Dielectric temperature stability and energy storage performance of B-site Sn4+-doped BNKBST ceramics

The 0.65Bi0.5Na0.25K0.25TiO3–0.35Bi0.2Sr0.7Ti1−xSnxO3 (BNKBST-xSn) ceramics were synthesized via a solid-phase reactive sintering technique. The effects of doping Sn4+ ions on the energy storage, dielectric, ferroelectric properties and microstructure characteristics for BNKBST ceramics were systematically studied. Remarkably, BNKBST-0.02Sn exhibits a superior dielectric temperature stability, manifested as the change rate for dielectric constant ∆ε/ε150°C is smaller than 15% during a very wide temperature range of 30–400 °C. In addition, BNKBST-0.02Sn ceramic achieves a high energy storage density Wrec = 0.81 J/cm3 (under the electric field 80 kV/cm) with an outstanding energy storage efficiency 89.5%, which make it reasonable to be applied in dielectric capacitors due to its excellent dielectric thermal stability and energy storage properties. The electrical conductivity behaviors of BNKBST-xSn were also analyzed with the assistance of impedance spectroscopy.