EFFECTS OF QUENCHED IMPURITIES AND RELATIVE ANTIFERROELECTRIC FERROELECTRIC PHASE-STABILITY ON THE INCOMMENSURATELY MODULATED POLAR STRUCTURES OF LA-MODIFIED LEAD-ZIRCONATE-TITANATE/

Structure-property relationship studies have been performed in the La- modified lead zirconate titanate (PLZT) solution as a function of quen ched La impurity content and Zd/Ti ratio. For Zr/Ti ratios of 90/10 an d 85/15. an incommensurate antiferroelectric state was found to be sta bilized with increasing La content. Temperature-dependent investigatio ns demonstrated that the incommensurate structure becomes pinned into long-time metastable states, rather than transforming to a commensurat e phase. Also, the modulation wavelength (lambda) was found to increas e significantly with the decreasing Zr/Ti ratio and decreasing La cont ent. The results of this study clearly demonstrate that the incommensu rately modulated polar structures of PLZT are dependent on the relativ e antiferroeletric/ferroelectric phase stability and the concentration of quenched La impurities. (C) 1997 American Institute of Physics.