Intrinsic and Extrinsic Size Effects in Fine‐Grained Morphotropic‐Phase‐Boundary Lead Zirconate Titanate Ceramics

The processing, electromechanical properties, and microstructure of lead zirconate titanate (PZT) ceramics over the grain‐size range of 0.1‐10 μm were studied. Using measurements over a large temperature range (15‐600 K), the relative role of extrinsic contribution (i.e., domain‐wall motion) was deduced to be influenced strongly by the grain size, particularly for donor‐doped PZT. Analytical transmission electron microscopy studies were conducted to investigate the trend in domain configurations with the reduction of grain size. The correlations between domain density, domain variants, domain configurations (before and after poling), spontaneous deformation, and the elastodielectric properties were qualitatively discussed, leading to new insights into the intrinsic and extrinsic effects and relevant size effects in ferroelectric polycrystalline materials.