Energy storage performance and stability of Sr(Ti0.85Zr0.15)O3-modified BNBST relaxor ferroelectric ceramics under low electric fields

To promote the miniaturization and integration of next-generation pulsed electronic devices, it is of significant importance to develop lead-free dielectric ceramic capacitors that can achieve excellent energy storage performance and high reliability under low electric fields ( E ). In this work, ceramics of (1- x )(Bi _0.5 Na _0.5 ) _0.65 (Ba _0.3 Sr _0.7 ) _0.35 TiO ₃ - x Sr(Ti _0.85 Zr _0.15 )O ₃ ( x  = 0, 0.1, 0.2, 0.3, 0.4), denoted as (1- x )BNBST- x STZ, were prepared via the conventional solid-state method. The microstructure, dielectric and energy storage performance (e.g., stability and charge-discharge behavior) of the synthesized ceramics were systematically investigated. The introduction of STZ reduced oxygen vacancies, refined grain size, enhanced dielectric relaxor behavior, and delayed polarization saturation. As a result, the 0.8BNBST-0.2STZ ceramic achieved a high recoverable energy storage density ( W _rec = 3.01 J/cm³) and efficiency ( η  = 82.9%) under a low electric field of 210 kV/cm. Moreover, it exhibited excellent energy storage stability across a broad temperature range (20∼160 °C), frequency range (1∼100 Hz), and cycling endurance (1∼10⁵ cycles). Most importantly, it demonstrated high power density ( P _D = 51.21 MW/cm³) and ultrafast charge-discharge rates ( t _0.9 = 50 ns) in pulsed performance. Overall, the 0.8BNBST-0.2STZ ceramic is a potential candidate for dielectric capacitors used under low electric fields