Enhanced Energy-Storage Properties and Good Temperature Stability in 0.92(Sr_0.7Bi_0.2)TiO₃–0.08Bi(Mg_0.5Hf_0.5)O₃ Relaxor Ferroelectric Ceramic

Herein, the (1 − x)(Sr_0.7Bi_0.2)TiO₃–xBi(Mg_0.5Hf_0.5)O₃ (SBT–100xBMH, 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.