Synthesis and Raman investigation of sol–gel-derived relaxor ferroelectric thin films

Pb(Fe2/3W1/3)O3 (PFW) thin films were deposited on platinized silicon substrate by a chemical solution deposition technique. Room-temperature X-ray diffraction (XRD) revealed a pure cubic crystal structure of the investigated material. The microstructure indicated good homogeneity and density of the thin films. A Raman spectroscopic study was carried out on PFW to study the polar nano-regions in the temperature range 85–300 K. The Raman spectra showed a change in the peak intensity and a shift towards the lower wavenumber side with temperature. The Raman spectra also revealed the transition from the relaxor to the paraelectric state of PFW. There was no evidence of a soft mode in the low-temperature region, in contrast to the normal ferroelectric behavior. The polar nano-regions tend to grow and join at low temperatures (∼85 K), which become smaller with increase in temperature. The presence of strong Raman spectra in the cubic phase of the material is due to the presence of distributed Fm3m(Z = 2) symmetry nano-ordered regions in the Pm3m(Z = 1) cubic phase. Copyright © 2007 John Wiley & Sons, Ltd.