Improvement of electric fatigue properties in PLZT ferroelectric ceramics due to SrBi2Ta2O9 incorporation

The influences of SrBi2Ta2O9 (SBT) on dielectric and ferroelectric properties of Pb0.94La0.04(Zr0.70Ti0.30)O-3 ceramics were investigated systematically. X-ray diffraction (XRD) patterns of PLZT-SBT composite showed that there was no chemical reaction between PLZT and SBT. SEM pictures on fracture section reflected a main transgranular fracture mode. An abnormal and interesting increase of dielectric constant was observed after SBT incorporation. Hysteresis loops of PLZT-SBT composites turned to slimmer shape with the increase of SBT content. No apparent decrease of switchable polarization strength was found in PLZT-SBT composites after repeated polarization switching. HRTEM picture of SBT grain in PLZT-SBT composite revealed a transformation from order to disorder near the tip of grain boundary as well as low angle of grain boundary, which could release concentrated internal stress and served as improvement mechanism of electric fatigue endurance in PLZT-SBT composites. (C) 2002 Elsevier Science B.V. All rights reserved.