Raman spectroscopy of ferroelectric thin films

During a ferroelectric phase transition or domain rearrangement, ions or molecules in a ferroelectric material move in highly cooperative manner from their initial lattice positions into the final positions they occupy and the collective response results into a "soft" lattice vibrational mode. Moreover, the structural changes are always accompanied by at least a few other changes in the normal mode behavior of the material. In the present work, Raman spectroscopy is conveniently employed to study such vibrational modes and other related phenomena in ferroelectric materials at the sub-microscale levels. We have investigated ferroelectric thin films of various lead and barium based perovskites prepared by sol-gel technique. The effect of processing conditions, A- and B- site substitutions , and size dependance on their Raman spectra were analyzed in terms of the structure-property correlations.