Effect of bismuth on the dielectric and piezoelectric properties of Pb_(1−x)Bi_2x/3(Nb_0.92Sn_0.0375Ti_0.0625)₂O₆ high-temperature piezoelectric ceramics

In this study, Pb_(1−x)Bi_2x/3(Nb_0.92Sn_0.0375Ti_0.0625)₂O₆ (PBxNST, x = 0–0.28) ceramics were prepared via the solid-state reaction method. All specimens were indexed as the orthogonal ferroelectric phases, based on the XRD analysis. XPS and EPR results indicated that the introduction of Bi³⁺ generated the oxygen vacancies, which could promote the densification and improve the piezoelectric performance of the PbNb₂O₆-based ceramics. In addition, a certain amount of Bi³⁺ could lead to the ferroelectric phase transition from a normal behavior to a diffused phase transition (DPT). The optimal piezoelectric properties were obtained at x = 0.24, whose d₃₃ = 98 pC/N and k_p=0.33, while the effective operating temperature remained well up to 350 °C. All experimental results indicated that the introduction of Bismuth was conducive to the improvement of piezoelectric performance.