High-entropy and phase engineering induced dislocation networks for improving energy storage in BNT-based ceramics

Achieving high recoverable energy density (W_rec) and superior energy efficiency (η) remains a major challenge for dielectric energy storage ceramics. In this study, Bi_0.35Na_0.35Ba_0.09Sr_0.21TiO₃-based ceramics were optimized through the synergistic strategy of high-entropy design and phase engineering. By introducing BaZrO₃ into the Bi_0.35Na_0.35Ba_0.09Sr_0.21TiO₃ (BNBST) matrix to form (1-x) BNBST - xBZ (x = 0.1, 0.15, 0.2, 0.25), the configurational entropy (ΔS_config) was significantly increased, enhancing lattice disorder. Meanwhile, tailoring the tolerance factor (t) allowed deliberate modulation of the phase composition. BZ incorporation induced abundant local dislocations and the formation of polar nanoregions (PNRs), which together suppressed large-scale polarization reversal and enhanced the electric field response. As a result, the 0.8BNBST-0.2BZ (BZ2) ceramic achieved an outstanding W_rec of 2.88 J/cm³ and an η of 91.2 % under 260 kV/cm. Additionally, the ceramics exhibited excellent frequency and cycling stability across 1–200 Hz and up to 10⁵ cycles. This work highlights the effectiveness of combining high-entropy and phase engineering strategies in advancing the energy-storage performance of dielectric ceramics, offering valuable guidance for next-generation materials design.