Ba₄(Sm_1-zBi_z)_9.333Ti₁₈O₅₄dielectric ceramics with high-permittivity, low loss under low frequency and ultra-fast discharge capability

Ba_6-3xSm_8+2xTi₁₈O₅₄tungsten bronze ceramics are widely used as microwave dielectric materials; however, there is an increasing demand for low-frequency dielectric performance—such as high dielectric constant and ultra-low loss—in applications like capacitive voltage dividers. In this study, Bi-doped tungsten bronze ceramics Ba₄(Sm_1-zBi_z)₉.₃₃₃Ti₁₈O₅₄(z = 0.3–0.45) exhibited remarkable dielectric performance, achieving a permittivity up to 119 and a loss tangent below 0.1 % at 1 kHz, along with excellent stability against temperature and electric field variations. Spectroscopic and microstructural analyses indicated that Bi³⁺substitution enhances lattice polarizability and induces local distortion, leading to increased dielectric constant while maintaining low loss and minimal nonlinearity. Impedance analysis demonstrated a single dominant conduction mechanism, with reduced activation energy at higher Bi content ascribed to microstructural evolution. Notably, Ba₄(Sm₀.₅₅Bi₀.₄₅)₉.₃₃₃Ti₁₈O₅₄ceramics showed ultra-fast discharge capability, evidenced by a rapid current peak within 14 ns, which is attributed to dominant ionic displacement polarization. These findings highlight the potential of Bi-doped Ba₄Sm₉.₃₃₃Ti₁₈O₅₄ceramics as promising candidates for reliable energy storage and high-voltage electronic applications at low frequencies.