Polar Vortices in Relaxor Ferroelectric Ceramics for High-Efficiency Capacitive Energy Storage.

Chen, Fangling; Chen, Mo; Zhang, Jingji; Liu, Weishen; Du, Huiwei; Zong, Quan; Yu, Huanan; Zhang, Yang et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

Polar vortices are predominantly observed within the confined ferroelectric films and the ferroelectric/paraelectric superlattices. This raises the intriguing question of whether polar vortices can form within relaxor ferroelectric ceramics and subsequently contribute to their energy storage performances. Here, we incorporate 10 mol % CaSnO<sub>3</sub> into the 0.7NaNbO<sub>3</sub>-0.3Sr<sub>0.7</sub>Bi<sub>0.2</sub>TiO<sub>3</sub> matrix, yielding a coexistence of phases: 48.8% orthorhombic <i>P</i>2<sub>1</sub>/<i>ma</i>, 49.1% tetragonal <i>P</i>4<i>bm</i>, and 2.1% tetragonal <i>P</i>4<sub>2</sub>/<i>mnm</i> SnO<sub>2</sub>, which is confirmed by the combination of X-ray diffraction and transmission electron microscopy. The ceramic features a pronounced core-shell structure with the shell region rich in stripe nanoscale domains of the <i>P</i>2<sub>1</sub>/<i>ma</i> phase and the core region consisting of polar nanoregions deficient in the <i>P</i>2<sub>1</sub>/<i>ma</i> phase, forming polar vortices. Consequently, the ceramic achieves an impressive recoverable energy storage density of 6.83 J cm<sup>-3</sup> and an exceptional efficiency of 95.7% at a high breakdown strength of 750 kV cm<sup>-1</sup>, along with superior stability in frequency, temperature, and cycling. These results not only offer a viable approach for developing high-performance energy storage ceramics through the controlled formation of polar vortices but also offer the potential for direct electric-field control of polar vortices for high-speed data processing and storage.