Phase transition-induced high electromechanical activity in [(K_(0.5)Na_(0.5))_(1-x)Li_x](Nb_(0.8)Ta_(0.2))O_3 lead-free ceramic system

摘要

A high electromechanical activity is observed in the [(K_(0.5)Na_(0.5) )_(1-x)Li_x](Nb_(0.8)Ta_(0.2))O_3 (x = 0,0.02, and 0.03) lead-free ceramic system at and around the orthorhombic (O)-tetragonal (T) phase transition temperature (T_(O-T)). This activity is found to originate from an O-Tphase transition region at ambient temperature rather than a classical morphotropic phase boundary (MPB) region intrinsic in the Pb(Zr_(1-x)Ti_x)O_3 (PZT) lead-based ceramic system. Li modification enables a large decrease in T_(O-T) instead of constituting a classical MPB. In contrast to the nearly temperature-independent classical MPB behavior in the PZT system, the strong temperature-dependent phase transition behavior in the system may impose a challenge to temperature demanding applications.