Superior energy storage performance of Sr0.7Bi0.2TiO3-modified Na0.5Bi0.5TiO3-K0.7La0.1NbO3 lead-free ferroelectric ceramics

https://doi.org/10.1016/j.jallcom.2024.176188

Na_0.5Bi_0.5TiO₃ (NBT)-based ceramics exhibit significant potential as energy storage dielectric materials due to their high maximum polarization (P_max). However, their limited energy storage density significantly restricts their practical applications. To address this, this study optimizes the dielectric energy storage characteristics of lead-free relaxor ferroelectric ceramics based on 0.91Na_0.5Bi_0.5TiO₃-0.09 K_0.7La_0.1NbO₃ (NBT-KLN) by incorporating Sr_0.7Bi_0.2TiO₃ (SBT) relaxor additives. The introduction of SBT helps maintain large polarization and induces local disorderly fields, promoting the formation of polar nanoregions. Subsequently, a viscous polymer processing (VPP) technique was employed to reduce defects and enhance density, markedly improving the breakdown strength (BDS). The findings indicate that the BDS of the optimized 0.30SBT (VPP) ceramics increased to 440 kV/cm, while achieving a high energy storage efficiency (η) of 78 % and an elevated energy storage density (W_rec) of 6.29 J/cm³. Additionally, the 0.30SBT (VPP) ceramics demonstrate excellent temperature stability across a broad temperature range from 30 to 120 °C, making them ideal for long-term operation in variable environments. This study demonstrates superior results compared to previous research, thereby opening up new avenues for developing novel lead-free relaxor ferroelectric ceramics with superior energy storage characteristics.