Achieving high energy-storage performance of medium-entropy (Na0.25Bi0.25Ca0.25Sr0.25)TiO3 lead-free relaxor ferroelectric ceramic for pulsed power capacitor

Abstract

Advanced electrostatic energy-storage science and technology based on dielectric ceramics capacitors are widely applied in pulsed power systems. Recently, entropy increasing design engineering has been considered as an available method to promote electrical characteristics in dielectric energy-storage ceramics. In this study, medium-entropy (Na0.25Bi0.25Ca0.25Sr0.25)TiO3 (NBCSTO) ceramics with good energy-storage properties were obtained by a conventional solid-state reaction method. The microstructure and element analysis results show that a perovskite structure was identified for the NBCSTO sample, and no secondary phases were detected. Furthermore, a dense microstructure and small grain size lead to a high breakdown electric field strength (EB) of 430 kV/cm of the NBCSTO ceramic, which also displays the features of relaxor ferroelectrics. Importantly, a high Wrec⁓5.84 J/cm3 along with a medium η⁓80 % were simultaneously achieved in the NBCSTO ceramic, as well as good energy-storage stability. Moreover, the NBCSTO ceramic exhibits both a high PD and a fast discharging speed. All the above results indicate that the NBCSTO ceramic may be potential eco-friendly material for capacitor used in the pulsed power systems.