Chemical nature of the enhanced energy storage in A-site defect engineered Bi0.5Na0.5TiO3-based relaxor ferroelectrics

Defect engineering has attracted significant interest in perovskite oxides because it can be applied to op-timize the content of intrinsic oxygen vacancies (V-O) for improving their recoverable energy-storage density (W-rec). Herein, we design 0.84Bi(0.5+x)Na(0.5-x)TiO(3)-0.16KNbO(3) (-0.02 <=& nbsp;x <=& nbsp;0.08) relaxor ferroelectric ceramics with A-site defects and discuss the influence of VO on W-rec. The composition with x = 0.02 has a high W-rec (3.35 J/cm(3)) as well as a high efficiency (eta = 91%) at 240 kV/cm, and exhibits excellent temperature, fre-quency, and fatigue stabilities. This optimized composition also provides a large discharge-energy-density (W-D = 1.0 J/cm(3)), a high power-density (P-D = 66 MW/cm(3)), a fast discharge-rate (122 ns) at 150 kV/cm, and favorable temperature-induced charge-discharge properties (CDPs). Electron paramagnetic resonance, X-ray photoelectron, and Raman spectroscopic results reveal that the outstanding comprehensive perfor-mance of the designed materials is attributed to the coupling effect of low contents of dimeric (Ti'(Ti -& nbsp;) V-O center dot )(x) & BULL; clusters and high contents of trimeric (Ti'(Ti)& nbsp;- V-O center dot center dot & nbsp;- Ti'(Ti))(x) clusters. This work provides key insights relevant for developing lead-free ceramics with excellent energy-storage properties (ESPs). (C)& nbsp;2022 Elsevier B.V. All rights reserved.