The influence of pH dependent ion leaching on the processing of lead-zirconate-titanate ceramics

The chemical stability of a powder with the nominal composition Pb(Zr0.53Ti0.47)O3 (PZT) in water at pH 3, 7, and 10 for 14 days was studied to evaluate the effect of the pH on the subsequent sintering and properties of the ceramic. The concentrations of the Pb, Zr and Ti ions were 5.4, 0.09 and 0.02 mol.%, respectively, measured in the supernatants at pH 3 by inductively coupled-plasma mass spectroscopy. The PZT powder dissolved incongruently in acidic pHs. After sintering the ceramic was porous and contained a perovskite phase as well as traces of ZrO2. At pH 7 and 10 the amounts of leached ions were 10,000-times lower than that at pH 3. After sintering the single-phase ceramic was dense, with piezoelectric properties similar to those of PZT ceramics prepared from the non-aged powder. This study reveals that the neutral and alkaline regions are suitable for suspension preparation and subsequent processing.