IR spectroscopy of PbTiO₃ thin films obtained from different annealing methods

Polycrystalline PbTiO₃ thin films have been prepared by rapid thermal annealing (RTA) and slow rate annealing (SRA) methods based on a modified sol-gel process. Infrared (IR) reflectance spectra have been carried out to study the PbTiO₃ thin films. All eight IR active phonon modes have been observed in the films. Differences in frequencies of the corresponding phonon modes in sample prepared from RTA and SRA methods are also obtained: the frequencies of most phonon modes in the former case are lower than that in the latter. Stress in the thin films is considered to be the dominant factor to affect the actions of phonon modes, especially the soft modes.