High energy storage density obtained by Bi(Ni0.5Hf0.5)O3-modified NBT-based ceramic at a low electric field

Na0.5Bi0.5TiO3 (NBT) ceramic is a potential dielectric material for the manufacture of high-performance dielectric ceramic capacitors due to its high polarization and environmentally friendly characteristics. In this work, (1–x)(0.70Na0.5Bi0.5TiO3–0.30SrTiO3)–xBi(Ni0.5Hf0.5)O3 (NBST–xBNH) ceramics have been prepared based on the strategy of refining grain size and inducing polar nano-regions (PNRs). As a result, the NBST–0.15BNH ceramic achieved large energy density and efficiency (Wrec = 4.11 J/cm3, η = 82.1%) at a low electric field of 240 kV/cm. This performance is outstanding compared to existing reports at similar breakdown electric fields. The introduction of Sr2+ enabled the NBST to have a high relaxation property, and the introduction of BNH induced PNRs, which ensured the high energy storage efficiency of the ceramics. BNH doping refined grain size, which contributed to the large breakdown electric field strength of the ceramics. In addition, stability tests showed that the NBST–0.15BNH ceramic had excellent thermal and frequency stability. The ceramic also demonstrated a fast discharge rate (t0.9 = 148 ns) in the charge-discharge test.