Role of impurities in the sintering behavior and properties of lead zirconate titanate ceramics

Small amounts of impurities are always present in the raw materials for the mass production of lead zirconate titanate (PZT) ceramics. In this work, the effects of these impurities on sintering kinetics were investigated. The sintering behavior of PZT ceramics was monitored in situ by a thermo-optical measuring device. Two sources of raw materials were used, industrially used and highly pure (99.99%) powders. The highly pure powders were doped with different impurities, characteristic of industrially used materials. Sintering was enhanced by Si and-to a smaller extent-by Na, Ca, and Ba. Hf can have a large impact, if the stoichiometry is not adjusted properly according to its concentration. In addition, the crystal phase of the titania component affected its reactivity and lead loss during calcination, which indirectly changed the sintering behavior. The effects of the impurities on the dielectric and piezoelectric properties were also discussed.