Optimization of polarization and electric field of bismuth ferrite-based ceramics for capacitor applications

For the purpose of meeting the requirements of protecting environment and sustainable development, bismuth ferrite (BiFeO3, BF)-based lead-free ceramics have gained immense attention for pulsed power capacitor applications due to their large spontaneous polarization, low sintering temperature as well as non-toxic and harmless. However, the low energy storage properties (ESPs) and unstable performance of BF-based ceramics are not good for practical applications. In this work, novel bismuth ferrite-based lead-free ceramics of (1-x)(0.67BiFeO3-0.33BaTiO3)-xNa0.73Bi0.09NbO3 ((1-x)BFBT-xNBN) were designed and fabricated successfully by optimizing the polarization and electric field. With increasing the content of NBN, the remnant polarization decreased rapidly as well as the slim and pinched polarization-electric field loops together with high electric field can be observed. Notably, ultrahigh ESPs with the total energy storage density (Wtot) of 6.65 J cm−3 and the recoverable energy storage density (Wrec) of 5.57 J cm−3 can be achieved at high electric field of 410 kV cm−1. At the same time, the η is greater than 80% and the variation of Wrec is less than ±5% over a broad frequency range (1–100 Hz) and temperature range (30–150 °C). In addition, the η is stabilized around 89% and the variation of Wrec is less than ± 2% after 104 cycles. Therefore, the (1-x)BFBT-xNBN lead-free ceramics not only possess ultrahigh ESPs but also the ESPs exhibit outstanding stability, which is promising candidates for high performance pulsed power capacitor applications.