Enhanced energy storage properties of KNbO modified (BiNa)TiO-BaTiO based lead-free relaxor ferroelectric ceramics

Dielectric capacitors are widely used in pulse devices because of their fast charge/discharge speed. However, the low energy storage density limits their application. In this work, (1 − x )(Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 Ti 0.99 (Y 0.5 Nb 0.5 ) 0.01 O 3 - x KNbO 3 (BNBTYN-100 x KN) lead-free relaxor ferroelectric ceramics were fabricated via a solid-state sintering technique. K + and Nb 5+ were completely diffused into the BNBTYN lattice and formed solid solutions. The incorporation of KNbO 3 reduced the symmetry of BNBTYN-100 x KN ceramics and destroyed the long-range ordered ferroelectric domains, leading to thinning of hysteresis loops. The relaxor degree increased with the KN content, resulting in the improvement of efficiency. Therefore, using BNBTYN-5KN ceramics an energy storage density of 1.246 J cm −3 and an efficiency of 78.7% at 104 kV cm −1 were obtained. In addition, the BNBTYN-5KN ceramics exhibited this energy storage density with outstanding temperature stability (in the range of 20-120 °C) and excellent fatigue resistance. These results reveal that BNBTYN-5KN ceramics is a promising material for energy storage. KNbO 3 doping is used to increase the relaxor degree, reduce the remanent polarization, and improve the energy storage performance.