Fatigue endurance enhancement of Sn-doped Pb(Lu1/2Nb1/2)O3–PbTiO3 ceramics

Abstract

Several mechanisms and methods have been proposed to study the nature of electric fatigue in ferroelectric materials with perovskite structure, including defect agglomeration, field screening and the reorientation of defect dipoles. To ascertain the effect of defect, defect dipoles in particular on the fatigue behavior in perovskite ferroelectrics, 0.51Pb(Lu_1/2Nb_1/2)O₃–0.49PbTi_1−xSn_xO₃ ferroelectric ceramics were fabricated in this work. It is found that the fatigue endurance has been enhanced after Sn-doping. An abnormal strong self-rejuvenation of polarization was also detected for un-poled and un-aged samples resulting from the reorientation of defect dipoles. The defect dipoles were determined by the confirmed change of the valence of Sn ions and the appearance of oxygen vacancies. The reorientation was also confirmed by the internal bias of P–E hysteresis loops during the fatigue process. With more Sn doped into the matrix, the symmetry changed from a coexistence of rhombohedral and tetragonal phase to a rhombohedral phase. The remnant polarization decreased, while the coercive field first decreased then increased as x increased, which resulted from the composition variance and the effect of defect dipoles. It indicates that the defect dipoles play an important role in the electric fatigue behavior of Sn-doping PLN–PT ceramics.