Simultaneously enhanced insulation and piezoelectricity in Zr-doped BiFeO₃-BaTiO₃lead-free ceramics

Bismuth ferrite-barium titanate (BF-BT) piezoelectric ceramics typically suffer from high leakage current and dielectric loss, which impede full domain polarization and weaken their piezoelectric response. To address these limitations, BF-BT ceramics were doped with varying amounts of ZrO₂and systematically assessed its effects on phase composition, microstructure, and electromechanical properties. Rietveld refinement of X-ray diffraction (XRD) data shows that the undoped ceramic primarily consist of rhombohedral ((Formula presented) 3(Formula presented) ) and cubic (Pm(Formula presented) m) phases, with the (Formula presented) 3(Formula presented) phase accounting for 35.83 %, increasing Zr content steadily raises the (Formula presented) 3(Formula presented) fraction. Scanning electron microscopy (SEM) microstructural analysis reveals that average grain size grows with Zr doping, reaches a peak at 0.3 wt% Zr, then decreases at higher levels. Importantly, Zr doping boosts the resistivity at 400 °C from 1.3 × 10²to 7.4 × 10⁴ Ω cm and markedly enhances electrical homogeneity. At 0.3 wt% Zr, the ceramics achieve a peak piezoelectric coefficient (d₃₃∼ 204 pC/N) while retaining a relatively high Curie temperature (T_c = 443 °C). These findings demonstrate that high-valence Zr⁴⁺doping is an effective strategy to suppress leakage current and improve piezoelectric performance in BF-BT piezoelectric ceramics.