Entropy-Regulated Local Multiphase Polarization States for Near-Zero Energy Loss in Relaxor Ferroelectrics.

Wang, Zhentao; Zhao, Weichen; Xi, Zhaochen; Liu, Wenyuan; Li, Da; Xu, Diming; He, Guoqiang; Liu, Yang et al. · ACS Nano · 2026

basic_science · Level V

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Abstract

How to further regulate the size and stability of polar nanoregions (PNRs) remains a fundamental constraint to simultaneously achieving ultrahigh efficiency (η) and large recoverable energy density (<i>W</i><sub>rec</sub>), thereby limiting the development of near-zero-loss dielectric capacitors. Here, guided by phase-field simulations, we propose an entropy-driven local multiphase polarization state in which rhombohedral (R)- and tetragonal (T)-symmetry PNRs of ∼1 nm in size are embedded within a cubic (C) matrix, effectively reducing hysteretic loss by lowering the domain-switching barriers in Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub>-based ceramics. Consequently, an ultrahigh η of 95.1%, a large <i>W</i><sub>rec</sub> of 6.8 J cm<sup>-3</sup>, and, simultaneously, an ultrafast discharge time of 240 ns are achieved in the high-entropy (1.76R) ceramic capacitors. The results indicate that entropy regulation can facilitate low-loss dielectric behavior, offering a viable approach for designing near-zero-dissipation energy-storage materials.