Lead-free high-temperature dielectrics with wide temperature stability range induced from BiFeO₃-BaTiO₃-based system

Lead-free BNSTNZ ((Bi,Na,Ba,Sr)(Ti,Nb,Zr)O₃)-modified BF35BT (0.65BiFeO₃-0.35BaTiO₃) dielectrics were investigated by conventional solid-state reaction method. Dielectric permittivity of BFBT-BNSTNZ ceramics was suppressed through addition of BNSTNZ content, while dielectric temperature stability range was expanded from 105 °C to 412 °C as BNSTNZ content increases from 0.025 to 0.1, due to the ferroelectric-relaxor phase transition. In particular, x = 0.10 exhibits the widest stability temperature range from 88 °C to 500 °C having small variation of (Δε_m/ε_{m 150 °C} ≤ 15%) with high dielectric permittivity (> 1000) and low dielectric loss (tanẟ ≤ 0.1) in temperature range from 50 °C to 250 °C. Moreover, high room temperature energy storage density (W_store) of 0.75 and 0.57 J/cm³ with energy storage efficiency (ƞ) of 57% and 78% for x = 0.03 and x = 0.10, respectively, was achieved. These results indicate that BFBT-BNSTNZ can be a promising system for high-temperature dielectric and energy storage applications.