Microstructural and electrical characterization of La-doped PZT ceramics prepared by a precursor route

The effect of a powder processing route on the microstructure and electrical properties of 2 mol% La-doped PZT powders with tetragonal, rhombohedral and morphotropic compositions was investigated. Powders were prepared by using mixed-oxide and precursor methods, and different sintering regimes were used to control the grain size of the ceramics. It was shown that, by using the precursor method, ceramics with a submicrometer grain size and a narrow grain size distribution could be obtained. In addition, the precursor method results in ceramics with higher chemical homogeneity with respect to the Zr/Ti-distribution within the grains compared to the mixed-oxide route. In the case of the morphotropic composition, the chemical homogeneity affects the magnitude of the coercive field. The coercive field also increases with decreasing grain size, due to larger internal elastic stresses related to grain boundaries.