Enhancing piezoelectric coefficient with high Curie temperature in BiAlO₃-modified BiFeO₃–BaTiO₃ lead-free ceramics

In this work, the lead-free piezoelectric ceramic (1-x)[0.65Bi_1.05FeO₃–0.35BaTiO₃] – xBiAlO₃, (BFBT-xBA) (where x = 0, 0.010, 0.015, 0.020, 0.025, and 0.030), were synthesized by a solid-state reaction method, followed by air quenching process. The effects of BiAlO₃ (BA) on the crystal structure, morphology and electrical properties of 0.65Bi_1.05FeO₃-0.35BaTiO₃ (BF-BT) ceramics have been investigated. With the incorporation of BA-content (x = 0.010) the coexistence of rhombohedral and pseudocubic phases were observed. Scanning electron microscope (SEM) micrographs revealed that the average grain size of BF-35BT ceramics increased with the addition of BA. Well-saturated ferroelectric (P–E) hysteresis loops with definite remnant polarization (P_r) and coercive field (E_c) were observed. As a result, improvements in ferroelectric and piezoelectric properties with relative high Curie temperature (T_C) were obtained at the optimum composition (x = 0.010). In addition, the static piezoelectric coefficient (d₃₃) was enhanced from 97 pC/N for the base composition (x = 0) to 210 pC/N for the optimum (x = 0.010) composition.