO₃, BFO) possesses very large spontaneous polarization, which provides a great potential in dielectric energy-storage capacitors. However, the presence of large remanent polarization heavily restricts the achievement of excellent performance in the energy storage field. Herein we designed local compositional disorder and constructed quenched random fields to maximize the discrepancy between the maximum polarization and the remanent polarization by means of introducing Zn²⁺ and Ta⁵⁺ at B-sites together in BiFeO₃-based solution. Interestingly, pinched-hysteresis loops were observed in this Ba(Zn_1/2Ta_2/3)O₃-modified BFO-based solution. Ultrahigh recoverable energy density (2.56 J cm⁻³) was first reported under low electric field (16 kV mm⁻¹), which is much superior to the previous results regarding BFO-based bulk ceramics. In addition, an excellent recoverable energy density (>2 J cm⁻³) and a high efficiency (>80%) were obtained simultaneously in this BZT-modified BFO-based bulk material under low electric field (<20 kV mm⁻¹). These results demonstrate that the strategy of constructing weakly coupled polar structures is feasible and effective to boost the energy density and efficiency for BiFeO₃-based bulk ceramics, which may pave a significant step towards utilizing energy-storage applications for BiFeO₃-based materials.