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

摘要

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 (P-max) heavily restricts its applications in the energy storage field. In order to significantly increase P-max 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 P-max of 42.11 mu C cm(-2) and large breakdown electric field (E-b) of 210 kV cm(-1) were attained in Bi0.5Na0.5TiO3-modified BT-based solution, giving rise to ultrahigh W-rec of 2.57 J/cm(3). The significantly improved W-rec 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 W-rec is less than 3% in the temperature range of 20-120 degrees 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.