Temperature dependence of dipolar modes in ferroelectric BaTiO3by infrared studies

Abstract

Temperature dependence of $A_1$ modes in tetragonal phase and $F_{1u}$ modes in cubic phase of BaTi${\mathrm{O}}_3$ has been studied by ir (infrared) reflectivity measurements. The spectra have been analyzed using Kramers-Kronig analysis and the coupled-mode classical oscillator fit. The results are in excellent agreement with each other and are compatible with the earlier Raman measurements. Such a compatibility indeed favors the conclusion of Pinczuk et al. with regard to the interpretation of the broad peaks at 270 and 520 ${\mathrm{cm}}^{-1\mathrm{}}$ in the Raman spectrum to be of first order. A critical analysis of the earlier work in BaTi${\mathrm{O}}_3$ is presented.