Novel barium zirconate titanate-based lead-free ceramics with stably high energy storage performance over a broad temperature and frequency range

Lead-free relaxor ferroelectric ceramics with high recoverable energy storage density and energy storage efficiency over a broad temperature and frequency range are attractive for pulsed power capacitor applications. In this work, novel barium zirconate titanate-based lead-free relaxor ferroelectric ceramics are designed via introduction of Bi(Zn_0.5Sn_0.5)O₃ with heterovalent ion substitution at both A- and B-sites which could disrupt long-range order, induce polar nanoregions (PNRs), and reduce remnant polarization (P_r). The (1 − x)Ba(Zr_0.15Ti_0.85)O₃–xBi(Zn_0.5Sn_0.5)O₃ ((1 − x)BZT–xBZS) (x = 0.02, 0.06, 0.10, and 0.14) ceramics were prepared using a conventional solid-state reaction method. In addition, the structure, dielectric, ferroelectric, and energy storage properties of (1 − x)BZT–xBZS ceramics were systematically studied. All (1 − x)BZT–xBZS ceramics exhibited pure perovskite structure. With the increase of BZS content, the relaxor ferroelectric feature of (1 − x)BZT–xBZS ceramics tended to increase gradually, and slim linear P–E loops were obtained in x = 0.10–0.14. A high recoverable energy storage density W_rec of 2.16 J/cm³ and a high energy storage efficiency η of 90.3% were simultaneously achieved in x = 0.10 at 250 kV/cm, together with excellent temperature and frequency stability, which were superior to those of the reported barium zirconate titanate-based ceramics. Our work provides an effective strategy to optimize the energy storage performance of lead-free barium zirconate titanate-based ceramics toward practical applications.