Large strain under a low electric field in lead-free bismuth-based piezoelectrics

摘要

In this letter, the composition and electric field dependent strain behavior of (1-x)Bi_(0.5) (Na_(0.78)K_(0.22))_(0.5)TiO_(3-x)Bi(Mg_(0.5)Ti_(0.5))O_3 (BNKT-BMT) were investigated to develop lead-free piezoelectric materials with a large strain response at a low driving field for actuator applications. A large strain of 0.35% (S_(max)/E_(max) = 636 pm/V) at an applied field of 55 kV/cm was obtained with a composition of 4 mol. % BMT. In particular, the electric field required to deliver large strains was reduced to a level that revealed not only a large S_(max)/E_(max) of 542 pm/V at a driving field as low as 35kV/cm, but also remarkably suppressed the large hysteresis.