Microstructure, dielectric, and piezoelectric properties of BiFeO3–SrTiO3 lead-free ceramics

BiFeO 3 –SrTiO 3 (BF–ST) ceramics have been considered a novel class of lead-free dielectric materials exhibiting notable dielectric constants and remarkable thermal stability. In this work, we fabricated a series of (1 − x )BF– x ST (0.32 ≤ x ≤ 0.44) ceramics near the morphotropic phase boundary and comprehensively investigated their microstructure and electrical properties, which seeks to optimize the piezoelectric performance. As the ST content increases, a gradual reduction in the rhombohedral phase fraction is observed alongside a corresponding increase in the cubic phase fraction. Although x = 0.38, the maximum grain size of 5.66 μm is obtained, accompanied by a distinctive heterogeneous core–shell microstructure, which demonstrates a high remanent polarization of 51.2 μC/cm 2 and a maximum d 33 value of 72 pC/N. Furthermore, impedance spectroscopy analysis reveals the formation of a conductive core and a nonconductive shell within the sample. These findings highlight the potential of optimized BF–ST ceramics as promising alternatives to lead-based piezoelectric materials, offering exceptional ferroelectric and piezoelectric properties.