COEXISTENCE OF RELAXOR AND NORMAL FERROELECTRIC PHASES IN MORPHOTROPIC PHASE-BOUNDARY COMPOSITIONS OF LANTHANUM-MODIFIED LEAD-ZIRCONATE-TITANATE

Hot-stage transmission electron microscopy studies of lanthanum-modifi ed lead zirconate titanate (Pb1-xLax-(Zr0.53Ti0.47)(1-x/4)O-3 (PLZT 10 0x/53/47) have been performed for compositions close to the morphotrop ic phase boundary (MPB). These studies have revealed the coexistence o f relaxer and normal ferroelectric phases, Lanthanum substitution disr upts long-range ferroelectric order, resulting in short-range polar or dering, Investigations also have been performed using dielectric spect roscopy, electrically induced polarization, and strain methods, Three phases have been found for 10/53/47: a low-temperature tetragonal phas e, a high-temperature cubic phase, and an intermediate-temperature pse udocubic phase that exhibits relaxer ferroelectric behavior, Induced s train studies of 10/53/47 show a gradual change from butterfly-shaped to slim-quadratic loops with increasing temperature, In addition, the remanent strain decreases with increasing temperature, and reversible strain shows a peak at 80 degrees C that corresponds to the appearance of intermediate phase.