Composition fluctuations and their influence on the properties of lead zirconate titanate ceramics

This paper reports that ceramic bodies prepared by a mixed oxide route have spatial fluctuations in their chemical composition. The extent of fluctuation depends on the characteristics of the starting powders as well as on the processing schedule. Characteristics such as particle size, surface area and reactivity of the powders, purity, etc. have been found to influence the chemical homogeneity in the sintered product. Similarly, such process variables as the mode and extent of mixing of the powders, calcination temperature and time, compaction pressure, sintering atmosphere, time and temperature, all have been found have a significant effect on the chemical homogeneity. The fluctuations in chemical composition usually have an undesirable effect on the properties. Better chemical homogeneity has been reported in sampled in which powders made by processes such as sol-gel or coprecipitation have been used. The fluctuations in chemical composition are believed to be largely responsible for a finite width of the morphotropic phase boundary (MPB) in the lead zirconate titanate (PZT) ceramics, which are used for piezoelectric applications.