Multi-ion Synergistic Regulation and Energy Storage Properties of Strontium Barium Niobate-based Tungsten Bronze Ceramics

Driven by the demand for electronic system miniaturization, the development of dielectric energy storage materials characterized by high energy storage density, high efficiency, and excellent temperature stability has been necessitated to overcome the energy density limitations of dielectric ceramic capacitors. In this study, we focus on lead-free strontium barium niobate (SBN) ceramics of the unfilled Tungsten Bronze structure. We introduce Bi³⁺/Na⁺ ion pairs at the A site, utilizing the lone pair effect of Bi³⁺ to enhance the polarization response, while compensating for crystal lattice distortion with Na⁺; at the B site, we substitute Nb⁵⁺ with Ta⁵⁺ and, through a high-temperature solid-state reaction process, prepare the ceramic (Sr_0.42–x/2Ba_0.53–x/2Bi_x/2Na_x/2La_0.05)(Nb_1.95–xTa_xSn_0.05)O₆(BNTx) via high-temperature solid-state reaction process. The study found that moderate doping induced the formation of weakly coupled polar nanodomains, reducing the relaxation activation energy to 0.058 eV and significantly lowering the dipole reversal barrier. The grain refinement and increased grain boundary resistance resulting from doping effectively suppressed leakage current. Ultimately, the BNT0.1 ceramic achieved an energy storage density of 5.45 J·cm^–3 and an ultra-high energy storage efficiency of 95.61% at 500 kV·cm⁻¹, with current and power densities reaching 1508.5 A·cm⁻² and 211.2 MW·cm⁻³, respectively.