Enhancement of energy storage performance in BNT-based energy ceramics via polar nanoregions induced by doping (Al_0.5Ta_0.5)⁴⁺ composite particles

The ultrafast charge/discharge rate and environmentally friendly properties of dielectric ceramics have garnered significant attention; however, their limited energy storage density remains a key challenge for broader application. In this study, Bi_0.35Na_0.35Ba_0.09Sr_0.21Ti_(1-x)(Al_0.5Ta_0.5)_xO₃ (BNBST-100xAT) relaxor ferroelectric ceramics were synthesized using a conventional solid-state reaction method. The microstructure, energy storage properties, and cyclic fatigue performance were systematically evaluated as a function of the (Al_0.5Ta_0.5)⁴⁺ (AT) complex ion doping concentration. Results revealed that AT complex ion doping reduced the symmetry of the BNBST ceramics, disrupted long-range ferroelectric order, and enhanced relaxor behavior, leading to thinner hysteresis loops. Notably, the BNBST-4AT ceramic exhibited a recoverable energy density (W_rec) of 1.312 J/cm³ and an energy efficiency (η) of 81.37 % under an applied field of 140 kV/cm, along with excellent cycling stability. These findings demonstrate that BNBST-100xAT ceramics hold great potential as a lead-free material for advanced energy storage applications.