EFFECT OF OXYGEN OCTAHEDRON ROTATIONS ON THE PHASE-STABILITY, TRANSFORMATIONAL CHARACTERISTICS, AND POLARIZATION BEHAVIOR IN THE LEAD-ZIRCONATE-TITANATE CRYSTALLINE SOLUTION SERIES

Lead zirconate titanate (PZT) ceramics with Zr/Ti ratios between 95/5 and 55/45 have been examined by transmission electron microscopy (TEM) , dielectric spectroscopy, Sawyer-Tower polarization techniques, and d ilatometric measurements, The relative phase stability in the high-Zr- content end of the PZT phase diagram is believed to be directly relate d to the coupling of the polarization to various oxygen octahedral rot ational systems, The transformation between the high- and low-temperat ure rhombohedral ferroelectric phases (FE(R(HT))-FE(R(LT))) in PZT 90/ 10 was found to be associated with a transition between a high-tempera ture M-type and a low-temperature R-type oxygen octahedral rotational system, However, with increasing Ti content (Zr/Ti < 80/20), a transit ion between a disordered R-type tilted state to a low-temperature orde red R-type tilted state was found near the FE(R(HT))-FE(R(LT)) boundar y, The transition between the disordered and ordered R-type tilted sta tes became increasingly gradual with increased Ti content, In the diso rdered R-type tilted state, local strains due to random octahedral rot ations are believed to disrupt the long-range polar order, resulting i n an inability to sustain a remnant polarization, A modified phase dia gram illustrating the various oxygen octahedral tilted states and pola rization behaviors is presented.