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<p>The localized charge carriers are the primary factor responsible for generating high interfacial polarization in dielectric ceramics. Therefore, such materials are characterized by low dielectric breakdown strength and weak energy storage performance. In the present study, we aim to suppress the localized charge carriers in (Na<sub>1/2</sub>Bi<sub>1/2</sub>)TiO₃ ceramics by forming an ergodic relaxor phase characterized by high configurational entropy (<i>ΔS</i>), elevation of grain resistance (<i>R</i><sub><i>g</i></sub>), and high activation energy (<i>E</i><sub><i>a</i></sub>), to enhance their breakdown strength. The (0.8-x)(Na<sub>1/2</sub>Bi<sub>1/2</sub>)TiO₃–0.2SrTiO₃–xBaTiO₃ (<i>x</i> = 0.0, 0.05, 0.10, and 0.15) compositions were synthesized using a solid-state reaction technique. The crystal lattice symmetry increases as <i>ΔS</i> increases with increasing BaTiO₃ (BT) content, resulting in disruption of the long-range ferroelectric order in the (Na<sub>1/2</sub>Bi<sub>1/2</sub>)TiO₃–0.2SrTiO₃ (NBT-ST) ceramic and weakening of the B–O bond coupling. Two unique dielectric anomalies associated with high-temperature polar nanoregions (PNRs) in the ergodic relaxor (ER) state and low-temperature PNRs in the non-ergodic relaxor (NR) state are identified at <i>x</i> &lt; 0.1. Impedance spectroscopy results revealed that the highest <i>R</i><sub><i>g</i></sub> and <i>E</i><sub><i>a</i></sub> were obtained at <i>x</i> = 0.10, resulting in a mismatch between grain and grain boundary resistance (<i>R</i><sub><i>gb</i></sub>). This cascade effect led to a reduction in localized charge carriers, suppression of interfacial polarization, and enhancement of the breakdown strength to 320&#xa0;kV/cm in the BNSTB<sub>0.1</sub> ceramic. This work offers a promising paradigm for enhancing breakdown strength in perovskite ceramics to meet the demanding requirements of energy storage applications.</p>

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Suppression of localized charge carriers via entropy and ergodic relaxor strategy for improvement breakdown strength of perovskite ceramics

  • 期刊论文

  • 发表日期：

    2025年10月2日

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  • Asmaa Al-Rasheedi,
  • Abd El-razek Mahmoud,
  • K. A. Aly,
  • Yasser A. M. Ismail,
  • Amira. A. Kamal

摘要

The localized charge carriers are the primary factor responsible for generating high interfacial polarization in dielectric ceramics. Therefore, such materials are characterized by low dielectric breakdown strength and weak energy storage performance. In the present study, we aim to suppress the localized charge carriers in (Na1/2Bi1/2)TiO₃ ceramics by forming an ergodic relaxor phase characterized by high configurational entropy (ΔS), elevation of grain resistance (Rg), and high activation energy (Ea), to enhance their breakdown strength. The (0.8-x)(Na1/2Bi1/2)TiO₃–0.2SrTiO₃–xBaTiO₃ (x = 0.0, 0.05, 0.10, and 0.15) compositions were synthesized using a solid-state reaction technique. The crystal lattice symmetry increases as ΔS increases with increasing BaTiO₃ (BT) content, resulting in disruption of the long-range ferroelectric order in the (Na1/2Bi1/2)TiO₃–0.2SrTiO₃ (NBT-ST) ceramic and weakening of the B–O bond coupling. Two unique dielectric anomalies associated with high-temperature polar nanoregions (PNRs) in the ergodic relaxor (ER) state and low-temperature PNRs in the non-ergodic relaxor (NR) state are identified at x < 0.1. Impedance spectroscopy results revealed that the highest Rg and Ea were obtained at x = 0.10, resulting in a mismatch between grain and grain boundary resistance (Rgb). This cascade effect led to a reduction in localized charge carriers, suppression of interfacial polarization, and enhancement of the breakdown strength to 320 kV/cm in the BNSTB0.1 ceramic. This work offers a promising paradigm for enhancing breakdown strength in perovskite ceramics to meet the demanding requirements of energy storage applications.