Simultaneously achieved high energy density and excellent thermal stability of lead-free barium titanate-based relaxor ferroelectric under low electric field

Abstract

Dielectric capacitors with high power density and excellent temperature stability are highly demanded in pulsed power systems. BaTiO3-based lead-free relaxor ceramics have been proven to be a promising candidate for energy storage applications. However, the presence of low maximum polarization (Pmax) heavily restricts its applications in the energy storage field. In order to significantly increase Pmax under low electric field, a strategy, via introducing Bi0.5Na0.5TiO3 (BNT) and Ca2+, constructing local compositional disorder and decreasing grain size, is propounded in this work. High Pmax of 42.11 µC cm−2 and large breakdown electric field (Eb) of 210 kV cm−1 were attained in Bi0.5Na0.5TiO3-modified BT-based solution, giving rise to ultrahigh Wrec of 2.57 J/cm3. The significantly improved Wrec is much superior to the previous other lead-free dielectric ceramic under moderate electric fields (< 220 kV cm−1). In addition, an excellent temperature stability (the variation of Wrec is less than 3% in the temperature range of 20–120 °C) was obtained in this BNT-modified BT-based bulk materials. These results demonstrate that the strategy is practicable and effective to hike the energy density up for BaTiO3-based bulk ceramics, which may pave a significant step towards utilizing energy storage applications for BaTiO3-based materials.