Enhanced energy‐storage performances and thermal stability in BNT–LST‐based ceramics by tuning domain configuration and bandgap

Abstract Low energy‐storage density and inferior thermal stability are a long‐term obstacle to the advancement of pulse power devices. Herein, these concerns are addressed by improving bandgap and fabricating polar nanoregions, and the superior high efficiency of ~ 86.7%, excellent thermal stability of ~ 2% (31–160 °C) and energy density of ~ 6.8 J·cm –3 are achieved in Bi 0.5 Na 0.5 TiO 3 –La 0.1 Sr 0.8 TiO 3‐ δ –NaNbO 3 ceramics. The high breakdown strength (460 kV·cm –1 ) is ascribed to the broadened bandgap and refined grain. Slim ferroelectric loops originate from the construction of polar nanoregions (PNRs) in a pseudocubic matrix, and transmission electron microscope and piezoelectric force microscope measurements reveal the occurrence of PNRs. The phase‐field stimulation and UV–Vis spectrophotometer measurement reveal that the increased grain boundary density and bandgap are beneficial for promoting breakdown strength. The strategy provides an efficient path to prepare Bi 0.5 Na 0.5 TiO 3 La 0.1 Sr 0.8 TiO 3‐ δ ‐based ceramics with superior efficiency, high energy density and outstanding thermal stability.