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 (Pmax) 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 Pmax, low remnant polarization (Pr) and slim P-E loops. On the other hand, the improvement of configuration entropy (ΔSconfig) 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 ΔSconfig increases from 0.98 R to 1.44 R, a giant energy storage density (Wrec) of 8.11 J/cm3 as well as a high efficiency (η) of 90.2 % are synchronously obtained. Significantly, the optimum sample shows outstanding dielectric temperature stability (ΔC/C25°C ≤ ± 15 %, −55 ∼ 165 °C) in accordance with X8R. This work demonstrates that the medium entropy superparaelectrics are a shortcut to achieve next-generation ceramic capacitors with high comprehensive performance.