Enhanced Energy Storage and Mechanical Properties of BT-Based Relaxor Ferroelectric Ceramics via Composition Optimization Strategy

Barium titanate (BT)-based lead-free ceramics are extensively utilized in capacitors, owing to their superior energy storage capabilities. However, pure BT ceramics are limited by high remnant polarization (P_r) and low breakdown strength (E_b), which hinder their energy storage performance. In this work, an optimization strategy is implemented by introducing Bi(Mg_2/3Nb_1/3)O₃ (BMN) and NaTaO₃ (NT) components into the BT ceramics to obtain a relaxor ferroelectric ceramic with markedly enhanced energy storage properties and excellent mechanical characteristics. The intrinsic wide band gap of NT, coupled with the incorporation of BMN and NT fostering significant grain refinement, contributes to a notable enhancement in the E_b of the ceramics. The codoping of Bi³⁺, Mg²⁺, and Nb⁵⁺ disrupts the long-range ferroelectric order via domain engineering. The results show that the BT-BMN-NT ceramics exhibit a high recoverable energy density (W_rec) of 6.22 J/cm³ and an energy efficiency (η) of 80.21% under an electric field of 650 kV/cm, along with excellent thermal stability and excellent charge-discharge performance. Collectively, these findings highlight the significant promise of BT-BMN-NT ceramics for deployment in advanced pulsed power capacitor applications.