Entropy regulation enhanced superior energy storage density and high temperature stability in lead-free relaxors

The inferior energy storage capability and high temperature reliability of ceramic capacitors are a main factor restrict the further application. In this article, we propose to overcome the above issues through increasing the configuration entropy (∆Sconfig). The novel high entropy ceramics (1-x) (Na0.5Bi0.47La0.03)0.94Ba0.06TiO3-xCa0.7La0.2Ti0.85Hf0.15O3 were successfully designed and synthesized to enhance comprehensive performance. With the ∆Sconfig rises from 0.98 R to 1.54 R, the optimum composition exhibits outstanding recoverable energy storage density (Wrec) of 6.21 J/cm3 under 420 kV/cm and dielectric high temperature stability (∆C/C25 °C ≤ ± 15%, −59–372 °C) in accordance with X9R, which can be ascribed to refined grain size, improved bandgap width, inhibited leakage current and interfacial polarization and modified relaxor behavior caused by the improvement of ∆Sconfig. Interestingly, the high entropy composition was firstly tested fatigue endurance at 150 °C and 200 °C and shown prominent high temperature reliability. These results provide a new viewpoint for designing high temperature capacitors.