Aliovalent Sm-doping enables BNT-based realxor ferroelectric ceramics with > 90% energy efficiency

Dielectric capacitors, as physical powers, are critical components of advanced electronics and pulse power systems. However, achieving high energy efficiency without sacrificing recoverable energy density remains a challenge for most dielectric materials. In this work, the aliovalent Sm³⁺ doped Ba_0.12Na_0.3Bi_0.3Sr_0.28TiO₃ (BNBST) relaxor ferroelectric at the A site was used to design a defect-induced phase/domain structure to improve polarization switching. A high energy efficiency of 91%, together with a recoverable energy density of 2.1 J/cm³, was achieved in Sm_0.07–BNBST ceramics at a low electric field of 114 kV/cm, exceeding those of other dielectric materials under the same electric field. In addition, Sm_0.07–BNBST ceramics exhibit good energy storage stability and endurance and fast charging‒discharging speeds, demonstrating their great potential in electrostatic capacitor applications. This work provides an approach to achieve high-performance dielectrics through aliovalent rare earth doping and builds a close relationship between the defect-engineered phase/domain structure and polarization switching for energy storage.