Remarkable energy storage capability and dielectric temperature stability in (Na0.5Bi0.5)TiO3-based medium entropy superparaelectrics

Eco-friendly dielectric ceramics with excellent energy storage performance and dielectric temperature stability are the kernel parts of pulsed power devices in the next-generation. However, the contradiction between high breakdown electric field (Eb)and maximum polarization (P-max) restricts the improvement of comprehensive performance. Herein, we report a novel strategy of entropy engineering in the superparaelectric state to address the above concerns. On the one hand, near-linear polarization response can be achieved in the superparaelectric state, which can be beneficial to obtain a large P-max, low remnant polarization (Pr) and slim P-E loops. On the other hand, the improvement of configuration entropy (Delta S-config) is conducive to refining grain size and domain size, enhancing bandgap width, and suppressing leakage current and interfacial polarization, thus the generation of large Eb. Therefore, with the Delta S-config increases from 0.98 R to 1.44 R, a giant energy storage density (W-rec) of 8.11 J/cm(3) as well as a high efficiency (eta) of 90.2 % are synchronously obtained. Significantly, the optimum sample shows outstanding dielectric temperature stability (Delta C/C-25 degrees C <= +/- 15 %, -55 similar to 165(degrees)C) in accordance with X8R. This work demonstrates that the medium entropy superparaelectrics are a shortcut to achieve nextgeneration ceramic capacitors with high comprehensive performance.