Temperature stability lock of high-performance lead-free relaxor ferroelectric ceramics

Lead-free dielectric ceramics are considered a highly promising material for pulse power capacitors due to their excellent energy storage performance. However, it is challenging to achieve high-temperature energy storage performance of dielectric ceramics to meet the needs of practical applications. Here, an effective strategy for constructing temperature stability lock is designed to regulate the phase composition and temperature stability based on the polymorphic polarization structure. By realizing the ergodic-state-dominated metastable relaxation structure, high energy storage performance and temperature-insensitive structure can be achieved in relaxor ferroelectric ceramics. Taking the Bi0.5Na0.5TiO3-based solid solution as an example, we demonstrate the metastable relaxation structure induced by the proportion of phase composition. This leads to a large recoverable energy density (Wrec) of 10.7 J cm−3 and a high efficiency (η) of 91 %. Together with the good thermal stability of Wrec (7.1 ± 0.1 J cm−3) and η (86 ± 5 %) values at 500 kV cm−1 in the temperature range from 20°C to 200°C, outperforming all reported Bi0.5Na0.5TiO3-based energy storage ceramics. Our work provides a method for obtaining lead-free dielectric ceramics with high-temperature energy storage performance through temperature stability lock.