Ferroelectric/semiconductor (BiFeO₃–BaTiO₃/AlN) lead-free ceramic composites featuring enhanced real-time d₃₃ temperature stability

Although the BiFeO₃–BaTiO₃ (BF–BT)-based lead-free ceramics possess the ultrahigh Curie temperature T_c and relatively large piezoelectric constant d₃₃, there is still a huge fluctuation of the real-time d₃₃ in the temperature range from room temperature to the depolarization temperature T_d, which hinder their practical applications. Herein, the water-quenched (WQ) ferroelectric/semiconductor (BF–BT: AlN) 0-3-type composite ceramics are fabricated to significantly augment the real-time d₃₃ temperature stability. The 0.7BF–0.3BT/0.45%AlN-WQ composite ceramic not only possesses the ultrahigh T_d of 420 °C and relatively large d₃₃ of 152pC/N but also features the superior real-time d₃₃ temperature stability in the temperature range from 30 to 420 °C (Low fluctuation factor F_f = 32%). The superior real-time d₃₃ temperature stability stems from the development of built-in field associated with the water-quenching, the increased tetragonal P4mm phase percentage and the charge compensation effect caused by the semiconducting nature of AlN. Besides, both coexistence of rhombohedral R3c and tetragonal P4mm and the increased grain size are responsible for the relatively large d₃₃. Therefore, this work proffers a general methodology for improving the real-time d₃₃ temperature stability in lead-free BF-BT-based piezoceramics.