Stabilizing polar P21ma phase in Bi0.5Na0.5TiO3-Na0.91Bi0.09Nb0.94Mg0.06O3 relaxors by CaTiO3 additive to promote energy storage density, efficiency and discharge rate
Ziming Li, Hao Wang, Jingji Zhang, Shengyang Wu, Huiwei Du, Quan Zong, Jiangying Wang, Zhili Jia, Wangfeng Bai, Peng Zheng
Abstract
Eco-friendly Bi 0.5 Na 0.5 TiO 3 relaxor ferroelectric has attracted considerable attention for pulsed power capacitor applications due to its large saturation polarization. However, high remnant polarization and low breakdown strength ( E b ) restrict its application. Herein, linear dielectric CaTiO 3 (CT) is introduced into Bi 0.5 Na 0.5 TiO 3 -Na 0.91 Bi 0.09 Nb 0.94 Mg 0.06 O 3 (BNT-NBNM) ceramic to enhance its E b . Interestingly, CT additive can stabilize polar orthorhombic P 2 1 ma phase. As a result, a high recoverable energy density of 6.4 J/cm 3 and a high efficiency of 92% at 400 kV/cm as well as an ultrafast discharge rate of 57 ns are obtained in 0.63BNT-0.27NBNM-0.1CT ceramic. Furthermore, temperature dependent Raman spectra reveal that the superior temperature stability of energy storage properties over the temperature span of 30–150 °C is due to insensitive B-O vibration to temperature. The results demonstrate an effective strategy to construct superior and stable BNT-based energy storage materials for pulsed power capacitor applications.