| Two types of oxygen octahedral rotational systems (R- and M-type) were found in the rhombohedral phase field of lead zirconate titanate (PZT). A hierarchy of domain structure was observed in the high temperature rhombohedral ferroelectric (FE) state, where local octahedral tilt domains on the scale of ;Incorporation of La into PZT (PLZT) was found to disrupt long-range FE order. Near the antiferroelectric (AFE-FE) phase boundary within the high-Zr phase region of PZT, an incommensurate antiferroelectric (AFE;Finally, it was shown that an increase in the ease of polarization switching is essential for maximum electrically-induced strains in PLZT ceramics. For PLZT compositions close to the morphotropic phase boundary (MPB), this was realized by adjusting the base composition to be close to the boundary between tetragonal and rhombohedral states, where the polarization has maximum equivalent orientations by which to switch. For PLZT compositions locating in either the rhombohedral or tetragonal states, the ease of polarization switching was facilitated by La-doping until the point where the normal micron-sized ferroelectric domains began to break up into tweed-like subdomain structures. Polarization switching may then occur through the subdomain state, rather than by the creation and subsequent motion of normal micron-sized domain boundaries. |
