Improvement of dielectric and energy storage properties in Sr_0.85Bi_0.1ZrO₃ modified (Bi_0.5Na_0.5)_0.7Sr_0.3TiO₃ lead-free ceramics

In recent years, with the rapid development of electronic components industry, higher requirements are put forward for energy storage density and efficiency of pulse power capacitors. In this work, the improved energy storage density and efficiency of (Bi_0.5Na_0.5)_0.7Sr_0.3TiO₃ (BNST)-based ceramics have been obtained by introducing the Sr_0.85Bi_0.1ZrO₃(SBZ). The addition of SBZ reduced phase transition temperature to about 50 ºC, accompanied by relaxation enhancement. A high recoverable energy density (W_rec = 3.53 J/cm³) and energy efficiency (η = 87.15%) were synchronously achieved in 0.875BNST-0.125SBZ ceramic under 270 kV/cm. Moreover, excellent temperature stability (20–120 ºC) and frequency stability (5–200 Hz) for energy storage have been achieved at 150 kV/cm. A power density (P_D) of 7.32 MW/cm³ and the transitory discharge time (t_0.9 = 0.86 μs) were achieved for 0.875BNST-0.125SBZ ceramics under 120 kV/cm. These characteristics indicate that 0.875BNST-0.125SBZ ceramic is expected to be applied in high-power equipment.