THE INFLUENCE OF MOBILE VS. RANDOMLY QUENCHED IMPURITIES ON FERROELECTRIC PHASE-TRANSFORMATIONS

A comparative study of the influence of both mobile and randomly quenc hed impurities and their associated defect complexes on ferroelectric phase transformations in lead zirconate titanate ceramics has been per formed by dielectric spectroscopy and transmission electron microscopy . These investigations have shown a strong dependence of the structure -property relations on the mobility of impurities and/or defect comple xes in the temperature range near and below the phase transformation. Impurities-defects which are mobile until temperatures below the trans formation are believed to preferentially locate near domain boundaries , resulting in polarization pinning. For these compositions, no eviden ce of relaxer ferroelectric behavior was observed. However, for the co mpositions whose impurities-defects were essentially immobile from tem peratures above the ferroelectric phase transformation, relaxer behavi or and polar nanodomains were found. Studies of the influence of elect rical and thermal histories on properties provided additional insights into the influence of impurity-defect mobility.