Ferroelectric phase transformation characteristics of ceramic have been studied by combined thermo-Raman and dielectric measurements. The temperature dependence of Raman bands at 311 and 721 shows that tetragonal to cubic phase transformation occurs over a range of temperature. The increase in the bandwidths of these bands indicates that this transformation is an order-disorder transformation. The differential thermo-Raman intensity thermograms show a dip at a temperature corresponding to the maximum rate of phase transformation and this temperature can be defined as phase transformation temperature The ferroelectric transformation temperature corresponding to the peak in the obtained from the temperature dependence of dielectric constant is found to coincide with This indicates that maximum in dielectric constant occurs at the maximum rate of phase transformation. Both and exhibit thermal hysteresis. The Curie temperature obtained from the intersection of tangential of inverse dielectric constant to the temperature axis and is found to be less than and in agreement with O. G. Vendik and S. P. Zubko [J. Appl. Phys. 88, 5343 (2000)] calculations. Thermo-Raman spectroscopy coupled with dielectric constant measurement is shown to be an effective technique to investigate the phase transformation in ferroelectric materials.
Phase transformation studies of ceramic using thermo-Raman and dielectric constant measurements
Natesan Baskaran, Anil Ghule, Chetan Bhongale, Ramaswamy Murugan, Hua Chang; Phase transformation studies of ceramic using thermo-Raman and dielectric constant measurements. J. Appl. Phys. 15 June 2002; 91 (12): 10038–10043. https://doi.org/10.1063/1.1481771
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