Lead-free bismuth sodium titanate (BNT)-based ceramics have attracted strong attention as environmentally benign dielectric materials for high-efficiency electrostatic energy-storage capacitors. A key challenge is that pristine BNT typically exhibits large hysteresis, high remnant polarization, and limited dielectric reliability, which restrict recoverable energy storage and efficiency under practical electric fields. Here, we present a focused mini-review of recent studies to clarify how composition design, phase boundary tuning, defect chemistry, and microstructural control collectively enable slim or pinched polarization-electric field (P-E) behavior and improved energy-storage functionality in BNT-related bulk ceramics. The reviewed outcomes consistently show that stabilizing relaxor states governed by polar nanoregions (PNRs), often via solid-solution engineering and secondary relaxor/antiferroelectric-like incorporation, suppresses irreversible switching and reduces hysteresis loss, while densification and grain-size control enhance electrical homogeneity and breakdown strength. In addition, defect-mediated tuning of oxygen vacancy-related complexes is highlighted as an independent lever to control relaxor ergodicity and polarization reversibility, providing a complementary route to slim-loop optimization. These insights are expected to guide integrated design strategies that couple phase/relaxor-state engineering with defect and microstructure optimization, accelerating the development of reliable, temperature-robust, lead-free dielectric capacitors based on BNT-related ceramics.

Citations

• Progress and outlook of dielectric energy storage characteristics of Lead–free (K,Na)NbO3 based bulk ceramics/composite films for capacitors
  Twinkle, Varun Kamboj, Chetna, Arun Kumar Singh, Gurpreet Singh, Sanjeev Kumar
  Current Opinion in Solid State and Materials Science.2026; 44: 101297.     CrossRef
• Structural Stability and Electromechanical Response of Lead-Free (Bi1/2Na1/2)TiO3‒SrTiO3 Ceramics Under A-Site Strontium Non-Stoichiometry
  Yubin Kang, Trang An Duong, Gwang-Hwi Jeong, Chang Won Ahn, Yong-Jai Kwon, Hyoung-Su Han
  Journal of Electrical and Electronic Materials.2026; 39(5): 549.     CrossRef

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