Improved energy storage performance of Bi(Mg0.5Ti0.5)O3 modified Ba0.55Sr0.45TiO3 lead-free ceramics for pulsed power capacitors

(1–x)Ba0.55Sr0.45TiO3–xBi(Mg0.5Ti0.5)O3 (x = 0, 0.08, 0.1, 0.12, 0.15, 0.2) ceramics were fabricated via a solid-state reaction route. The ultrahigh recoverable energy density (Wrec = 4.05 J cm−3), efficiency (η = 78%), maximum polarization (Pmax = 51.40 μC cm−2), and high dielectric breakdown strength (BDS = 230 kV cm−1) were achieved for the 0.9BST−0.1BMT ceramic. The fast discharge rate (t0.9∼0.14 μs), current density (CD∼637.02 A cm−2), high power density (PD∼38.70 MW cm−3), good temperature stability (20−180 °C), frequency stability (10−500 Hz), and fatigue endurance for cycling (105) of 0.9BST−0.1BMT ceramic make it suitable for the development of energy-storage devices. The relaxor behavior with a high Wrec (3.06 J cm−3) and η (93%) at BDS (220 kV cm−1) was also achieved for the 0.8BST−0.2BMT ceramic. This study systematically investigates the correlation among the structural, dielectric, impedance, and energy storage properties of BMT-doped BST ceramics.