Boosting dielectric temperature stability in BNBST-based energy storage ceramics by Nb2O5 modification

Exploring environment-friendly energy storage ceramics simultaneously featuring large recoverable energy storage density (W-rec), high-energy storage efficiency (n), and excellent temperature stability is highly desirable for the application of pulsed power systems. Herein, Nb2O5 was introduced to modify BNBST-based lead-free relaxor ferroelectric ceramics in an effort to enhance the dielectric temperature stability. (Bi0.5Na0.5)(0.65)(Ba0.3Sr0.7)(0.35)(Ti0.98Ce0.02)O-3 (BNBSTC) + x wt%Nb2O5 (0 <= x <= 4) ceramics were prepared by a solid-state reaction method. The phase structure, microstructure, dielectric, and energy storage properties of the ceramics have been systematically studied. It was found that the epsilon(r)-T curve was flattened, and the dielectric temperature stability was effectively improved due to the addition of Nb2O5. A noticeable W-rec (1.44 J/cm(3)) with high eta (84.1%) was obtained in BNBSTC + 2 wt%Nb2O5 ceramics at a low electric field of 90 kV/cm, which was mainly due to a refined P-E loop induced by Nb2O5. In addition to excellent frequency and anti-fatigue cycle stability, this ceramic provides a new solution for designing pulsed power capacitors with high energy density and high temperature stability under low voltage driving conditions.