Enhanced thermal stability, hardening of piezoelectric property, and mediated electromechanical response in (Bi 0.5 Na 0.5 )TiO 3 -based piezoceramics via composite approach

Abstract The use of Bi 0.5 Na 0.5 TiO 3 (BNT)-based materials is largely limited by their inherent thermal depolarization where the piezoelectric properties decreases remarkably. It is intractable to simultaneously realize high piezoelectric properties and reliable thermal stability over the required operating range in BNT-based systems. Here, we demonstrated an alternative design method to commonly applied chemical doping or substituting to tailor the functional properties, by judiciously forming 0–3 type composites of ferroelectric 0.83(Bi 0.5 Na 0.5 )TiO 3 -0.17(Bi 0.5 K 0.5 )TiO 3 with semiconductor ZnO inclusions (BNT-BKT:ZnO) to balance the aforementioned paradox. In BNT-BKT:0.1ZnO composite, we achieved distinguished comprehensive performance: high thermal stability of piezoelectric coefficient d 33 (maintaining 73% of the initial value at 120 °C); good fatigue characteristic (deterioration of 8% up to 10 5 cycles in the field-induced strain); and relatively large room temperature d 33 of 109 pC/N. The mechanism for the enhanced fatigue behavior was mainly ascribed to the lower defect density arising from the lower oxygen vacancy concentration in composites as compared to pure BNT-BKT. Most interestingly, hardening of piezoelectric properties usually produced by doping with lower valence elements, was realized in composites, as characterized by nearly two-fold increase in mechanical quality factor ( Q m ) in comparison to BNT-BKT. Our research not only offers a feasible paradigm for tailoring functional properties of BNT-based materials though composite engineering, but also inspires further works to benefit a wide range of functionalities in other ferroelectric materials.