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<p>Lead-free relaxor ferroelectric ceramics are promising candidates for advanced pulsed power systems owing to their combination of exceptional power density and ultrafast charge-discharge capabilities. However, the simultaneous realization of ultrahigh recoverable energy density (<i>W</i><sub>rec</sub>) and high efficiency (<i>η</i>) remains a persistent challenge, as strategies to enhance polarization typically increase hysteresis losses. To address this issue, we propose a strategy actively constructing a superrelaxor critical state—a crossover from dynamic to static/frozen relaxor states—through targeted compositional tuning and polarization configuration control. Guided by phase-field simulations and first-principles calculations, we introduce BaHfO<sub>3</sub> into a Sr<sub>0.5</sub>Bi<sub>0.25</sub>Na<sub>0.25</sub>TiO<sub>3</sub> relaxor matrix. This approach successfully shifted the dielectric maximum temperature to room temperature and enhanced the strength of relaxor behavior. Atom-scale structural characterization reveals that this structure weakens local domain interactions within 3 − 5 nm refined polar nanoregions yet preserving robust polar atomic displacements, effectively bridging the kinetic advantage of superparaelectrics with the dipole magnitude of classical relaxors. As a result, the superrelaxor critical state delivers a giant energy-storage capability, including <i>W</i><sub>rec</sub> of 16.2 J/cm<sup>3</sup> with a high <i>η</i> of 92%, outperforming most reported lead-free ceramics. This work establishes a generalizable strategy for engineering critical polarization states in dielectric oxides toward next-generation capacitive energy storage.</p>

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Constructing superrelaxor critical state towards giant energy storage in lead-free dielectric ceramics

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月10日

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  • Bing Xie,
  • Zhiqing Li,
  • Huajie Luo,
  • Xiaoming Shi,
  • Kaina Wang,
  • Zhiyong Liu,
  • Kun Guo,
  • Haibo Zhang,
  • Tianyu Li,
  • Zhenxiang Cheng,
  • Shujun Zhang

摘要

Lead-free relaxor ferroelectric ceramics are promising candidates for advanced pulsed power systems owing to their combination of exceptional power density and ultrafast charge-discharge capabilities. However, the simultaneous realization of ultrahigh recoverable energy density (Wrec) and high efficiency (η) remains a persistent challenge, as strategies to enhance polarization typically increase hysteresis losses. To address this issue, we propose a strategy actively constructing a superrelaxor critical state—a crossover from dynamic to static/frozen relaxor states—through targeted compositional tuning and polarization configuration control. Guided by phase-field simulations and first-principles calculations, we introduce BaHfO3 into a Sr0.5Bi0.25Na0.25TiO3 relaxor matrix. This approach successfully shifted the dielectric maximum temperature to room temperature and enhanced the strength of relaxor behavior. Atom-scale structural characterization reveals that this structure weakens local domain interactions within 3 − 5 nm refined polar nanoregions yet preserving robust polar atomic displacements, effectively bridging the kinetic advantage of superparaelectrics with the dipole magnitude of classical relaxors. As a result, the superrelaxor critical state delivers a giant energy-storage capability, including Wrec of 16.2 J/cm3 with a high η of 92%, outperforming most reported lead-free ceramics. This work establishes a generalizable strategy for engineering critical polarization states in dielectric oxides toward next-generation capacitive energy storage.