Improved Electric Breakdown Strength and Energy Storage Performances in La(Mg_2/3Nb_1/3)O₃ and MnO₂-Modified BiFeO₃–SrTiO₃ Ceramics

Dielectric capacitors have become an important component in current pulsed power devices and thus have attracted great research interest in recent years. Among all kinds of dielectric materials, the bismuth ferrite (BiFeO3)-based ceramic capacitors show possible applications in dielectric energy storage because of their large polarization. However, the relatively high conductivity badly limits the improvement of electric breakdown strength, thus leading to low energy density. Herein, the perovskite end-member La(Mg2/3Nb1/3)O3 and sintering aid MnO2 were simultaneously introduced into BiFeO3-SrTiO3 solid solutions to improve the relaxation features and electric breakdown strength. Accordingly, a high recoverable energy density of 6.3 J/cm3 and an acceptable efficiency of 74.3% were realized under 450 kV/cm. In addition, the good frequency/thermal stability and superior charge-discharge performances were also realized. This work provides feasible approaches to modify the capacitive energy storage of BiFeO3-based relaxor ferroelectric ceramics.