Enhanced energy-storage performance and dielectric temperature stability of (1-x)(0.65Bi_0.5Na_0.5TiO₃-0.35Bi_0.1Sr_0.85TiO₃)-xKNbO₃ ceramics

Leed-free ferroelectric (1-x)(0.65Bi_0.5Na_0.5TiO₃−0.35Bi_0.1Sr_0.85TiO₃)-xKNbO₃ (BNBST-xKN) ceramics were prepared by the conventional solid state sintering method. The dielectric, ferroelectric and energy-storage properties were systematically investigated. Temperature dependent permittivity curves showed the relaxation properties of BNBST ceramics enhanced with the increase of KNbO₃. BNBST-15KN exhibited a high permittivity of 3484 and low dielectric loss of 0.003 at 150 °C. Furthermore, Δε/ε_{150 °C} varied no more than 10% within the tmperature range of 30–297 °C, indicating an excellent dielectric temperature stability. The introduction of KNbO₃ gave rise to a large P_m while P-E loops kept slim in shape. Therefore, the optimum energy-storage performance was realized in BNBST-15KN with an energy-storage density W_rec of 1.32 J/cm³ and energy-storage efficiency η of 82.5% at 95 kV/cm, accompanied with superior temperature stability and fatigue performance. The results demonstrated that BNBST-xKN system was a promising lead-free candidate for energy-storage applications.