Optimization of energy storage density in relaxor (K, Na, Bi)NbO3 ceramics

Energy storage properties have been widely investigated in lead-free relaxor ferroelectric ceramics due to high polarization saturation ( P s ) and low remnant polarization ( P r ). Among these lead-free relaxor ferroelectric ones, the investigation of energy storage in KNN-based ceramics showed some unique characteristics. In this work, (K 0.48 Na 0.52 ) 1−3 x Bi x NbO 3 relaxor ceramics were synthesized by the conventional solid-state method, and the phase structure of diffusion rhombohedral (R) phase can be found. In addition, the recoverable energy storage density ( W rec ) increased with the increase of the electric fields, and a high W rec of ~1.04 J/cm 3 under a low dielectric breakdown strength (DBS) of ~189 kV/cm was achieved in the ceramics with x = 0.04. In particular, the influences of composition and sintering parameters on the W rec values were also studied. As a result, an optimum W rec value can be possessed in the relaxor KNN-based ceramics even if low DBS values were applied, which maybe benefits the development of energy storage materials and devices.