Bismuth ferrite-based lead free ceramics and multilayers with high recoverable energy density

Lead-free ceramics with high recoverable energy density (Wrec) and energy storage efficiency (η) are attractive for advanced pulsed power capacitors to enable greater miniaturization and integration. In this work, dense bismuth ferrite (BF)-based, lead-free 0.75(Bi1-xNdx)FeO3-0.25BaTiO3 (BNxF-BT) ceramics and multilayers were fabricated. A transition from a mixed pseudocubic and R3c to a purely pseudocubic structure was observed as x increased with optimum properties obtained for mixed compositions. Highest energy densities, W ~ 4.1 J/cm3 and Wrec ~ 1.82 J/cm3 were achieved for BN15F-BT, due to the enhanced breakdown field strength (BDS ~ 180 kV/cm) and large maximum polarization (Pmax ~ 40 μC/cm2). Multilayers of this composition possessed both high Wrec of 6.74 J/cm3 and η of 77% and were stable up to 125 °C. Nd doped BF-based ceramics with enhanced BDS and large Wrec are therefore considered promising candidates for lead-free energy storage applications.