Exploring different sintering atmospheres to reduce nonlinear response of modified KNN piezoceramics

摘要

Dense lead-free (K_(0.44)Na_(0.52)Li_(0.04)(Nb_(0.86)Ta_(0.10)Sb_(0.04))O_3 piezoelectric ceramics are prepared by the conventional mixed oxide method. The effect of different sintering conditions (synthetic air, O_2 and Ar) on some structural, dielectric and piezoelectric properties is studied. A long sintering time (16 h) promotes the formation of a secondary phase, whichis assigned to K_3LiNb_6O_(17), tetragonal tungsten-bronze. High values oflongitudinal piezoelectric constant are obtained when ceramics are sintered under Ar or O_2 for low dwell time (2 h). However, the nonlinear response turns out to be significantly dependent on the sintering atmosphere. Results are discussed taking into account the formation of complex defects capable of pinning domain wall when oxygen vacancies are created by sintering. Thus, sintering in an inert atmosphere appears to be a good way of reducing nonlinear response in KNN-based piezoceramics.