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

Abstract

Lead-free ceramics with high recoverable energy density (W_rec) 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(Bi_1−xNd_x)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 the optimum properties obtained for mixed compositions. The highest energy densities, W ∼ 4.1 J cm⁻³ and W_rec ∼ 1.82 J cm⁻³, were achieved for BN15F-BT, due to the enhanced breakdown field strength (BDS ∼ 180 kV cm⁻¹) and large maximum polarization (P_max ∼ 40 μC cm⁻²). The multilayers of this composition possessed both a high W_rec of 6.74 J cm⁻³ and η of 77% and were stable up to 125 °C. Nd doped BF-based ceramics with enhanced BDS and large W_rec are therefore considered promising candidates for lead-free energy storage applications.