Enhanced piezoelectric properties of 0.7BiFeO3–0.3BaTiO3 ceramics with high Curie temperature via Sr(Zr0.5Ti0.5)O3 modification

BiFeO 3 –BaTiO 3 (BF–BT)-based piezoelectric ceramics have attracted significant attention due to their high Curie temperature ( T C ) and high residual polarization ( P r ), making them a highly promising lead-free piezoelectric ceramic system. However, their poor piezoelectric performance severely limits their practical applications. In this study, using the solid-state reaction method, we systematically investigated the addition of Sr(Zr 0.5 Ti 0.5 )O 3 (SZT) on the crystal structure, microstructure, dielectric, ferroelectric, and piezoelectric properties of (0.7− x )BiFeO 3 –0.3BaTiO 3− x Sr(Zr 0.5 Ti 0.5 )O 3 ( x = 0–0.008) ceramics. The results indicate that the introduction of SZT effectively suppresses the formation of Bi 25 FeO 40 , improves sintering density, and promotes grain growth (the average grain size reaches 4.82 μm at x = 0.006). More importantly, SZT doping caused Sr 2+ to further enhance the eccentric displacement of A-site ions; this localized structural distortion, in synergy with the transition of Bi 3+ from a disordered to an ordered arrangement under an external electric field, significantly improved the piezoelectric properties of the ceramics. At the same time, doping effectively suppressed changes in the valence state of Fe 3+ , thereby reducing leakage current. When x = 0.006, the material exhibited optimal overall electrical properties: The piezoelectric constant d 33 reached ~ 197 pC/N, and the electromechanical coupling coefficient k p was 0.336, representing increases of 48 and 39%, respectively, compared to the undoped sample ( d 33 = 133 pC/N, k p = 0.241). The residual polarization intensity P r reached as high as 29.9 μC/cm 2 , the Curie temperature reached 501 °C, and the material exhibited excellent temperature stability and large piezoelectric strain (0.249% @ 40 kV/cm, inverse piezoelectric coefficient d * 33 = 622.5 pm/V). This study not only verifies the significant performance enhancement of SZT doping on BF–BT-based piezoelectric ceramics but also provides an effective strategy and experimental basis for the development of lead-free piezoelectric materials that combine high-voltage electroactivity with high thermal stability.