Enhanced energy storage density and efficiency in La(Mg2/3Ta1/3)O3-doped BiFeO3 based ceramics

High-performance dielectric capacitor materials are required for the miniaturization of electronic devices. To this end, (1-x)(0.65BiFeO3-0.35BaTiO3)-xLa(Mg2/3Ta1/3)O3 (BFBT-xLMT, x = 0, 0.06,0.10, 0.14 and 0.18) ceramics were fabricated by a solid-state method. The experimental results indicate that LMT doping can well improve the energy storage density (Wrec) and efficiency (η) of BFBT ceramics. Especially, the optimal energy storage performance (ESP) (Wrec=4.92 J/cm3, η = 85%) was obtained in BFBT-0.14LMT ceramics under 390 kV/cm. The enhancement of ESP of BFBT-0.14LMT ceramics can be ascribed to the decreased hysteresis of polarization (P) - electric field (E) loops resulting from the aggravation of the composition and charge disorder in the system, and the improved breakdown strength (Eb) which is related to the reduced grain size, the widened band gap (Eg) and the decreased oxygen vacancy concentration. Additionally, the thermal stability of ESP of BFBT-0.14LMT ceramics is also enhanced compared with pure BFBT ceramics. Meanwhile, BFBT-0.14LMT ceramics exhibit a fast discharge rate (t0.9 = 152 ns) under 180 kV/cm. These results indicate that BFBT-0.14LMT ceramics could be a promising dielectric capacitor material. In general, our study reveals that LMT is good dopant to enhance the Eb and ESP of BF-based ceramics.