Enhanced Piezoelectric Properties of BF-BST High Curie Temperature Lead-Free Ceramics via Fine Tuning the Composition

As the operational demands on piezoelectric devices grow increasingly stringent, there is an urgent need for materials capable of delivering stable performance at elevated temperatures. BiFeO3 (BF), a lead-free piezoelectric oxide with high-temperature resilience, is characterized by its notably high Curie temperature (Tc ∼ 835 °C), rendering it a promising candidate for high-temperature applications. However, its piezoelectric coefficients remain inadequate to satisfy practical requirements. The 0.7BiFeO3-0.3Ba(1-x) SrxTiO3 system (abbreviated as BF-BSxT) was designed to elucidate the roles of chemical disorder and local structural heterogeneities in the enhancement of functional properties through fine-tuning of the Sr content. The phase structure of the samples was carefully examined by X-ray diffraction. Rietveld refinement of the XRD data revealed that all BF-BSxT ceramics consist of coexisting R and PC phases. Optimized compositional disorder and local heterogeneities led to a moderate enhancement in the piezoelectric coefficient d33 value of 160 pC/N, a high Tc of 495 °C, and a remanent polarization Pr ≈ 22.1 μC/cm2 -were achieved in the BF-BSxT system at x = 0.06. These results indicate that BF-BSxT ceramics hold good potential for use in high-temperature piezoelectric devices.