Domain structure-property relations in lead lanthanum zirconate titanate ceramics

The domain structure and dielectric properties as a function of lanthanum concentration and Zr/Ti ratio have been investigated in rhombohedral and tetragonal lead lanthanum zirconate titanate (PLZT) ceramics. Transmission electron microscopy revealed that, with increasing lanthanum concentration and Zr/Ti ratio, the long-range ordered domains (macrodomains) reduced in width, initially being fine scale (20 nm) striations, but eventually forming a ''mottled'' contrast (5 nm), characteristic of a relaxer. Relative permittivity measurements as a function of temperature revealed a correlation between broadening of the dielectric maxima and the onset of relaxer-type behavior with the appearance of the striations and mottled (relaxer) contrast, respectively.