Structural study of the formation of lead zirconate titanate via sol-gel process

Abstract

The structures of the precursors Zr(OPrn)4 and Ti(OPrn)4 in solution were investigated by means of NMR and IR spectroscopy and, in the case of Zr(OPrn)4, by means of EXAFS spectroscopy. The results were confirmed by gel permeation chromatography, which reveals dimers on average. Following chemical modification of the precursors with acetic acid, their degree of association was unaltered. Hydrolysis and condensation reactions were controlled by esterification of propanol with acetic acid and accompanied by the growth of oligomers, presumably by the Ostwald ripening mechanism. The reaction of the chemically modified precursors with Pb(OAc)2 results, after calcining, in the formation of lead zirconate titanate (PZT). Addition of water to the sol immediately or after three weeks, led to different products. Large angle X-ray diffraction showed that ageing of the sol favours the formation of lead zirconate titanate and results in higher crystallinity.