Enhanced energy-storage properties in (Bi_0.5Na_0.5)TiO₃ ceramics by doping linear perovskite materials Ca_0.85Bi_0.1(Sn_0.5Ti_0.5)O₃

For energy storage applications in Bi_0.5Na_0.5TiO₃ (BNT)-based materials, the key challenges are the premature polarization saturation and low breakdown electric field (E_b), which confine the energy storage capacity of BNT and significantly restrict progress in advancing pulsed power capacitors. Hence, the cooperative optimization strategy of band structure and defect engineering was proposed, which successfully obtained a high recoverable energy density of 3.83 J/cm³ and an energy efficiency of 77.9 % in the Bi_0.5Na_0.5TiO₃-0.12Ca_0.85Bi_0.1(Sn_0.5Ti_0.5)O₃ (BNT-0.12CBST) ceramics. Doping the BNT matrix with CBST has been shown to not only reduce grain size but also enhance relaxor behavior, which collectively improves breakdown strength and delays polarization saturation. Furthermore, the x = 0.12 ceramic also exhibits a commendable discharge power density of 91.9 MW/cm³ and a transient discharge time of 40 ns. The higher resistivity and lower oxygen vacancy concentration are conductive to acquire superior breakdown electric field and energy storage performance. We determine the crystal structure, dielectric and ferroelectric properties of the studied ceramics in a wide range of temperatures and concentrations, and a phase diagram is constructed, which illustrates the complex phases present and their transformation behavior. Our work provides an effective strategy to optimize the energy-storage of dielectric ceramics, and shows great potential for practical applications in pulse power systems.