Enhanced energy storage performance and temperature stability achieved by a synergic effect in Nd3+/Ga3+ co-doped (Na0.5Bi0.5)TiO3 -based ceramics

(1-x)(0.75(Na0.5Bi0.5)TiO3-0.25SrTiO3)-xNdGaO3 ceramics (NBST-xNG, x = 0–0.06) were fabricated through a solid-state reaction method. High-valent Nd3+ ions enter the perovskite A-site to occupy Bi vacancies resulting from the volatilization of Bi, inhibiting the formation of oxygen vacancies and contributing to an enhanced breakdown electric field (Eb). Low-valent Ga3+ ions enter the B-site to substitute for Ti4+ ions, resulting in the formation of random electric fields (REFs) at the B-site due to co-occupying hetero-valence ions of Ga3+/Ti4+, which significantly reduces ferroelectric hysteresis. Therefore, a synergic effect of A- and B-sites co-doping was realized in NBST-xNG ceramics. Benefitting from this synergic effect, an enhanced recoverable energy storage density (Wrec) of 2.88 J/cm3 and an efficiency (η) of 83% are simultaneously obtained in NBST-0.04NG ceramics under a moderate electric field (E) of 200 kV/cm. Compared with most NBT-based ceramics, the values of (η vs Wrec/E2) for NBST-0.04NG ceramics show an obvious advantage, indicating excellent potential for application as an energy storage material. Moreover, Wrec and η of NBST-0.04NG ceramics exhibit excellent temperature stability from 30 °C to 200 °C due to the enhanced correlation strength of polar nanoregions (PNRs) and local structural stability. This work provides a potential strategy to improve the energy storage performance of NBT-based ceramics via the synergic effect of A- and B-site co-doping.