Enhanced breakdown strength and energy storage density of lead-free Bi0.5Na0.5TiO3-based ceramic by reducing the oxygen vacancy concentration

Abstract Lead-free 0.9(Na0.4Bi0.4Ba0.06Sr0.14Ti(1−x)TaxO3)-0.1NaNbO3 ceramics with x = 0 ~ 0.05 were synthesized via solid-state reaction method. Raman spectra and X-ray diffraction confirmed the perovskite structure of ceramics. The generation of oxygen vacancy was effectively inhibited after substitution of Ta for Ti. Leakage current density and average grain size decreased because of the reduction of oxygen vacancies, which subsequently contributed to the improvement of breakdown strength from 180 to 270 kV/cm. The ceramic with x = 0.01 exhibited an excellent recoverable energy storage density of 3.12 J/cm3 and an efficiency of 87.86% at 270 kV/cm. The power density of 79.98 MW/cm3 with a short time around 350 ns for releasing 90% of the discharge energy density was obtained. The superior cycling reliability with less than 7% degradation over 105 cycles and the excellent thermal stability with a variation of discharged energy density less than 5% from 25 to 150 °C guarantee the promising prospects of application.