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With the rapid advancement of pulsed power electronics, electric vehicles, avionic systems, and renewable energy grids, dielectric capacitors have emerged as indispensable components due to their ultrahigh power density and ultrafast charge–discharge rates. Traditional lead-based dielectric ceramics, however, pose severe environmental and health hazards during their fabrication, usage, and disposal. Sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT)-based lead-free relaxor ferroelectric ceramics have attracted increasing attention as promising alternatives owing to the large spontaneous polarization induced by the Bi3+ 6s2 lone-pair electron configuration and their broad operational temperature stability arising from diffuse phase transitions. Nevertheless, challenges remain in coordinating polarization response, dielectric breakdown strength (Eb), and relaxation behavior across different operational voltages. Therefore, developing field-tailored multiscale design strategies is essential to meet growing performance demands in diverse electrostatic energy storage applications.
Recently, a team of material scientists led by Pu Mao from Nanchang Hangkong University, China, systematically reviewed the energy storage theories, phase-transition controversies, physical characteristics, and multiscale synergistic design strategies for BNT-based lead-free dielectric ceramics under various electric fields.
The team published their work in Journal of Advanced Ceramics on September 29, 2026.
“In this review, we systematically examine the fundamental principles of dielectric energy storage, key capacitive determinants, and the evolutionary history of BNT-based ceramics. It emphasizes that optimizing BNT-based ceramics requires tailored multiscale regulatory strategies based on the deep physical coupling among polarization behavior, dielectric breakdown strength, and relaxation behavior,” said Pu Mao, associate professor at the School of Materials Science and Engineering at Nanchang Hangkong University (China), an expert whose mainly engaged in research work related to giant dielectric ceramics, dielectric energy storage ceramic materials, polymer-based dielectric composite materials, and ferroelectric/piezoelectric catalysis.
“Under low electric fields (<300kV/cm), the primary design objective is maximizing polarization difference (ΔP=Pmax−Pr) and energy efficiency while ensuring fast response for low-voltage electronic components, which is mainly achieved by domain and defect engineering to break long-range ferroelectric order into dynamic polar nanoregions. In the moderate electric field range (300-500kV/cm), maintaining high energy storage efficiency while avoiding premature dielectric breakdown demands precise regulation of activation energies to suppress polarization saturation and mitigate oxygen vacancies via chemical doping or sintering control. Under high electric fields (>500kV/cm), high-entropy strategies and multi-phase heterostructures are particularly effective: the former leverages multi-element chemical disorder and wide-bandgap ions to elevate intrinsic dielectric breakdown strength, while the latter utilizes dielectric and conductivity discontinuities at interface layers to suppress electrothermal breakdown paths,” said Pu Mao.
“Given the multiscale nature, microstructural complexity, and multi-field coupling environments associated with BNT-based ceramics, traditional trial-and-error experimental approaches are increasingly inefficient. Fortunately, integrating machine learning models and high-throughput computational screening captures complex nonlinear relationships, facilitates multi-objective optimization, substantially reduces experimental iterations, and drastically accelerates the development of high-performance lead-free dielectrics,” said Pu Mao.
“Future research should focus on the following areas: (1) In situ dynamic characterization and multiscale modeling: Combining advanced in situ characterization tools (such as in situ electron microscopy and synchrotron radiation) with multiscale computational methods (first-principles calculations and phase-field simulations) to capture real-time interfacial evolution, defect engineering, and dynamics of polar nanoregions (PNR) under external electric fields. (2) Data-driven material discovery: Employing machine learning and high-throughput data-driven modeling to establish accurate predictive links among composition, microstructure, and macroscopic properties, accelerating the rational design of new BNT-based systems. (3) Long-term reliability under multi-field coupling: Investigating fatigue failure, insulation resistance degradation, and lifetime performance under combined electrical, thermal, mechanical, and humid operating conditions to ensure device reliability. (4) Large-scale fabrication and MLCC integration: Overcoming scale-up processing bottlenecks and establishing precise control over large-scale fabrication and sintering parameters to facilitate the transition from laboratory pellets to multilayer ceramic capacitor (MLCC) architectures, ” said Pu Mao.
About author
Pu Mao is currently an associate professor working in the School of Materials Science and Engineering, Nanchang Hangkong University, P.R. China. He obtained his Ph.D. degree from the School of Materials Science and Engineering, Xi’an Jiaotong University, in 2020. He was a visiting Ph.D. student in the Department of Materials Science and Engineering, National University of Singapore, in 2019-2020. His research interests focus on high-performance lead-free ferroelectric ceramics, colossal permittivity ceramics, polymer-based nanocomposite dielectric films for energy storage applications, and so on.
DOI LINK: 10.26599/JAC.2026.9221358
About Journal of Advanced Ceramics
Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen . JAC’s 2025 IF is 14, ranking in Top 1 (1/34, Q1) among all journals in “Materials Science, Ceramics” category, and its 2025 CiteScore is 24.6 (6/133) in Scopus database. ResearchGate homepage:
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