High-entropy ceramics with bandgap engineering enable ultrafast energy discharge

Mar 16, 2026

Lead-free tungsten bronze ceramics combine high-entropy design and bandgap engineering for high energy density and ultrafast discharge performance.

(Nanowerk News) Researchers at Guilin University of Technology have produced a new family of lead-free ceramic capacitors that store and release electrical energy with unusual speed and efficiency. The team, led by Professor Changzheng Hu, combined a high-entropy lattice strategy with bandgap tuning to create tungsten bronze-structured ceramics that withstand exceptionally high electric fields while minimizing energy loss during rapid charge-discharge cycles.

Key Findings

Dielectric ceramic capacitors are central to modern electronics and pulsed power systems because they can charge and discharge at extremely high speeds while delivering high power density. Yet practical use has been limited by modest recoverable energy storage density and energy efficiency, particularly under harsh operating conditions such as elevated temperatures or intense electric fields. Schematic illustrating how high-entropy design and bandgap engineering jointly improve energy storage in tungsten bronze ceramics. The high-entropy approach converts large ferroelectric domains into weakly coupled polar nanoregions, refines grain size to increase grain boundary density, and widens the electronic bandgap through tantalum substitution. Polarization-electric field curves (top right) and energy density data (bottom right) show that the Ta-0.5 composition achieves the highest recoverable energy density and efficiency. (Image: Reproduced from DOI:10.26599/JAC.2026.9221260, CC BY) (click on image to enlarge) To address these constraints, the team synthesized a series of ceramics with the composition Ba2.38Sr2.12Sm0.5Gd0.5Ti1Zr1Nb8-xTaxO30. Their approach combined two complementary strategies. The high-entropy design incorporates multiple different cations into the crystal lattice, generating considerable atomic-scale disorder. That disorder suppresses the continuous ferroelectric alignment that normally extends through the material and instead favors the emergence of polar nanoregions, which are small clusters of aligned electric dipoles that reverse direction more readily under an applied field. Because these polar nanoregions switch with less resistance, the ceramic wastes less energy during each charge-discharge cycle and achieves stronger overall polarization. The second strategy involved progressively replacing niobium with tantalum in the lattice. Higher tantalum content widened the electronic bandgap, the energy gap that separates conducting from insulating behavior. A wider gap suppresses the thermal excitation of charge carriers, raising the material’s electrical resistance and allowing it to tolerate stronger fields before breaking down. “The synergy between high-entropy effects and bandgap engineering allows us to finely tune the microstructure and electronic properties,” said Professor Hu. “We observed grain refinement, increased resistivity, and a broader bandgap—all of which contribute to a significantly enhanced breakdown electric field.” The composition labeled Ta-0.5 delivered the strongest results. At 830 kV·cm-1 it stored 7.93 J·cm-3 of recoverable energy at an efficiency of 94.25%. In over-damped discharge mode, the ceramic released 5.20 J·cm-3 within 1.56 µs. Under-damped testing yielded a current density of 971.34 A·cm-2 and a power density of 155.41 MW·cm-3. The material also proved thermally stable. Its discharge energy density shifted by less than 10% between 30 °C and 180 °C, a characteristic that matters for applications in aerospace and electric vehicles where operating temperatures can swing widely. “Our work demonstrates that high-entropy tungsten bronze ceramics, when combined with bandgap engineering, offer a powerful and versatile platform for next-generation energy storage applications,” added Professor Hu. “This strategy opens new avenues for developing high-performance dielectric materials for pulsed power systems, electric vehicles, and aerospace technologies.” By pairing atomic-scale lattice disorder with electronic bandgap control in a single lead-free material system, the work offers a concrete design route for dielectric ceramics that need to operate reliably under high fields and variable temperatures. The study was published in Journal of Advanced Ceramics (“A high-entropy strategy for enhancing energy storage performance and enabling ultrafast discharge in tungsten bronze ceramics”).