Excellent energy storage performance in Sm-doped Bi ₆ Ti ₃ FeAlO18 films via synergistic regulation of weakly coupled relaxor design and grain refinement

A method for enhancing the energy storage performance of bismuth layer-structured ferroelectric films through synergistic regulation of weakly coupled relaxor design and grain refinement is proposed. By modifying the composition, Sm[Formula: see text] ions replaced a portion of the Bi[Formula: see text] ions in the Bi 6 Ti 3 FeAlO[Formula: see text] film. The incorporation of Sm[Formula: see text] ions weakens the interaction between dipoles, further enhancing the relaxor behavior. Meanwhile, the doping of Sm[Formula: see text] leads to a reduction in grain size and a substantial increase in the number of grain boundaries. Owing to the superior insulating characteristics of grain boundaries, this modification can significantly enhance the breakdown strength of the material. Thus, the Bi[Formula: see text]Sm[Formula: see text]Ti 3 FeAlO[Formula: see text] film achieved an ultrahigh energy storage density of 86.2[Formula: see text]J/cm 3 and an energy storage efficiency of 74.4% under 2500[Formula: see text]kV/cm. Notably, this film exhibits excellent stability in terms of frequency, temperature and fatigue resistance. This work not only brings a new dielectric capacitor material candidate with broad prospects but also provides practical guidance for achieving excellent energy storage performance in bismuth layer-structured ferroelectrics.