Ultrahigh Energy Storage in Tungsten Bronze Dielectric Ceramics Through a Weakly Coupled Relaxor Design.
basic_science · Level V
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- Record sourced from PubMed, PMID 38084796.
- Also identified by DOI 10.1002/adma.202310559.
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Abstract
Dielectric energy-storage capacitors, known for their ultrafast discharge time and high-power density, find widespread applications in high-power pulse devices. However, ceramics featuring a tetragonal tungsten bronze structure (TTBs) have received limited attention due to their lower energy-storage capacity compared to perovskite counterparts. Herein, a TTBs relaxor ferroelectric ceramic based on the Gd<sub>0.03</sub> Ba<sub>0.47</sub> Sr<sub>0.485-1.5</sub> <sub>x</sub> Sm<sub>x</sub> Nb<sub>2</sub> O<sub>6</sub> composition, exhibiting an ultrahigh recoverable energy density of 9 J cm<sup>-3</sup> and an efficiency of 84% under an electric field of 660 kV cm<sup>-1</sup> is reported. Notably, the energy storage performance of this ceramic shows remarkable stability against frequency, temperature, and cycling electric field. The introduction of Sm<sup>3+</sup> doping is found to create weakly coupled polar nanoregions in the Gd<sub>0.03</sub> Ba<sub>0.47</sub> Sr<sub>0.485</sub> Nb<sub>2</sub> O<sub>6</sub> ceramic. Structural characterizations reveal that the incommensurability parameter increases with higher Sm<sup>3+</sup> content, indicative of a highly disordered A-site structure. Simultaneously, the breakdown strength is also enhanced by raising the conduction activation energy, widening the bandgap, and reducing the electric field-induced strain. This work presents a significant improvement on the energy storage capabilities of TTBs-based capacitors, expanding the material choice for high-power pulse device applications.