Enhanced Energy‐Storage Properties and Good Temperature Stability in 0.92(Sr 0.7 Bi 0.2 )TiO 3 –0.08Bi(Mg 0.5 Hf 0.5 )O 3 Relaxor Ferroelectric Ceramic

Herein, the (1 −  x )(Sr 0.7 Bi 0.2 )TiO 3 – x Bi(Mg 0.5 Hf 0.5 )O 3 (SBT–100 x BMH, x  = 0.04–0.10) relaxor ferroelectric ceramics are fabricated via the high‐temperature solid‐state reaction method. Dielectric and ferroelectric measurements reveal a typical relaxor characteristic with diffused and frequency‐dependent dielectric peaks. The characteristic Weibull breakdown strength (BDS) of 470 kV cm −1 with satisfied reliability is obtained by DC breakdown measurement. A maximum recoverable energy density of 3.5 J cm −3 with the corresponding energy efficiency of 92% is simultaneously achieved at 380 kV cm −1 . The recoverable energy density exhibits minor degradations from ambient temperature to 200 °C with variation below 20%, whereas the energy efficiency is maintained above 90%. In addition, the SBT–8BMH ceramic possesses a fast charge–discharge speed with high discharge power density of 2.9 MW cm −3 . All the results make this lead‐free relaxor ferroelectric ceramic a promising potential candidate for high‐temperature energy‐storage capacitor applications.