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

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. • CaTiO 3 additive can stabilize polar orthorhombic P 2 1 ma phase. • A high W rec of 6.4 J/cm 3 and a high η of 92% as well as an ultrafast t 0.9 of 57 ns was obtained. • Superior temperature stability is due to insensitive B-O vibration to temperature.