Phase transformations in sol-gel prepared PbTiO3

The sol-gel preparation of PbTiO3 by two different methods is reported. Both methods began with titanium isopropoxide and lead acetate as organic precursors, but without or with hydrochloric acid as catalyst, respectively. Preparation procedures and working atmosphere also differred. The crystallization by thermal treatments and laser annealing was followed by XRD and Raman spectroscopy. When no hydrochloric acid was used, an intermediate pyrochlore phase, Pb2Ti2O6, was observed during the thermal treatment, and the final perovskite was obtained together with PbTi3O7 as the minor phase. Using the catalyst, the pure perovskite, PbTiO3, was obtained through an unidentified phase appearing at the beginning of the crystallization process. Frequency changes in the Raman spectra during the crystallization are attributed to pressure effects on the microcrystals.