ROLE OF DEFECT DISTRIBUTIONS AND MOBILITY ON FERROELECTRIC PHASE-TRANSFORMATIONS IN LEAD-ZIRCONATE-TITANATE

Studies of the influence of defect distributions and mobility on ferro electric phase transformations in lead zirconate titanate have been pe rformed by transmission electron microscopy, high resolution electron microscopy, polarization switching measurements, and dielectric spectr oscopy. Investigations focused on La3+ and K1+ modified lead zirconate titanates. Defects which could be randomly quenched-in from temperatu res significantly above that of the ferroelectric phase transformation resulted in relaxer ferroelectric behavior characterized by polar nan odomains. However, defects which remained mobile until temperatures si gnificantly below that of the phase transformation resulted in a norma l ferroelectric state which was characterized by domain pinning. Mobil e impurities/vacancies are revealed to order into chain fragments or c lusters which diffuse to domain boundaries resulting in a pinning of t he boundaries on cooling. (C) 1997 American Institute of Physics.