Advanced Physical Research

This study presents the successful synthesis of 0.970[(Pb_0.94Sr_0.05La_0.01)(Zr_0.51Ti_0.49)O₃]–0.024[Bi(Mn_1/2Ti_1/2)O₃]–0.006[Pb(Mn_1/3Sb_2/3)O₃] ceramics doped with x wt.% Li₂CO₃ (x = 0.0–1,0) using the conventional solid-state method. The incorporation of Li₂CO₃ effectively promotes densification through liquid-phase-assisted sintering, enabling a reduced sintering temperature of 1050 °C while simultaneously tailoring the defect chemistry and domain structure of the ceramics. Herein, the formation of a single-phase perovskite crystal structure, uniform elemental distribution, and the presence of morphological phase boundaries (MPBs) in the range of 0.4–0.6 wt.% Li₂CO₃ is confirmed through X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses. The corresponding hard piezoelectric ceramic at the optimal concentration (x = 0.6 wt.%) exhibits good dielectric properties, with a dielectric constant (ε) of 1196, a piezoelectric coefficient (d₃₃) of 430 pC/N, an electromechanical coupling coefficient (k_p) of 0.60, a mechanical quality factor (Q_m) of 1220, and a low dielectric loss (tanδ) of 0.005. The enhanced performance is attributed to the synergistic effects of improved densification, defect dipole formation, and MPB-induced phase instability. These findings demonstrate that Li₂CO₃ not only acts as a sintering aid but also plays a critical role in defect-mediated domain engineering, providing an effective strategy for optimizing high-performance hard piezoelectric ceramics for high-power ultrasonic and actuator applications.