Highly-reliable dielectric capacitors with excellent comprehensive energy-storage properties using Bi0.5Na0.5TiO3-based relaxor ferroelectric ceramics

The development of capacitors with high reliability and good comprehensive performances is of great significance for practical applications. In this work, lead-free relaxor ferroelectric (FE) ceramics of (1-x)(0.5(Bi0.5Na0.5)TiO3-0.5SrTiO3)-xBi(Mg2/3Nb1/3)O3 ((1-x)(BNT-ST)-xBMN) were prepared by a conventional solid-state reaction method. The introduction of BMN was found to enhance local structure disorder, leading to the significantly reduced size of FE nanodomains, which is responsible for the slim polarization-electric field hysteresis loops. A giant energy-storage density of 6.62 J/cm3 and a high efficiency of 82 % can be achieved simultaneously under a moderate electric field of 34 kV/mm at x = 0.08. It also exhibits high discharge density ∼ 2.74 J/cm3, large power density ∼ 248 MW/cm3 and ultrafast discharge rate ∼ 28 ns at 20 kV/mm in addition to excellent temperature (10–130 °C) and frequency (1–100 Hz) stabilities. These results demonstrate that the (1-x)(BNT-ST)-xBMN ceramic system is a promising lead-free candidate for advanced pulsed power capacitor applications.