Improvement of electric fatigue properties in Pb0.94La0.04(Zr0.70Ti0.30)O3 ferroelectric capacitors due to SrBi2Nb2O9 incorporation

The influences of SrBI2Nb2O9 (SBN) on dielectric and ferroelectric properties of (PLZT) ceramics were systematically investigated. X-ray diffraction patterns of PLZT/SBN composite showed that there was no chemical reaction between PUT and SBN in all cases. SEM pictures on the fracture section revealed a transformation from the transgranular to the intergranular mode with the increase of SBN content in composites. An abnormal and interesting increase of dielectric constant was observed after the incorporation of SBN in PUT bulks, which could not be explained via the mixing law of dielectrics. Although it turned to be a little shrinkage, hysteresis loops still kept well-formed shapes in PLZT/SBN composites. Compared with the serious degradation of switchable polarization in pure PUT sample after repeated polarization switching, no apparent decrease of switchable polarization strength was found in PLZT/SBN composites. The improvement mechanism of electric fatigue endurance in PUT ceramics after SBN incorporation was attributed to the facilitation of oxygen vacancies' mobility in the bismuth oxide layer in SBN. (C) 2001 Elsevier Science Ltd. All rights reserved.